[time-nuts] Determination of the placement of the first pps

Magnus Danielson magnus at rubidium.dyndns.org
Wed Jan 25 14:19:16 EST 2012

Hi Joe,

On 01/25/2012 08:04 PM, J. L. Trantham wrote:
> Magnus,
> Thanks for the research.  Now that I have read your information, I am going
> to have to go back and 'measure' the PPS output on my unit.  I just
> 'eyeballed' the '1 PPS' and it seemed close to 1 second.

Good luck. Hopefully I put you onto a working solution.

> It would be nice to find a serial command that would allow placing the 1 PPS
> at any arbitrary point in phase to match GPS.
> My impression of reading the posts about the FE-5680A is that the 1 PPS is
> likely there, just not easily documented.

Well, being lazy enough not to go into the lab and open up my 5680 I 
went hunting the web and it seems like there was more out there than we 
seems to have been piecing together.

Seems like a bit of more systematic research needs to be done. There are 
obviously at least two basic models, one older with 50,255+ MHz 
oscillators and various add-on boards and secondly the 60 MHz + DDS 
variant. Reverse-engineering the schematics and functions has only 
partly been done, but I haven't seen any systematic schematic popping 
out of the work.

There is already plenty of information available, but it is not 
coordinated and systematically done to the level that most aspects can 
be written down in a service type of document.


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