Don't forget that your HP3325 is DDS-based, too, so it adds its own phase error sawtooth. 73, Gerhard dk4xp

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@febo.com > [mailto:time-nuts-bounces@febo.com] Im Auftrag von dk4xp@arcor.de > Gesendet: Dienstag, 25. Januar 2011 15:14 > An: time-nuts@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@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

Very good read. Thank you for the effort and detail. You confirmed something I have thought about but never really dove into. Regards Paul WB8TSL On Tue, Jan 25, 2011 at 9:14 AM, <dk4xp@arcor.de> wrote: > > 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@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. >

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@febo.com > [mailto:time-nuts-bounces@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@febo.com > > [mailto:time-nuts-bounces@febo.com] Im Auftrag von dk4xp@arcor.de > > Gesendet: Dienstag, 25. Januar 2011 15:14 > > An: time-nuts@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@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@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

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@febo.com [mailto:time-nuts-bounces@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@febo.com > [mailto:time-nuts-bounces@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@febo.com > > [mailto:time-nuts-bounces@febo.com] Im Auftrag von dk4xp@arcor.de > > Gesendet: Dienstag, 25. Januar 2011 15:14 > > An: time-nuts@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@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@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@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

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@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@febo.com [mailto:time-nuts-bounces@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@febo.com >> [mailto:time-nuts-bounces@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@febo.com >>> [mailto:time-nuts-bounces@febo.com] Im Auftrag von dk4xp@arcor.de >>> Gesendet: Dienstag, 25. Januar 2011 15:14 >>> An: time-nuts@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@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@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@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@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

Well, do not feel bad. I am now in my 66th year and still learning. BTW, I built my first DDS back around 1970. Hard to believe. About the same time that I built my first digital filter. Used all discrete components and back then we still called them recursive and non-recursive. We never heard the term DSP till much much later. I remember using the "Remez Exchange Algorithm" to go from the S plane to the Z plane. Of course we also used the common "Matched Z" and others as well. My senior project in the late 60's was a switched capacitor filter. Seems like yesterday, and now I am an old man with 5 grandkids :). Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Ulrich Bangert Sent: Tuesday, January 25, 2011 2:01 PM To: Discussion of precise time and frequency measurement Cc: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] An (unknown?) nasty feature of the DDS principlefortime nuts applications 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@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@febo.com [mailto:time-nuts-bounces@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@febo.com >> [mailto:time-nuts-bounces@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@febo.com >>> [mailto:time-nuts-bounces@febo.com] Im Auftrag von dk4xp@arcor.de >>> Gesendet: Dienstag, 25. Januar 2011 15:14 >>> An: time-nuts@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@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@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@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@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@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

Am 25.01.2011 15:35, schrieb Ulrich Bangert: > 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. Yes, it's f-N, I must have stored that in the wrong winding of my brain... Fortunately, I had no need to repair my 3325B upto now. BTW, your effect has been described in detail in the article that Bruce cited on jan7 in the NoStateOfTheArtCounter thread. <http://sdrforum.org/pages/sdr06/sdr06_papers/1.3/1.3-01.pdf > (seems not to work anymore, may be a typo of mine) In the meantime, I have published my sin/cos table on http://opencores.org/project,sincos It should be easy to generate a version with BCD-coded phase input to make a decimal-friendly DDS.

On 1/25/2011 1:26 PM, Gerhard Hoffmann wrote: > Am 25.01.2011 15:35, schrieb Ulrich Bangert: >> 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. > Yes, it's f-N, I must have stored that in the wrong winding of my > brain... > Fortunately, I had no need to repair my 3325B upto now. > > BTW, your effect has been described in detail in the article that > Bruce cited on jan7 in the NoStateOfTheArtCounter thread. > > <http://sdrforum.org/pages/sdr06/sdr06_papers/1.3/1.3-01.pdf > > (seems not to work anymore, may be a typo of mine) > Now it seems to be found as the first doc in session 1.3 here: http://groups.winnforum.org/p/cm/ld/fid=58 > > In the meantime, I have published my sin/cos table on > > http://opencores.org/project,sincos > > It should be easy to generate a version with BCD-coded phase input > to make a decimal-friendly DDS. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > >

Another description of such artifacts occurs in the tutorial: http://www.analog.com/static/imported-files/tutorials/450968421DDS_Tutorial_rev12-2-99.pdf Bruce Gerhard Hoffmann wrote: > Am 25.01.2011 15:35, schrieb Ulrich Bangert: >> 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. > Yes, it's f-N, I must have stored that in the wrong winding of my > brain... > Fortunately, I had no need to repair my 3325B upto now. > > BTW, your effect has been described in detail in the article that > Bruce cited on jan7 in the NoStateOfTheArtCounter thread. > > <http://sdrforum.org/pages/sdr06/sdr06_papers/1.3/1.3-01.pdf > > (seems not to work anymore, may be a typo of mine) > > They've changed their name to http://www.wirelessinnovation.org However finding that paper may take a while. > In the meantime, I have published my sin/cos table on > > http://opencores.org/project,sincos > > It should be easy to generate a version with BCD-coded phase input > to make a decimal-friendly DDS. >