NTP is a standard Internet protocol for distributing accurate time to network time clients. There are a large number of public NTP time servers available on the Internet. However, it may often be the case, for security purposes, that an organisation may require an internal stratum 1 NTP time server. This article discusses a number of time sources that can be used as a reference clock for a stratum 1 time server.

Probably the most widely used NTP reference clock resource is currently the Global Positioning System (GPS). The GPS system consists of a number of orbiting satellites providing accurate positioning and location information. However, each GPS satellite also has an integral highly accurate atomic clock that can be used as a timing reference. Utilising the GPS system for time synchronisation has a number of advantages. GPS can provide a highly accurate source of time using a relatively low-cost antenna and receiver. A typical GPS receiver can provide timing information to within a few nanoseconds of UTC. Additionally, the GPS signal can be received anywhere in the world, where the antenna can be provided with a good view of the sky. The disadvantage of using the GPS system is the very fact that the antenna requires a view of the sky. In many installations, locating an antenna on a rooftop can be impractical or expensive.

There are also a number of national time and frequency radio transmissions that can be used to synchronise a stratum 1 NTP server. The advantage of using a radio time reference is that generally a good signal can be obtained indoors close to the host computer. This can greatly reduce potential installation costs. However, radio time references are generally less accurate than GPS systems. Typically, national time and frequency transmissions are accurate to 1 - 20 milliseconds. The radio transmission is regional and has a finite range dependant on transmitter power. Additionally, local interference or environmental issues can cause problems with reception. Placing a radio antenna too close to electrically noisy equipment can result in signal loss. Also, locating an antenna inside a metal enclosure or underground in a basement can also be a problem.

A number of national time and frequency standards are available broadcasting to the local region.

The WWVB time and frequency signal is a 60kHz radio broadcast transmitted from Fort Collins, Colorado, USA. The WWVB signal continuously transmits time and frequency signals throughout the US and much of Northern America. The signal provides UTC time to an accuracy of 100 microseconds.

The DCF-77 time and frequency signal is transmitted from Frankfurt, Germany. DCF-77 broadcasts timing information continously at 77.5kHz. The transmission covers Germany and much of Central and North Western Europe. Time and frequency information is broadcast to an accuracy of

D. Evans is a highly experienced technical author to the timing reference and telecommunications industry. David has provided a technical authoring resource to many Windows NTP server manufacturers and computer timing solutions providers. Click here for more detailed information about Windows NTP Server solutions.

Nowadays, people do not buy MP3 players with the single purpose of listening to music. They want gadgets. They want many different things in just one device. That is the reason why they buy sunglasses with MP3 audio players, players with GPS or games, and many other strange, yet useful combinations.

Some of them also carry podcasting functions. They offer the possibility for radio-like programs, or even TV-like video feeds available for automatic download into the device and for playing selectively at the choice of the owner. The digital audio player with the lowest storage capacity can incorporate several hours of podcasting. Such new uses appeared as players extended and technology improved.

Gadgets like this serve to a wide range of purposes, depending on their functions. They are for home use, for personal use, or just for mere play. Studies have shown that American teenagers, for example, spend $350 a year on gadgets, which sums up about half of their discretionary money.

On the other hand, average adults spend about $1,200 on such devices. MP3 players are the most popular among all. The fist one appeared not more than 10 years ago, but its history is as large as the world's. In addition, this happens because technology evolved at a rapid pace, models have improved continuously, and we can bet they will continue improving.

When purchasing MP3 players, people take in consideration different functions of the gadgets. They suits variable needs, such as getting on the groove while working out, or just working, amusing yourself while commuting on public transit. As gadgets, MP3 players are available in an overwhelming number of shapes, styles, sizes, storage functions.

If initially there were a few models that sold like hot cakes, now variety of choice is not at all a problem. Size and weight are not shallow features to consider. If we take as an example people who go on trips or joggers, they will definitely look for a smaller, lighter player. Why should they not combine it with sunglasses if the present digital technology allows them to use the same object for various purposes? Smaller than the smallest and lighter than the lightest are the goals of all manufacturers and they have a word to say when it comes to competition.

Storage capacity and battery life are also features to take in consideration when opting for one piece from a variety of MP3 players. They are inversely proportional to size and weight. They go by the principle: as big as possible, as long as possible. File format is hardly a problem now, since most of the devices allow you to store all types of music files.

Since we are also gadgets, we should obviously talk about other functions of the device. In this case, your player is at the same time a video player, a GPS, a camera. What is also important is to screen the device as easy as possible. After all, this is the first thing you do with a player: look for music after selective criteria – artist, album, song.

Shopping for the right MP3 players is not as difficult as it might seem, but lately only one player seems to be enough no longer. People usually want different things from their players. This is why they choose gadgets.

The current digital technology allows you to test your gadgets. When you go out of the house to buy MP3 players you know exactly where to go or what to look for. Moreover, we give you the possibility for virtual shopping. It cannot go easier than this!

Retail: $300

Street Price: Much Less

Of all the Timex Bodylink / Ironman heart rate monitors the Timex Ironman 5F011 is the one that most suits athletes - fitness enthusiasts. Runners, Cyclists, Skiers, Rowers, Triathletes, Hikers, etc, will all benefit from the inclusion of 8x (eight)heart rate training zones and 4 x interlinked countdown timers (for intervals), with additional warm up and cool down timers. Optionally, if used with the new 3D GPS unit (included) , the Timex 5F011 can provide both vertical and horizontal performance data including altitude, speed, distance, and predicted finish time.

Heart rate was 100% accurate even while running next to others wearing other units. Polar, Suunto, other Timex, Freestyle, did not affect this monitor at all.

The GPS unit took a few minutes to lock in and dropped a couple of times

during the test run, but overall performed better than my $600 Suunto. I

expected that as all of them have that problem on the first run, and on the

second test run, in locked in quicker.

Timex has it all together in this great modular unit. They have added multi

heart rate zone training, interval sessions and 3D functionality. A

combination of heart rate zones, optional speed / pace zones, auto-lapping,

time based intervals plus Finish Time Predictor (when using GPS 3D unit)

make this unit truly universal for all outdoor sports. For fitness training,

the best new feature is the FINISH TIME predictor. You tell it you are

running (or cycling) a 10K (or miles) , it works out your finish time based

on current speed and distance travelled so far. This is continually updated

while you run to help you achieve your Personal Best. Something we all want

every run.

With the addition of the 5G751 Data Recorder 2 and view your workout over a

map using or other online mapping software to actually see

how hard your heart was pumping up that hill, etc.. Its an additional tool

thats worth purchasing if you are serious, retails at $75, can find online

for less.

The book took a while to digest as this unit is FULL of features and

customizable options. Three manuals come with it and I'd recommend tinkering with it before you go out and try to run a very important event. Sure, one of the manuals is how to put on the chest strap and the other is about the GPS sensor, but Its worth the time to go over the manuals, as there is a lot of nice features that aren't obvious in the beginning. Everything thats full of options come with manuals, so I don't consider that a negative, but to some it could be daunting. Sure, you can just put it on and run, but that

would be like taking a Ferrari out and keeping it in 1st gear.

*Pros*: Timex, Size, features. Price per feature when compared to other

manufacturers.

*Cons:* GPS lock in speed, three manuals. Please note GPS lock in was faster

the second and third times I used the monitor.

*Summary:* If you are a serious athlete, wanting a serious tool for training

and don't mind read the book once or twice - this is the tool for you.

*Overall*: 4.8 of 5 Stars.

More info on the Timex BodyLink Series including the 5G751 Data Recorder:

GreatWestS Bodylink Info page

GreatWestSports , - A Site specializing in High Performance Gear and Watches for When Time Matters.

Buy the Timex 5F011 here: GreatWestSports - Timex 5F011 Bodylink System

Golf GPS systems are a fairly new technology that has helped many golfers improve their game. These GPS systems, or global positioning systems are meant to help the golfer judge distance along with a variety of other features. As the technology has become more popular among golfers so has the variety of golf GPS systems available to them. Different golfers want and need different information as they seek to improve their game, so in choosing a golf GPS system, the golfer needs to know exactly what he or she is looking for, while also considering price and convenience in using each type of system.

One type of golf GPS system is a sports watch with GPS capabilities. These watches are very convenient since the golfer does not have to carry around an extra piece of equipment with him or her while on the golf course. These watches are defiantly bigger then a traditional watch and are not recommended for wearing daily, but while on the course they are very functional. They can judge distance and some can even recommend which club to use. These watches are able to gain information about a particular golf course when the owner downloads information from the internet about the course into the watch; this eliminates the need to manually put in all of the information.

Sonocaddie is another type of golf GPS. These handheld devices are able to tell the golfer the distance between him or her and anywhere else on the course. Just like with the watch, these devices allow the person to download golf course information from their computer into the GPS system, making the information very accurate.

Sureshot GPS systems are also very useful particularly for those that like to travel to different countries to play golf. These GPS are capable of working worldwide and measures distance in both meters and yards. They are very portable, making it easy for the golfer to carry it along with him or her as he or she plays golf.

For people who have certain types of cell phones, there is also technology available that allows the person to download golf GPS information directly to their cell phone.

Along with these different types of golf GPS systems, there are others being developed. One type of technology is GPS golf balls. The use of this technology will allow the golfer to locate his or her ball if it is missing and will be able to tell the golfer how far the ball actually traveled.

There are many other types of golf GPS systems available to choose from. The different choices available to golfers interested in this type of technology could easily become overwhelmed as he or she tries to decide which one is the best. The best golf GPS system is the one that gives the individual golfer the information he or she needs and is the most convenient based on individual circumstances and individual person. The GPS sports watch may be perfect for one person, but may actually interfere with another golfer if that person is not used to wearing a watch, especially since this watch is larger then a normal watch.

Some golfers may be very comfortable with technology and would benefit from a golf GPS system with many features and capabilities. Other golfers, who are not as comfortable with technology would probably not benefit from very complicated systems and would prefer a simple model. The technology of any GPS system will not benefit anyone who does not know how to use it and take advantage of the information that comes from it.

AllGolfS is a new online Golf Equipment Store.

To check out our selection of Golf GPS Devices, please click here: Golf GPS Systems

Network Time Protocol (NTP) is one of the oldest Internet protocols currently in use. NTP was developed to disseminate accurate time to clients around a computer network. Simple Network Time Protocol (SNTP) is a much less complex implementation of NTP. SNTP lacks many complex synchronisation algorithms used by NTP which makes it ideal for implementation on small computers.

This article describes the differences between NTP and SNTP. The article also describes when the SNTP protocol can be safely implemented in place of NTP. The article also descibes the differences between a NTP server and a SNTP server.

NTP protocol packets transferred between a NTP server and client are identical to SNTP packets. Each field in a NTP packet of information has a corresponding field in a SNTP packet. NTP protocol packets are entirely interchangeable with SNTP protocol packets. Infact a NTP server has no way of telling if a time request originated from a NTP or SNTP client.

The difference between the NTP and SNTP protocols is contained within the sophisticated routines used to implement the protocols. NTP has sophisticated routines designed to monitor multiple time references and decide which is the optimal reference. NTP constantly monitors multiple time references for jitter and offset and decides which is the best one to synchronise. NTP corrects time by slewing the system clock. The host's system clock is accelerated or decelerated to slowly bring it into line with an accurate external time reference. Large stepped time adjustments are avoided. NTP has complex synchronisation algorithms that calibrate the system clock to match the frequency of an accurate reference clock.

SNTP is a simplified sub-set of the algorithms used by the NTP protocol. SNTP steps the host computers system time rather than slowly slewing it towards the correct time. Adjusting the system time in steps can cause time critical applications problems. SNTP also lacks the functionality to monitor multiple NTP server reference clocks and decide on the optimal source of time. Instead it utilises a list of references and in the event of failure of a reference it moves on to the next.

The SNTP protocol is best suited to synchronizing computers at the extremities of a computer network. It is ideally suited to less powerful processors, such as micro-controllers and embedded systems, which do not require the accuracy of NTP. The complex algorithms of NTP may not be practically implemented on small computers. NTP is ideal for use in dedicated NTP server systems and synchronising large networks of computers. Here, accurate time may be of the utmost importance and the sophisticated routines employed by NTP will help maintain synchronization.

David Evans has been involved in the telecommunications and network timing industry for a number of years. David is a free-lance technical author with a long history of involvement in installing and configuring NTP server systems. He has also provided a technical authoring service to many ntp server and reference clock manufacturers. Click here to find out more about ntp server systems.

Network Time Protocol is utilised by NTP server systems to distribute accurate time around a computer network. NTP is an Internet protocol solely used for the dissemination of time. By utilising a GPS or radio external reference clock, you can build a highly precise stratum 1 NTP Server for your network.

This article describes how to build and configure your very own stratum one NTP Server. By adding a relatively cheap GPS or radio time standards receiver to your Linux box, you can have your own precise NTP server. Your NTP server can be used to synchronize all the machines on your network to the precise time.

NTP is available as source code for compilation and configuration on a Linux machine. The source code freely downloadable from the NTP.org website. Most Linux installations, such as SUSE and Fedora provide NTP pre-installed. Many other Linux disto's provide NTP as a RPM.

In order to build a stratum one NTP server, you need an accurate external timing reference. Many timing references are available, most utilise GPS or national time and frequency radio sources such as WWVB, DCF77 and MSF. The Global Positioning System (GPS) is a great timing reference, since it is available worldwide and the equipment required for receiving time and positioning information is very low-cost.

Many GPS systems provide a serial port that can be connected to a PC serial port. The receiver generally provides continuous time and positioning information in a standard format known as NMEA. An NTP server can utilise the timing information provided by a NMEA receiver as an accurate timing reference. Some GPS receivers also provide a highly precise pulse per second (PPS) output that can be used as a highly accurate timing reference. Any timing pulse generated by a GPS receiver may need to be converted into a usable RS232 signal level. A TTL level pulse output can be converted to RS232 levels by feeding it into a RS232 driver.

There are many radio receivers available that receive transmitted national time and frequency information. WWVB is a US radio time and frequency transmission, DCF77 is transmitted from Germany, MSF is available throughout the UK. The advantage of a radio signal as a reference clock for your NTP server is that you can usually pick up a good signal indoors, close to the NTP server. In contrast, GPS requires an antenna with a good view of the sky.

Once you have your NTP server external reference clock set-up and installed, you need to configure the clock in the NTP configuration file 'ntp.conf'. This usually involves finding and specifying the reference clock code for your timing reference. Once configured, your NTP server will act as an accurate source of time for your network time clients.

Many modern operating systems can use the Network Time Protocol to synchronize time. Linux and Unix machines can utilise the NTP distribution itself. Modern Windows operating systems such as XP and 2003 have pre-installed SNTP clients that can point to the IP address or DNS name of a NTP server for synchronisation. Many network devices such as routers and switches can also utilise your NTP server for synchronization.

Dave Evans is a technical author with a background in NTP Server solutions and telecommunications. Dave provides a technical authoring service to NTP reference clock and NTP server manufacturers. Dave has also provided a configuration, installation and repair service for computer timing systems. Click here to find out more about ntp server systems.

Anytime that you take to the air in a plane you need to make sure that safety is on your mind. Of course, if you are a pilot you are well aware of this. With the summer months closing in, more and more pilots will begin to take to the air in order to exercise their interests in aviation. If you are one of those pilots, make sure that you have all of the equipment that you need in order to ensure your safety. You may already have everything that you need, but as you know you will want to check this just to ensure that it will last you another summer of flying.

One thing that every pilot should consider buying is a Garmin aviation GPS. Although there are other brands that you can purchase, the fact of the matter is that the Garmin aviation GPS systems are among the best in the industry. The nice thing about buying from Garmin is that they have a large selection of models for you to choose from. This makes it easy for pilots of all skill levels to find something that suits their needs. And of course, a larger selection also means that you will have an easier time finding one that fits in well with your budget.

There are many reasons that a Garmin aviation GPS may be the right choice for you. In addition to the benefits listed above, all Garmin systems are known to be reliable for a long time. This means that after you buy a unit you should be able to use it for many more years to come. For most pilots this sure beats having to upgrade each summer. You might as well buy a Garmin aviation GPS, and forget about replacing it for the foreseeable future.

With a complete and accurate towers and obstacles database, pilots will have the freedom to fly anywhere without having to worry about a thing.

Additionally, Garmin aviation GPS units come with a display that can be easily read in even the sunniest of conditions. This is something that is quite important; especially for summertime flying. After all, if your GPS system is washed out by sunlight it is not going to do you very much good. Garmin makes sure that you never have to deal with this potential safety problem when flying during the bright, summer months.

Summertime safety is something that is always on the mind of pilots. If you are going to be taking to the friendly skies this summer, you should consider buying a Garmin aviation GPS. One of these units will go a long way in keeping you and your passengers safe for many years to come.

Chris is an avid flyer. He loves small planes and enjoys working on his planes. He recommends visiting S for all your aviation needs including telex headsets !

g

I continue to marvel at the latest technology: iPods, MP3s, DVDs, HDTV, GPS, Satellite Communications, etc., etc., etc. In the 1930s we were quite thrilled by a radio in a cabinet that might also be holding a clock. I can still see the one my folks bought. It sat on a table in the living room and was able to receive 10 or 15 stations on AM. Radio was pretty new, but it was organized in Networks with names still known today NBC and CBS for example. The cartoon character, Dick Tracy, had a two-way wrist radio and was way ahead of his time. Programming was simple. News in the morning until nine; soap operas during the day; kids programs like Orphan Annie, Jack Armstrong the All-American Boy, and others that came on about 5:00 PM. In the evening we had news and commentary, but after 7: 00 PM came the shows: Kraft Music Hall with Bing Crosby, Red Skelton, Jack Benny, Eddie Cantor, Fibber McGee and Molly, and others. They came on weekly and most were a half-hour long. The best ones were programs like Lights Out, The Shadow, and The Lone Ranger. We were pretty happy with these and many others, for with the sound-effects used we could readily imagine locations and action. We participated in what was happening much as one does when reading a book.

