Re: [time-nuts] Programmable clock for BFO use....noise
Good choice Bert Kehren Sent from my Galaxy Tab® A Original message From: Gerhard Hoffmann Date: 9/16/18 6:30 PM (GMT-05:00) To: time-nuts@lists.febo.com Subject: Re: [time-nuts] Programmable clock for BFO usenoise Am 16.09.2018 um 23:11 schrieb Attila Kinali: > On Sun, 16 Sep 2018 22:08:19 +0200 > Gerhard Hoffmann wrote: > >> I'm also not a fan of using slowish, slew-rate challenged logic as a >> replacement >> for a low pass. When I want a low pass, I make it from nice, >> time-invariant RLC. > Unfortunately, using a low pass after the divider will not > prevent the down-mixing. The down-mixing happens as an inherent > property of digital circuits. Any filtering you do afterwards > will be too late. If you want to have low noise, then the only > way is to produce a non-square wave signal. Or in other words: > use a divider built from harmonic mixers*. Why do you assume that slew-rate limited mixers are any better than mixers with an ultra-short analog time window for doing mess? We should sort that out offline, we are just 20 miles apart? I propose the Zwickel pub in Dudweiler; I'm there with the mostly emerited Fraunhofer people on Friday evenings now & then. :-) :-) :-) > * That is, if you don't like Λ-dividers or DDS I do like DDS, and I don't see a reason for the D/A converters in front of the mixers. D/A converters remove the fun when you can just instantiate a multiplier. Cheers, Gerhard ___ 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] Programmable clock for BFO use....noise
Am 16.09.2018 um 23:11 schrieb Attila Kinali: On Sun, 16 Sep 2018 22:08:19 +0200 Gerhard Hoffmann wrote: I'm also not a fan of using slowish, slew-rate challenged logic as a replacement for a low pass. When I want a low pass, I make it from nice, time-invariant RLC. Unfortunately, using a low pass after the divider will not prevent the down-mixing. The down-mixing happens as an inherent property of digital circuits. Any filtering you do afterwards will be too late. If you want to have low noise, then the only way is to produce a non-square wave signal. Or in other words: use a divider built from harmonic mixers*. Why do you assume that slew-rate limited mixers are any better than mixers with an ultra-short analog time window for doing mess? We should sort that out offline, we are just 20 miles apart? I propose the Zwickel pub in Dudweiler; I'm there with the mostly emerited Fraunhofer people on Friday evenings now & then. :-) :-) :-) * That is, if you don't like Λ-dividers or DDS I do like DDS, and I don't see a reason for the D/A converters in front of the mixers. D/A converters remove the fun when you can just instantiate a multiplier. Cheers, Gerhard ___ 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] Programmable clock for BFO use....noise
Am 16.09.2018 um 20:00 schrub Mark Goldberg: For a radio BFO you want something with low phase noise (low jitter). The SI5351 is not designed for that, and it's jitter spec is 70 ps, which is pretty noisy. It even has a spread spectrum mode that would be even worse. They do have other parts designed for low jitter (< 1ps). Leo Bodnar's GPSDOs with variable output clock frequencies are based on those chips and they provide low phase noise, certainly enough for a radio Oh, a half of a 12AX7 has always been good enough for my needs as a BFO, xtal controlled or LC free running. 30 dB above the noise is S5, what more do you want? The real problems of a receiver are IP3 and that you have a preselector and a mixer that simply work without producing mess. LO jitter is probably > 100 times more important than the BFO, that is just for conversion of IF to audio. cheers, Gerhard, DK4XP (I do not use many 12AX7 any more, in real life that is just a down converter block in a corner of of a Virtex FPGA. ) ___ 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] Programmable clock for BFO use....noise
