Here is a very interesting device used in the
cellular phone industry
that has now become available on the surplus market.
The Z3801A is a "GPS Disciplined Oscillator". It is a very accurate, oven temperature controlled crystal oscillator. It is also a 6 channel GPS receiver. The timing signals from the GPS satellites are used to "nudge" or "Discipline" the crystal oscillator. The unit then provides exact day/time information via RS-422 or RS232, 1 Pulse Per Second signals, and a 10MHz signwave out that can be used as a reference for other equipment you may have (such as a Spectrum Analyzer, or Frequency Generator). Once set up and operating, the longer you leave it on, the more accurate it becomes. Single digit micro second accuracy with these units is common, nano second accuracy is not rare.
There are many good
www sites by other HAMS now on the web about this unit.
Please see
K8CU's site for more in depth information. He has also written a Windows
program (GPSCon) to control and observe the unit. The software also provides
a SNTP (Simple Network Time Protocol) server so you can keep all the PC's on
your local network set to the correct (well... the exact) time. It also will
post a report to a www server at a selectable interval (My
Z3801 my be seen here).
These units are availiable from BuyLegacy for about $250.00, and on E-Bay.
AD6A, Dave has an excellent guide to convert the unit from RS-422 to RS-232.
The unit does require an antenna (preferably mounted outdoors) for the GPs receiver.
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March 13, 2006