Radio technology did advance from the living room eventually. One day 1936 my Mother picked me up at school, and as I got into our 1935 black Ford, 4 door convertible, with leather seats, running boards, white walls and wire wheels, and a spare tire mounted in back continental style, I heard something I'd never heard before. My Mother smiled at me as I realized we now had an after market radio in the car. This was very exciting and forward looking stuff in those days. (Sadly no heater yet). Between that and the new phone we had installed in our apartment, I felt like we were on what was later called, "the cutting edge."

My Dad liked to buy the latest thing including an electric clothes washer with a wringer that was installed in the kitchen. Of course, Mom had to take the wash up one floor to the roof to dry the clothes outside. But the item I remember well was a portable radio he got for Mom. It looked like a piece of tan luggage. It was about 14 inches tall and 12 inches wide and 4 inches deep. The top had a lid that, when opened, revealed a dial and two knobs for volume and station selection. We were pretty excited. It could play when plugged into the wall, but, remember, I said it was portable. The back opened up and revealed a wet cell batter system. Periodically we put distilled water into it and it hummed along. It had good range and played all the stations we liked. Yep, there we were: right at the "cutting edge."

Come and see us at The writer is retired and lives in Redding, CA with his wife.

Anyone interested in aviation will need an aviation headset as well as some knowledge about GPS and how it assists pilots. One of the best GPS on the market for aviation is Garmin aviation GPS. The following information will show how the Garmin aviation GPS works and why it is important for pilots.

First of all, GPS stands for Global Positioning System. GPS relies on a network of 24 satellites to assist in navigation. The satellites are in space thanks to the US Department of Defense however everyone can use the technology if they have a GPS system thanks to the system becoming available in the 80s for use by al. GPS works despite the weather, location, and time of day. GPS is free to use although the actual device to detect the signal must be purchased.

The satellites in space that are used for GPS circle the earth two times every day in a fixed orbit. The information that is gathered is then transmitted back to the earth. GPS receivers like the Garmin aviation GPS then receive the information. Once the information is received by the receiver triangulation is utilized to determine the specific location of the user. It's interesting how GPS actually works because with so much transmitting and time difference it would seem the Garmin GPS could get it wrong. However the receiver simply notes the time a signal was received by a satellite in comparison to the time it was sent. The difference in time allows the receiver to determine how far away the satellite is in space. Additional satellites provide more distance measurements and the exact position of the user is then displayed on the electronic map. So, when you are flying and using Garmin aviation GPS you can easily determine where you are at all times thanks to the satellites, receiver, and lots of transmissions.

Fortunately, GPS is unbelievably accurate and users can count on the GPS system to give them accurate information. The reason why it is so accurate is due to parallel multi channel design. Garmin's receivers offer 12 parallel channels and as soon as the receiver is turned on the signal is picked up and locked onto. Then, no matter whether the user is in a location with tall buildings or lots of foliage the lock is maintained. There are some things that may change the accuracy of Garmin GPS including atmospheric changes. However, on average, these receivers have an accuracy of 15 meters.

Natalie Aranda writes about technology. Anyone interested in aviation will need an aviation headset as well as some knowledge about GPS and how it assists pilots. One of the best GPS on the market for aviation is Garmin aviation GPS. The following information will show how the Garmin aviation GPS works and why it is important for pilots.

With Father's Day just around the corner, it's time once again to figure out what I'm going to get my dad. Like many men, he's an electronics enthusiast through and through. He's what companies like (or love) to call an "early adopter" - someone who just can't wait to buy the latest gadget, the faster computer, the bigger HDTV, and anything else you can think of. His obsession definitely has its benefits, though. My sister and I regularly go through his "electronics graveyard" and get fully functional computers, DVD recorders, and all manner of accessories.

But this knack of his to buy the latest electronics makes it that much more difficult to figure out what to get him for his birthday, Christmas, and Father's Day. My sister and I are thinking about buying him a new digital camera for Father's Day, one that has 7.0 megapixels, an optical zoom, and a special setting for taking ebay pictures. Dad is an avid eBay seller, and the right photos can make the difference between selling an item at a decent price and at a great price. The new digital cameras that have the special eBay setting would complement two of his passions: electronics and eBay.

We're also considering buying him a GPS receiver. The Global Positioning System is a set of satellites in orbit high above the earth, and a GPS receiver can tell you, in terms of latitude and longitude, exactly where you are. Some GPS receivers have built-in mapping tools that not only include road maps, but that also show places of interest. So, for example, when Dad's traveling and needs to find a gas station, he can "ask" the GPS system where the nearest gas station is, and then receive directions to it.

A GPS receiver is also perfect for a new "sport" that I've become interested in, and one that I think Dad would love. Geocaching is a hobby that is quite a bit like a treasure hunt. People all over the globe hide small containers that contain trinkets and logbooks, ascertain the latitudinal and longitudinal coordinates of the hiding spots, and post them online. You can go online and find the coordinates of caches near where you live or travel, enter them into your GPS receiver, and then try and find the cache. It's not as easy as it sounds, but it sure is a lot of fun. Once you find a cache, you can pick up a trinket, leave a trinket, and sign the logbook. Dad's expressed an interest in geocaching, and since he does a lot of traveling for his work, my sister and I think that a GPS receiver and a book on geocaching might make the perfect Father's Day gift.

In my heart, I know that our dad will appreciate whatever gift we choose. Any type of electronics will tickle his fancy, and I'm sure that he'll enjoy either a digital camera or a GPS system. The only thing we have to worry about is whether he'll go out and buy one for himself before we get a chance to give him his Father's Day gift!

Chris Robertson is an author of Majon International, one of the worlds MOST popular internet marketing companies.

For tips/information, click here: Father's DayVisit Majon's Electronics directory.

The Network Time Protocol (NTP) is a standard Internet protocol for distributing time around a computer network. The protocol is widely used to synchronise computers and time critical applications to an accurate time reference.

This article describes the Network Time Protocol and provides an overview of how NTP servers utilise NTP to provide an accurate source of time to network time clients.

A Brief History

The NTP protocol is one of the oldest Internet protocols still in use today. It has been in continuous use for more than 25 years. The protocol was originally designed to synchronise computers and time critical processes across the Internet. Initially developed for the Linux operating system, the protocol has recently been partly ported to the Microsoft Windows operating system. NTP is installed by default in many Linux Unix and Free BSD distributions. Most NTP server systems utilise the Linux operating system due to its specialised kernel timing algorithms.

About the Protocol

NTP is a client-server based protocol. The NTP protocol provides clients with 3 fundamental products: system clock offset, round-trip delay and time dispersion of a specified external reference clock (such as GPS). The clock offset specifies the difference between the local system time and an external reference clock. The round-trip delay specifies the time latencies measured during the transfer of packets around the network. Time dispersion specifies the maximum error associated with timing information received from the external reference clock.

The NTP protocol has a hierarchical structure. A stratum 1 time server is the primary reference server and sits at the top of the heirachy. The primary reference server it is followed by secondary reference servers and clients. A radio or GPS external time reference is generally used to synchronise a stratum 1 NTP Server. At the highest level a primary reference NTP server has a stratum of one. Each lower-level NTP server and client is attributed a stratum one greater than the previous level. As the stratum increases, accuracy decreases due to inconsistencies in network path timing.

NTP utilises the User Data-gram Protocol (UDP), part of the TCP/IP protocol suite. Each NTP message consists of a number of fields: Leap Indicator; Version Number; Mode; Stratum; Poll; Precision; Root Delay; Root Dispersion; Reference Identifier; Reference Timestamp; Originate Timestamp; Receive Timestamp; Transmit Timestamp; Key Identifier and Message Digest. The fields are used to identify messages and provide time stamp and round-trip delay information.

The current release of NTP is version 4. All versions of the protocol are backwards compatible with previous versions. The only significant modification to the protocol between versions 3 and 4 is a slight header re-interpretation to accommodate IPv6.

NTP Server Modes of Operation

A stratum 1 NTP server has three modes of operation: unicast; anycast and multicast. The client initiates the unicast and anycast modes, the server responds with a NTP time message that the client uses for synchronisation. Multicast is a broadcast mode of operation, at periodic intervals time messages are broadcast to the entire sub-domain.

Accurate External Reference Clocks

The standard NTP distribution can operate with a number of external time references, or 'reference clocks'. The Global Positioning System (GPS) is a popular choice since it provides a global precise time reference. A number of national time and frequency radio broadcasts are also available, such as WWVB (US), DCF-77 (Germany) and MSF (UK).

The Simple Network Time Protocol (SNTP)

SNTP is a simplified version of the full-blown Network Time Protocol. SNTP is generally used where the complexities and high accuracy of the NTP protocol is not required. The SNTP protocol is often used by micro-controllers and SBC computers. The SNTP and NTP protocols are fully interchangeable. Any SNTP client can synchronise with a full-blown NTP server.

David Evans provides a technical authoring service to many computer time server manufacturers. David has many years experience of network timing systems in the telecoms industry. Click here for more information on time server systems.

The GPS system can be used to provide a highly accurate timing reference for computer network timing equipment such as NTP Server systems and other time critical applications.

This article describes how the Global Positioning System can be used to provide a precise timing reference and provides an overview of the equipment required.

The Global Positioning System is a US military solution for navigation. The system consists of 24 orbiting satellites. Each orbiting satellite has a highly accurate atomic clock synchronised to UTC time. The highly precise atomic clocks are used to calculate transmission times for coordination triangulation. However, the timing information provided by the satellites can also be used as an accurate timing reference for computer network timing systems, such as NTP Server systems.

The GPS satellites are continuously broadcasting time and position information. This information can be obtained anywhere in the world with a simple GPS receiver and antenna. There are no set up or subscription fees to utilise the GPS system. Accuracy

GPS receivers provide highly accurate position and timing information. Typically, a GPS receiver can provide positioning information to an accuracy of 15m. NTP Server systems can obtain timing information from the GPS system to a resolution of a few nanoseconds.

GPS Signals

The GPS signals transmitted from each satellite are very weak low-power radio signals, designated band L1 and band L2. The L1 frequency is the civilian GPS signal transmitted at 1575.42 MHz. The signals travel by line of sight and can pass through clouds, glass and plastics but are blocked by objects such as metal and brickwork. Therefore, the ideal location for a GPS antenna is on rooftop with a full 360-degree view of the sky. Often, installation on the side of a building with a 180-degree view of the sky will provide adequate results, provided the horizon is not too obscured. As a rule of thumb, the better the view of the sky, the greater the likelihood of a good consistent signal lock.

GPS Antenna Types

The GPS antenna is effectively an amplifier that boosts the weak GPS signal for transmission along a cable to the GPS receiver. GPS antenna's provided with NTP server systems or static applications utilise a pole-mounting system. The antenna screws onto a threaded pole for installation on rooftops. This arrangement provides the antenna with a rigid mount easily able to withstand adverse weather conditions. Typically the GPS antenna is fairly small in size, measuring less than 90cm in diameter. Patch type antennas are also available that are particularly suited to mobile or vehicle applications.

GPS Cabling Issues

The cable distance that can be utilised by a GPS system depends mainly on the amplification of the antenna and the quality of coax used in the installation. Typically, a GPS antenna may provide a gain of between 20 to 40 db. Coax cable such as RG58 has an attenuation of 0.64 db/m at 1575 MHz. Therefore, a cable run of 40m can be utilised. Also allow for signal reduction through any connectors. GPS Amplifiers, Splitters and Surge Suppressors

In-line GPS amplifiers provide further amplification of the GPS signal to increase the cable distance between the antenna and receiver. The amplifiers are fitted in-line on the coax antenna cable. A GPS amplifier may typically add a further 20 dB of gain, adding 30m of cable. Additionally, multiple in-line amplifiers may be utilised to further increase cable distance.

GPS splitters allow a single GPS antenna to be utilised by two or more GPS systems. Multiple GPS sytems may reduce cabling costs by sharing a single antenna. The GPS splitter splits the signal received from the GPS antenna into multiple outputs for synchronizing multiple NTP servers. GPS splitters are generally available with 2, 4 or 8 outputs.

Surge suppressors protect expensive NTP server equipment from electro-static discharges, such as lightning, that may be picked up by an externally mounted antenna. Surge suppressors are installed in-line on the coax cable between the antenna and receiver, ideally where the cable enters the building. Surge suppressors require a low-impedance ground, to discharge any surge picked up at the antenna.

D. Evans is a technical author with a wealth of experience, obtained over a 20 year period, in providing information on NTP server and computer timing equipment. Click here for more information and literature on computer network timing and NTP server systems.

Network Time Protocol (NTP) is a standard protocol for the transfer of time across the Internet and computer networks. The NTP protocol source code is 'open source' and can be freely downloaded from the NTP web site. The NTP primary development platform is LINUX but ports to Windows are also available.

This article describes how to debug a NTP server installation after compilation and configuration of the distribution.

NTP Server Debugging

Once the NTP distribution is installed and configured, correct operation needs to be verified. NTP includes a number of tools that can be used to query and debug a NTP server. The most widely used tool is 'ntpq' – the standard NTP query utility. The 'ntpq' utility can be run on the NTP Server installation or from any other computer on the network. The utility can be used to inspect NTP Server system variables to verify correct operation.

Using 'ntpq' – The NTP Query Utility

The 'ntpq' utility is run from a Linux command prompt. It can be run with a number of command line options. The most useful parameter is the '-p' option which display NTP server peer variables. Run the ntpq utility with the –p option, thus:

>ntpq –p 192.168.0.1 # where 192.168.0.1 is the IP address of the NTP server.

If the ntpq utility is run on the NTP server, the IP address may be omitted. Output similar to the information below may be generated.

remote refid st t when poll reach delay offset jitter

=============================================================

*127.127.0.32 .GPS. 1 u 18 64 377 0.000 0.412 0.015

+127.127.0.7 .MSF. 1 u 18 64 377 1.622 0.546 1.125

This first character on the left margin indicates the synchronisation status of each reference peer in the list. The currently selected reference peer is indicated by an asterisk ('*'). Additional peers marked with a '+' are also used in the computation, while peers marked with any other symbol are not used.

The 'remote' address corresponds to the server or peer entries in the NTP server configuration file. The 'refid' field indicates the time source utilised by the server. The 'st' field indicates the stratum, 't' indicates type; unicast, multicast or local. The 'when' field indicates the time since the reference was last contacted. The 'poll' field indicates the polling frequency of the reference. The 'delay' field provides the round-trip delay when contacting the reference. The 'offset' field is the difference between the reference time and the server time. The 'jitter' field indicates the dispersion of time stamps received from the reference.

In the event of problems synchronising to a reference peer, a four-character status string is entered in the 'refid' field. The status fields may consist of one of:

ACST - The association belongs to a anycast server.

AUTH - Server authentication failed.

AUTO - Autokey sequence failed.

BCST - The association belongs to a broadcast server.

CRYP - Cryptographic authentication or identification failed. The details should be in the system log file or the cryptostats statistics file, if configured. No further messages will be sent to the server.

DENY - Access denied by remote server. No further messages will be sent to the server.

DROP - Lost peer in symmetric mode. Please wait while the association is restarted.

RSTR - Access denied due to local policy. No further messages will be sent to the server.

INIT - The association has not yet synchronized for the first time.

MCST - The association belongs to a manycast server.

NKEY - No key found. Either the key was never installed or is not trusted.

RATE - Rate exceeded. The server has temporarily denied access because the client exceeded the rate threshold.

RMOT - Somebody is tinkering with the association from a remote host running ntpdc. Not to worry unless some rascal has stolen your keys.

STEP - A step change in system time has occurred, but the association has not yet resynchronized.

David Evans is a technical author who specialises in NTP Server and time synchronisation systems. Click here for more information about NTP Server time synchronisation.

With Windows Mobile 6, Microsoft set a skilled handyman to work on the creakier joists of its mobile operating system, but stopped well short of a gut renovation.

The new OS is really more of an honorable Version 5.5 than a true 6—an accumulation of new, useful features that doesn't disturb the operating system's underpinnings or solve some of its deeper problems.

The biggest change with Windows Mobile 6, in fact, is probably the names. Say goodbye to Pocket PC and Smartphone. Say hello to Professional, which means former Pocket PC phones, with touch-screens; Standard, which are former Smartphones, without touch-screens; and Classic, for those few remaining touch-screen PDAs without phone capability.

Windows Mobile 5 users won't be wowed when they boot up a Windows Mobile 6 device. Devices still take 40 seconds or so to start up, and performance is roughly the same as measured by Spb Benchmark and TCPMP video tests.

On the other hand, the new version doesn't break most third-party software; all of the software we tried, including Opera Mobile, Spb Benchmark, Skype, TCPMP and StyleTap, still worked.

The most striking application improvement is the new Office Mobile for Standard. One of the big criticisms of Windows Mobile for Smartphone was its inability to let users edit Microsoft Office documents.

