GPS or Radio Timing?

GPS and radio are the two most common time references used for network synchronization. Both have advantages and disadvantages.

Radio time references can often be received indoors, but can be prone to interference. Also metal structures can cause problems. If you happen to be located in a valley or near hills, radio reception can prove difficult. Radio signals also have a finite range, so you need to be reasonably close to the transmitter to receive the signal. Radio transmitters are generally located to serve a particular region or nation. Radio time references generally consist of continuous time and date information followed by an accurate pulse marking the start of the minute. Radio transmitters are located in a number of countries: UK, Germany, USA. They are referenced by their call sign: MSF in UK, DCF-77 in Germany and WWVB in USA.

GPS is a satellite based system – originally developed for positioning and navigation. However, it also has a very accurate timing component. Utilizing GPS for time servers has the big advantage that it can be received any where in the world. Provided a GPS antenna can be shown a good view of the sky, you will get a good consistent signal lock. Also, modern GPS time servers can operate with a much reduced view of the sky – or even in many instances indoors. GPS is also much more accurate that radio time references, making it the reference of choice for network timing applications.



About the Author.
Andy Shinton has spent his entire career within the IT industry, mainly in the Time and Frequency sector. Since 2002, he has headed TimeTools Research and Development Division. Andy regularly writes white-papers and articles about NTP and Network Timing Solutions.


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