Re: [time-nuts] Frequency division by 81
Hi Since we are now into the “system”…… Sometimes this alll gets easier at “standard” frequencies. Taking everything down to 1 Hz ( = 1 pps ), 10 Hz, or 100 or 1k KHz might be worth thinking about. Bob > On Jun 21, 2020, at 3:46 PM, Gilles Clement wrote: > > Dear Ole, > > Very interesting comments, thanks. > I am currently servoing a home brewed local 162kHz oscillator to the incoming > radio signal. The phase difference looks quite clean during day time (ground > wave propagation), but quite dirty at night, (additional fading of such long > wave signals at night ?). Allows me to remove the time phase modulation, and > reach reasonable results. > > What i am planning to do with the 81 divider, is to compare current output > with a « good » 10MHz OCXO (10811) to check with a TIC. > > I am (was) also, indeed, planning to try direct HF signal division to servo > the 10 MHz OCXO. But this may not work well, as you experienced... > > Best, > Gilles. > > >> Le 21 juin 2020 à 16:14, Ole Stender Nielsen via time-nuts >> a écrit : >> >> Dear Gilles, >> >> If I understand you correctly you will take the French time signal at 162 >> kHz and divide the frequency with 81 in an attempt to compare two 2 kHz >> signals, one originating from the time signal, and another from an OCXO. >> >> However, I would advice not to take the 162 kHz signal and try to divide it >> with 81. The 162 kHz signal you pick off the air is an analog signal, and it >> will suffer from all kinds of unwanted noise, dips and multipath phenomena. >> I assume you plan to condition the signal so that you can feed it to a >> digital divider. However, this is an invitation to cycle slips and jumps. >> >> An off-air frequency reference receiver like the Halcyon OFS-1 fed an >> amplified and filtered 162 kHz signal directly to a divider, and the >> resulting performance was awful. Take a look at >> https://dabbledoo.weebly.com/halcyon-ofs-1.html >> >> If you live very close to the transmitter site, it may work to condition and >> then divide the 162 kHz signal, but if not, you will not be happy. >> >> Best regards >> Ole >> >>> Den 21-06-2020 kl. 09:30 skrev Gilles Clement: >>> Hi, >>> Comparing a reference signal at 162kHz with local 10MHz ocxo. Expected Adev >>> 10E-11 at 10sec. >>> 162kHz / 81 = 2kHz = 10MHz / 5000 >>> GC >>> > Le 21 juin 2020 à 05:49, Bob kb8tq a écrit : Hi *Any* divide approach followed by a flip flop clocked by the input clock will meet that same basic requirement. While it *sounds* like it would improve things, it very much depends on the details. What are you trying to do? What is the input frequency? What is the phase noise requirement? Bob > On Jun 20, 2020, at 2:22 PM, Gilles Clement wrote: > > Hi Robert, > You are right, its the lambda divider that was discussed. Need to better > understand this approach > 74HC40103 could also do the 81 Pi-divide easily, but I tend to prefer > the PICDIV concept where the controller is clocked by the signal to > divide (So limited or no noise is added). AVR family could do it, as > most of the instructions take only one clock. > Gilles. > > >>> Le 20 juin 2020 à 19:48, Robert LaJeunesse a >>> écrit : >> Gilles, if I read the Calosso-Rubiola paper correctly a Pi divider is >> pretty much your standard square-wave producing digital divider, such as >> a 74163 (for even divides). There's odd-value (3,5,7) Pi dividers shown >> at >> https://www.theremin.us/Circuit_Library/symmetrical_digital_dividers.html. >> What the Calosso-Rubiola paper promotes is the Lambda divider, which is >> depicted in figure 2 of the paper. >> >> Bob L. >> >>> Sent: Friday, June 19, 2020 at 10:27 AM >>> From: "Gilles Clement" >>> To: "Poul-Henning Kamp" >>> Cc: "Discussion of precise time and frequency measurement" >>> >>> Subject: Re: [time-nuts] Frequency division by 81 >>> >>> Hi, >>> Could you point me to a practical design example of a Pi divider ? >>> >>> >>> Envoyé de mon iPad >>> > Le 19 juin 2020 à 08:56, Poul-Henning Kamp a > écrit : > I need to divide the output of an OCXO by a factor D=81 for testing > purposes. So with minimum added phase noise. Two stages of divide by 9 PI-dividers ? http://rubiola.org/pdf-articles/conference/2013-ifcs-Frequency-dividers.pdf -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. >>> ___ >>>
Re: [time-nuts] Frequency division by 81