Now, Office Mobile lets you view PowerPoint presentations and view and edit Word and Excel documents—a little. In Word, editing is restricted to inserting and deleting text, and a few very basic formatting commands like bold and underline; there's no font or paragraph formatting, nothing rich.

In Excel Mobile, there's a neat zoomed-out "overview" mode, basic formula functions and support for multiple spreadsheets, but there's no "new" option in either program. That's right, these programs are for editing e-mail attachments, not creating new documents.

The new OneNote Mobile, part of OneNote 2007, can create new documents, but it isn't included by default with Windows Mobile 6.

Read the full story on Windows Mobile 6

The Toronto Wireless User Group is a member of the Oreilly User Group Program.

SOURCE:

http://www.torwug.org/Articles/newsletters/Feb14_2007/ar_02.asp

The Global Positioning System (GPS) was funded, developed and controlled by the US Department of Defense. Since the late seventies, GPS has become an important aid to navigation around the world. Initially designed for the US military, GPS became publicly available years later and it is now considered an important feature in lots of consumer products.

How does GPS work? Well, basically there are three elements that make everything work: satellites, earth monitoring stations and receivers (ex: cell phone, telefone celular). GPS provides specially coded satellite signals that can be processed in a GPS receiver, enabling the receiver to compute position, velocity and time.

Today, most cell phones (telefone celular) are not limited to carry on just a conversation. Features like mp3 player, digital camera and video camera have all become standards in the latest cell phone models. It is expected that the GPS feature will soon be added to this list, and it will offer the capability of tracking any cell phone user.

The capability of tracking a cell phone user becomes important in emergency situations, like a car accident, thru the use of 911 emergency phone call, where every minute may be a matter of life or death. In situation like this, the GPS system may pinpoint the exact location of the road accident, enabling emergency services to be quickly dispatched.

It is important to mention that so far most GPS system in cell phone (telefone celular) is restricted to tracking information only. However, one can have navigational capability thru the use of full screen cell phone/PDA combos with map displays and other cellular phone accessories, and third party paid services. If one does not want to sign up for a monthly paid subscription service, he can make use of one-time-paid-only software programs that will enable some of the navigational capabilities.

Although there are many benefits in using GPS cell phones (telefone celular), there are some people who are concerned about the violation of personal privacy. Since the US Congress has not authorized location tracking without actual evidence of wrongdoing, there have been court hearings which have not approved the requests of government agencies in obtaining the cell phone GPS tracking information for suspects or ordinary citizens.

This privacy matter has made some progress towards the cell phone user`s rights, since there are some laws that have been passed which guarantees that GPS cell phone users will have some protection from the release of the tracking information, with the exception of 911 emergency cell phone calls (telefone celular). It is expected that these laws will guarantee that the benefits of GPS in cell phones will be enjoyed by everyone without infringing anybody`s privacy.

Sometimes when there is a technological innovation, there are also some concerns about privacy or some rights infringements. But no matter how much of a concern this is, it seems that a compromise will always have to be reached, so that new technologies will take their places in everyone`s lives. After all, we all live in a globalized consumer world. By the way, have you already got your GPS cell phone?

Roberto Sedycias

IT Consultant for PoloMercantil

This article is under GNU FDL license and can be distributed without any previous authorization from the author. However the author´s name and all the URL´s (links) mentioned in the article and biography must be kept.

This article can also be accessed in portuguese language from the News Article section of page PoloMercantil

Roberto Sedycias has a bachelor degree in Business Administration and over 20 years experience in systems analysis and computer programming. Currently working as IT consultant for www.PoloM

Fleet GPS Tracking: What It Can Do For Your Business

Are you a freight broker? If you are, it is your job and your responsibly to ensure that your client's goods are transported from one location to the next, safely. When it comes to running a freight broker business, like all other businesses, you are taking a gamble on the truck drivers or transporters that you hire. That is why you may want to think about protecting yourself, your business, and, in some cases, your truck drivers or transporters. You can do this with fleet GPS tracking.

Fleet GPS tracking involves putting a small device into each of your trucks. Of course, this will require the cooperation of any truck drivers, especially if they own their own trucks, but, in most cases, you will find that most are more than happy to do so. As previously stated above, fleet GPS tracking can also help the truck drivers or transporters that you employ. One of the reasons for that is because you know where they are at all times.

Fleet GPS tracking is made possible thanks to the Global Positioning System. This system is what makes it possible to track anything with a GPS tracking system, including a fleet of your trucks. When it comes to safety, a fleet GPS tracking system can not only help your business, but your truck drivers or transporters as well. For instance, should one of your drivers veer off the road unseen, you could be able to tell exactly where they are and when the vehicle's last movements were. This would not only allow you to recover your client's merchandise quicker, but it would also allow you to seek help for one of your drivers if they were injured.

As a freight broker, you likely already know that many transportation vehicles are the targets of theft. Many times, the merchandise being transported from one location to another is valuable and that is what tends to make it a prime target for thieves. The thing with these types of thefts is that they often take the whole vehicle, like in a hijacking, and then unload the merchandise elsewhere. If this were to ever happen to you and one of your trucks, fleet GPS tracking would enable to you to not only know where your truck has been, but where it is at the current time. Fleet GPS tracking could assist authorities with recovering the property you, your company, and your driver was transporting.

As you can see, fleet GPS tracking can actually play an important part in your business. Although you may never need to use fleet GPS tracking, why take the chance of not having it. With the ability to help your truck drivers in the event of an emergency and the ability to track thieves, fleet GPS tracking equipment and software is more than worth the already affordable costs.

Quentin Chamberlain is a writer for RM Tracking . com where you can find accurate information about Fleet GPS Tracking and other related information.

Fleet Management GPS: How It Can Help to Reduce Theft

Are you in charge of running your own delivery business? If you are, you likely have your own fleet of delivery vehicles, as well as drivers. While your drivers may be able to go about delivering goods to your customers without any problems, there is always the chance that problems could arise. To minimize your risks or your liabilities, you may want to think about purchasing fleet management GPS tracking equipment, as well as have it activated.

When you have fleet management GPS tracking, you are able to manage or keep track of all of your delivery truck whereabouts. As a business owner, this should give you a sense of security. Knowing where your delivery trucks are at all time gives you control over the situation, even though you may be watching from your office desk. What is nice about fleet management GPS, as mentioned above, is that it helps to limit your liabilities or your risks should something go wrong, as most problems can easily be fixed with fleet management GPS.

When one of your clients ask you and your business to delivery one for their products or a bunch of their products from one location to another, they often expect you to do so in a specific time frame. Although you will likely be able to meet all deadlines, there is a chance that a problem could arise. For instance, if one of your trucks were to break down, veer off the road, or get involved in a multi-car accident, you will need to send a replacement delivery truck to pick up the stranded merchandise. Fleet management GPS tracking would give you the exact location of your delivery truck, as well as the driver, making it easier for you to send backup or assistance.

Depending on the type of merchandise you delivery, you may find your business being the target of theft. Although having fleet management GPS might not necessarily prevent one of your delivery vehicles from getting stolen, it may make it easier for you to recover your vehicle, as well as your client's merchandise. For instance, in most delivery truck thefts, most drivers notice right away or within the hour that their truck has been stolen. With a simple call to authorities and a quick look at your fleet management GPS tracking programs, and your delivery truck, most likely with the merchandise still inside it, could be recovered in as little as an hour or two.

Even if you consider your delivery business to be a small one, you can still benefit from fleet management GPS. In all honesty it doesn't matter if you only have one delivery truck or van or one hundred of them, fleet management GPS can assist you and your business. In fact, it can even be done at an affordable price. By carefully choosing which fleet management GPS tracking equipment you use, as well as which GPS tracking company you do business with, you should be able to use and benefit from fleet management GPS without having to incur large business debts.

Quentin Chamberlain is a writer for RM Tracking . com where you can find accurate information about Fleet Management GPS and other related information.

Does Your Car Need Car Tracking GPS?

Are you a car owner? If you are, have you heard of car tracking GPS? If you have, do you have car tracking GPS installed and activated in your vehicle? If you do not, you may want to think about getting it, as it can come in handy for you many times in your life.

When it comes to car tracking GPS, there are many car owners who wonder whether or not they really need car tracking GPS. Although anyone can have car tracking GPS installed and activated in their vehicles, there are some instances where it could definitely come in handy. Just a few of the many signs that you may need or benefit from having car tracking GPS are outlined below.

If you are a business owner, you could definitely benefit from having car tracking GPS installed and activated in all of your company vehicles. Should one of your company vehicles get stolen, your car tracking GPS could help authorities find your car in what seems like record time. If one of your work vehicles ended up stranded or in an accident, car tracking GPS could be used to send assistance.

If you regularly travel long distances, it may be a good idea to have car tracking GPS equipment installed and activated in your personal vehicle. As it was previously mentioned, car tracking GPS can be used to help you out in the event of an emergency. Whether you were involved in a multi-car accident, a single car accident, the victim of auto theft, or had a medical emergency on the road, car tracking GPS can offer you assistance. If someone who is looking for you don't know where to look, they or the authorities could use your car tracking GPS equipment to find out your approximate location.

If you are interested in getting car tracking GPS on one of your vehicles or a number of them, whether you are a personal car owner or a business owner, you will need to find a car tracking GPS company to do business with. Unless your car or cars already has car tracking GPS equipment installed in it, you may want to think about finding a car tracking GPS company to do business with. There are some companies who prefer that you use a certain piece of equipment. Waiting before you purchase any equipment will make it easier for you to do business with the company of your choices, as well as save money by not buying unnecessary car tracking GPS equipment.

As it was previously mentioned, if you are a business owner or just a car owner who would like to know where their car is at all times, you are urged to at least consider getting car tracking GPS equipment installed and activated in your vehicle. In fact, you don't even need a reason to have car tracking GPS. If you would feel more comfortable having it activated in your business vehicles or your personal vehicles, you are advised to just go ahead and do so.

Quentin Chamberlain is a writer for RM Tracking . com where you can find accurate information about Car Tracking GPS and other related information.

How to Find a Live GPS Tracking Company to Do Business With

Are you interested in having live GPS tracking equipment installed and activated for your cell phone or your vehicle? If you are, you will need to find a live GPS tracking company to do business with. A live GPS tracking company is a company that will record all of your movements, as well as give you access to those movements through their own customized programs. A live GPS tracking company is what makes it possible for you to benefit from having GPS equipment installed on your cell phone or in your vehicle.

If you are interested in having GPS tracking activated in your personal vehicle, cell phone, or even your work vehicles, you will need to find a live GPS tracking company to do business with, as previously mentioned. When it comes to finding a live GPS tracking company to do business with, you will find that you have a number of different options. Perhaps, the easiest option is to use the internet.

When it comes to finding a live GPS tracking company to do business with, it is advised that you perform a standard internet search. When performing a standard internet search, you may want to search with the phrases "live GPS tracking," "GPS tracking company," or another similar phrase. Your standard internet search will likely return a number of different results. Some of those results should include the online websites of live GPS tracking companies. You will want to examine each of those online websites for additional information.

When examining the online website of a live GPS tracking company, there are a number of points that you will want to examine. One of those points is location of service. While most live GPS tracking companies service the entire United States and sometimes even foreign countries, there are some live GPS tracking companies that have limitations. Before doing business with a live GPS tracking company, you will want to examine the areas serviced; as you want to make sure that the places you travel to can be recorded, as that is what live GPS tracking is all about.

You will also want to examine the equipment used by a live GPS tracking company. Many live GPS tracking companies require that their own equipment is used; however, not all do. If you have a cell phone that already has live GPS tracking equipment installed on it or if your vehicle does, you will want to see if the equipment that you already have can be used or activated. If it can, this may be able to save you a considerable amount of money on equipment.

By using the internet and a standard internet search, you should be able to find a number of live GPS tracking companies to do business with. GPS tracking is good for your personal cell phone, your personal vehicle, or, if you are a business owner, your business phones and vehicles.

Quentin Chamberlain is a writer for RM Tracking . com where you can find accurate information about Live GPS Tracking and other related information.

How an Auto GPS System Works

Have you heard of an auto GPS system before? Although a large number of individuals have auto GPS systems installed and activated in their vehicles, not everyone does. If you are one of those individuals, one who is currently driving around a vehicle without an auto GPS system, you may want to think about further examining the systems, namely how they work.

An auto GPS system is often referred to as the equipment that is used. An auto GPS system is also commonly referred to as a GPS receiver. When a GPS system has been activated, by doing business with a GPS tracking company, it works in conjunction with the Global Navigation Satellite System. This system is composed on multiple satellites that orbit in space. These satellites are what make it possible for an auto GPS system to work and transmit the location of an automobile with an auto GPS system installed and activated on it.

It is most well-known that an activated auto GPS system can give the exact location of a vehicle with an activated system in it. While the location of an automobile is perhaps the most important, as it can be used to help out in emergencies or in the event of theft, location is not the only piece of information that an auto GPS system can divulge. Many auto GPS systems can also give information on the speed of the vehicle being driven, as well as where it has been in the past, often times up to a few weeks or even a few months! When you think about it, it is pretty amazing what an activated auto GPS system can do.

If you would like to have an auto GPS system installed and activated in one of your personal vehicles, you will need to find a GPS tracking company to do business with. These companies are the ones that will give you access to all of the information from your auto GPS system. When choosing a GPS tracking company to do business with, you will want to examine the services offered, as well as the cost of those services. In terms of service, you will want to know how you can go about accessing all of the information transmitted from your auto GPS system. Do you need to contact the GPS tracking company in question or can you simply visit an online website to get the information that you need? You will also want to examine the equipment that they use or prefer, if there is any preference.

If you already know that you would like to have an auto GPS system installed and activated in your vehicle or if you would like more information, you are urged to seek additional information from a well-known GPS tracking company or auto GPS system supplier. When it comes to deciding whether or not you should have an auto GPS system activated in your vehicle, the best decision to make is a well informed one.

Quentin Chamberlain is a writer for RM Tracking . com where you can find accurate information about Auto GPS System and other related information.

How Car GPS Tracking Can Help Save Your Life

Have you recently bought a cell phone for yourself? If you have, there is a good chance that your phone may come with GPS capabilities, as most new, modern cell phones now do. Although having GPS tracking on your phone is nice, you may not have your cell phone with you at all times. That is why you may want to think about equipping your car with GPS tracking equipment. Car GPS tracking, one day, may very well help to save your life.

When it comes to car GPS tracking, there are many vehicle owners who wonder why it is so important. What is it about car GPS tracking that makes it worth the money? As previously mentioned, car GPS tracking may very well help to save your life. This, essentially, is because car GPS tracking enables a tracking company, the authorities, or your family to know where you are. In the event of an emergency, this may very well help to save you life.

Although many automobile accidents involve multiple vehicles, not all do. If you went off the road and didn't have your cell phone with you, you might be unable to call for help. Also, if you were injured you may be unable to seek help, even if you had a cell phone with you. If someone, whether it be a friend, family member, or your work, was expecting you and you didn't show, there is a good chance that they would start looking for you or contact the authorities. Unless you left detailed instructions on your intended route, your searchers may not know where to look, unless your car was equipped with car GPS tracking. Car GPS tracking would not only show searchers where to look, but it gives them your exact location.

Another situation that car GPS tracking may be able to offer assistance is in the event of a car theft or a hijacking. Should you be kidnapped or taken when the car was hijacked, the above mentioned situation would come into play. If someone knew that you were missing they could activate your car GPS tracking to find your exact location. Even if you weren't in the car, but it was still stolen, the authorities could use your car GPS tracking to find out exactly where you car is. It is not uncommon for stolen cars to never be found, but with car GPS tracking, your stolen car could literally be found in as little as an hour.

The above mentioned situations are just a few of the many where having car GPS tracking could come in handy. If your vehicle isn't already equipped with car GPS tracking, you should definitely look into it more.

Quentin Chamberlain is a writer for RM Tracking . com where you can find accurate information about Car GPS Tracking and other related information.

The Celestron SkyScout has been out in the market now for about a year, though I just recently learned about it. Usually I am not really all that interested in the latest hi-tech gadgets but I have never seen anything quite like the SkyScout.

Quite simply, the SkyScout is more of an educational tool than a toy. It was invented to help educate the average backyard astronomer, though through the use of some of todays latest technology, I feel as if the SkyScout would work well for even a more advanced amateur.

At first glance, there doesn't seem to be that much to it. It is rather lightweight but it is rubber armored and feels solid in the hand. There are volume controls for the audio and brightness adjustments for the menu screens and viewfinder. About the size of a handheld camcorder, it runs on 2 AA batteries. When turned on, the GPS system immediately goes to work locating satellites. Doing some research, I found out that the SkyScout employs special software that can calculate where the stars and planets are at that particular moment. It also utilizes 3 "axix sensors" which act to measure the earth's gravitational and magnetic fields.

Using the menu in the viewfinder, you simply navigate via simple instructions to locate a particular heavenly object such as Mars. Blinking arrows indicate which way to point the device - up, down, left or right until your target is reached. You can also point and press the target button while pointing at any visible object (it can identify over 6,000) and it will tell you what you are looking at. It works no matter where you may be located on the planet, of course.

Headphones are also included, though the quality is poor. If you want audio information, you simply point the device at a planet or star then once again press target, and select the audio function on the menu and you will be greeted with a woman's voice that supplies

facts and information about any one of over 200 objects.

Some of the Celestron SkyScouts unique features are "Tonight's Must-See List" (tells the user the 10 most interesting things to look at in the sky that night),"Constellation Lessons" (shows a picture of the constellation, and helps the user locate the other stars in that particular constellation) and "Content Cards" – an SD (secure digital) card slot is readily available for additional content.