For a radio BFO you want something with low phase noise (low jitter). The SI5351 is not designed for that, and it's jitter spec is 70 ps, which is pretty noisy. It even has a spread spectrum mode that would be even worse. They do have other parts designed for low jitter (< 1ps). Leo Bodnar's GPSDOs with variable output clock frequencies are based on those chips and they provide low phase noise, certainly enough for a radio. Regards, Mark On Sun, Sep 16, 2018 at 10:22 AM, Chris Waldrup wrote: > How about using a ProgRock on Hans Summers QRP Labs website? This is a > programmable crystal replacement. > > Chris > KD4PBJ > > > On Sep 14, 2018, at 8:06 PM, paul swed wrote: > > > > The beauty of a $2 arduino and a drop of code snitched from Engineer > google. > > OK enough of that back to the thread. > > Regards > > Paul > > WB8TSL > > > >> On Fri, Sep 14, 2018 at 8:04 PM, Mike Feher wrote: > >> > >> Not when I built them in the late 60's and early 70's. All discrete. 73 > - > >> Mike > >> > >> > >> > >> Mike B. Feher, N4FS > >> > >> 89 Arnold Blvd. > >> > >> Howell NJ 07731 > >> > >> 848-245-9115 > >> > >> > >> > >> -----Original Message----- > >> From: time-nuts On Behalf Of Richard > >> (Rick) Karlquist > >> Sent: Friday, September 14, 2018 7:15 PM > >> To: Discussion of precise time and frequency measurement > >> ; ed breya > >> Subject: Re: [time-nuts] Programmable clock for BFO usenoise > >> > >> > >> > >> > >>> Finally, of course, you can use DDS. This is nearly an ideal case for > >> > >> > >> > >> The trouble with a DDS is that you need a microcontroller with software > >> just > >> to baby sit the thing. > >> > >> > >> > >> Rick N6RK > >> > >> > >> > >> ___ > >> > >> time-nuts mailing list -- <mailto:time-nuts@lists.febo.com> > >> time-nuts@lists.febo.com To unsubscribe, go to > >> <http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > >> 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] Programmable clock for BFO use....noise
On Sun, 16 Sep 2018 22:08:19 +0200 Gerhard Hoffmann wrote: > I'm also not a fan of using slowish, slew-rate challenged logic as a > replacement > for a low pass. When I want a low pass, I make it from nice, > time-invariant RLC. Unfortunately, using a low pass after the divider will not prevent the down-mixing. The down-mixing happens as an inherent property of digital circuits. Any filtering you do afterwards will be too late. If you want to have low noise, then the only way is to produce a non-square wave signal. Or in other words: use a divider built from harmonic mixers*. Attila Kinali * That is, if you don't like Λ-dividers or DDS -- The bad part of Zurich is where the degenerates throw DARK chocolate at you. ___ 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] Programmable clock for BFO use....noise
Just the info I wanted! Thanks, N0UU > On September 16, 2018 at 8:49 AM Didier Juges wrote: > > Not the same part number but probably similar in terms of performance: > > > http://www.ko4bb.com/getsimple/index.php?id=microprocessor-crystal-oscillator-comparison > > Bottom line: use a true crystal oscillator, or make your own PLL, not a > programmable "microprocessor crystal" > ___ 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] Programmable clock for BFO use....noise
Am 15.09.2018 um 17:38 schrieb Richard (Rick) Karlquist: If you divide by something that is not a power of 2, then it is important that each stage produces an output waveform with a 50% duty cycle. Otherwise flicker noise which has been up-mixed by a previous stage, will be down-mixed into the signal band, increasing the close-in phase-noise. Wow, another thing I never knew. The conventional wisdom was to divide by any number (even or odd) and then follow that divider with a divide by 2 flip flop to get 50%. Now, that is in question. The now correct answer is to us a variable modulus prescaler to divide by P and P+1, controlled by a toggle flip flop to make half the divisions at P and half at P+1. Resynchronize the output of the divider to the undivided clock with another D-FF and everything but that last D-FF will fall out of the equation for phase noise. I'm also not a fan of using slowish, slew-rate challenged logic as a replacement for a low pass. When I want a low pass, I make it from nice, time-invariant RLC. regards, Gerhard. ___ 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] Programmable clock for BFO use....noise
Hi Chris, On 09/16/2018 07:22 PM, Chris Waldrup wrote: > How about using a ProgRock on Hans Summers QRP Labs website? This is a > programmable crystal replacement. I have one of those but have not had the time to put it up for a real test. Also got the GPS module that should fit, as you can train it to slave a PPS. It would be interesting to take the setup for a test-ride. Need to clean the desk with other things in order to be able to focus on fun projects like that. Cheers, Magnus ___ 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] Programmable clock for BFO use....noise
