[time-nuts] HP53132A vs SR625

Ed Palmer ed_palmer at sasktel.net
Sun Mar 17 13:56:50 EDT 2013


Hi Said,

That equation looks similar in form to the specs for any counter. What 
are the comparable equations for the  53132A or the 5370(A or B)?

Ed

On 3/17/2013 10:41 AM, Said Jackson wrote:
> Volker,
>
> The error I have seen was in the high xE-011's to the low xE-010's. the only way around it was to turn on relative measurements, which then subtracted out this error. That error makes the unit almost useless to me.
>
> The factory told me as long as it is within specs they will ship it after cal and not bother trying to improve this.
>
> The "acceptable" specs are pretty crappy in tim-nuts terms: +/-350pico * frequency with a 1s gate time. Thats straight from the user manual and assuming no reference error. From the manual:
>
> Frequency Accuracy:
> < ± ((100ps typ [350 ps max])/Gate + Timebase Error ) x Frequency
>
> That equates to up to +/-3.5E-010 if my math is right!
>
> Not so impressive. I can confirm Ricks comment about HP 53132A units not showing that type of error.
>
> Not knowing how big the error is without another non-SRS counter to compare to, and if it may actually be bigger than spec is a problem. I don't remember if it shows up when feeding the counter its own reference.
>
> Bye
> Said
>
>
> Sent From iPhone
>
> On Mar 16, 2013, at 16:06, Volker Esper <ailer2 at t-online.de> 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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