[time-nuts] Synchronizing to WWV

Brian Kirby kilodelta4foxmike at gmail.com
Sat Dec 19 07:21:58 UTC 2009


We'll, if you need millisecond accuracy its OK.  But if you running real 
clocks - rubidium  or cesium, WWV is just not good enough.

If you look around, you can pick up a OEM GPS receiver board for under 
$40.  You can also find cheap patch antennas for $9/10 - at TAPR.  Put 
the receiver in a case of your choice, provide 5 volts to run it - use a 
MAX232 IC to convert TTL to RS232 and you can have microsecond or better 
accuracy say for under $100 max.  The old Motorola Oncore VPs are still 
useful and will keep you within +/- 55 nS of UTC.   The M12 I believe 
was +/- 15 nS.  I believe Garmin has a GPS18 which is a senor type unit, 
the Receiver is built into the antenna and it provides time under 1 uS.  
The unit is terminated into RS232 or USB, cost you $79.

There was also a group purchase on this list for the Trimble Thunderbolt 
and I see them on Ebay for $130, which is good, thats a real GPS DO.



Justin Pinnix wrote:
> Hi Nuts,
>
> Most of you have probably seen this before, but I ran across a great
> 1975-vintage paper on how to synchronize your clocks and frequency standards
> to WWV's HF broadcasts.  The equipment needs are very basic - a clock, a
> radio, and an oscilloscope.  The procedure is simple and far more reliable
> than the tone-detection method I attempted earlier.
>
> NBS Technical Note 668 - The Use of National Bureau of Standards High
> Frequency Broadcasts for Time and Frequency Calibrations (
> http://tf.nist.gov/timefreq/general/pdf/453.pdf)
>
> Yes, I realize that GPS is literally a million times more accurate, but if
> all you need is milliseconds,  this will do the job cheaper than a GPSDO or
> it could serve as a backup.  Plus it's a lot of fun to stare at the traces.
> They are quite hypnotic.
>
> Thanks,
> -JP
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