[time-nuts] HP53132A vs SR625

Brooke Clarke brooke at pacific.net
Sat Mar 16 20:32:07 EDT 2013


Hi Volker:

The HP HP53132A can measure frequency at the rate of 12 digits per second, that's way better than ordinary counters, but 
when measuring time interval it's the same as any other counter.
The big disadvantage of the HP53132A in my opinion is it's user hostile menu system.
http://www.prc68.com/I/TandFTE.shtml#HP51132
If you're going to be measuring frequency then this counter may make more sense than the SRS unit.

The SR620 was designed to be a time interval counter, and that's what gets measured when working with precision 
frequency or time signals.  It's great for this because it has a large number of digits.
In addition there's a way to make 1,000 measurements and average them to increase the precision compared to a one shot 
measurement.  The front panel is much much easier to use than the HP.
http://www.prc68.com/I/TandFTE.shtml#SR620

Have Fun,

Brooke Clarke, N6GCE
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

Volker Esper wrote:
>
> What "small error" are we speaking about? The statement that SRS users have to tolerates a small error while HP users 
> don't seems a little to general to me. IMHO we might be a bit more precise. Anyone who's already done an error 
> analysis for - say - a 10MHz count and a comparison of the counters?
>
> In real life every type of equipment has it's domain, where it has it's specific advantage. Could it be, that's the 
> case for these counters, too?
>
> Cheers
>
> Volker
>
>
> Am 16.03.2013 19:57, schrieb Rick Karlquist:
>>>> 1) I paid quite a bit of money and I had it "calibrated" and fixed by
>>>> SRS,
>>>> and it still exhibits a significant frequency offset with a "perfect"
>>>> reference  and "perfect" DUT!!!
>>>> SRS says a small frequency error is "normal", well that prevents me from
>>>> using the unit as a frequency counter, for me it's only useful as a
>>>> relative
>>>> display frequency counter. HP doesn't have such a frequency error, so no
>>>> worries there.
>> I worked with the guy who designed the HP53132A.  He would
>> never tolerate as "normal" a so-called small error.  The term
>> "frequency counter" brings to mind something that digitally counts
>> zero crossings and should never have an error.  First of all, even
>> if that is all you do, it is still possible to screw it up.
>> Secondly, "counters" have relied on analog interpolation even going
>> back to the HP524 circa 1950.  There is no theoretical basis of having zero
>> error in this case, but the idea is that you display the number of
>> digits that are commensurate with the worst case accuracy of your
>> interpolator.  Again, my colleague who designed the interpolator
>> did very high quality work.  I am pleased to learn that our stuff
>> is better than the stuff from the company up the road.
>>
>> Rick Karlquist N6RK
>> HP Santa Clara Division 1979-1998
>> (still working for Agilent!)
>>
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>
>
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