[time-nuts] 1 pps Accuracy in two locations

[djl]

Maybe Grace Hopper's aid will help? 11.8 inches = one nanosec, so a ps 
is .0118 inches. You really want two clocks not occupying the same space 
to be correlated to that accuracy?
Don

On 2019-12-04 08:55, Tom Van Baak wrote:
> Martyn,
> 
>> I'm always being asked to provide equipment that can produce two 1
>> pps outputs aligned to each other to within a few ps.
> 
> They should look at their best 1PPS on a 'scope. You can get ns with
> care; I doubt ps is possible. I mean, that's THz BW isn't it?
> 
> Can you share with us what their application is?
> 
> 
>> So they are asking for two of my GNSS frequency standards with 1 pps
>> outputs.
>> 
>> The 1 pps outputs being derived from the rubidium oscillator (which
>> is aligned to GPS/GNSS)
>> 
>> The best I think I can achieve is in the low ns range.
> 
> Right. It will be ns, not ps. Forget about using GNSS for ps level 
> timing.
> 
> 
>> Does anyone know how this can be achieved?
> 
> Google for papers by high-end national timing laboratories. Words
> like: active temperature stabilized (phase stabilized) bidirectional
> optical fiber links.
> 
> Very possible, very expensive, quite common now. I'd guess most of the
> timing centers in Europe are linked this way.
> 
> /tvb
> 
> 
> 
> 
> On 12/4/2019 1:40 AM, martyn at ptsyst.com wrote:
>> Hello,
>> 
>>   I'm always being asked to provide equipment that can produce two 1 
>> pps
>> outputs aligned to each other to within a few ps.
>> 
>>   These two 1 pps pulses are not in the same location and could be 100 
>> metres
>> to a few km away.
>> 
>>   So they are asking for two of my GNSS frequency standards with 1 pps
>> outputs.
>> 
>>   The 1 pps outputs being derived from the rubidium oscillator (which 
>> is
>> aligned to GPS/GNSS)
>> 
>>   The best I think I can achieve is in the low ns range.
>> 
>>   Does anyone know how this can be achieved?
>> 
>>   Regards
>> 
>>   Martyn
>> 
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> 
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-- 
Dr. Don Latham  AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304