[time-nuts] Thunderbolt? (re simple gpsdo.)

[Chuck Forsberg WA7KGX N2469R]

I was thinking ... starting with a 5680a and a GPS with
accurate 1pps but no 10 MHz ...

Feed both 1pps signals to a 74ls123 to stretch the pulses to something 
longer.
A 74ls74 is strobed by one of the one-shots, its D input being the other 
one-shot.

Connect both one-shots and the 74 to an Arduino's inputs.  An Arduino serial
output connects to the 5680a.

The Arduino watches the one-shots to obtain rough lock, then pays attention
to the 74 output for fine lock.  Between the jitter on the 1pps and the 
very long
time constant(s) used to control the 5680a it just might work.

Attached: Phase plot of two Thunderbolts using same antenna but different
GPSDO parameters.  Plenty of jitter/noise/whatever.

-- 
Chuck Forsberg WA7KGX N2469R     caf at omen.com   www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
   Omen Technology Inc      "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231   503-614-0430

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