[time-nuts] HP 5372A vs. 5370A

Magnus Danielson magnus at rubidium.dyndns.org
Thu Feb 10 20:05:33 UTC 2011


Ed,

On 10/02/11 00:00, Ed Palmer wrote:
> Magnus Danielson wrote:
>> The Frequency vs. Time view is lovely.
>>
>> The 5372A does calculate ADEV but does not provide ADEV plots.
>>
> Since they don't specify, I'm assuming that it uses the original,
> non-overlapping calculation. True?

Well... it does care since it is the corner case tau = tau0.
It will give you the Allan Variance and Allan Deviation for the 
time-base you have setup.

> I was wondering about that. Is that info buried in the programming
> manual? I haven't gone through the binary programming section hardly at
> all.

Yes, if you dig into it you will realize it. It is very open in this 
sense. There is also a patent relating to the hardware accelerated 
histogram functionality.

>> Another approach is to use the Fast Port which taps into the hardware
>> and would allow longer runs. I have not much documentation on it and
>> experience on how it works. Needs to play with it.
>>
> My unit doesn't have the Fast Port option so that isn't a possibility
> for me. You'd obviously need some custom hardware to make it happen.
> More complications.

I will play with it.

>> The HP5372A programmers manual is really an inside-out manual where
>> you learn the internal formats and how they are processed for the
>> various views and results. Very open in what it does and how you can
>> duplicate the measurements from binary format. It's a bit confusing
>> initially, but once you spent the time to learn it, it makes sense.
>>
>> There are a few GUI-hacks I would like to have, for longer
>> measurements I would like to have an ETA count-down, but real-time
>> update for certain views would be lovely.
> I wrote a little GPIB program to automate some measurements. I added an
> approximate 'percent completed' printout. It really comes in handy.

That would be handy.

Cheers,
Magnus



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