[time-nuts] An (unknown?) nasty feature of the DDS principlefortime nuts applications
Ulrich Bangert
df6jb at ulrich-bangert.de
Tue Jan 25 19:00:48 UTC 2011
Bob,
I don't know the 33250 from my own experience but after all my Stanford Research DS345 buy on ebay may not have been the best decision in my life. At best I can say that I learn something new every day despite being at the childish age of 55!
Ulrich Bangert
Ortholzer Weg 1
D-27243 Gross Ippener
Germany
Am 25.01.2011 um 18:07 schrieb "Bob Camp" <lists at rtty.us>:
> Hi
>
> Jitter from the sawtooth phase modulation on a DDS output is indeed a very
> real thing. I have an Agilent 33250A generator sitting here on the bench
> that makes a very nice variable jitter signal source.
>
> Bob
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Ulrich Bangert
> Sent: Tuesday, January 25, 2011 9:59 AM
> To: 'Discussion of precise time and frequency measurement'
> Subject: Re: [time-nuts] An (unknown?) nasty feature of the DDS
> principlefortime nuts applications
>
> Ahhh,
>
> I see what you mean because a few pages later there is word of a "phase
> accumulator". But this phase accumulator is a part of the electronics that
> is responsible for generating the control voltage of a VCO that enables the
> device to produce odd frequencies despite the integer dividers in the main
> loop. That IS different from what a phase accumulator's task is in a DDS.
>
> 73s de Ulrich, DF6JB
>
>> -----Ursprungliche Nachricht-----
>> Von: time-nuts-bounces at febo.com
>> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Ulrich Bangert
>> Gesendet: Dienstag, 25. Januar 2011 15:35
>> An: 'Discussion of precise time and frequency measurement'
>> Betreff: Re: [time-nuts] An (unknown?) nasty feature of the
>> DDS principlefor time nuts applications
>>
>>
>> Gerhard,
>>
>> see page 8.6ff of the service manual to see that the HP3325
>> is not DDS based but uses a "Fractional N Synthesizer scheme"
>> which is something completely different and is not prone to
>> the described effects. Nevertheless it is true that the
>> HP3325 contibutes phase noise to the measurement but I had
>> anticipated that this was clear to everybode in the auditorium.
>>
>> 73s de Ulrich, DF&JB
>>
>>> -----Ursprungliche Nachricht-----
>>> Von: time-nuts-bounces at febo.com
>>> [mailto:time-nuts-bounces at febo.com] Im Auftrag von dk4xp at arcor.de
>>> Gesendet: Dienstag, 25. Januar 2011 15:14
>>> An: time-nuts at febo.com
>>> Betreff: Re: [time-nuts] An (unknown?) nasty feature of the
>>> DDS principle for time nuts applications
>>>
>>>
>>>
>>> Don't forget that your HP3325 is DDS-based, too, so it adds
>>> its own phase error sawtooth.
>>>
>>> 73, Gerhard dk4xp
>>>
>>>
>>> _______________________________________________
>>> 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.
>
>
> _______________________________________________
> 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_lists.febo.com
mailing list