[time-nuts] Need 10 MHz for DSN space-probe hunting

Chris Caudle chris at chriscaudle.org
Tue Sep 13 16:26:33 EDT 2016


On Tue, September 13, 2016 2:24 pm, taylor david wrote:
> Briefly, Mike, there's an easy to use unit here, which takes a puck GPS
> antenna and can run off USB +5V:
>   http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=234


Mike already mentioned he has a Thunderbolt.  That product you referenced
only has phase noise measurements down to 100Hz offset, but comparing to
the Thunderbolt phase noise measurements that Tom posted at the link
below, a Thunderbolt running on a good quality linear power supply has
about 20dB less phase noise at 100Hz:

http://www.leapsecond.com/pages/tbolt/noise.htm

Probably the best solution for Mike is use the Thunderbolt that Mike
already has, get a better power supply, and look at the advice for setting
up the Thunderbolt which has been rehashed on the list over the last few
days (week?  two weeks? I lose track).  For multiplying up you want good
frequency stability, not close tracking of PPS to correct time, so follow
the advice about longer time constant and more damping to get frequency
stability rather than low offset to GPS/NIST time.

-- 
Chris Caudle




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