[time-nuts] SRS SR620 External Source Issue -- Help Request -- A thought

[Didier Juges]

Dr Bruce Griffiths wrote:
> TheInfamousFlavio at hotmail.com wrote:
>   
>>> ...if my model is correct the apparent offset in the
>>> mean will be increased by a factor of 10 over that for a a 1 second gate
>>> time.
>>>
>>> Bruce
>>>     
>>>       
>> Looks like you're right Bruce.  I did both 1, 0.1 and 0.01 gate times and 
>> the error increased by a factor of 10.
>>
>> And it doesn't sound like this is a fixable in any easy sort of manner, 
>> right? 
>>
>>
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>>   
>>     
> Flavio
>
> If the SR620 can do some simple arithmetic before displaying the result, 
> then this calibration problem is easily corrected.
> Otherwise you will have to do the corrections on a PC (or hand held 
> calculator).
> The correction will vary with time and temperature so you will need to 
> measure it periodically.
>
> Corrected frequency = measured frequency*(nominal gate time)/(nominal 
> gate time + differential delay).
> In your case the differential delay appears to be about 150 picoseconds.
>
> Bruce
>
>   
Bruce/Flavio,

Could that be mostly corrected (at constant temperature) by inserting 
the proper delay at the right place (in the form of a short piece of 
coax cable)?

It seems that the error could be easily reduced by a factor of 10.

Didier