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

Don Latham djl at montana.com
Sat Dec 31 00:41:32 EST 2011

Don't need to stretch, use the two hardware interrupt pins...

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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"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
R. Bacon
"If you don't know what it is, don't poke it."
Ghost in the Shell

Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304

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