Overall I thought it was a very innovative device and apparently I was not alone.

Awards? It's won a few including PC Magazine's Last Gadget Standing, Popular Mechanics' Editor's Choice, Popular Science's Best of What's New and CES's Best-Of Innovations.

If you are in the market for a fun and educational experience, then put away your flashlights and starcharts all you astronomy buffs. Pick up a few extra batteries go out into the night sky and give the SkyScout a try and see what you think.

Dennis Mason is an online marketer and entrepreneur who specializes in reviewing a wide variety of products. For more information on the Celestron SkyScout please see

The SkyScout personal planetarium from Celestron made its debut just about a year ago with some fanfare after receiving several awards from industy publications. Is this cool handheld device really something that will educate, thrill and entertain or is it just an overpriced toy? What makes it so different from other products for stargazing enthusiasts?

After using the SkyScout the first thing to strike me as impressive is the fact that you no longer need complex charts for stargazing. With this device you know what you are looking at. Basically, this simple tool tells you what you're looking at as you point it into the night sky (works in daylight too) and also guides you to any other objects that you want to see. It uses and electronic display to accomplish this. It also has audio output and you can listen to detailed information on 200 different types of objects, though it can identify more than 6000 planets, constellations and stars. The menu functions are quite clear and easy to understand and navigate.

The SkyScout also comes with USB port so that you can hook it up to your computer for updates such as a shuttle flyover. Sorry Mac users, PC only.

The gizmo knows exaclty where it is in relation to the rest of the cosmos. It locates your exact position by using a GPS receiver. An electronic compass tells it what direction it's pointing. It also uses special software to assist in calculating the position of the heavenly objects at that moment.

One particularly interesting feature is the Sky Tour Audio Presentation which gives a tour of the best objects to view for your time and location.

There are a few things that could use improvement. For one, you must have a PC to upload recent data as mentioned earlier. Mac users are out of luck. Second, some users claim that it goes through batteries (2 AA) quickly. Finally, no lens cap is included.

The SkyScout is referred to as a Personal Planetarium. I think this describes it quite accurately. This clever device could in fact be operated even a child, though hopefully he or she will be in bed at night so you can have it all to yourself.

Dennis Mason is an online marketer and entrepreneur who specializes in reviewing a wide variety of products. For more information on the Celestron SkyScout please visit

There was quite a buzz when the a new gadget, the SkyScout personal planetarium from Celstron, came on the market a year ago. Now any amateur stargazer can easily find and identify one of thousands of celestial objects using this device.

What exactly is the SkyScout and what does it do? How does it work? What are some of its features and what are the pros and cons of purchasing the SkyScout personal planetarium?

The SkyScout locates objects two different ways. It can tell you what star or planet you are pointing at, or it will guide you to it, by selecting the name of the star from a list. The database contains over 6,000 planets, constellations and stars. Not only that, it also gives you some pretty impressive information about each one as well.

The science behind these functions works via a GPS receiver(locates your current position on earth), a special type of software that can calculate where the stars and planets are at that particular moment and 3 "axix sensors" which act to measure gravitational and magnetic fields.

Some of it's cool features include:

Tonight's Must See List ,Constellation Lessons, Updatable Software and Data and Sky Tour Content Cards (SD Card slots for extra content), and a built in field guide.

The field guide includes such topics as Introducion to Astronomy, Glossary of terms, text bios of great astronomers, text of man-made space objects (Hubble Telescope, Space

Shuttle, Space Station) and a historic guide to popular comets.

SkyScout even "talks" to you. Using audio headphones, the handheld device will tell you stories about the some of the most popular stars and planets that you are looking at.

I particularly like the fact that there is a built in USB interface (connect to your

computer)so it's easy to keep up with new objects as they are dicovered.

Here is a list of my pros and cons:

Pros

Great technology, fun for all types stargazers, students, campers, people of all ages.

Very simple to use yet advanced enough for amateur astronomists.

Very lightweight and easy to use. About the size of a handheld camcorder.

It can identify over 6000 heavenly bodies, 88 constellations (only a little over 200 celestial objects have audio files)

It has a Rugged feeling,

It is equipped with audio controls and you can control adjustment of brightness in the viewfinder

Cons

Goes through batteries (uses 2 AA) very quickly.

GPS may take awhile to start working and its capabilities will be compromised if the user is near metal.

Anyone who has ever tried to use a star chart at night with a flashlight is probably going to appreciate and enjoy this intruguing new product. Celestron is a well known and respected company and leader in the field of optics. Though the SkyScout may be used and appreciated even by children, the SkyScout is definately no toy.

Dennis Mason is an online marketer and entrepreneur who specializes in reviewing a wide variety of products. For more information on the Celestron SkyScout please visit

The Global Positioning System – or GPS – has taken the world by storm. What was once a proprietary item used only by the government, is now in demand by retail consumers worldwide. Those who have become used to GPS rely upon its accurate directional services; and the word continues to spread. A Magellan GPS is one of the more popular brands of GPS.

GPS utilizes the government's network of 24 satellites that consistently circle the earth, providing timely and accurate logistical information. It was designed in the late 1970's by the United States Department of Defense to be used as a reliable navigational tool for the military. But today, GPS has become mainstream, finding its way to consumers through a variety of convenient systems. GPS receivers are hand-held units that literally fit into the palm of your hand. This portable system has the ability to connect to the Global Positioning Satellites which, through a series of calculations based on longitude and latitude can instantly and accurately pinpoint the user's location. The screen of the GPS receiver illustrates a map of the area, including roads, terrain, and landmarks, and places the user's location relative to these points of reference. Travelers and outdoor enthusiasts who take to the mountains every weekend have found the GPS receivers to be invaluable in providing accurate navigation and ensuring safety.

Magellan GPS, a brand of GPS receivers, is one of the more popular systems on the market today. While some users prefer to use the Magellan GPS as a hand-held device, others use it as a permanent navigational device that is mounted in their vehicles. In this role, the Magellan GPS uses a destination address supplied by the driver to efficiently navigate the driving route. Further, if your vehicle becomes the victim of theft, it can be effectively tracked by the signals sent by the Magellan GPS.

In other cases, parents use the Magellan GPS as a tracking device to monitor their teenage drivers. The system will ensure that fledgling drivers are not left disoriented in unfamiliar territory and can alert parents to any suspicious activity.

The Magellan GPS, because of its increasing popularity, can be purchased in most retail outlets. Prices vary depending on number of features offered in each system. There is also comprehensive information provided online detailing the different Magellan GPS systems, including features, price, and user experiences. Take the time to research any GPS before you purchase to ensure that it meets your needs with regard to the manner in which you will use the system, frequency of use, and budgetary guidelines.

For easy to understand, in depth information about Magellan GPS visit our ezGuide 2 GPS.

GPS, or Global Positioning System, is a system that helps an individual determine where he is located as well as where other things are located. GPS has become incredibly popular over the years with even more mobile devices available. However, GPS in aviation has been around longer. As long ago as 1978 GPS was being experimented with and a satellite was sent into space to test the technology. That has been almost 30 years ago and today GPS is in many people's cars! Nevertheless, aviation was one of the first industries to become involved with GPS because location and speed are very important in the field of aviation.

The United States Department of Defense handles GPS, but allows the public to use it for free. The GPS in an airplane basically has a map of the route from the original location to the destination. Information is programmed into the GPS and it helps for autopilot and things of that nature. It also tells the pilot where they are headed, how far away they are from the destination, as well as the height of the plane. GPS is invaluable to pilots and it is very helpful.

One popular option is the Garmin aviation GPS. This GPS system is designed specifically for the use in aircraft. Not all GPS systems will work in an aircraft like they would in a car, so buying a specialized aircraft GPS is important. An aviation headset is still important even with the use of the GPS because you will need to communicate with the tower not to mention you will need to protect your hearing.

Of course, GPS has been around since the '70s, but it has not been fully operational in aircrafts that long. It was not until the mid 1990s that GPS became fully functional with 24 satellites and aviation accepted the new technology and put it to work. Since the mid 1990s the GPS system has become incredibly important for pilots and all airplanes are now outfitted with this device. It helps pilots stay on course and if something happens the system lets them know how to get back on the right path. GPS isn't just important for pilots, but also for every day drivers. And, although GPS has been around for quite some time it is just gaining popularity and understanding with the general public.

Natalie Aranda is a freelance writer. One popular option is the Garmin aviation GPS. Not all GPS systems will work in an aircraft like they would in a car, so buying a specialized aircraft GPS is important. An aviation headset is still important even with the use of the GPS because you will need to communicate with the tower not to mention you will need to protect your hearing.

The Network Time Protocol (NTP) defines a set of algorithms for the dissemination of time across the Internet. The NTP protocol can be used to synchronise the system time on your Linux Server with a highly accurate Internet time reference.

This article describes how to configure the Network Time Protocol (NTP) daemon on your Linux server to synchronise with an Internet based NTP server. It also provides a list of well-know public Internet time references.

Obtaining the NTP Source Code Distribution

The Linux NTP source code distribution is publicly available 'open source' software. The distribution can be freely downloaded from the NTP web site 'ntp.org'. The latest NTP version for Linux is 2.4.2. A port is also available for Windows platforms, but the primary development platform for NTP is the Linux operating system. A number of Linux based operating systems such as Mandrake and Redhat offer NTP as an installable RPM package.

Once download is complete, the NTP distribution should be configured and compiled on the host computer.

Configuration of the NTP Daemon

The NTP daemon is configured through entries in the primary NTP configuration file 'ntp.conf'. The NTP configuration file contains a list of commands that instruct the daemon to synchronise with a specified NTP server. NTP servers are specified using the 'server' command followed by the domain name of the server thus:

server ntp2c.mcc.ac.uk

server ntp.cis.strath.ac.uk

A number of access control options are also available to restrict the use of your NTP server by network time clients. To only allow machines on your own network to synchronize with the server use:

restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap

Alternatively, you can restrict all access to your NTP server with the following command:

restrict default ignore

Multiple directives can be specified to restrict access to a specified range of computers.

Using NTP Authentication

NTP authentication is used by time clients to authenticate the time server to prevent rogue server intervention. NTP authentication is based on encrypted keys. A key is encrypted and sent to the client by the server, where it is unencrypted and checked against the client key to ensure a match.

NTP keys are stored in the 'ntp.keys' file in the following format:

Key-number M Key (The M stands for MD5 encryption), e.g.:

1 M secret

5 M RaBBit

7 M TiMeLy

10 M MYKEY

The NTP configuration file 'ntp.conf' specifies which of the keys are trusted. Any keys specified in the keys file but not trusted will not be used for authentication, e.g.:

trustedkey 1 7 10

NTP Client Authentication Configuration

The NTP client also needs to be configured with similar authentication information as the server. The client may use a subset of the keys specified on the server. A different subset of keys can also be used on different clients, e.g.:

Client A) Client B)

1 M secret 1 M secret

7 M TiMeLy 5 M RaBBit

trustedkey 1 7 trustedkey 1

Controlling the NTP Server Daemon

Once configured, the NTP daemon can be controlled using the commands: 'ntpd start'; 'ntpd stop' and 'ntpd restart'.

Querying the NTP Server Daemon

The NTP server daemon can be queried using the 'ntpq –p' command. The ntpq command queries the NTP server for synchronisation status and provides a list of servers with synchronisation information for each server.

Public Internet NTP Servers

Public NTP servers provide subscription free, highly accurate, timing references for computer time synchronisation. Below is a list of popular public NTP time servers.

Stratum 1 Public NTP Servers

- 194.35.252.7 - Computing Systems Research Ltd. United Kingdom - NTP V4 primary (Odetics GPS), Sun/Sparc Solaris 2.6

ntp.my-inbox.co.uk - 81.168.77.149 - Falmouth, Cornwall, UK - NTP V4.2.0 primary (MSF Radio Clock Receiver), Trustix Linux

Stratum 2 Public NTP Servers

- 194.164.127.6 - Telehouse Europe, London E14 - NTP V4 secondary Sun UltraSPARC Solaris 8

ntp2d.mcc.ac.uk - 130.88.203.12 - University of Manchester, Manchester, England - NTP secondary (S2), SGI/Irix

ntp2c.mcc.ac.uk - 130.88.200.4 - University of Manchester, Manchester, England - NTP secondary (S2), PC/FreeBSD

- 194.207.34.9 - ExNet Ltd, London, UK - NTP secondary (stratum 2), Sun-4/Unix

audaxsystems.co.uk - 193.201.200.83 - Interhouse London E14 - NTP V4, SuSE 9.0 (Stratum 1)

- 194.164.127.5 - Telehouse Europe, London E14 - NTP V4 secondary Sun UltraSPARC Solaris 8

ntp.cis.strath.ac.uk - University of Strathclyde, Glasgow, Scotland - NTP V4 secondary

- 194.164.127.4 - Telehouse Europe, London E14 - NTP V4 secondary Sun UltraSPARC Solaris 8

David Evans is a technical author that specialises in Linux NTP Server synchronisation systems. Click here to find out more about Linux NTP Server systems.

Vehicle tracker, also known as GPS vehicle tracking system, is a device that uses satellite signals to track vehicles. The device is placed inside of the vehicle, allowing either real-time or passive monitoring of its location.

How a vehicle tracker works

Vehicle tracker emits a signal that is picked up via satellite and conveyed to a monitoring system. A subscription service to the tracking company allows you to get reports and access to real-time monitoring displays.

There are two types of vehicle trackers available. One type offers passive tracking. A monitoring device is placed in the vehicle and data can be retrieved later to determine where the vehicle has been and the mileage driven. The other type is real time tracking, which is more extensive. It allows the vehicle's location to be monitored on a computer while it is being driven. Special software is loaded onto the computer to allow you to receive real-time information on the location, speed and direction of travel. Typically these movements are shown on a gridded map, making it user-friendly.

Why use a vehicle tracker

Anti-theft device – One of the major concerns of new vehicle owners is theft. With the use of a tracker, your vehicle can be quickly located if it is stolen. A deterrent to criminals, you can display the sticker, which indicates your vehicle is equipped with GPS. Many insurance companies offer discounted vehicle insurance rate to those who have a gps tracking system installed in their vehicle.

Navigation tool – The vehicle tracker or GPS can be used as a navigation tool. Newer vehicle tracking systems not only provide directions, but also suggest alternative route when traffic congestion is detected. You can also receive traffic information such as availability of parking spaces and the nearest public transport line.

Business – Many companies that have fleets of vehicles will find GPS tracking system helpful. The reports provide information on business mileage driven and location of vehicles.

Emergency – While cell phones may not be able to specifically locate you via 911 services, the GPS tracking device can detect your exact position. This enables you to receive medical or emergency assistance as quickly as possible. Some new vehicles are equipped with GPS tracking systems that are useful in emergency situations.

Surveillance – Vehicle tracker can be used to track a family member's whereabouts. It is useful for tracking teens and others who may only be allowed minimal vehicle access. The device can be mounted inside the vehicle so that it is virtually undetectable.

Benefits of using a vehicle tracking device

There are many benefits to using a tracking device in your vehicle. Emergency location is an important factor when considering getting a vehicle tracker. This can help bring peace of mind to those who travel frequently or who may need to drive late at night or in unknown areas. Many thousands of vehicles are stolen each year. Stolen vehicles can be more easily recovered and the perpetrators caught through the use of vehicle trackers. GPS vehicle tracking system is a fantastic street navigator, so you no longer need to worry about getting lost or being stucked in a traffic jam.

GPS system is becoming popular for providing vehicle tracking solutions to personal and business needs. FInd affordable GPS vehicle tracking systems that can save you time and cost

I first crossed the gulf stream on a small sailboat back in 1979. I was on a sailboat that my good friend and I had just bought a few weeks before. My partner and I had named the boat the "Impossible", as we thought it was impossible for a couple of guys like us to have such a fine sailing vessel. It was equipped with all the modern navigation instruments available at the time, a compass and large hat to shade your eyes!

It was my first time leaving the boundaries of land and sailing away to the Bahamas that I had only dreamed about. Crossing the gulf stream accurately on a boat only going five miles an hour with the entire body of water traveling north at three miles per hour was and still is a challenge to your navigation or "dead reckoning" skills. My friend had sailed across the gulf stream several times before with his father and I had put my faith in his ability to navigate. We managed to make landfall in West End Grand Bahamas, which was where we were aiming which was very gratifying. I was hooked as a sailor from that point on by the seemingly magical appearance of a spot of land on the horizon that was indeed our destination.

Last year I had sailed my boat to Florida after many years in the Bahamas to do some long overdue maintenance to the boat after being damaged in several hurricanes that had swept through the Bahamas the previous year. While in Florida I had added a new auto-pilot,

xm radio, stereo and speaker system, and global positioning satellite or GPS systems.

In the middle of the gulf stream I was laying back having lunch when I realized just how much modern navigation had changed in only 25 years since my first trip across the stream. I thought if I just had a remote control for my auto-pilot, I could cross the stream without even having to get up to check the charts. The satellite radio was on my favorite jazz channel, I had just talked to my wife on my new digital telephone, The gps units were both showing the exact position. The only thing left to do was put out a couple fishing lines to catch a tuna for dinner. Times certainly have changed.

Happy Trails,

Capt. Buck

Ken Rissler has been sailing and traveling world wide for many years and currently operates the web sites I and

NTP or Network Time Protocol to give it its full name is an internet protocol designed to distribute precise time around a network. NTP is a UDP based protocol used to synchronize system time on network infrastructure, such as servers, workstations and network equipment .

