[time-nuts] Freq cal to 1ppm without GPSDO

[John Beale]

Hi Murray,

Thanks to you and the others for your replies. After some more HF reception 
problems here, I have come to the same conclusion as you. I found an Oncore 
M12+ timing GPS is available pretty cheap from Hong Kong, so that's my plan.

best regards,
John Beale


 > 1. My best advice is to get hold of a cheap GPS module with a 1pps 
(seconds pulse) output. Connect it up, and when you have a fix, use the 
1pps to trigger your digital oscilloscope. Set the timebase to 1us/div to 
start with, and ultimately 100ns, and observe the 10MHz output of your 
TCXO. You will see the waveform drifting slowly. Counting how long it takes 
to slip one cycle will tell you how far off the TCXO is. If you have a 
counter with Time Interval mode capability, you could use that, using the 
GPS to start and 10MHz to stop, again observing the drift.