[time-nuts] Re: Counter internal resolution error

[Magnus Danielson]

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    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
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