This article describes how to utilise the Network Time Protocol authentication features to authenticate time references when synchronizing clients to a NTP server.

NTP Server Security

Network Time Protocol is used to provide a precise time reference for time critical applications. Therefore, NTP can pose a security risk if malicious users attempt to corrupt a NTP timestamp to create a false time on network equipment.

NTP provides increased security in the form of authentication. Authentication is intended to overcome security risks by ensuring that any response received from an NTP time server has come from the intended reference. The client sends a request for time to a NTP server. The server then responds to the client with a precise timestamp along with one of a number of agreed encrypted keys. On receipt of the timestamp, the client un-encrypts the key and verifies it against a list of trusted keys. The client can then be sure that the received timestamp was indeed transmitted from the intended time reference. NTP utilises MD5 encryption (Message Digest Encryption 5), which is a 128-bit cryptographic hash function, which outputs a fingerprint of the key. MD5 is a highly secure encryption algorithm, widely used on the internet for authentication and security purposes.

NTP Authentication Keys

NTP authentication keys are codes that are encrypted on both the server and client that are used to identify the NTP time server. NTP authentication keys are stored in a file usually called 'ntp.keys'. Each authentication key consists of a key number, an encryption code and the key itself.

E.g. NTP server keys:

2 M VisioN

5 M SeRvEr

7 M TiMeLy

10 M MYKEY

12 M TiDy

14 M MaGic

The authenication key number acts as a reference to the specified authentication key. The encryption code specifies the type of encryption to be utilised, e.g. 'M' for MD5 encryption. The actual keys must be identical on both the client and the NTP time server. The client may utilise a sub-set of the authentication keys specified on the NTP Server. The keys are case sensitive.

E.g. client keys:

5 M SeRvEr

7 M TiMeLy

10 M MYKEY

14 M MaGic

Trusted Authentication Keys

Trusted authentication keys are specified in the NTP server configuration file, 'ntp.conf'. Trusted keys specify which subset of keys are currently activeand can be used by the NTP server. This allows a sub-set of trusted keys to be selected from a potentially large keys file. The trusted keys specifier allows key references to be changed easily without editing the keys file. Trusted keys are selected using the 'trusted-keys' configuration command.

E.g.

trusted-keys 7 10 14

This specifies that authentication keys with the key references of 7, 10 and 14 are trusted and can be used by the NTP installation.

NTP Security Summary

Essentially, authentication is used by the client to authenticate that the NTP server is who he says he is, and that no rogue server intervenes. The key is encrypted and sent to the client by the server where it is unencrypted and checked against the client keys to ensure a match. Authenication provides NTP with a high level of security to prevent malicous tampering of timestamp information.

The author, David Evans, develops SNTP and NTP server time synchronization solutions that ensure accurate time on computers and computer networks. Dave has been heavily involved in the development of dedicated time server systems, Ethernet NTP digital wall clock systems and atomic clock products. Click here to find out more about SNTP and Linux NTP Server solutions.

GPS stands for Global Positioning System. It is a satellite radio navigation system built by the United States Department of Defense. Research on the system began in the 60's and the first GPS satellite was launched in 1978. It took a while for the entire system to come online but finally on April 27, 1995 it became fully operational. At first, the GPS network was only for military use but in the 80's the United States government authorized the general public to make use of it too.

The GPS network is composed of:

Satellites

Earth Monitoring Stations

GPS receivers

What is a GPS Satellite?

There are currently 24 satellites orbiting the earth is 6 distinct trajectories. Each satellite completes two orbits around the earth each day, traveling at a speed of about 7,000 MPH. At the highest point in their orbit they are over 12,000 miles above the earth. From this height, the satellite signals can be received over a large percentage of the surface of the earth. A GPS unit works by receiving multiple satellite signals and calculating the receiver's position based on triangulation of the different signals. Accuracy is increased with each additional satellite signal that is received so the orbits of the satellites are set so that at most points on the earth there are at least 4 signals that can be received. Of course, this is in theory only since the landscape around you can block some or all of the GPS signals.

What is a GPS Earth Monitoring Station?

There are four unmanned monitoring stations in the US and one manned master station which is located in Colorado Springs, Colorado. The four unmanned stations relay position data from the satellites to the master station. The master station uses the relayed information to correct the position of the sat tiles and sends the corrected information back to the satellites. This synchronizes the data that each satellite transmits to your GPS receiver and ensures that your receiver is always working with accurate information.

What is a GPS Receiver?

GPS satellites transmit low power radio signals that can only be picked up if your GPS unit has a direct "line of sight" to the satellite. The signals can penetrate things like glass, plastic and clouds but not solid structures like buildings or rocks. A GPS unit works by triangulating your location based on the position of at least three satellites in the GPS system. It compares the time it takes to receive a signal from each of the satellites in range and calculates your location based on the data.

If you are only able to pick up three satellite signals, your GPS unit can report your location in latitude and longitude. However, when the GPS unit picks up signals from at least four satellites it also calculates your altitude. Now it can report your trip distance, distance to a destination, travel speed and even your altitude if your GPS receiver features an altimeter.

How accurate a GPS unit is depends on its ability to find and lock onto a satellite's signal. As you might expect, you get what you pay for and the more expensive GPS units are generally more accurate. The best consumer units claim accuracy to within a few feet while the older or less expensive units can be off up to 30-40 feet or more. Where you plan to use your GPS receiver could determine if it's worth shelling out the extra money for increased accuracy. If you're using your GPS unit in flatter terrain with a good open view of the sky a less expensive unit could perform nearly as well as the top of the line receiver. However, if you plan to use your receiver in dense tree cover, while hiking in ravines or narrow valleys, or among tall buildings you'll gain much better accuracy with a more higher end GPS unit.

Now you know the basics about how GPS works and can answer the question "What is GPS?".

©2007, Mark Hamilton. Read more about handheld GPS at HandheldGPSI

If you get into bird watching, there is a chance you will get really hooked. If so, there is one piece of equipment you must have, but probably haven't thought of.

Birding is one those things you kind of just fall into. You might have discovered it after questioning a neighbor's intent when you see him standing in his backyard look at your home with binoculars. Regardless, one you start taking birding up, you can get addicted. Unlike many addictions, this one will not cause you health problems. If you have it bad, however, it can result in your traveling all over the world to see exotic species you just can't live without.

Bird watching in the US is a fairly safe endeavor. As long as you are not being shot at during hunting season, there isn't a lot that can go wrong. You can get bit by bugs, but most of our country has a fairly organized layout that prevents most people from getting lost and so on. Foreign birding destinations may not be so accommodating.

Let's say you really have the birding itch. You have some money in the bank account and are ready for an exotic trip. Hey, the bird species in the Amazon are known to be exotic and amazing – a veritable heaven on earth for birders. Off to Brazil you fly. Into the Amazon you go with your guide. Unfortunately, you get separated. Despite trying to back track and finally yelling your head off, you are lost. In the Amazon. Houston, we have a problem. A BIG PROBLEM.

If you are planning on taking trips where you are going to be in the proverbial jungle, you need to fork over some cash for a very important piece of equipment. In this case, we are talking about a GPS unit. GPS is simple a global positioning unit that tells you where you are on this great planet of ours. The units used to be the stuff of spy stories, but they are sold over the counter now and are common in a number of new cars. They are not cheap, but are cheaper than they used to be. You can expect to pay $400 on up for one. If you're lost in the Amazon or somewhere else, you will be glad you spent the money.

Okay, so a GPS unit tells you where you are. So what? You already know you are lost. Well, these handy, dandy little units do something special. Before you start walking away from your vehicle, you can program in your starting location. If you get lost, the unit can tell you where you are now in relation to the original starting point. Now you know what direction to head, which will both get you back to safety and make you feel a whole lot better!

You probably don't need a GPS unit for birding around your home area. If you are taking a trip to an unknown location, however, they are well worth the expense.

Rick Chapo is with NomadJ - makers of bird watching journals that make unique gifts for birding enthusiasts.

Time is an abstract concept that we generally take for granted. Time passes in years, months, days, hours, minutes and seconds without much thought. However, humans have developed extremely complex ways of measuring time and maintaining accurate time references. From sundials to atomic clocks and NTP time servers, to maintain time on computer networks, people have strived to accurately measure time.

This article discusses the fundamental nature of time, how it is measured, by movement, and how it is related to the concept of space. It also describes the spin-offs from high technology time references and International time standards.

Time Measured By Movement

Humans relate and measure time with reference to movement. The hands of a clock moving around a clock-face describe hours, minutes and seconds. A year is described by the rotation of the Earth around the Sun. A month is described by the rotation of the moon around the Earth. A day is described by the rotation of the Earth itself. In fact space and time are closely intertwined.

Space and Time

Einstein's General Theory of Relativity suggests time is closely related to the concept of space. Both time and space began with the Big Bang and the creation of the Universe some 14 Billion years ago. At the instance of the Big Bang, all matter was tightly packed into a tremendously dense, infinitely small, hot state. The universe, suns, planets and all matter contained within them emerged from this infinitely small dot.

The Theory of Relativity suggests that the Universe will reach a maximum size and begin to collapse back to its original state. The universe will become denser and hotter and return to a state similar to that from which it started. However, some of the latest observations of space have shown that galaxies are moving away from us at an ever-increasing rate. This implies that the Universe will continually cool and expand.

Measuring Time

The study of time measurement is called Horology. During Human history a large variety of devices have been used to measure time. Sundials were among the earliest examples of time measurement devices. A sundial casts a shadow on a series of markings that indicate the current hour of the day. More commonly in use today are mechanical or electronic clocks. Mechanical clocks are generally regulated by the movement of a pendulum. Electronic clocks are based on the resonance, or movement, of a crystal oscillator.

Modern atomic clocks, based on frequency reference masers, can maintain accurate time measurement to an astonishing degree. Atomic clocks form the basis of the Global Positioning System (GPS), which can provide positioning information for any location on the planet. NTP time servers use the Network Time Protocol and GPS time to ensure time synchronisation of computers and computer networks across the globe.

World Time

The measurement of time is critical to the modern way of life. So much so that International Standards exist to coordinate time. The basis of world time is Coordinated Universal Time (UTC). World time is split into a series of longitudinal time zones. Time zones are generally one hour apart and their local time is referenced as an offset from UTC time.

Summary

Time is an abstract concept that is inextricably linked to the concept of space and the creation of the Universe. Humans have strived for millennia to maintain accurate time references. Modern technology allows us to maintain highly accurate time references. Atomic clock technology has resulted in the creation of the GPS system and NTP time servers. The world has created an internationally agreed measurement of time, UTC time.

The author, Simon Davies, is a Product Author who specialises in the documentation of GPS NTP server and time server synchronisation solutions. Click here if you would like more information about NTP Server and Time Server solutions.

A tracking device that is used as a way for locating people and places is called Global Positioning System or GPS for short. This device works by the use of satellites and was first used only by the military. This type of tracking technology is now being used in many devices that can be purchased by consumers everywhere. GPS navigation systems are being installed in many of the new vehicles that are being designed. Other devices are being designed for older models that can be installed into any vehicle. You can purchase handheld devices for hiking or other activities. One of the most common devices that contain this tracking system is the cell phone. Cellular GPS systems were installed in cell phones as a way of tracking people in the event they were in trouble.

Using Cellular GPS technology requires that the Global Positioning System be used together with the towers and satellites used by the network. These networks can locate a person within 100 meters of their location. However, this technology is a lot more basic than what is used in navigational systems. It requires that you have the assistance of a wireless network or you can not use this tracking system. Still it is a nice addition to any cell phone. You will feel a lot safer knowing that if you get lost or break down on the road somewhere your cell phone can be used to find your location.

The reason that this navigational technology was first placed into cell phones was because the Federal Communications Commissions required that phone companies design their cell phones with some type of tracking device. The GPS technology was the most advanced and simplest to use therefore, most phone companies decided it was the best choice which is how Cellular GPS was born. All newer model cell phones have this tracking device even if you do not have access to it personally.

The Cellular GPS technology that is found in your cell phone can help you find directions just like the navigational systems that you see installed in many vehicles. You have the convenience of having your phone and a way to find the fastest way to get to your destination. This is great technology that has came a long way. However, keep in mind that even though GPS technology is found in most all new phones you still may not have access to it. This will depend on the phone service that you choose, the plan you decide on and the type of cell phone that you buy.

Learn more about GPS Cellular and other GPS Tracking Devices at

Global Positioning Systems (GPS) are growing in rapidly popularity and are becoming an everyday navigational tool. You commonly see GPS installed in a vehicle but it is also available in a hand help form that is similar to size of a pocket PC or cell phone. GPS units have the ability to be loaded with map data of any where in the world.

A GPS uses a series of satellites to pinpoint your exact location with amazing accuracy. There are more sophisticated systems that have the ability to determine you position on the ground as well as an altitude reading.

GPS units have grown so much in popularity that it forced the prices down to a reasonable amount as long as you are looking for a basic unit that provides you with your latitude and longitude. If you want more features you can go with a more expensive sophisticated unit. Considering there is such a large range of options on a GPS unit need to determine what you will be using the system for before purchasing.

Garmin is the world's top manufacturer of GPS unit. You can choose from an enormous range of Garmin units that are on sale in retail stores and online. These Garmin GPS units range not only in features but in color and size as well, so you are sure to find the unit that is perfect for you.

Those who are purchasing a GPS unit to aid while they are hiking should go with a waterproof design for when you are crossing rivers and to protect you if you were to get stuck in a storm. Some models have different numbers of waypoints which is another word for terrestrial coordinates such as latitude, longitude, and altitude. Basic waypoints are effective for the majority of hikers but you can always upgrade to a model that offers more features.

A popular Garmin GPS model for hikers is the eTrex because it is lightweight, waterproof, and has the ability to display up to five hundred waypoints. This device also features a number of controls on the side which gives you the ability to control the size of the display.

A Garmin Aviation GPS is fully equipped with Jeppesen databases as well as background land mapping. The newest GPS has log-book compatible features which make flight reporting much easier.

Most Garmin GPS units range from one hundred to three hundred dollars, but there are some systems that are priced well above the three hundred mark. Purchasing GPS units is just like any other electrical device; you get what you pay for. If you spend around two hundred dollars you are able to get a device that is suitable for hiking.

Natalie Aranda is a freelance writer. A Garmin Aviation GPS is fully equipped with Jeppesen databases as well as background land mapping. Most Garmin GPS units range from one hundred to three hundred dollars, but there are some systems that are priced well above the three hundred mark.

In modern computer networks, computer time synchronization is of critical importance. Many transaction-processing operations require accurate synchronisation of client and server in order to maintain a coherent processing order.

The latest versions of the Microsoft Windows operating systems have a time synchronization utility built into the operating system, called 'w32time'. The Microsoft time applet runs as a service and allows a Windows network to provide synchronization of a domain.

This article discusses how to configure the latest Windows operating systems to operate as a network time server. The article describes how to change the registry entries to configure w32time.

Before changing any of the registry settings, it is generally a good idea to backup the registry. This is so that if any problems arise, the registry can be restored to its previous state.

Microsoft Windows 2000 Based Network Time Server

Microsoft Windows 2000 has a pre-installed network time synchronization service, which can synchronize to a NTP Time Server. By changing the time service registry settings, the service can also act as a network time client and time server to synchronize other computers in the domain.

Firstly check to ensure the 'Windows Time' service, w32time, is present in the systems service list. The application executable is 'w32time.exe'. The parameter list for w32time should be present in the in the registry at: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters

The Windows 2000 operating system can operate as a time client and synchronise to a time server by setting the parameter 'NTP Server' to the IP address of a Time Server.

By default, the Windows 2000 machine will synchronize to the specified time server every 8 hours, or 3 times a day. In order to maintain more accurate synchronization, the synchronization period can easily be reduced. Set the 'Period' parameter to how many times each day synchronisation is required. Setting the parameter to 48 will activate synchronization with the time server once every half hour, which is about right.

The Windows 2000 operating system can also be configured to act as a time server by setting the 'Local NTP' registry flag to the value '1'.

After changing the registry settings for w32time, the service must be restarted for the settings to be activated. 'W32time' can be re-started from the service control panel in the Administrative Tools menu. The service can also be controlled via the DOS net command by using: 'net start w32time' and 'net stop w32time'

Microsoft Windows 2003 Based Network Time Server

Microsoft Windows 2003 expanded on the original Windows 2000 SNTP synchronization service by providing a true NTP implementation. The pre-installed Windows 2003 time service can synchronize to a NTP Server. By modifying registry settings, the time service can act as both a time server and client to synchronize other servers and workstations in the domain.

Ensure that the 'Windows Time' service, w32time, is present in the systems service list. The registry parameters for the Windows 2003 w32time should be present in the registry at: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time

To configure Windows 2003 to synchronize to an external time server, edit the following entries in the registry:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config\AnnounceFlags

Set the 'Announce Flags' registry entry to 5 indicating a reliable time reference.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NTPServer\Enabled

Changing the 'Enabled' flag to the value 1 enables the NTP Time Server.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\Type

Set the 'Type' registry entry to 'NTP', which specifies synchronization to a NTP time server.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NTPClient\SpecialPollInterval

The 'Special Poll Interval' registry entry defines the period in seconds that the Windows 2003 operating system should poll the time server. A recommended value is 900, which equates to a polling period of every 15 minutes.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\NtpServer

This parameter is used to provide domain names or IP addresses of NTP time servers that the operating system can synchronize to. Each domain name or IP address should be separated by a space.

