[time-nuts] LPRO-101 with Brooks Shera's GPS locking circuit

Brooke Clarke brooke at pacific.net
Tue Dec 19 16:42:28 EST 2006


Hi Brendan:

It's interesting that the PRS10 can time stamp the 1 PPS input with a 
resolution of 10 ns.  I wonder how they do that.
http://www.thinksrs.com/downloads/PDFs/Catalog/PRS10c.pdf

When I picked up my PRS10 at the factory during the tour I learned that 
the 10 MHz oscillator in the PRS10 was an improved version of the SC10.  
There's an Allan plot for the PRS10 at:
http://www.thinksrs.com/products/PRS10.htm <- overall PRS10 page
http://www.thinksrs.com/assets/instr/PRS10/PRS10diag2.htm  <- Just the plot

Have Fun,

Brooke Clarke

w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com



Brendan Minish wrote:

>On Tue, 2006-12-19 at 11:05 -0800, Brooke Clarke wrote:
>  
>
>>Hi Brendan:
>>    
>>
>
>  
>
>>Keep in mind that this design does work and that the above items relate 
>>to optimization not bug fixes.
>>    
>>
>
>I currently have the Brooks Shera design disciplining my LPRO-101
>without any mods and using the ADC connected directly however the gain
>is not high enough for the small EFC range of the LPRO. 
>It does work, it will keep it locked OK even with the longest
>time-constant and the figures appear to make 'sense'. I guess that with
>the excellent stability of the Rubidium Oscillator the lack of loop gain
>may even be an advantage as it will reduce sensitivity to other sources
>of short and medium term error 
>
>I certainly intend trying the modified PIC software to improve gain and
>lengthen the filter time.
>
>I would however be most interested in building and comparing with an
>alternative discipline arrangement
>
>Anyone care to comment on projects based around the SRS PRS10 module and
>how it fares out in the scheme of things ?
>
>73
>Brendan EI6IZ 
>
>
>
>
>
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>  
>



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