How about using a ProgRock on Hans Summers QRP Labs website? This is a programmable crystal replacement. Chris KD4PBJ > On Sep 14, 2018, at 8:06 PM, paul swed wrote: > > The beauty of a $2 arduino and a drop of code snitched from Engineer google. > OK enough of that back to the thread. > Regards > Paul > WB8TSL > >> On Fri, Sep 14, 2018 at 8:04 PM, Mike Feher wrote: >> >> Not when I built them in the late 60's and early 70's. All discrete. 73 - >> Mike >> >> >> >> Mike B. Feher, N4FS >> >> 89 Arnold Blvd. >> >> Howell NJ 07731 >> >> 848-245-9115 >> >> >> >> -Original Message- >> From: time-nuts On Behalf Of Richard >> (Rick) Karlquist >> Sent: Friday, September 14, 2018 7:15 PM >> To: Discussion of precise time and frequency measurement >> ; ed breya >> Subject: Re: [time-nuts] Programmable clock for BFO usenoise >> >> >> >> >>> Finally, of course, you can use DDS. This is nearly an ideal case for >> >> >> >> The trouble with a DDS is that you need a microcontroller with software >> just >> to baby sit the thing. >> >> >> >> Rick N6RK >> >> >> >> ___ >> >> time-nuts mailing list -- <mailto:time-nuts@lists.febo.com> >> time-nuts@lists.febo.com To unsubscribe, go to >> <http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> >> 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] Programmable clock for BFO use....noise
Hi Coming back to the basics of the design: If you are playing with a normal radio, a BFO that drifts under a few Hertz is going to be pretty much un-noticable. Drift is a bit of an elastic term in this case since it can cover a bunch of different parameters on an oscillator (temperature as things warm up / aging / retrace / voltage stability ….). For fun, lets say that 25.3 Hz over a day and 5C is “adequate” for the task. Oddly enough this makes the math easy. 25.3 Hz / 253 KHz = 1 / 10,000 = 100 ppm. A crystal that drifts 1 ppm / C is not a super duper part at room temperature. Over our 5C range, that’s only 5 ppm. It would have to be 10X worse to really eat into our budget. Aging / warmup / retrace wise, a crystal that moves a couple ppm in the first day is moving a lot. Again not a big hit to our budget. Voltage stability on a properly designed circuit with a normal voltage regulator should be very small compared to the budget. Maybe it’s a ppm, probably less. Bottom line - the crystal likely is doing >10X better than what our arbitrary spec would require. That’s why a lot of radios do just fine with an L/C based BFO. For even more fun, take a look at the likely drift of the mechanical filters involved. They are not going to be as stable as the crystal ….. Even a crystal filter at 250KHz isn’t going to be as stable as the AT cut based evaluation above. Bob > On Sep 16, 2018, at 7:49 AM, Didier Juges wrote: > > Not the same part number but probably similar in terms of performance: > > http://www.ko4bb.com/getsimple/index.php?id=microprocessor-crystal-oscillator-comparison > > Bottom line: use a true crystal oscillator, or make your own PLL, not a > programmable "microprocessor crystal" > > On Fri, Sep 14, 2018, 11:15 AM wrote: > >> Off topic for this list, but you guys are experts in oscillator noise! >> >> Playing with some mechanical filters. Need USB and LSB crystals for the >> BFO. No one seems to make crystals anymore, especially in the 253 KHz >> range! >> >> Looking at the DigiKey Cardinal programmable oscillators. Cheap and >> available: CPPC1LZ A5B6 >> >> Anyone have an idea how noisy these would be after a division by 4 to get >> them in range? >> >> Thanks, >> >> N0UU >> ___ >> 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] Programmable clock for BFO use....noise
Hi Most of the traditional rules about phase noise apply out to 10 or 20% of the “carrier” frequency. If the carrier is 1Hz, then you are talking about the traditional definitions holding out to 0.1 or 0.2 Hz relative to carrier. That’s *deep* in the 1/F noise part of the divider’s “noise curve”. Since the ADEV of the 1 PPS is typically no worse than the ADEV of the 10 MHz, it would be hard to come up with a model where the 1 PPS has picked up a lot of extra noise. Bob > On Sep 15, 2018, at 9:05 PM, Scott Stobbe wrote: > > That is fascinating. So, the 1PPS line on a GPSDO (a divide by 10Meg in > many cases) is 70 dB worse than the traditional 20log(N) PN scaling? > > On Sat, Sep 15, 2018 at 11:40 AM Richard (Rick) Karlquist < > rich...