Debugging the Windows Time Synchronisation Service

A number of problems may be encountered when configuring the Windows time synchronisation service. Both the SNTP and NTP protocols operate using the UDP protocol. Therefore, the TCP/IP network protocol must be active for SNTP\NTP to operate correctly. Additionally, synchronisation problems may become apparent when SNTP or NTP attempts to synchronise to an inaccurate time reference or if network round-trip delays are excessive.

Synchronizing Time on Other Network Devices

In addition to synchronizing Microsoft Windows machines, network time servers can also be utilised to synchronise other network devices, such as switches, routers and hubs. Any network device that can synchronise to a NTP or SNTP time server can be pointed to the Windows network time server to synchronise time. In this way the whole network and accompanying devices can be synchronised to an accurate time reference.

David Evans is an experienced Systems Engineer who has been involved in the development of NTP time server systems over a number of years. Ranging from dedicated NTP server systems to NTP synchronised Ethernet digital wall clock systems, Dave has a wealth of experience in the field of network time synchronisation. Please click here for more information about NTP server and time server solutions.

Car manufacturers are getting on top of car safety features being demanded by motoring groups, road safety organisations and motoring industries across the world.

At the 2006 Detroit Auto Show, Honda showed off its line of ASV-3 vehicles, which have the latest advanced road traffic accident safety technologies. Such vehicles could potentially reduce the number of car accident compensation claims that arise as the result of car crashes.

They include a system that uses cameras and radars to provide drivers with information about approaching vehicles and other obstacles. Sensors exchange position data about cars with the same technology on the road to let the driver know where they are in relation to other cars.

Caution can also be given if cars get too close and there is a risk of a vehicle accident so that appropriate repositioning can occur.

Other safety features give drivers steering and brake assistance. A car's emergency response system with GPS (Global Positioning System) technology helps drivers who experience a road traffic accident to get help.

Honda said it plans to offer all of these safety features in mass production vehicles and so it is thought that fewer car accident compensation claims will be made. Real-time traffic information (RTTI) has already been added to its navigation systems in select 2007 models of cars, including the BMW 6 Series.

The premium feature, free to owners for four years, gives drivers up-to-date road traffic information and dynamic re-routing maps in the case of congestion or car accidents.

The company is providing the service via Clear Channel's Total Traffic Network, amongst other sources of data.

In 2007, a service called Weatherlink will be introduced which will deliver real-time weather information to in-car navigation systems to reduce the number of car accidents and car accident compensation.

Next year, Volvo will sell a new model with a blind spot information system (BLISS), which helps drivers identify another vehicle in the car blind spots.

Other models include a wireless communication system, with a digital display on the dashboard that would indicate when another car was within a quarter of a mile. The icon would change from green to yellow if the car came within cautionary distance.

If it's possible that a collision will occur, the icon will change to red and the seat will begin to vibrate, alerting the driver to stop or change lanes. An automatic braking feature will immediately stop the car, which could prevent car accidents and reduce the amount of car accident compensation claims that are made.

Earlier this year, BMW started selling cars with night vision capabilities so that drivers can see better driving home in the dark.

BMW uses infrared technology with thermal-imaging cameras that can detect human beings, animals and objects in front of the car before they become visible to the human eye in headlights to reduce car accidents and car accident compensation.

The car of the future won't just be more fuel-efficient. It's also likely to help you get where you're trying to go if you're facing dangerous conditions.

This article may be published on another website free of charge, on the condition that a link is provided from this article to our website: Car Accident Advice Line helps people to claim compensation after they have been injured in a car accident that was not their fault. You can call us now on 0808 143 43 42

Each PC has an integral real-time clock that maintains internal system time. PC clocks have low-cost crystal oscillators that are notoriously prone to drift. With time each computer in an organisation drifts at different rates. After a relatively short period of time, there can be large differences between the system times of each computer on the network. Unsynchronised computer time can lead to many problems.

This article discusses the importance of network time synchronisation and of having an accurate network time server resource in an organisation.

Computer Time

Computer system time is maintained by low-cost real-time clock and crystal oscillator components. Crystal oscillators are manufactured with relatively low tolerance; each one oscillates at a slightly different rate. Additionally, crystals change frequency slightly with temperature variance. This all has the effect that computers are notoriously poor at maintaining an accurate time. Each computers time in an organisation will drift at slightly different amounts unless they are synchronised in some way.

Network Synchronisation Issues

Poor network time synchronisation can cause a number of problems. In a transaction-processing environment, transactions generated from various PC's may have an irregular time-stamp. Unsynchronised computers may be vulnerable to fraud, particularly in an environment where transaction time is an important issue. Additionally, problems can arise with shared network files, if computers with unsynchronised system times are using the same resource.

Network Time Servers

Network time servers obtain accurate time from an external time reference and offer an accurate time resource to network time clients. Time servers utilise the Network Time Protocol (NTP), which is a UDP based protocol over TCP/IP. A number of external time references are available, such as GPS and regional radio frequency transmissions. The GPS (Global Positioning System) is a subscription free service that offers highly accurate time. GPS antennas require a good view of the sky in order to obtain timing information. Regional time and frequency transmissions include: MSF transmitted from Rugby (UK) with coverage of the British Isles and North-Western Europe; DCF-77 transmitted from Frankfurt (Germany) with coverage of much of Central Europe; WWVB transmitted from Colorado (US) with coverage of much of the US and Canada. Other regional radio time reference include: TDF (France); CHU (Canada); JJY (Japan) and HBG (Switzerland).

Internet Time Servers

There are many Internet based NTP time server resources available that can be utilised for network time synchronisation. However, utilising an Internet time server can have a number of issues. The time server is located outside of the firewall, so a port must be left open in order to access the time server. This obviously has security implications. Additionally, time server accuracy, reliability and provision of service may be problematic.

Local Dedicated Network Time Server

A local dedicated network time server overcomes many of the issues associated with Internet based references. A local time server is located inside the security firewall and so requires no external access, negating security issues. Additionally, a local time server will have improved accuracy due to consistent network paths between clients and server. Also there is no provision of service issues since the time server is owned by the organisation where it is installed.

Summary

Network time synchronisation is an important factor in modern computer network installations. Internet based network time servers may provide a solution to network synchronisation, but there are security issues that arise with there use. Local dedicated network time servers overcome the security and accuracy issues with internet based services by providing a secure, accurate and reliable network time synchronisation solution.

The author, Dave Evans, is a Software Engineer who is involved in the development of Radio and GPS NTP time server synchronization solutions that ensure accurate time on computer networks. Click here to find out more about Radio and GPS NTP and Time Server solutions.

Network Time Protocol (NTP) is used to advertise time to network time clients on an IP network. NTP is a UDP based protocol that is used to synchronise system time on network devices. This article describes how to utilise NTP authentication to authenticate a time reference when synchronising network time clients to a NTP server.

NTP Server Authentication

NTP is used to provide an accurate time reference for time critical processes. Therefore, NTP can pose a security risk if malicious users attempt to modify or replicate a timestamp to create a false time on a network device.

NTP authentication is intended to overcome security risks by ensuring that any response received from an NTP server has actually come from the intended reference. The client sends a request for time to a NTP server. The NTP server responds to the client with a timestamp along with one of a number of agreed encrypted keys. On receipt of the timestamp, the client un-encrypts the key and verifies it against a list of trusted keys. The client can then be sure that the received timestamp was indeed transmitted from the intended NTP server. NTP utilises MD5 encryption (Message Digest Encryption 5), which is a 128-bit cryptographic hash function, which outputs a fingerprint of the key. MD5 is a highly secure encryption, widely used on forums and by online communities for authentication purposes.

NTP Keys

NTP keys are codes that are encrypted on both the server and client that are used to identify the NTP server. NTP keys are stored in a file usually called 'ntp.keys'. Each key consists of a key number, an encryption code and the key itself.

E.g. NTP server keys:

1 M secret

5 M SeRvEr

7 M TiMeLy

10 M MYKEY

11 M TroPical

14 M MaGic

The key number acts as a reference to the specified key. The encryption code specifies the type of encryption to be utilised, e.g. 'M' for MD5 encryption. The actual keys must be identical on both the client and the NTP server. The client may utilise a sub-set of the keys specified on the NTP Server. The keys are case sensitive.

E.g. client keys:

5 M SeRvEr

7 M TiMeLy

10 M MYKEY

14 M MaGic

Trusted Keys

Trusted keys are specified in the NTP configuration file, 'ntp.conf'. Trusted keys specify which subset of keys are currently activeand can be used by the NTP server. This allows a sub-set of trusted keys to be selected from a potentially large keys file. Trusted keys are selected using the 'trusted-keys' configuration command.

E.g.

trusted-keys 5 7 14

This specifies that keys with the key references of 5, 7 and 14 are currently trusted and can be used by the NTP installation.

Summary

Essentially, authentication is used by the client to authenticate that the NTP server is who he says he is, and that no rogue server intervenes. The key is encrypted and sent to the client by the server where it is unencrypted and checked against the client keys to ensure a match.

David Evans develops NTP server time synchronization solutions that ensure accurate time on computers and computer networks. Dave has been heavily involved in the development of dedicated time server systems, NTP synchronized digital clock systems and atomic clock synchronization products. Click here to find out more about NTP Server solutions.

The latest Windows operating systems from Microsoft have a time synchronization service installed by default called 'Windows Time'. The time service allows a Windows network to provide time synchronization of all machines within a domain. This article introduces how to set up the Windows 2000 and Windows 2003 operating systems to operate as a NTP time server. The article describes how to modify registry entries to configure the Windows Time Service.

Before modifying any registry entries it is a good idea to backup the registry. In the even of any problems, the registry can then be restored to its former state.

Windows 2000

Windows 2000 has an integrated network time synchronization service, installed by default, which can be configured to synchronize to a Time Server. In fact, by changing associated registry settings, the service can act as both a time client and a time server to synchronize other network time clients.

The Windows Time service should be present in the systems service list. The application executable is 'w32time.exe'. The parameter list for time service should be present in the in the registry at:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParameters

The Windows 2000 operating system can operate as a time client and synchronize to a time server by setting the parameter 'NTP Server' to the IP address of a Time Server.

By default, the Windows 2000 machine will synchronize to the specified time server every 8 hours, or 3 times a day. This may not be enough to maintain accurate synchronization and can be easily increased. Setting the 'Period' parameter to how many times each day synchronization is required can reduce the period. Setting the 'Period' parameter to 48 will activate synchronization with the time server once every half hour.

The Windows 2000 operating system can also be configured to act as a time server by setting the 'Local NTP' registry setting to '1'.

After changing any of the registry settings for the windows time service, the service must be restarted for the settings to take effect. The time service can be started or stopped from the service control applet in the Administrative Tools menu. The service can also be controlled via the DOS net command using:

'net start w32time' and 'net stop w32time'

Windows 2003

With Windows 2003, Microsoft has reportedly expanded on the original Windows 2000 time service by providing a true NTP implementation. The Windows 2003 time service, installed by default, can synchronize to a NTP Server. Indeed, by changing registry settings, the time service can act as both a time server and client to synchronize other network clients in the domain.

The 'Windows Time' service should be present in the systems service list. The application executable is 'w32time.exe'. The parameter list for the Windows 2003 time service should be present in the registry at:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32Time

To configure the Windows 2003 operating system to synchronize to an external time server, edit the following registry entries:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParametersType

Set the 'Type' registry entry to 'NTP', which specifies synchronization to a NTP time server.

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNTPClientSpecialPollInterval

The 'Special Poll Interval' registry entry defines the period in seconds that the Windows 2003 operating system should poll the time server. A recommended value is 900, which equates to a polling period of every 15 minutes.

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeConfigAnnounceFlags

Set the 'Announce Flags' registry entry to 5 indicating a reliable time reference.

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNTPServerEnabled

Changing the 'Enabled' flag to the value 1 enables the NTP Time Server.

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParametersNtpServer

The 'NTP Server' parameter is used to provide a list of DNS names or IP addresses, separated by a space, of time servers that the Windows 2003 operating system can synchronize to.

Troubleshooting

A number of problems may be encountered when setting up the Windows Time Service. Network Time Protocol operates using the UDP protocol over TCP/IP. Therefore, the TCP/IP network protocol must be operational for NTP to operate successfully. Synchronization problems may also arise when NTP attempts to synchronize to an inaccurate timing reference or if network delays are overly excessive.

Synchronizing Network Components

In addition to synchronizing Windows servers and workstations, time servers can also be used to synchronise network components, such as switches, routers and hubs. Any network components that can synchronise to a NTP time server can be pointed to the Windows server to achieve synchronization. In this way the whole network and accompanying components can be accurately synchronized.

D. Evans develops NTP time server synchronization solutions that ensure accurate time on computers and networks. Dave has been heavily involved in the development of dedicated time server systems, NTP synchronized digital clock systems and atomic clock synchronization products. Click here to find out more about Time Server solutions.

The MSF-60 atomic clock synchronised radio time transmission is utilised by many NTP Time Server and PC computer systems to provide accurate synchronisation of time critical applications. This article describes how the MSF-60 time signal is decoded by NTP Time Server and computer systems to provide an accurate timing reference.

The MSF-60 Time Transmitter

The MSF-60 time signal is a long-wave radio time signal broadcast from Rugby, Warwickshire, England. The radio signal is maintained by BT Radio Engineering Services under contract from the National Physics Laboratory (NPL). From 1st April 2007 the MSF-60 transmission will transfer to Anthorn, Cumbria, using atomic clock and time code equipment provided by VT Communications.

When decoded, the MSF-60 time signal provides a highly accurate timing reference for NTP Servers, clocks and other computer timing equipment.

Signal Coverage

The MSF-60 radio time signal broadcast can be satisfactorily received throughout the British Isles and much of North-West Europe. Reception problems can generally be attributed to local environmental conditions. The radio signal can be blocked by metal structures or frames, which act as a Faraday cage. Additionally, signal reception can be difficult near electrically noise equipment. Radio receivers should also be located above ground.

The MSF-60 Time Code

Time and date information is transmitted continuously, repeated each minute. The data is transmitted as on-off carrier modulated, pulse-width coded data signal. Each data bit is transmitted as one pulse per second. The data transmitted consists of the current time and date, leap second indicator, daylight saving time indicator and parity bits.

A 500-millisecond carrier off period indicates the start of each minute. The other 59 seconds consist of between 100 and 300 milliseconds carrier off and at least 700 milliseconds of carrier on.

Transmitted Data.

Time and date information is presented in BCD (Binary Coded Decimal) format and is encoded as follows: bits 1-16 are used to convey information about the difference between atomic and astronomical time (DUT1).

The remaining bits, 17 to 59, contain date and time information about the current minute as follow: bits 17-24, BCD encoded year (00-99); bits 25-29, BCD month of year (01-12); bits 30-35, BCD encoded day of month (01-31); bits 36-38, BCD encoded day of week (0-6, 0 = Sunday); bits 39-44, BCD encoded hour (00-23); bits 45-51, BCD encoded minute (00-59).

During British Summer Time, bit 58 is set to '1'. Also in the 60 minutes leading up to a change in British Summer Time, bit 53 is set to '1'.

Dave Evans develops NTP Time Server synchronisation systems to ensure accurate time on PC’s and computer networks. Dave has been involved in the development of dedicated NTP Time Server systems, NTP synchronised digital wall clock systems and atomic clock time synchronisation products. Click here to find out more about SNTP and NTP Time Server Systems.

Do you travel a lot? Have you found yourself wishing you had a better way of finding your end point instead of using old fashion paper maps? If so, then you need an Car and Truck GPS. If you don't know a lot about these devices, then you should know that they are the most modern way to find your way away. They can tell you exactly how to reach your end point by giving you precise directions. These directions are so advanced that it can even tell you when you need to make a turn and in which direction you are traveling. Choosing an Car and Truck GPS that is right for you will depend on how you plan on using the system.

These navigational systems work by using satellites to find your location and then mapping out a route to your end point. Without pinpointing your current location a new end point cannot be found. The system uses latitude and longitude to determine where you are and then to find the location you programmed as your end point. These systems can give you several routes to the location that you are searching for and it is your choice which one you decide to use. There are several different types of Car and Truck GPSs that you can choose for your vehicle.

There are both cheap and expensive Car and Truck GPSs available. Some of the cheaper models plug into the cigarette lighter of your vehicle and is great for the occasional use. However, these are a little harder to use than some of the other types. If you plan on using your system often, then you may want a bigger one with more features. There are several styles and sizes of these to choose from, so make sure you pick one that is suited for your vehicle. You wouldn't want to choose a system that makes it uncomfortable when passengers are riding.

Some of these systems feature several different ways for you to find your end point. In other words, you can find a end point by using things like the address of the place you are searching for, a street name or choose a location from the map. These systems can use voice commands to help you find your end point. Many of them will also tell you the location of the nearest airport, bus station, train stations, ATM's and banks. The Car and Truck GPS is a great asset to any vehicle that can ensure you never get lost or miss a turn again.

Are You Looking for Auto GPS System? Find it here at…

PC's have internal real time clocks designed to maintain system time. The internal clocks rely on relatively low-cost crystal oscillators, which are notoriously inaccurate. In many cases PC system time can drift by several minutes each day. This article describes various methods of maintaining a highly accurate time on your PC. It describes how to utilise Internet time references, radio and GPS clocks and dedicated NTP server systems.

