[time-nuts] 10MHz Rubidium reference source for frequencycounter

Charles Steinmetz csteinmetz at yandex.com
Mon Nov 3 15:43:47 EST 2014


Tom wrote:

>As I understand it, his project is to use the high frequency output 
>of a ublox NEO-7M to discipline a MV89 with a James Miller-style analog PLL.
>    *   *   *
>(perhaps someone can post an English translation for us)

Tom,

I have a machine-translated PDF (~2.5MB), but nowhere to put it 
up.  If you have web space for it, please feel free to do so 
(assuming that Karen does not object).

I have reservations about the potential of any Miller-style GPSDO, 
because using an analog PLL essentially guarantees that the crossover 
to GPS will be at a tau orders of magnitude lower than it should be 
-- the Miller unit crosses over about 3 OOM too low (see attached 
plot, from <http://www.leapsecond.com/pages/gpsdo/>).

The beloved Thunderbolt also crosses over about 2.5 OOM too early, if 
you use the factory loop settings (id.).  But it has an ADPLL with 
adjustable parameters, so a time nut can tune the loop for best 
performance with the particular OCXO in the unit.  (See 
<http://www.ke5fx.com/tbolt.htm>.)

Best regards,

Charles


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