[time-nuts] Re: Residual Measurement on Keysight 53230A

[Bob Camp]

Hi

This actually splits into two rabbit holes very quickly:

The ADEV side is probably the easy one. If you look at the counter as a device with X.X ps of 
error on each reading. The longer the reading, the less that jitter is relative to the measure. If
you have some sort of averaging on, the more samples you average, the more noise you throw
out. 

The other rabbit hole involves the 5323x counters in general. Their ref out ports have issues. 
One could be a bit more descriptive, but this is a public list. Simple answer is not to use the 
ref out for anything important. As long as you do that, they work pretty well. Don’t do that and
you will be dealing with nutty issues all over the place. 

On a different topic (we never stay on topic for long), the 5323x devices very much like a fast
slew rate at the input. If you drive them with a fast edge, they perform quite a bit better than 
the spec sheet suggests. Keysight has a video up demonstrating this on YouTube. If anything,
the video understates the level of improvement possible. 

https://www.youtube.com/watch?v=4DfLkxVe7Lk
Keysight 53230A Single Shot Resolution Demo
youtube.com

So, it’s not a horrible counter. You just want to avoid that ref out. 

Bob

> On Jan 19, 2023, at 9:51 AM, Jim Muehlberg via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Lincoln said that it was "Better to remain silent and be thought a fool than to open one's mouth and remove all doubt."
> 
> OK, here we go..
> 
> In my quest to understand and make good use of the above mentioned counter, I've taken what I believe to be a residual measurement.  That is, taking the ref out and measuring it with itself.  I get different answers depending on the sample interval.  Is that what I should expect?  If I were a mathamagitian, I suppose it would be obvious from the ADEV equation, but I can't see it.  Am I setting up the counter incorrectly?
> 
> The data sheet lists ADEV at 1s, which is 0.01ppb ( I have option 10 - high stability OCXO).  Not sure how to equate that to the ADEV plot. (1E-11?) And why do they only give that one point?
> 
> Maybe I should have been a "volt nut".  The math would be easier!
> 
> -- 
> Jim<53230A residual.png>_______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe send an email to time-nuts-leave at lists.febo.com