Re: [time-nuts] Basic regenerative-divider questions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY > At drive levels below saturation, the loss of a mixer depends on the LO > signal level. > Consequently the feedback loop gain of a regenerative divider depends on > the input signal level. > Hence one would expect there to be a well defined threshold at which the > lop gain is sufficient for regeneration to occur. Yep. The theory makes perfect sense, but it's still interesting to watch the f/2 signal appear from nowhere like that. You expect behavior like that when you're playing with tunnel diodes or other unusual parts, but not with an ordinary mixer and filter. Even a regenerative receiver gives some warning when it's about to break into oscillation... -- john, KE5FX ___ 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.
Re: [time-nuts] Basic regenerative-divider questions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY John Miles wrote: >> Am I missing something here? >> >> I always thought mixers were non linear by definition, and >> relying on that >> non linearity to function:-) >> > > Sure, a mixer is nonlinear with respect to the multiplicative function it > applies to its two inputs to obtain the desired output. It should, however, > behave linearly with respect to multiple frequency components that may be > present at any *one* input. You don't want it to modify either input > signal, just multiply them together. > > Think of a mixer with a perfect sine wave at its RF input and a square wave > at its LO input. It's nonlinear with respect to the switching action caused > by the LO signal, but it had better be linear with respect to how it handles > the sine wave being switched on and off. If it distorts the sine wave > input, it will generate harmonics that you probably didn't want. And if you > apply two or more tones to the mixer's input at once, you want only those > same tones coming out, with the usual +/- translation by the LO frequency. > To the extent that the mixer allows the RF input tones to interact or > multiply with each other, it's nonlinear. > > This wasn't such a big deal in the old days when your radio had a high-Q > tuned circuit in front of its first mixer, but modern designs work by > shovelling a large portion of the spectrum into the mixer at once. > Nonlinearity is a bad thing in that case. > > -- john, KE5FX > > John At drive levels below saturation, the loss of a mixer depends on the LO signal level. Consequently the feedback loop gain of a regenerative divider depends on the input signal level. Hence one would expect there to be a well defined threshold at which the lop gain is sufficient for regeneration to occur. Bruce ___ 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.
Re: [time-nuts] Basic regenerative-divider questions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY > Am I missing something here? > > I always thought mixers were non linear by definition, and > relying on that > non linearity to function:-) Sure, a mixer is nonlinear with respect to the multiplicative function it applies to its two inputs to obtain the desired output. It should, however, behave linearly with respect to multiple frequency components that may be present at any *one* input. You don't want it to modify either input signal, just multiply them together. Think of a mixer with a perfect sine wave at its RF input and a square wave at its LO input. It's nonlinear with respect to the switching action caused by the LO signal, but it had better be linear with respect to how it handles the sine wave being switched on and off. If it distorts the sine wave input, it will generate harmonics that you probably didn't want. And if you apply two or more tones to the mixer's input at once, you want only those same tones coming out, with the usual +/- translation by the LO frequency. To the extent that the mixer allows the RF input tones to interact or multiply with each other, it's nonlinear. This wasn't such a big deal in the old days when your radio had a high-Q tuned circuit in front of its first mixer, but modern designs work by shovelling a large portion of the spectrum into the mixer at once. Nonlinearity is a bad thing in that case. -- john, KE5FX ___ 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.
Re: [time-nuts] Basic regenerative-divider questions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY They are non-linear when considering the LO port, and we try to make them linear considering the RF and IF ports, that's what makes them hard to do :-) Didier KO4BB > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] > Sent: Saturday, September 29, 2007 5:39 PM > To: time-nuts@febo.com > Subject: Re: [time-nuts] Basic regenerative-divider questions > > In a message dated 29/09/2007 23:28:23 GMT Daylight Time, > [EMAIL PROTECTED] > writes: > > Yep, but usually they're not quite _that_ nonlinear. :) I'm > used to thinking of mixers as linear devices, from the > IMD/IP3 perspective. > > > > > Am I missing something here? > > I always thought mixers were non linear by definition, and > relying on that non linearity to function:-) > > regards > > Nigel > GM8PZR > > > > > > > ___ > 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.
Re: [time-nuts] Basic regenerative-divider questions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY In a message dated 29/09/2007 23:28:23 GMT Daylight Time, [EMAIL PROTECTED] writes: Yep, but usually they're not quite _that_ nonlinear. :) I'm used to thinking of mixers as linear devices, from the IMD/IP3 perspective. Am I missing something here? I always thought mixers were non linear by definition, and relying on that non linearity to function:-) regards Nigel GM8PZR ___ 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] HD drive clock (no, really)
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Department of Weird Clock Projects" http://www.misc.hackaday.com/2007/09/15/hard-drive-clock-not-a-lame-clock-with-a-hd-face/ -- Margaret Stephanie Leber CCP, SCJP SCWCD <[EMAIL PROTECTED]> http://voicenet.com/~maggie AOPA 925383 -- Amateur Radio Station K3XS -- ARRL 39280 -- AMSAT 32844 "The art of progress is to preserve order amid change and to preserve change amid order."-A.N.Whitehead ___ 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.
