[time-nuts] Ashtech Z-12-R Operation?

[Bruce Griffiths]

Tom Van Baak wrote:
>> Hi:
>>
>> I got an Ashtech Z-12-R that powers up and displays the start up
>> screen, see:
>> http://www.prc68.com/I/AshtechZ12.shtml
>>
>> But it does not progress or respond to button presses.  Does someone
>> have a pdf manual or know how to kick start one of these?
>
> Brooke,
>
> My Z12-T requires an external 20 MHz reference clock; I'm not
> familiar with your -R model but it too may require this. It's not
> uncommon for high-end geodetic-grade timing receivers to rely
> on an external clock (e.g., cesium or maser). The idea is that
> all received GPS signals are referenced to a real external clock
> instead of an internal or virtual gps clock, or something like that.
>
> So try that first. The quality of the 20 MHz is not important just
> to see if it starts working. But clearly, to get good results, you'll
> want to lock your 20 MHz to something atomic.
>
> When I got my Z12 I played a bit with how to get 20 MHz. See:
> http://www.leapsecond.com/pages/20mhz/
>
> /tvb
>
>
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>
Tom

An injection locked oscillator with high level subharmonic injection
also works well.
Just use the appropriate topology for the oscillator and injected signal.
The injection locked oscillator acts like a first order PLL with built
in phase detector and loop filter.
The one drawback is that the phase shift with respect to the injected
signal is determined by the oscillator tank detuning.
A low Q tank is used so the phase shift tempco will be relatively small
if low tempco tank components are used.

Bruce