Two 74HC393N and one 74HC86N Dip all for less than $ 2 will do the job Bert Kehren In a message dated 6/21/2020 3:57:59 PM Eastern Standard Time, k8yumdoo...@gmail.com writes: Can you stand a few 10's of nano-Hz error in the 162 kHz signal? If so, a 48-bit DDS can get you that close to 162 kHz when the 10 MHz is right on. However, dealing with the off-the air signal would be problematic as has been pointed out, not to mention the added complication of the signal having phase modulation. I've occasionally entertained myself measuring and plotting the pilot carrier of a UHF DTV station about 35 miles from home, and the received signal is festooned with all manner of interesting phase "defects". Fortunately deep dropouts seem to be very infrequent. Admittedly 162 kHz should be rather more stable than ~578 MHz, but still ... Have you considered using a good GPSDO? Although the short term phase stability is not real good, it's otherwise a turn-key and fairly straightforward solution if getting an accurate 10 MHz local reference is your goal. Dana On Sun, Jun 21, 2020 at 1:30 PM Bob Fleming wrote: > French time signal is phase modulated. If I recall correctly. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Frequency division by 81
Dear Ole, Very interesting comments, thanks. I am currently servoing a home brewed local 162kHz oscillator to the incoming radio signal. The phase difference looks quite clean during day time (ground wave propagation), but quite dirty at night, (additional fading of such long wave signals at night ?). Allows me to remove the time phase modulation, and reach reasonable results. What i am planning to do with the 81 divider, is to compare current output with a « good » 10MHz OCXO (10811) to check with a TIC. I am (was) also, indeed, planning to try direct HF signal division to servo the 10 MHz OCXO. But this may not work well, as you experienced... Best, Gilles. > Le 21 juin 2020 à 16:14, Ole Stender Nielsen via time-nuts > a écrit : > > Dear Gilles, > > If I understand you correctly you will take the French time signal at 162 kHz > and divide the frequency with 81 in an attempt to compare two 2 kHz signals, > one originating from the time signal, and another from an OCXO. > > However, I would advice not to take the 162 kHz signal and try to divide it > with 81. The 162 kHz signal you pick off the air is an analog signal, and it > will suffer from all kinds of unwanted noise, dips and multipath phenomena. I > assume you plan to condition the signal so that you can feed it to a digital > divider. However, this is an invitation to cycle slips and jumps. > > An off-air frequency reference receiver like the Halcyon OFS-1 fed an > amplified and filtered 162 kHz signal directly to a divider, and the > resulting performance was awful. Take a look at > https://dabbledoo.weebly.com/halcyon-ofs-1.html > > If you live very close to the transmitter site, it may work to condition and > then divide the 162 kHz signal, but if not, you will not be happy. > > Best regards > Ole > >> Den 21-06-2020 kl. 09:30 skrev Gilles Clement: >> Hi, >> Comparing a reference signal at 162kHz with local 10MHz ocxo. Expected Adev >> 10E-11 at 10sec. >> 162kHz / 81 = 2kHz = 10MHz / 5000 >> GC >> Le 21 juin 2020 à 05:49, Bob kb8tq a écrit : >>> >>> Hi >>> >>> *Any* divide approach followed by a flip flop clocked by the input clock >>> will meet >>> that same basic requirement. While it *sounds* like it would improve >>> things, it >>> very much depends on the details. >>> >>> What are you trying to do? What is the input frequency? What is the phase >>> noise >>> requirement? >>> >>> Bob >>> On Jun 20, 2020, at 2:22 PM, Gilles Clement wrote: Hi Robert, You are right, its the lambda divider that was discussed. Need to better understand this approach 74HC40103 could also do the 81 Pi-divide easily, but I tend to prefer the PICDIV concept where the controller is clocked by the signal to divide (So limited or no noise is added). AVR family could do it, as most of the instructions take only one clock. Gilles. >> Le 20 juin 2020 à 19:48, Robert LaJeunesse a écrit >> : > Gilles, if I read the Calosso-Rubiola paper correctly a Pi divider is > pretty much your standard square-wave producing digital divider, such as > a 74163 (for even divides). There's odd-value (3,5,7) Pi dividers shown > at > https://www.theremin.us/Circuit_Library/symmetrical_digital_dividers.html. > What the Calosso-Rubiola paper promotes is the Lambda divider, which is > depicted in figure 2 of the paper. > > Bob L. > >> Sent: Friday, June 19, 2020 at 10:27 AM >> From: "Gilles Clement" >> To: "Poul-Henning Kamp" >> Cc: "Discussion of precise time and frequency measurement" >> >> Subject: Re: [time-nuts] Frequency division by 81 >> >> Hi, >> Could you point me to a practical design example of a Pi divider ? >> >> >> Envoyé de mon iPad >> Le 19 juin 2020 à 08:56, Poul-Henning Kamp a écrit : >>> >>> I need to divide the output of an OCXO by a factor D=81 for testing purposes. So with minimum added phase noise. >>> Two stages of divide by 9 PI-dividers ? >>> >>> http://rubiola.org/pdf-articles/conference/2013-ifcs-Frequency-dividers.pdf >>> >>> -- >>> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 >>> p...@freebsd.org | TCP/IP since RFC 956 >>> FreeBSD committer | BSD since 4.3-tahoe >>> Never attribute to malice what can adequately be explained by >>> incompetence. >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to >
Re: [time-nuts] Frequency division by 81
Can you stand a few 10's of nano-Hz error in the 162 kHz signal? If so, a 48-bit DDS can get you that close to 162 kHz when the 10 MHz is right on. However, dealing with the off-the air signal would be problematic as has been pointed out, not to mention the added complication of the signal having phase modulation. I've occasionally entertained myself measuring and plotting the pilot carrier of a UHF DTV station about 35 miles from home, and the received signal is festooned with all manner of interesting phase "defects". Fortunately deep dropouts seem to be very infrequent. Admittedly 162 kHz should be rather more stable than ~578 MHz, but still ... Have you considered using a good GPSDO? Although the short term phase stability is not real good, it's otherwise a turn-key and fairly straightforward solution if getting an accurate 10 MHz local reference is your goal. Dana On Sun, Jun 21, 2020 at 1:30 PM Bob Fleming wrote: > French time signal is phase modulated. If I recall correctly. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Frequency division by 81
French time signal is phase modulated. If I recall correctly. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Frequency division by 81
Hi Ok, that’s all very do-able with “normal” CMOS logic and standard counter configurations. There is no need for anything exotic. Two divide by 9’s or 4 divide by threes would do the trick. Anything derived from the 74161 will give you a quick low chip count answer. Bert’s XOR divider will give you symmetric output. Any family from 74ls on should be fast enough. Bob > On Jun 21, 2020, at 3:30 AM, Gilles Clement wrote: > > Hi, > Comparing a reference signal at 162kHz with local 10MHz ocxo. Expected Adev > 10E-11 at 10sec. > 162kHz / 81 = 2kHz = 10MHz / 5000 > GC > >> Le 21 juin 2020 à 05:49, Bob kb8tq a écrit : >> >> Hi >> >> *Any* divide approach followed by a flip flop clocked by the input clock >> will meet >> that same basic requirement. While it *sounds* like it would improve things, >> it >> very much depends on the details. >> >> What are you trying to do? What is the input frequency? What is the phase >> noise >> requirement? >> >> Bob >> >>> On Jun 20, 2020, at 2:22 PM, Gilles Clement wrote: >>> >>> Hi Robert, >>> You are right, its the lambda divider that was discussed. Need to better >>> understand this approach >>> 74HC40103 could also do the 81 Pi-divide easily, but I tend to prefer the >>> PICDIV concept where the controller is clocked by the signal to divide (So >>> limited or no noise is added). AVR family could do it, as most of the >>> instructions take only one clock. >>> Gilles. >>> >>> > Le 20 juin 2020 à 19:48, Robert LaJeunesse a écrit : Gilles, if I read the Calosso-Rubiola paper correctly a Pi divider is pretty much your standard square-wave producing digital divider, such as a 74163 (for even divides). There's odd-value (3,5,7) Pi dividers shown at https://www.theremin.us/Circuit_Library/symmetrical_digital_dividers.html. What the Calosso-Rubiola paper promotes is the Lambda divider, which is depicted in figure 2 of the paper. Bob L. > Sent: Friday, June 19, 2020 at 10:27 AM > From: "Gilles Clement" > To: "Poul-Henning Kamp" > Cc: "Discussion of precise time and frequency measurement" > > Subject: Re: [time-nuts] Frequency division by 81 > > Hi, > Could you point me to a practical design example of a Pi divider ? > > > Envoyé de mon iPad > >>> Le 19 juin 2020 à 08:56, Poul-Henning Kamp a >>> écrit : >> >> >> >>> I need to divide the output of an OCXO by a factor D=81 for testing >>> purposes. So with minimum added phase noise. >> >> Two stages of divide by 9 PI-dividers ? >> >> http://rubiola.org/pdf-articles/conference/2013-ifcs-Frequency-dividers.pdf >> >> -- >> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 >> p...