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

Magnus Danielson magnus at rubidium.dyndns.org
Tue Jan 24 13:50:41 EST 2012

On 01/24/2012 12:42 PM, J. L. Trantham wrote:
> Thanks Chris.
> It seems such a logical feature to have, I would think it would have been
> included perhaps by a serial command.  My old CS clocks have this feature
> though I have never taken the time to sync them.

"Jumping" the PPS into about the right phase is done within a second and 
is well worth the effort. I use this myself and it works well.

Forcing "sync" on atomic clocks is badly needed. The frequency steering 
range is small so frequency limit sideways would take ages.


> Joe
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Chris Albertson
> Sent: Tuesday, January 24, 2012 12:34 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Determination of the placement of the first pps
> On Mon, Jan 23, 2012 at 5:50 PM, J. L. Trantham<jltran at att.net>  wrote:
>> Is this, in any way, related to the fact the Earth has a Moon?
>>   is there a way to
>> 'sync' the 1 PPS output of an FE-5680A to an external signal, such as
>> a GPS receiver or TBolt?  I would think that might be possible given
>> their original purpose.
> The 1PPS is not in the units specs.  It is just by luck that it works.
>    However we could adjust the phase of the 1PPS by running the unit fast or
> slow for some period of time and then going back to exact 10MHz.  But that
> method could take a LONG time, like tens of thousands
> of seconds.    Better I think to test the phase and if it is "off" by
> more than say, 0.01 second to just power the unit off and restart and
> see what luck gives you.   I bet 100 power cycles is faster than
> moving the phase by 0.5 seconds.
> Maybe the answer is to wire up a few decade divers and divide the 10MHz to
> 1pps yourself.  Thenyou can let a known good PPS reset your counters and get
> the phase correct instantly

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