Internet Time References

The Internet utilises the Network Time Protocol to distribute accurate time information to network time clients. NTP has been an important part of the Internet for over 25 years. The protocol was born through the need to provide synchronisation of time critical processes across the Internet.

Most modern operating systems, including Windows XP, 2003 and LINUX have the ability to synchronise time with a NTP Server. There are a host of Internet based NTP Servers with public access that can be used to synchronise your PC. Below is a list of popular Internet based public access NTP Server references:

time.nist.gov - US based time reference.

ptbtime1.ptb.de - German time reference.

ntp.my-inbox.co.uk - UK time reference.

canon.inria.fr - French time reference.

- Canadian time reference.

Windows XP has pre-installed SNTP client software that can synchronise time with a NTP server. This is achieved by simply entering the domain name of an Internet NTP Server in the time properties tab. The host computer will then periodically contact the NTP Server and synchronise the system time to the specified reference.

LINUX and UNIX systems have the NTP software distribution available from the NTP website, The NTP application runs as a daemon, constantly monitoring specified NTP servers. The application reads a list of NTP servers from a configuration file, 'ntp.conf', and periodically synchronises time. A list of NTP server references is specified with the 'server' configuration command thus:

server time-a.nist.gov # NIST, Gaithersburg, Maryland NTP server

server time-c.timefreq.bldrdoc.gov # NIST, Boulder, Colorado NTP server

Once configured, the NTP daemon can be started, stopped and restarted using the commands: 'ntpd start'; 'ntpd stop' and 'ntpd restart'.

Radio and GPS Clock Timing References

There are many commercially available radio and GPS clock timing references for PC's. Radio and GPS clocks obtain accurate time from national radio timing references or from the GPS system. The devices have serial or USB interfaces and provide an accurate timing reference to PC's. Driver software periodically synchronises the system time of the host computer to the received reference time. Often reference clock drivers are available that interface to the NTP application software to provide your own dedicated NTP server.

Radio time receivers often have the advantage of having the ability to obtain a good signal, indoors, close to the host computer. However, the signal can only be received locally to the transmitter. There are a number of radio time broadcasts available: MSF transmitted from Rugby, UK; DCF-77 transmitted from Frankfurt, Germany; WWVB transmitted from Colorado, USA; CHU, Canada and TDF, France. GPS has the advantage of providing a global time and frequency solution; however, an externally located antenna is required which can be impractical.

Dedicated NTP Servers

NTP servers are dedicated time servers that obtain time from an external source, such as radio or GPS, and provide a network with an accurate timing reference. NTP servers are generally rack-mountable devices with an external antenna and an Ethernet connection. The devices obtain time from a radio or GPS timing reference and maintain an accurate internal time. The accurate time is then distributed to network time clients over an IP network. Dedicated NTP servers often minimize the set-up and configuration effort required to get a NTP server installation up and running.

Dave Evans develops NTP Server synchronisation systems to ensure accurate time on PC’s and computer networks. Dave has been involved in the development of dedicated NTP server systems, NTP synchronised digital wall clock systems and atomic clock time synchronisation products. Click here to find out more about SNTP and NTP Server Systems.

The Windows operating systems from Windows 2000 onwards has an in-built time synchronisation service – 'Windows Time'. The Windows Time service facilitates a Windows network to provide synchronisation of all machines within a domain. This article describes how to configure the Windows 2000 and Windows 2003 time service as a NTP server. It shows how to manipulate registry entries to configure the Windows Time Service.

Before modifying registry entries it is good practice to backup the Windows registry. This allows the registry to be restored in the event of problems.

Windows 2000 Configuration

Windows 2000 has an integrated time synchronisation service, installed by default, which can synchronise to a NTP Server. Indeed, by manipulating registry settings, the service can act as both an SNTP client and SNTP server to synchronise other network clients.

The 'Windows Time' service should be present in the systems service list. The application executable is 'w32time.exe'. The parameter list for w32time can be found in the registry at:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters

Windows 2000 can operate as an NTP client and synchronise to an NTP server by setting parameter 'NTP Server' to the IP address of a NTP Server.

By default, the Windows 2000 machine will synchronise to the specified NTP server every 8 hours (or 3 times a day), which may not be enough to maintain accurate synchronisation. The period can be reduced by setting the 'Period' parameter to how many times a day synchronisation is required. Setting the period to 48 will activate synchronisation with the NTP server once every half hour.

Windows 2000 can also be configured to act as an NTP server by setting the 'Local NTP' parameter to '1'.

After editing any of the registry entries for the windows time service, the service must be restarted for the settings to take effect. The services can be started or stopped from the service control applet in 'administrative tools'. Alternatively the service can be controlled via the DOS net command thus:

net start w32time

net stop w32time

Windows 2003 Configuration

Windows 2003 has expanded on the original Windows 2000 time service by providing a true NTP implementation. The time service, installed by default, can synchronise to a NTP Server. Indeed, by manipulating registry settings for the service it can act as both an NTP server and client to synchronise other network clients in the domain.

The 'Windows Time' service should be present in the systems service list. The application executable is 'w32time.exe'. The parameter list for w32time can be found in the registry at:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time

To configure a Windows 2003 machine to synchronise to an external NTP server, edit the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\Type

Change the server type to NTP by specifying 'NTP' in the 'Type' registry entry.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config\AnnounceFlags

Set the 'Announce Flags' registry entry to 5, to indicate a reliable time source.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NTPClient\SpecialPollInterval

The 'Special Poll Interval' registry entry defines the period in seconds that the Windows 2003 machine should poll the NTP server. A recommended value is 900 seconds, which equates to every 15 minutes.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NTPServer\Enabled

Changing the 'Enabled' flag to the value 1 enables the NTP Server.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters\NtpServer

The 'NTP Server' parameter is used to provide a list of IP addresses or DNS names, separated by a space, of NTP servers that the Windows 2003 machine can synchronise to.

NTP Troubleshooting

A number of problems can be encountered when configuring the Windows Time Service. NTP operates using the UDP protocol over TCP/IP. Therefore the TCP/IP network infrastructure must be operational for NTP to be effective. Synchronisation issues may arise when NTP attempts to synchronise to an inaccurate time reference or if network delays are excessive.

Synchronising Network Infrastructures

As well as synchronising Windows servers and workstations, NTP can also be used to synchronise network hardware, such as routers, switches and hubs. Any network hardware that can synchronise to a NTP server can be pointed to the Windows server to achieve time synchronisation. In this way the whole network and accompanying infrastructure can be synchronised.

Dave Evans develops NTP Server synchronisation systems to ensure accurate time on PC’s and computer networks. Dave has been involved in the development of dedicated NTP server systems, NTP synchronised digital wall clock systems and atomic clock time synchronisation products. Click here to find out more about SNTP and NTP Server Systems.

Synchronised digital clocks allow a number of individual time clock displays to show identical accurate time. Individual stand-alone digital clocks each drift at different rates eventually all display differing times. This article discusses the methods utilised to achieve synchronised digital clock time displays throughout an organisation.

Radio-Controlled Digital Clock

Many digital clocks are available with radio receivers that synchronise to radio time broadcasts that are freely available in many areas. Time and frequency broadcasts such as the DCF-77 broadcast from Germany, the MSF-60 broadcast from the UK and the WWVB broadcast from the US. These time and frequency broadcasts provide an accurate timing reference for digital clocks to synchronise. However, often installation problems are encountered due to the fact that in particular locations the radio signal quality may be very low or even non-existent. Mounting radio-controlled digital clocks in basements or inside metal structures or too close to electrically noisy equipment can all cause radio reception difficulties. Also, radio transmissions are local to the transmitter and do not extend beyond a finite range.

Wired Digital Clock Systems

Many synchronised digital clock systems operate on a bespoke serial network. They utilise a multi-drop RS422 or RS485 wired serial network. Each clock is generally mains powered at the point of installation. The digital clocks synchronise to a master clock on the wired network that may be synchronised to a GPS or radio external time reference. Only an optimally located single external timing receiver is required to synchronise all the clocks. The advantage of such systems is that the equipment costs are fairly low. However, this can often be outweighed by the installation costs of a dedicated network for the clock system.

Ethernet NTP Digital Clock Systems

Ethernet NTP digital wall clock time displays utilise NTP over Ethernet to display a continuously accurate synchronised time. The digital clocks connect directly to an Ethernet network and periodically synchronise using SNTP to a NTP Time Server.

Ethernet NTP digital clock time displays are available with four-inch high numerals with four or six digits. The large time display makes the clocks easily visible from a distance of up to 150 feet. The large wall clock obtains time from an intranet or Internet based NTP server, to provide an accurate time display, synchronised to one-fifth of a second. Ethernet NTP digital wall clocks operate with any NTP or SNTP time resource such as a dedicated NTP Time Server. Additionally, the units can utilise Internet based time sources, such as NIST.

For simplicity of operation, synchronised digital clocks are Power-over-Ethernet (PoE) devices (IEEE 802.af) using the same network components as IP telephones. The large digital wall clocks plug into an Ethernet jack on a local area network. No mains socket is required; the device is powered from the network jack plug. Installation is therefore very straightforward, and it's easy to move units around.

A synchronised Ethernet NTP digital clock system has a number of advantages. Firstly, installation costs are reduced due to the use 'common' network components, such as CAT5 and Ethernet hubs and switches. In many cases the network infrastructure may already be present. Additionally, no mains spur is required at the clock location, reducing installation costs. The clocks can also reference multiple time sources in the event of failure of a time reference.

The devices are powered over standard CAT5 cabling using Power-over-Ethernet (IEEE 802.af), the same Ethernet standard as Voice-over-IP telephones. If your network is not PoE enabled, single or multi-port mid-span converters (power injectors) are available at very reasonable cost.

Ethernet NTP Digital Clock Configuration

Networked digital clocks can easily be configured from any PC on the same network segment as the clocks. Configuration simply consists of opening a telnet session to a specified clock and entering password information. Once a connection is established there are a number of configuration commands available to the administrator. All digital clocks can therefore be configured from a single point.

Time Zone Configuration

NTP Ethernet digital clocks can be configured to the display local time in any time zone. There are a number of pre-configured common time zones that can easily be selected. Alternatively, any time zone and daylight saving configuration can be specified by supplying offsets and daylight saving start and end times.

Dave Evans develops Digital Clock and NTP Server synchronisation systems to ensure accurate time on PC’s and computer networks. Click here to find out more about NTP Server and Digital Clock Systems.

Television is not the only "cool" thing using satellites these days. For anyone who likes to travel or wander, the GPS satellite navigation systems that have been on the market for a few years are handy on-the-road companions. Some automotive manufacturers offer GPS in select car models however GPS can also be purchased after market and can be operated outside of the car as well. Satellite GPS navigates through signals received from the myriad of satellites orbiting earth and is extremely accurate using the maps that are loaded into its memory.

So what does a satellite GPS device offer that a road atlas doesn't? GPS satellite systems provide directions while traveling, generally through voice instructions which allow the person to keep their eyes on the road. No more pulling off to the side of the road to study a map, struggling to read illegible print, or trying to find just the right spot with only a dome light for illumination.

Satellite GPS devices are also "smart" as many can also provide updates on weather and traffic information and then assist in mapping an alternate route when barriers exist in the pre-planned route. This flexibility and problem solving make it an invaluable tool when traveling in an unfamiliar area.

Satellite GPS devices are also great to use when hiking, camping, cross country skiing, and participating in similar outdoor activities. Their small size and light weight make them a great tool outside of the car and are often recommended by outdoor enthusiasts and organizations for safety purposes.

Most satellite GPS devices sold in the US contain maps and points of interest such as airports, hospitals, and so forth to the tune of over one million locations. However, these devices aren't limited to the boundaries of the US obviously. For those who wish to use the device when traveling outside the country, many devices have flash cards which can be used to download the appropriate maps corresponding with their destination making satellite GPS a great travel companion.

For many potential users an important consideration is ease of use. Many satellite GPS devices, such as the portable Sony Nav-U, are ready to use right out of the box. It has maps and over 1.6 million points of interest loaded into its memory. It offers a full color 3.5" touch screen display and 2-way speaker system. Cost of an average satellite GPS device is in the range of $400 to $600 dollars but given years of good service and flexibility of use it would seem an excellent investment.

In the world of navigation or route finding, it seems that satellite GPS devices will eventually put basic road maps and compasses into the same realm as typewriters and carbon paper.

Christine Peppler believes that consumers should not have to possess a technology degree to be able to choose home electronics and entertainment devices. Take advantage of the wealth of simple to understand, useful information and shopping available on her website at

Network Time Protocol (NTP) provides algorithms and defines messages for the synchronisation of time clients to an accurate time reference. This article discusses how to configure a Linux NTP Time Server to synchronise time with an Internet based public NTP Server.

NTP server systems fall into two categories: primary reference servers and secondary reference servers. Primary reference servers use an external timing reference to provide time, such as GPS or radio clocks. Secondary reference servers synchronise with primary reference NTP servers and offer slightly reduced accuracy. Primary reference servers are designated stratum 1 servers, while secondary servers have a stratum greater than 1.

The NTP Distribution

The NTP source code is freely available from the Network Time Protocol web site. The current version available for download is 4.2.4. NTP is available for the Linux operating systems with ports available for Windows NT. Once the source code is downloaded, it should be configured, compiled and installed on the host machine. Many Linux operating systems, such as RedHat, offer NTP RPM packages.

Configuring NTP

The 'ntp.conf' file is main source of configuration information for a NTP server installation. Amongst other things, it contains a list of reference clocks that the installation is to synchronise. A list of NTP server references is specified with the 'server' configuration command thus:

server time-a.nist.gov # NIST, Gaithersburg, Maryland NTP server

server time-c.timefreq.bldrdoc.gov # NIST, Boulder, Colorado NTP server

Controlling the NTP Server Daemon

Once configured, the NTP daemon can be started, stopped and restarted using the commands: 'ntpd start'; 'ntpd stop' and 'ntpd restart'. The NTP server daemon can be queried using the 'ntpq –p' command. The ntpq command queries the NTP server for synchronisation status and provides a list of servers with synchronisation information for each server.

NTP Access Control

Access to the NTP server can be restricted using the 'restrict' directive in the ntp.conf file. You can restrict all access to the NTP server with:

restrict default ignore

To only allow machines on your own network to synchronize with the server use:

restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap

Multiple restrict directives can be specified in the ntp.conf file to restrict access to a specified range of computers.

Authentication Options

Authentication allows a matching passwords to be specified by the NTP server and associated clients. NTP keys are stored in the ntp.keys file in the following format: Key-number M Key (The M stands for MD5 encryption), e.g.:

1 M secret

5 M RaBBit

7 M TiMeLy

10 M MYKEY

In the NTP configuration file ntp.conf, specify which of the keys specified above are trusted, i.e. are secure and you want to use. Any keys specified in the keys file but not trusted will not be used for authentication, e.g.:

trustedkey 1 7 10

The NTP server is now configured for authentication.

Client Configuration for Authentication

The client needs to be configured with similar information as the server, however, you may use a subset of the keys specified on the server. A different subset of keys can be used on different clients, e.g.:

Client A)

1 M secret

7 M TiMeLy

trustedkey 1 7

Client B)

1 M secret

5 M RaBBit

7 M TiMeLy

10 M MYKEY

trustedkey 7 10

Essentially authentication is used by the client to authenticate that the time server is who he says he is, and that no rogue server intervenes. The key is encrypted and sent to the client by the server where it is unencrypted and checked against the client keys to ensure a match.

Dave Evans develops Linux NTP Server synchronisation systems to ensure accurate time on PC’s and computer networks. Click here to find out more about Linux NTP Time Server systems.

Cell phone mania was not merely created because of the cell phones itself. Since new cell phone models provide amazing features to their users, such as cool ring tones to cool cell phones, these dainty gadgets are now considered must-have items.

With that in mind, marketing experts say that while communication is considered as the top reason why people would like to own a cell phone, this eventually becomes the second best factor. At most, people desire to own a cell phone because of their cool features.

Take for example the utilization of cool ring tones. Ring tones were not conceptualized for functionality alone but more on the entertainment aspect. They were made to attract consumers.

The Way They Were

In the beginning, ring tones were primarily made available as monophonic sound files. As technology develops, the need for more realistic ring tones is gradually taking its place. Hence, cell phone manufacturers had come up with technologically advanced mobile phones fit to modernize the industry.

However, cell phone revolutions were not mere results of technological advancements. Ring tones of cool cell phones were primarily made to boost sales. The idea is more of a marketing strategy for most cell phone manufacturers rather than innovation. The development of mobile phones is more slanted on consumer attraction instead of communication advancement. This is because ring tones and other features were being developed as amusement items and not just means of enhancing the gadgets' call and text services.

So to speak, ring tones of cool cell phones attract costumers to buy these remarkable devices. Surveys show that 7 out of 10 cell phone users buy these gadgets because they wanted to be a part of the crowd. Consequently, 9 out of 10 consumers wanted to be updated and in fashion.

These cool ring tones of cool cell phones are available in different varieties. They are mostly patterned according to the latest craze in music. Some ring tones are made even cooler because of the different types of sounds used like the animal sounds.

You can even record ring tones to cool cell phones. You can record an excerpt of your favorite song since you cannot record the whole song due to limited phone memory. You can even record voices. You can record something that your friend or your loved has said aloud to you.

Ring tones for cool cell phones are also available on various wap sites. You can download them using your wap-enabled cell phone. You can also download ring tones for your cool cell phones through your service provider. Requests are usually done through SMS.

