[time-nuts] Re: Counter internal resolution error

[Magnus Danielson]

I also recall one paper relating to laser ranging measurement of the 
moon which also looked at temperature dependence of counters, and SR620 
showed more sensitivity than some other counters. For some measurement 
purposes, the impact is less than for others.

A fun experiment would be to use a delay-stepper to plot this. I 
accumulated equipment for that over the years, with increasing 
resolution and performance but never got around to it. Good little 
practical experiment now that I was able to steer the Colby DL10 
programmable trombone delay.

There is two common reasons for non-linearity, one is from the 
interpolator itself where error-pulse shaper as well as pulse-to-voltage 
converter has non-linearities. Another one is du to leakage of either 
clock or other input shifts the trigger point due to lacking isolation. 
Such non-linearities can be handled through measurement setup and at 
times with averaging.

Some properties can be managed through wise use of the autocalibration.

Then again, most of the times I do not bother to go the extra stretch, 
but it is good to know the effects are there so one can consider them 
and if needed cope with them.

So, time to close down computer, check out and leave Vancouver after a 
WSTS conference.

Cheers,
Magnus

On 2023-03-17 16:57, Demetrios Matsakis wrote:
> I don’t know how SR counters are today, but when we were upgrading our 
> infrastructure over a decade ago we found other counters had better 
> linearity.  Rover et al’s open source article has a good discussion of 
> these issues, although of course you need to have one if you are going 
> to experiment. Â See G. D. Rovera, M. Siccardi, S. Romisch, and M. 
> Abgrali, “Time delay measurements: estimation of the error budget”, 
> Metrologia 56, 2019 035004
>
>> On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts 
>> <time-nuts at lists.febo.com> wrote:
>>
>> Dear Michael,
>>
>> On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
>>> Dear time-nuts
>>>
>>> Counter specs often include an “internal resolution” error. For example,
>>> the SR620 specs say that it is 25 ps in single-shot, but this can be
>>> reduced to 4 ps with sufficient, repeated measurements. Can anyone 
>>> Â Â Â offer
>>> any enlightenment as to the origin of this error, and the statistical
>>> distribution it has? I mentioned the SR620 but information about the 
>>> 53230A
>>> would be interesting too.
>>
>> First of all, the single-shot resolution is somewhat of a hallmark 
>> measure when it comes to counters.
>>
>> The interpolator resolution is part of this, but consider that there 
>> exists non-linearities in the interpolator which makes the error 
>> larger. I recall there being a plot of the non-linearity in the SR620 
>> manual.
>>
>> It is not uncommon to have interpolator resolution better than 
>> non-linearities, but the later may be more subtle to most.
>>
>> Averaging can help, but depending to specifics, it's hard to give a 
>> number.
>>
>> Cheers,
>> Magnus
>>
>>>
>>> Cheers
>>> Michael
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at lists.febo.com
>>> To unsubscribe send an email to time-nuts-leave at lists.febo.com
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com
>> To unsubscribe send an email to time-nuts-leave at lists.febo.com
>