Re: [time-nuts] Basic regenerative-divider questions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Yep, but usually they're not quite _that_ nonlinear. :) I'm used to thinking of mixers as linear devices, from the IMD/IP3 perspective. I'll build up the 4:1 divider from the Gupta paper as soon as I have time, and see how it works... -- john, KE5FX > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Behalf Of Bruce Griffiths > Sent: Saturday, September 29, 2007 2:56 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Basic regenerative-divider questions > > > ); SAEximRunCond expanded to false > Errors-To: [EMAIL PROTECTED] RETRY > > John Miles wrote: > >> Did you experience the start of oscillation also as you went from > >> +3 dBm to > >> +4 dBm? The impulse may be part of getting the oscillation running. > >> > > > > No; nothing happens until the +4.8 dBm to +4.9 dBm transition. > There is no > > hysteresis at all; the output vanishes upon falling back to > +4.8. It's an > > interesting effect, to see such a pronounced on-off transition > arising from > > a few basic linear components! > > > > -- john, KE5FX > > > > > John > > However the regenerative loop includes a mixer which itself is > inherently nonlinear. > > Bruce > ___ 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.
Re: [time-nuts] Basic regenerative-divider questions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY John Miles wrote: >> Did you experience the start of oscillation also as you went from >> +3 dBm to >> +4 dBm? The impulse may be part of getting the oscillation running. >> > > No; nothing happens until the +4.8 dBm to +4.9 dBm transition. There is no > hysteresis at all; the output vanishes upon falling back to +4.8. It's an > interesting effect, to see such a pronounced on-off transition arising from > a few basic linear components! > > -- john, KE5FX > > John However the regenerative loop includes a mixer which itself is inherently nonlinear. Bruce ___ 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.
Re: [time-nuts] Basic regenerative-divider questions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY > Did you experience the start of oscillation also as you went from > +3 dBm to > +4 dBm? The impulse may be part of getting the oscillation running. No; nothing happens until the +4.8 dBm to +4.9 dBm transition. There is no hysteresis at all; the output vanishes upon falling back to +4.8. It's an interesting effect, to see such a pronounced on-off transition arising from a few basic linear components! -- john, KE5FX ___ 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.
Re: [time-nuts] Basic regenerative-divider questions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY From: Enrico Rubiola <[EMAIL PROTECTED]> Subject: Re: [time-nuts] Basic regenerative-divider questions Date: Sat, 29 Sep 2007 16:55:49 +0200 Message-ID: <[EMAIL PROTECTED]> Dear Enrico, > I worked on low-noise regenerative dividers long time ago. > See my home page http://rubiola.org , click on "more journal articles" > > 22. E. Rubiola, M. Olivier, J. Groslambert, Phase noise in the > regenerative frequency dividers (PDF, 670 kB), > IEEE Transact. Instrum. Meas. vol.41 no.3 pp.353-360, June 1992. ©IEEE. For convenience: http://www.femto-st.fr/~rubiola/journal-articles/rubiola1992im-regenerative-divider-noise.pdf > Notice that you can divide by 4 with a single divider, > using the 3rd harmonics internally generated by the double balanced > mixer. > Dividing 80 MHz, you feed a 20 MHz back to the mixer. > A 60 MHz signal is generated by the mixer. > 80 MHz - 60 MHz = 20 MHz, here you go. Which is what the NIST articles explicitly exercises. They create a double- frequency oscillation loop having 1/N and (N-1)/N times the input frequency. A very quick introduction is available in http://tf.nist.gov/timefreq/general/pdf/1800.pdf Care to comment on that strategy Enrico? It should be noted that both the 1/N and (N-1)/N frequencies is actually equally available, just that usually the (N-1)/N variant is filtered out. You could also acheive 3/4, 4/5, 5/6, 7/8 etc. divisions. Similarly, both frequencies could be output and also their difference could be included by addition of a mixer (and isolational amps) resulting in an (N-2)/N output. For the 1/4 case you could thus get 1/2 as a side-effect. Naturally, for higher N values would the (N-1)/N be close to the (N+1)/N which results from the 1/N addition with the input frequency. The same basic strategy could also be used get values beyond the input frequency if we choose to use the sum frequency rather than the difference frequency for the high frequency, i.e. by choosing (N+1)/N over (N-1)/N. It would result in the same synchronous regenerate interlocked system. It would allow for 3/2, 4/3, 5/4, 6/5, 7/6, 8/7, 9/8 ratios. A similarly post-processing would only be meaningfull for the sum-products of the two outputs, thus resulting in (N+2)/N ratios, giving 4/2 (2/1 = 2), 5/3, 6/4 (3/2 = 1,5), 7/5 (1,4), 8/6 (4/3), 9/7, 10/8 (5/4 = 1,25). In all these, the 1/2 frequency is notched out from the system. If it where to be included, a trinary oscillation scheme could be used where the 1/2 frequency support itself through the input frequency and the lower and upper frequencies would interlock around the 1/2 frequency rather than the input frequency. This would be equalent to having an 1/2 frequency divider followed by a 1/N divider. Could be an interesting solution when more compact solutions is needed. > Another issue is the correction of the phase noise of a digital divider > using a double-balanced mixer. > Read this *smart* article > > D. Huffman, Extremely low noise frequency divider, > Microwave Journal November 1985, pp. 209--210 Isn't this the same as the Richard Karlquists http://www.karlquist.com/FCS95.pdf Cheers, Magnus ___ 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.
