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GPS-based reference clock

Almost any GPS receiver outputting 1 pulse per second (1pps) will meet your 1mS tolerance. I say almost as I certainly can't vouch for all of them!

A simple downsteam module with either a hardware division system could show and distribute time-of-day once synced. Obviously a PIC-type processor board could also read the NMEA data stream for time etc, and use the 1pps for syncing, then distributing TOD by the method and in the format you choose. Which is a faster-to-fruition system depends on your micro skills vs hardware design and implementation. Some time later (not in your time window unfortunately) I will be using a PIC 16F877 dev board to do something very similar behind my GPS-derived frequency reference unit.

Reply to
budgie
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Where are you in the world? An ordinary wristwatch can maintain that kind of accuracy over the long term, then there's WWV, and in the US, they keep the line freq. synced up so good that clocks can go for years without losing a second.

Of course, if this is just an exercise in GPS, then I'm out of the loop. )-;

Good Luck! Rich

Reply to
Rich Grise

within 1 mS? Some *ordinary* watch.

Just assume the quartz crystal can maintain 1ppm through temperature variations (on or off the wrist). That's 83mS per day. To achieve 1mS over 1 day (ignoring jitter) would require ~12*10^-9 oscillator performance. Stunning.

(assuming my maths are OK at this time of day)

yes

Indeed they do - but by counting cycles. Short term it would never be able to be within 1mS.

Without a very stable frequency reference locked to some time standard, 1mS would be hard to achieve. GPS provides his best (and likely most affordable) solution.

Reply to
budgie

Tony (remove the "_" to reply by email)

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Tony

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