@freebsd.org | TCP/IP since RFC 956 >> FreeBSD committer | BSD since 4.3-tahoe >> Never attribute to malice what can adequately be explained by >> incompetence. > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. >>> >>> ___ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe, go to >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Frequency division by 81
Dear Gilles, If I understand you correctly you will take the French time signal at 162 kHz and divide the frequency with 81 in an attempt to compare two 2 kHz signals, one originating from the time signal, and another from an OCXO. However, I would advice not to take the 162 kHz signal and try to divide it with 81. The 162 kHz signal you pick off the air is an analog signal, and it will suffer from all kinds of unwanted noise, dips and multipath phenomena. I assume you plan to condition the signal so that you can feed it to a digital divider. However, this is an invitation to cycle slips and jumps. An off-air frequency reference receiver like the Halcyon OFS-1 fed an amplified and filtered 162 kHz signal directly to a divider, and the resulting performance was awful. Take a look at https://dabbledoo.weebly.com/halcyon-ofs-1.html If you live very close to the transmitter site, it may work to condition and then divide the 162 kHz signal, but if not, you will not be happy. Best regards Ole Den 21-06-2020 kl. 09:30 skrev Gilles Clement: Hi, Comparing a reference signal at 162kHz with local 10MHz ocxo. Expected Adev 10E-11 at 10sec. 162kHz / 81 = 2kHz = 10MHz / 5000 GC Le 21 juin 2020 à 05:49, Bob kb8tq a écrit : Hi *Any* divide approach followed by a flip flop clocked by the input clock will meet that same basic requirement. While it *sounds* like it would improve things, it very much depends on the details. What are you trying to do? What is the input frequency? What is the phase noise requirement? Bob On Jun 20, 2020, at 2:22 PM, Gilles Clement wrote: Hi Robert, You are right, its the lambda divider that was discussed. Need to better understand this approach 74HC40103 could also do the 81 Pi-divide easily, but I tend to prefer the PICDIV concept where the controller is clocked by the signal to divide (So limited or no noise is added). AVR family could do it, as most of the instructions take only one clock. Gilles. Le 20 juin 2020 à 19:48, Robert LaJeunesse a écrit : Gilles, if I read the Calosso-Rubiola paper correctly a Pi divider is pretty much your standard square-wave producing digital divider, such as a 74163 (for even divides). There's odd-value (3,5,7) Pi dividers shown at https://www.theremin.us/Circuit_Library/symmetrical_digital_dividers.html. What the Calosso-Rubiola paper promotes is the Lambda divider, which is depicted in figure 2 of the paper. Bob L. Sent: Friday, June 19, 2020 at 10:27 AM From: "Gilles Clement" To: "Poul-Henning Kamp" Cc: "Discussion of precise time and frequency measurement" Subject: Re: [time-nuts] Frequency division by 81 Hi, Could you point me to a practical design example of a Pi divider ? Envoyé de mon iPad Le 19 juin 2020 à 08:56, Poul-Henning Kamp a écrit : I need to divide the output of an OCXO by a factor D=81 for testing purposes. So with minimum added phase noise. Two stages of divide by 9 PI-dividers ? http://rubiola.org/pdf-articles/conference/2013-ifcs-Frequency-dividers.pdf -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Stanford University online GPS course