With the demands for cool ring tones, some websites were even made available to dedicate ample space for ring tone downloads. You can transfer them to your phone using data cable or wireless connection such as bluetooth or infrared.

You can also opt for the pay service where in you have to key in some special numbers and send it to a special number. This is somehow based on the country where you are in and the kind of service provider that you have. Once received, charges will be made and the ring tone for your cool cell phone will be sent directly.

Hence, downloading a ring tone can be easy but needs some little requirements. So before you choose your ring tone, it is best that you consider these factors first.

#1 Cell phone model

Not all cell phones support all of the cool sound files available as cool ring tone downloads. Keep in mind that ring tones are classified as monotones, polyphonic, and those that support MP3 files.

Hence, if your cell phone does not support MP3 files, you cannot download them into your cell phone because it will not run correctly or it can never be run at all. Same thing goes when your cell phone only supports monotones. You cannot play cool polyphonic ring tones on your cool cell phones.

Sometimes, files are different from each other even if they have the same file extension. For instance, a cell phone that has 42 instruments will play polyphonic tones better compared to a cell phone that has only 32 sounds.

#2 Service provider

The availability of ring tones will be dependent on your service provider. Some ring tones were made exclusively for a particular service provider.

Indeed, ring tones for your cool cell phones have definitely increased sales and have created a great impact in the cellphone industry.

For more information now go to:

or

Believe it or not, pink is currently the color that is considered trendiest. The fact of the matter is that wedding gowns that are being made today are colored pink! This is good news for lovers of pink. There are now pink cellular phone units. The following are the hottest and hippest pink cellular phones in town today.

The Motorola V3m RAZR Pink Cellular Phone

This pink cellular phone from Motorola is currently the classic all time cellular phone. The RAZR V3m Motorola is integrated with a VGA camera, a Bluetooth, video MPEG4 playback as well as a slim design.

The RAZR Motorola is a clamshell thin pink cellular phone that was regarded initially as a phone that is fashion exclusive. Plus, it comes with a tag price of a whooping five hundred dollars as well as an eight hundred dollars service agreement.

It was only in the year 2005 when this pink cellular phone from Motorola entered the wide mass market as a phone that is mid priced. It was also in the year 2006 when this pink cellular phone became available in the United Kingdom for a mere seventy pounds.

Meanwhile, in Australia, the Motorola pink cellular phone was priced at two hundred and seventy nine dollars, while in Canada it sold for less than four hundred fifty dollars. The fact of the matter is, the development of this pink cellular phone began in the year 2003.

By the next two years, Motorola had become very popular due mostly to its distinct look as well as slim size. Meanwhile, the first hot pink cellular phone was actually released in the year 2005. Tt became available in America the following year.

Pink cellular phone from Sanyo SCP-3100

Believe it or not, this new pink cellular phone from Sanyo is actually a successor of Sanyo VI-2300. This pink cellular phone has an external large grayscale display as well as a 1.8" 65k internal colored one. Its functions are basically similar with the Sanyo 2300.

The only difference is that this pink cellular phone comes with a mirror, VGA camera as well as a self timer. Besides the color pink, this cellular phone also comes in the colors espresso and silver. This Sanyo pink cellular phone is considered as a low end cell phone that specifically targets those consumers who actually prefer a simple pink cellphone.

The Sanyo pink cellular phone is affordable and comes in a solid clamshell. It also features a voice recording, VGA camera, roaming analog as well as a good quality speakerphone sound. However, this Sanyo pink cellphone is not able to show caller ID. There may also be instances where the internal display colors may look washed out.

However, this Sanyo pink cellphone has features that are solid. Though this pink cellular phone may not look attractive, it is a decent mobile that belong to the mid tier.

Pink cellular phone - The Sanyo Katana

This new pink cellular phone is from Sanyo Katana. It is an ultra-thin pink cellular phone that could be compared to the RAZR Motorola brand V3i. Believe it or not, this clamshell fun pink phone is equipped with a VGA camera that is built in the unit, a connectivity Bluetooth capability, a QVGA 2.2 inch Main LCD Display, a speakerphone built in the pink phone, a one inch external LCD TFT display as well as a 65k capable color.

The word Katana comes from the legendary weapon, a sword originally used by the knights in feudal Japan, or the Samurai. The pink cellular phone from Sanyo Katana provides a design that is ultra sleek and stunning that it evokes a deep passion for artistry and craftsmanship that has long been imbued in the old generations of master Japanese sword smiths.

The features of the pink cellular phone from Sanyo Katana is that its battery is superior in performance as it allows a maximum of almost four hours in talk time. Its Bluetooth features is able to support the HFP, HSP, DUN profiles. Its digital camera has a VGA resolution, its capable to zoom in up to twenty steps, the brightness is controllable. This pink cellular phone also comes with a self-timer as well as picture effects and color tone.

All in all, the pink cellular phone is in! It is cool and the features offered by the cellular phones above fit anyone's preference and lifestyle. Choose the best pink cellular phone unit that best suits you.

For more information now go to:

or

The Network Time Protocol (NTP) is utilised by NTP Server systems to distribute accurate time information to network time clients. The NTP protocol is widely used throughout the Internet to provide synchronisation of computers and processes. This article discusses how NTP server systems utilise the Network Time Protocol to provide networks with an accurate reference of time.

NTP Overview

NTP has been in use as an Internet protocol for over 25 years. It is the longest running continuously operating Internet protocol. The protocol was born through the need to provide synchronisation of time critical processes across the Internet. NTP primarily runs on LINUX and UNIX platforms including Free-BSD but has also been, in part, ported to Windows operating systems. Dedicated NTP server systems generally utilise the LINUX operating system.

The NTP Protocol

NTP is designed to provide network time clients with three products: system clock offset, round-trip delay and dispersion relative to a specified reference clock. Clock offset is the time difference between the local clock and reference clock. Round-trip delay measures the amount of time the protocol takes to receive a response from the server. Dispersion is the maximum error of the local clock relative to the specified reference.

NTP Stratum

NTP operates in a hierarchical manner, the primary reference followed by secondary references and clients. At the top of the hierarchy, the primary reference is usually synchronised to an external time source such as a radio or GPS clock. The primary reference is attributed a stratum of one. Each level down in the hierarchy is attributed a stratum one greater than the preceding level. As the stratum increases, the accuracy of the reference degrades slightly due to inconsistencies in network path timing. Secondary references have a stratum of between two and fifteen.

NTP Messages

NTP utilises the UDP (User Data-gram Protocol) protocol. The NTP message consists of a number of fields: Leap Indicator; Version Number; Mode; Stratum; Poll; Precision; Root Delay; Root Dispersion; Reference Identifier; Reference Timestamp; Originate Timestamp; Receive Timestamp; Transmit Timestamp; Key Identifier and Message Digest.

The leap indicator warns of an impending leap second addition or deletion. The version number indicates the NTP version in use. Mode specified the NTP mode of the current message. Stratum is an eight-bit value indicating the hierarchical level of the reference clock. Poll interval specifies the maximum interval between messages. Precision specifies the accuracy of the local clock. Root delay indicates the round-trip delay time to the reference. Root dispersion indicates the nominal error relative to the primary reference. Reference identifier is a 4-character ASCII string identifying the reference source, such as GPS, DCF or MSF. Reference timestamp specifies the time at which the reference clock was last corrected. The Originate Timestamp specifies the time the NTP request message departed the client for the NTP server. Receive timestamp specifies the time the NTP request message was received by the NTP server. Transmit timestamp specifies the time the NTP response message was transmitted by the server to the client. The key identifier field is utilised when authentication is required and provides the message authentication code.

NTP Server Operation

A NTP server can operate in three modes: unicast; anycast and multicast. In unicast and anycast modes, the client transmits a NTP request message to the server. The server responds with a NTP time message that the client uses for time synchronisation. In multicast mode, NTP time messages are broadcast at periodic specified intervals.

NTP Reference Clocks

Primary NTP servers can synchronise with a number of external reference time sources. The GPS (Global Positioning System) is often used to provide an accurate timing reference. There is also a number of national time and frequency radio broadcasts available. The WWVB radio time broadcast is transmitted from Colorado and covers most of the US. The DCF-77 radio time signal is broadcast from Frankfurt, Germany, and covers much of central and Western Europe. The MSF radio time signal is broadcast from Rugby, UK, and covers the British Isles and much of Western Europe. Other local time and frequency radio broadcasts include: TDF, France, and CHU, Canada.

NTP Versions

The current release of NTP is version 4. The only significant modification to the protocol between versions 3 and 4 is a slight header re-interpretation to accommodate IPv6.

SNTP – Simple Network Time Protocol

SNTP is a simplification of the Network Time Protocol, where the complexities of the full-blown protocol are not required. SNTP can be implemented when the high synchronisation performance of NTP is not required. The message format of the SNTP protocol is almost identical to that of the NTP protocol. However, the complex subroutines designed to maintain a highly accurate synchronised time are removed or simplified. Small computers with reduced processing power, such as micro-controllers or monitoring equipment most often use SNTP. The SNTP and NTP protocols are fully interchangeable, a SNTP client can synchronise to a NTP server without any issues.

More Information: NTP RFC's

The original Network Time Protocol was introduced in RFC 958 (Request for Comments: 958). The full NTP version 3 protocol and synchronisation algorithms are described in RFC 1305. The SNTP version 4 protocols are described in RFC 2030.

Dave Evans develops atomic clock time synchronisation systems to ensure accurate time on PC’s and networks. Click here to find out more about SNTP server and NTP Server systems.

An atomic clock provides an extremely accurate source of time. There are various types of atomic clock, mostly found in laboratories: Caesium Clocks; Hydrogen Clocks; and Rubidium Clocks. Most commercially available atomic clock time synchronisation systems utilise a radio or GPS time signal that is linked to an accurate time reference. In this manner a highly accurate source of time is readily available to everyday users, without the expense of installing highly expensive and complex equipment.

This article provides an overview of atomic clock systems with particular emphasis on their use with NTP server systems for PC and computer network time synchronisation.

Radio Atomic Clock

Time References Radio time transmissions such as the MSF-60 (UK), DCF-77 (Germany) and WWVB (US) time signals broadcast highly accurate time information from a radio transmitter. The time transmissions are derived from an atomic clock time reference, and can be received by timing equipment with a low-cost radio receiver. The MSF-60 radio signal is transmitted from Rugby in the United Kingdom with coverage of the whole of the British Isles and much of North-Western Europe. The DCF-77 time signal is transmitted from Frankfurt, Germany, and covers most of Central Europe. While the WWVB signal is transmitted from Fort Collins, Colorado, USA.

MSF-60 Time Transmission

The MSF-60 time signal is a long wave radio time signal broadcast at 60kHz from Rugby in the UK. The radio signal is maintained by BT Engineering Services. The MSF-60 time signal is generated from extremely accurate atomic clocks located at the National Physics Laboratory (NPL). When decoded, it provides a highly accurate timing reference for NTP servers, reference clocks and other computer timing equipment.

DCF-77 Time Transmission

The DCF-77 time signal is a long-wave radio time signal broadcast at 77.5kHz from Mainflingen, near Frankfurt, Germany. The radio signal is maintained by T-Systems, a sub-division of Deuche Telecom, and has been in operation since 1959. The DCF-77 signal is generated from extremely accurate atomic clocks located at the German National Physics Laboratory. When decoded, it provides a highly accurate timing reference for clocks and computer timing equipment.

WWVB Time Transmission

The WWVB time signal continuously broadcasts time and frequency signals at 60 kHz from Fort Collins, Colorado, USA. The time reference is maintained by the US National Institute of Standards and Technology. WWVB has provided continuous time and frequency broadcasts since 1962. The signal provides a timing reference with an accuracy of less than 100 microseconds.

GPS Atomic Clock Time Reference

The Global Positioning System (GPS) is a US military system for worldwide navigation. The system consists of 24 orbiting satellites, each satellite has a highly accurate atomic clock on-board synchronised to UTC time. The satellites continuously broadcast time and position information. The time and position information can be obtained worldwide with a GPS receiver and antenna. GPS works continuously in any whether conditions, anywhere in the world. Additionally, there is no set up fee or subscription charges to utilise the GPS systems. Many computer timing systems and NTP Server systems utilise GPS as an accurate external timing reference. GPS timing is generally much more accurate than radio based timing references.

Computer Time Synchronisation

Accurate computer time synchronisation can be achieved by combining a GPS or Radio timing receiver with a RS232 or USB interface. Software drivers can then be installed on the host PC to obtain accurate time and synchronise the host PC's system time. Most PC operating systems can be synchronised, including Microsoft Windows 2000, 2003 and XP, LINUX, UNIX and Novell. In many cases, the host PC's system time can be synchronised to within a few microseconds of the correct time.

Network Time Synchronisation

The standard protocol for achieving computer network time synchronisation is the Network Time Protocol (NTP). NTP is the standard way of distributing time around the Internet and other networks. Stratum 1 NTP servers obtain time from an external timing reference, such as GPS, MSF-60, DCF-77 or WWVB. The external time reference is then used to synchronise the NTP server system time. The synchronised system time is then used by the NTP Server to distribute accurate time to network time clients over an IP network. NTP operates in a hierarchical manner; lower stratum NTP servers obtain time from higher stratum devices.

NTP server systems can synchronise to within a few microseconds of the correct time. Depending on network traffic, NTP time clients can synchronise to within a few milliseconds of a NTP server.

Dave Evans develops atomic clock time synchronisation systems to ensure accurate time on PC’s and computer networks. Click here to find out more about GPS NTP Server and Atomic Clock systems.

If you are like most people you spend a lot of time stuck in traffic. According to statistics U.S. drivers spend about an average of 47 hours a year in traffic, and in large urban areas, drivers can spend more than 60 hours a year.

That is why a growing number of drivers are finding they can reduce time and increase comfort by using technology that helps them find and chart the best route to their destination by adding GPS navigation systems to their vehicles.

A GPS, or Global Positioning System, is a device that uses satellite technology to pinpoint the location of a receiver. This GPS receiver will provide the driver with important information such as location, estimated time, and recommend a route to a destination. These systems have become so sophisticated that some have added the benefit of playing music. Simply download the desired files onto the hard drive and users can have their music library wherever they go.

Here at Car L we carry a varied to fit everyone's needs. Whether you are looking for city, off-road driving, or hiking trails, we carry them all. Is portable or an installed unit better for you? How easy is the screen display to read? And car the unit provides information on current traffic conditions? These are some of the questions you may want to ask yourself before looking at our wide array of items.

The DCF-77 radio time transmission is utilised by many NTP server and PC computer systems to provide accurate synchronisation of time critical applications. This article describes how the DCF-77 time signal is decoded by NTP server and computer systems to provide an accurate timing reference.

The DCF-77 Time Transmitter.

The DCF-77 time signal is a long-wave radio time signal broadcast from Mainflingen, near Frankfurt, Germany. The radio signal is maintained by T-Systems, a sub-division of Deuche Telecom, and has been in operation since 1959. The DCF-77 signal is generated from extremely accurate atomic clocks located at the German National Physics Laboratory. When decoded, it provides a highly accurate timing reference for clocks and computer timing equipment.

DCF-77 Time Code.

Time and date information is transmitted continuously, repeated each minute. The data is transmitted as an amplitude modulated, pulse-width coded data signal. Each data bit is transmitted as one pulse per second. The data transmitted consists of the current time and date, leap second indicator, daylight saving time indicator, transmitter identifier and parity bits.

The duration of each transmitted pulse is decoded as follows: a second mark with a duration of 100 milliseconds is decoded as a binary zero; a second mark with a duration of 200 milliseconds is decoded as a binary one.

Transmitted Data.

Time and date information is presented in BCD (Binary Coded Decimal) format and is encoded as follows: bits 0-14 are unused, but may provide future status information; bit 15 indicates use of backup transmitter; bit 16 (A1), indicates the announcement of daylight saving change; bit 17 (Z1), indicates daylight saving is in use (CEST); bit 18 (Z2), indicates standard time (CET); bit 19 (A2), announces a leap second; bit 20, indicates start of time information; bits 21-27, BCD encoded minutes; bit 28 (P1), parity bit covers bits 21-27; bits 29-34, BDC encoded hours; bit 35 (P2), parity bit covers bits 29-34; bits 36-41, BCD encoded day of month; bits 42-44, BCD encoded day of week; bits 45-49, BCD encoded month of the year; bits 50-57, BCD encoded year; bit 58 (P3), parity bit covers bits 36-57.

The DCF-77 data bits 1-14 are generally unused by any decoding algorithm and may provide status information in future broadcasts. The time zone bits Z1 and Z2 indicate current daylight saving time status. When CET time is being broadcast, Z1 is zero and Z2 is one, for CEST time, Z1 is one and Z2 is zero. The daylight saving change announcement bit, A1, indicates an imminent change to or from CET. The leap second announcement bit indicates the imminent insertion of a leap second. The three parity bits P1-P3 compliment the preceding information to an even number of ones (even parity).

Examples:

Received DCF-77 bit stream: 00000000000000000010100000000011010110000001001001000110011 Decoded time and date: Tuesday 01/12/1998 16:00

Received DCF-77 bit stream: 00000000000000000010110000001011010110000001001001000110011 Decoded time and date: Tuesday 01/12/1998 16:01

Dave Evans develops atomic clock time synchronisation systems and NTP server systems to ensure accurate time on PC networks. Click here to find out more about DCF-77 NTP Server solutions.