[time-nuts] Differences / Jitter Between Frequency Standard Sources

Azelio Boriani azelio.boriani at screen.it
Thu Nov 24 15:47:36 EST 2011


Or modern counters where internally every type of measurement is reduced to
a time interval measurement like the HP53132 (150pS resolution).

On Thu, Nov 24, 2011 at 8:04 PM, David Bobbett <d.bobbett at tiscali.co.uk>wrote:

> Just as an aside, you /can /get rid of the 'dithering digit' problem if
> you use a counter which employs a reciprocal counting technique.
>
> I use a Thandar Thirlby TF830 locked to a 10MHz reference derived from a
> Tbolt, but I'm sure there must be others.
>
>
> David Bobbett, G4IRQ
>
>
>
>
> On 24/11/2011 18:01, Robin Kimberley wrote:
>
>> Any frequency counter will have an given accuracy  +/- the LSD (least
>> significant digit), so alternating between  10.0000000 and 9.9999999 looks
>> perfectly normal to me.
>>
>> Rob Kimberley
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Frederick Bray
>> Sent: 24 November 2011 17:56
>> To: time-nuts at febo.com
>> Subject: [time-nuts] Differences / Jitter Between Frequency Standard
>> Sources
>>
>> I have what would probably be considered to be a "newbie" question, so
>> please excuse my likely ignorance.
>>
>> I have a HP 5385A frequency counter, which I am using with an external
>> standard.  If I try to compare one 10 MHz standard against another, using
>> one as the external standard and the other as the device being measured,
>> the
>> readout fluctuates between 10.0000000 and 9.9999999.  This happens when I
>> am
>> comparing a Z3801A and the Trimble look-a-like using the same GPS antenna
>> and identical cables (including length) between the GPS antenna splitter
>> and
>> the two units.  I have also used identical
>> cables between the 10 MHz outputs and the counters.   Hence, cable
>> variations shouldn't be the issue.
>>
>> The same thing happens comparing the Timesource 2700 against either of the
>> GPS standards.
>>
>> Is this attributable to the different standards or the frequency counter?
>>  I
>> haven't yet set up a dual trace scope to compare the various sources
>> directly, but that will be my next step.
>>
>> Thanks for any comments, etc.
>>
>> Fred Bray
>> W6WAW
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>
>>
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>  _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



More information about the time-nuts mailing list