On Sun, 21 Jun 2020 at 02:00, Alexander Sack wrote: > > This is indeed a fantastic course. The professor's explanation of the > pseudorange, the estimanda, and how to linearize them are absolutely must > see TV! > > I found his textbook a bit lacking though (there are better texts). > > -aps IIRC there are two profs and both had written text books on GPS. -- Dr. David Kirkby, Kirkby Microwave Ltd, drkir...@kirkbymicrowave.co.uk https://www.kirkbymicrowave.co.uk/ Telephone 01621-680100./ +44 1621 680100 Registered in England & Wales, company number 08914892. Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United Kingdom ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 81, not quite a random number
And of course 06:06:06 on the 6th June 2006, for those using 2-digit years. I snapped that on our old time system at work, with the time displayed by the top unit, and the date on the bottom unit. Ah - simple pleasures :-) Peter ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Stanford University online GPS course
Thank you Peter for posting this! 73's, John W. AJ6BC On Wed, Jun 3, 2020, 11:33 Peter Vince wrote: > I've just been told about an online undergraduate course on the GPS system > done by Stanford University. I don't remember reading about it on here, > and a quick check of the archives drew a blank. The course is completely > free, and on YouTube at: > > > > https://www.youtube.com/watch?v=o1Fyn_h6LKU=PLGvhNIiu1ubyEOJga50LJMzVXtbUq6CPo=1 > > Turns out it was made in 2014, and the website mentioned is no longer > available. However, the course does look very interesting. It is split > into six sections, and the intention seems to have been for students to do > these one a week. Each section is split into ten videos of about ten to > twenty minutes each, so it comes in bite-sized chunks. I've just watched > the first section, and it was very gentle and understandable - largely > because it was covering material I already knew. There is the promise of > some heavy mathematics later on, so we'll have to see. > > So if you are running out of things to do in self-isolation on a rainy > afternoon, you might care to give this a look - it may well help with our > understanding! > > Regards, > > Peter > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Frequency division by 81
Hi, Comparing a reference signal at 162kHz with local 10MHz ocxo. Expected Adev 10E-11 at 10sec. 162kHz / 81 = 2kHz = 10MHz / 5000 GC > Le 21 juin 2020 à 05:49, Bob kb8tq a écrit : > > Hi > > *Any* divide approach followed by a flip flop clocked by the input clock will > meet > that same basic requirement. While it *sounds* like it would improve things, > it > very much depends on the details. > > What are you trying to do? What is the input frequency? What is the phase > noise > requirement? > > Bob > >> On Jun 20, 2020, at 2:22 PM, Gilles Clement wrote: >> >> Hi Robert, >> You are right, its the lambda divider that was discussed. Need to better >> understand this approach >> 74HC40103 could also do the 81 Pi-divide easily, but I tend to prefer the >> PICDIV concept where the controller is clocked by the signal to divide (So >> limited or no noise is added). AVR family could do it, as most of the >> instructions take only one clock. >> Gilles. >> >> Le 20 juin 2020 à 19:48, Robert LaJeunesse a écrit : >>> >>> Gilles, if I read the Calosso-Rubiola paper correctly a Pi divider is >>> pretty much your standard square-wave producing digital divider, such as a >>> 74163 (for even divides). There's odd-value (3,5,7) Pi dividers shown at >>> https://www.theremin.us/Circuit_Library/symmetrical_digital_dividers.html. >>> What the Calosso-Rubiola paper promotes is the Lambda divider, which is >>> depicted in figure 2 of the paper. >>> >>> Bob L. >>> Sent: Friday, June 19, 2020 at 10:27 AM From: "Gilles Clement" To: "Poul-Henning Kamp" Cc: "Discussion of precise time and frequency measurement" Subject: Re: [time-nuts] Frequency division by 81 Hi, Could you point me to a practical design example of a Pi divider ? Envoyé de mon iPad >> Le 19 juin 2020 à 08:56, Poul-Henning Kamp a écrit >> : > > > >> I need to divide the output of an OCXO by a factor D=81 for testing >> purposes. So with minimum added phase noise. > > Two stages of divide by 9 PI-dividers ? > > http://rubiola.org/pdf-articles/conference/2013-ifcs-Frequency-dividers.pdf > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > p...@freebsd.org | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by > incompetence. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. >>> >>> ___ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe, go to >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
