Science/Engineering/Technical forums

A GPS makes a great Atomic clock if you need high accuracy - the GPS will generate a one second clock synchronised to an Atomic clock.

Depends on what you mean by accuracy -- long term, yes, it's probably the best any of us would do unless we built our own atomic clocks or bought them surplus (possible).
But the instant by instant accuracy (jitter) of these is pretty bad. I once faced that with synching things to WWV stations. Over long times, yes, it's as good as can possibly matter.
But over short intervals, atmospheric effects can be much worse than a wristwatch oscillator -- which is why even coming straight down from space (no "skip" that depends on ionosphere reflective layer heights that change path lengths) you need to get several GPS satellites to get a good fix (and of course there is deliberate jitter put into the sat signals, still).

So it depends on what you need.....a very slow adjusting TXCO based on a cycle counting error scheme with very long time constant using one of the above as a reference system for long term accuracy is needed to "have it all".

Or
By getting the right GPS module you can have this

http://gpsdo.i2phd.com/

so simple

EDIT or if you like micros

I like the QST article better -- the hams understand phase jitter, but I'd bet they don't use that for the reference for an FM transmitter -- still too jittery for that. I did this once and it was a real job of work to make a very low phase-noise output. I guess it's like most things "it depends" on what you're needing to do. The time guys and the low phase jitter guys can get to be quite fanatic on their topics, but most real applications may not need that level....

I use the QST article based on Brooks Shera's project. At the time Brooks was working
at Los Alamos and still corresponded with me to help on some of the minor points.

I use its output (10Mhz 1 V PP) to drive my DSP-10 (another QST project combination
of computer and computer driven and FFT box) With the Shera standard driving it it is so
tight in frequency I just key in the requested receive frequency and THAT's WHAT I GET.