Re: [time-nuts] Basic regenerative-divider questions
); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY
Folks,
deep in my database, there is this reference
R.\ C.\ Harrison,
``Theory of regenerative frequency dividers using double balanced
mixers''
{\em IEEE Trans.\ on Microwawe Theory and Technology},
MTT-S Symp.\ Digest vol.\ 1, June 1989, pp.\ 459--462.
There, you can find some issues about the filter.
Keep the group delay small, otherwise the divider may
enter in chaotic regime.
A short description on where chaos comes from is found in
G.\ Immovilli, G.\ Mantovani
``Analysis of the Miller Frequency divider by two in view of
applications to
wideband FM signals''
{\em Alta Frequenza}
vol.\ 17 no.\ 11, November 1973, pp.\ 313--323.
Very best to all
Enrico
Enrico Rubiola
professor of electronics
web:http://rubiola.org
e-mail: [EMAIL PROTECTED]
FEMTO-ST Institute
32 av. de l'Observatoire
25044 Besancon, FRANCE
voice: +33(0)381.853940 (E.Rubiola)
voice: +33(0)381.853999 (switchboard)
fax:+33(0)381.853998
___
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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Re: [time-nuts] Basic regenerative-divider questions
Dear all, I worked on low-noise regenerative dividers long time ago. See my home page http://rubiola.org , click on "more journal articles" 22. E. Rubiola, M. Olivier, J. Groslambert, Phase noise in the regenerative frequency dividers (PDF, 670 kB), IEEE Transact. Instrum. Meas. vol.41 no.3 pp.353-360, June 1992. ©IEEE. Notice that you can divide by 4 with a single divider, using the 3rd harmonics internally generated by the double balanced mixer. Dividing 80 MHz, you feed a 20 MHz back to the mixer. A 60 MHz signal is generated by the mixer. 80 MHz - 60 MHz = 20 MHz, here you go. Another issue is the correction of the phase noise of a digital divider using a double-balanced mixer. Read this *smart* article D. Huffman, Extremely low noise frequency divider, Microwave Journal November 1985, pp. 209--210 Very best, Enrico On 29 Sep 2007, at 3:02 , John Miles wrote: > Submitted for general discussion: I have a need to divide a low- > noise 80-MHz > clock by two, twice, to obtain 40 MHz and 20 MHz outputs, and my > current > thinking is that the quietest way to do this is with a pair of > cascaded > regenerative dividers. Does anyone have any 'favorite' papers or > application notes on regenerative divider design/construction? > > In particular, what considerations go into determining the > bandwidth of the > post-mixer filter, and how important is the phase-shift network > often seen > in the feedback path? My overriding concern here is phase-noise > performance. > > -- john, KE5FX > > > > ___ > 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. Enrico Rubiola professor of electronics web:http://rubiola.org e-mail: [EMAIL PROTECTED] FEMTO-ST Institute 32 av. de l'Observatoire 25044 Besancon, FRANCE voice: +33(0)381.853940 (E.Rubiola) voice: +33(0)381.853999 (switchboard) fax:+33(0)381.853998 ___ 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.
Re: [time-nuts] Basic regenerative-divider questions
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY From: "John Miles" <[EMAIL PROTECTED]> Subject: Re: [time-nuts] Basic regenerative-divider questions Date: Fri, 28 Sep 2007 21:40:04 -0700 Message-ID: <[EMAIL PROTECTED]> > > A divide by 8 conjugate regenerative divider has been built and tested > > by NIST. > > > > In principle it would be possible to generate F/2, F/4 and F/8 outputs > > simultaneously by adding parallel conjugate filtered feedback paths > > tuned to 3F/2, 7F/8, 3F/4, F/2, F/4 and F/8. > > However the difficulties associated with optimising the phase shifts and > > gains of all the filtered feedback paths may be more trouble than > > its worth. > > Yes, I imagine I'll take the lazy way out and just run separate dividers in > parallel from a 2- or 3-way splitter following the OCXO. Thanks for the > uploads and links. Got some reading to do this weekend. Each divisor would be really simple anyway. > I rigged up a divider last night with a 220-MHz SAW filter and a > randomly-chosen Mini-Circuits mixer, MMIC amp, and 2:1 splitter. I was > surprised at how well it worked without any tweaking. It was kind of > surreal to see the f/2 output appear abruptly once the 440-MHz input reached > a certain level. At +4 dBm of excitation there was nothing at the output, > but with +5 dBm at the input, a nice clean 220 MHz signal appeared out of > nowhere at +16 dBm. Did you experience the start of oscillation also as you went from +3 dBm to +4 dBm? The impulse may be part of getting the oscillation running. Cheers, Magnus ___ 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.
