Hi Ulbrich, Sorry but not everybody a digital and/or a professional guru... can you please be a more specific.... namely to show us the pre filter and other circuit....if you do not mind. Understand that the key point is the PLL or the phase comparator circuit.........if you want to build you own GPS-DO.....
Many thanks and best regards, Ernie. -----Original Message----- From: Ulrich Bangert <[email protected]> To: 'Discussion of precise time and frequency measurement' <[email protected]> Sent: Sat, Mar 31, 2012 2:53 pm Subject: Re: [time-nuts] CW12-TIM vs M12M and the world Bert, sometimes a manual can be a true treasure chest! Just download the PRS-10 anual at http://www.thinksrs.com/downloads/PDFs/Manuals/PRS10m.pdf and find starting on page 13 the complete instructions on how to build your wn GPSDO. A basic knowledge of math, programming and control theory is eeded to understand the manual but then: It works. I have constructed my own DIY GPSDO on the base of the information that I have found there, ncluding the pre-filter. Best regards lrich > -----Ursprungliche Nachricht----- Von: [email protected] [mailto:[email protected]] Im Auftrag von [email protected] Gesendet: Samstag, 31. Marz 2012 13:46 An: [email protected] Betreff: Re: [time-nuts] CW12-TIM vs M12M and the world Ulrich can you tell us more about your pre filter? Thank you Bert Kehren In a message dated 3/31/2012 6:23:49 A.M. Eastern Daylight Time, [email protected] writes: Thomas, > Has anyone compared the M12M to the M12+? I have done some measurements on the M12+ with typical results as shown in http://www.ulrich-bangert.de/M12Performance.jpg The red line is the raw phase data of the M12's PPS against a PPS derived from a local FRK-L rubidium. Note that you do not observe an overall difference frequency (and a resulting drift in phase) because the FRK-L is disciplined by the GPS. The blue line is the sawtooth corrected phase data and it becomes immediatly clear HOW IMPORTANT applying the correction is. The yellow line show you what happens if the sawtooth corrected phase data is sent through a pre-filter (lowpass with 1/3 the time constant of the main pll loop) before entering the loop itself. That is something that I learned from the PRS-10 manual. You may decide on your own which data you would like to work on in a GPSDO. Best regards Ulrich Bangert > -----Ursprungliche Nachricht----- > Von: [email protected] > [mailto:[email protected]] Im Auftrag von Tom Knox > Gesendet: Freitag, 30. Marz 2012 22:19 > An: Time-Nuts > Betreff: Re: [time-nuts] CW12-TIM vs M12M and the world > > > > Has anyone compared the M12M to the M12+? > Thanks for all the input, it is really appreciated. > best wishes; > Thomas Knox > > > > > CC: [email protected] > > From: [email protected] > > Date: Fri, 30 Mar 2012 09:53:17 -0700 > > To: [email protected] > > Subject: Re: [time-nuts] CW12-TIM vs M12M and the world > > > > Hello Ed, Azelio, > > > > We should also compare the same parameters. Sawtooth error > of the m12+ > > of +/-25ns is not its standard deviation, it's max/min. > Compare that > > number to your 30ns max/min measurement on the 5372a. > > > > Standard deviation of the m12+ is around 2ns with correction. That > > needs to be compared to the 5ns you measure on the 5372a as that is > > the best performance you will get from the CW12. Yes the > uncorrected > > 1pps of the m12 is worse, but it is designed to be used with > > correction. So in the end the m12m still performs better than the > > CW12. > > > > Bye, > > Said > > > > Sent From iPhone > > > > On Mar 29, 2012, at 1:56, Azelio Boriani <[email protected]> > > wrote: > > > > > We (that is my company) use the CW12-TIM (NMEA version) > and its PPS > > > wonders as usual, nothing different from a uBlox LEA-5T > or the M12M. > > > > > > On Thu, Mar 29, 2012 at 9:32 AM, Hal Murray > > > <[email protected]> wrote: > > > > > >> > > >>>> The sawtooth error on the Motorola M12+ is about +/- > 25ns, while > > >>>> the CW12-TIM has a sawtooth error of +/- 2 ns, so > correcting for > > >>>> the sawtooth error is not as critical with the CW12-TIM. > > >> > > >>> The first claim > > >>>> The sawtooth error on the Motorola M12+ is about +/- 25ns > > >>> is correct but are you absolutely sure that the second claim is > > >>> correct too????? > > >> > > >>> It would mean a factor >10 improvement of the CW12-TIM > against the > > >>> M12 > > >> which > > >>> is hardly believeable. > > >> > > >> The 25 ns probably comes from period of the the free > running clock > > >> they are using. It doesn't seem unreasonable to me to get 10x > > >> better if they use a GPSDO for the local clock so they > can get the > > >> PPS edge right where they want it. > > >> > > >> > > >> > > >> -- > > >> These are my opinions, not necessarily my employer's. I > hate spam. > > >> > > >> > > >> > > >> > > >> _______________________________________________ > > >> time-nuts mailing list -- [email protected] > > >> To unsubscribe, go to > > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > >> and follow the instructions there. > > >> > > > _______________________________________________ > > > time-nuts mailing list -- [email protected] > > > To unsubscribe, go to > > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > and follow the instructions there. > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ______________________________________________ ime-nuts mailing list -- [email protected] o unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts nd follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
