Bob Paddock wrote: > On Tuesday 03 April 2007 21:48, Dr Bruce Griffiths wrote: > >> An Australian Electronics magazine recently published a circuit for a >> GPS disciplined crystal oscillator. >> This particular implementation is the worst I've ever seen. >> > > What would you consider the best you have ever seen? > > Bob
Probably Quartzlock's carrier phase disciplined OCXOs. Although a few improvements spring to mind. If we are only considering phase locking to a GPS timing receiver's PPS output the HP58503 and its ilk weren't too bad although the double oven OCXO implementation used is a bit of a kludge. The Post was intended as a warning don't be tempted to build the circuit as you will be disappointed. The logic circuitry appears to have been designed by 2 people, one who knew how to cascade counters correctly and one who didn't. Whoever designed the PLL and its filters seems to be particularly clueless. Using parts of a hex inverter for an oscillator and its buffers as well as using the rest as buffers for other frequencies is also asking for trouble. Its a shame that an opportunity for demonstrating the performance that is achievable with a well designed crystal oscillator without an oven can be. The choice of a GPS receiver with a PPS timing accuracy more than 30 times worse than that possible with most good GPS timing receivers didn't help. Bruce _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