@karlquist.com> wrote: > >> Another great posting from Attila that keeps the S/N ratio >> on this list high. >> >> On 9/15/2018 3:26 AM, Attila Kinali wrote: >> >>> possible logic family for the task. Otherwise the harmonics of the >>> switching of the FF will down-mix high frequency white noise down >>> to the signal band (this is the reason for the 10*log(N) noise scaling >>> of digital divider that Egan[1] and Calosso/Rubiola[2] and a few others >>> mentioned). >> >> Wow, I never knew this in 45 years of designing synthesizers! >> I do remember that some of the frequency counter engineers at HP >> talked about noise aliasing. I think this is another way of >> describing the same problem. >> >> About 10 years ago, the frequency synthesizer chip vendors started >> talking about a Figure of Merit (FOM) that predicted phase noise floor, >> and it also included the 10 LOG N noise scaling. An application >> engineer at ADI told me this was a characteristic of the sampling phase >> detector that all these chips used. But I always wondered if the >> frequency divider could come into play. The way FOM is defined, >> it doesn't distinguish between phase detector and divider noise. >> >> At Agilent, we used to make a lot of lab demos using a Centellax >> (now Microsemi AKA Microchip) frequency divider that could divide by any >> number between 8 and 511 up to 10 GHz. It was absolutely fabulous for >> dividing 10 GHz down to 2.5 GHz. But 20 LOG N quit working if I tried >> to divide down to 50 MHz. Now you have explained it. >>> >>> If you divide by something that is not a power of 2, then it is important >>> that each stage produces an output waveform with a 50% duty cycle. >> Otherwise >>> flicker noise which has been up-mixed by a previous stage, will be >> down-mixed >>> into the signal band, increasing the close-in phase-noise. >> >> Wow, another thing I never knew. The conventional wisdom was to >> divide by any number (even or odd) and then follow that divider >> with a divide by 2 flip flop to get 50%. Now, that is in question. >> The now correct answer is to us a variable modulus prescaler to >> divide by P and P+1, controlled by a toggle flip flop to make >> half the divisions at P and half at P+1. >> >> Does anyone else have experience with these issues? >> >> Rick N6RK >> >> >> ___ >> 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] Programmable clock for BFO use....noise
That is fascinating. So, the 1PPS line on a GPSDO (a divide by 10Meg in many cases) is 70 dB worse than the traditional 20log(N) PN scaling? On Sat, Sep 15, 2018 at 11:40 AM Richard (Rick) Karlquist < rich...@karlquist.com> wrote: > Another great posting from Attila that keeps the S/N ratio > on this list high. > > On 9/15/2018 3:26 AM, Attila Kinali wrote: > > > possible logic family for the task. Otherwise the harmonics of the > > switching of the FF will down-mix high frequency white noise down > > to the signal band (this is the reason for the 10*log(N) noise scaling > > of digital divider that Egan[1] and Calosso/Rubiola[2] and a few others > > mentioned). > > Wow, I never knew this in 45 years of designing synthesizers! > I do remember that some of the frequency counter engineers at HP > talked about noise aliasing. I think this is another way of > describing the same problem. > > About 10 years ago, the frequency synthesizer chip vendors started > talking about a Figure of Merit (FOM) that predicted phase noise floor, > and it also included the 10 LOG N noise scaling. An application > engineer at ADI told me this was a characteristic of the sampling phase > detector that all these chips used. But I always wondered if the > frequency divider could come into play. The way FOM is defined, > it doesn't distinguish between phase detector and divider noise. > > At Agilent, we used to make a lot of lab demos using a Centellax > (now Microsemi AKA Microchip) frequency divider that could divide by any > number between 8 and 511 up to 10 GHz. It was absolutely fabulous for > dividing 10 GHz down to 2.5 GHz. But 20 LOG N quit working if I tried > to divide down to 50 MHz. Now you have explained it. > > > > If you divide by something that is not a power of 2, then it is important > > that each stage produces an output waveform with a 50% duty cycle. > Otherwise > > flicker noise which has been up-mixed by a previous stage, will be > down-mixed > > into the signal band, increasing the close-in phase-noise. > > Wow, another thing I never knew. The conventional wisdom was to > divide by any number (even or odd) and then follow that divider > with a divide by 2 flip flop to get 50%. Now, that is in question. > The now correct answer is to us a variable modulus prescaler to > divide by P and P+1, controlled by a toggle flip flop to make > half the divisions at P and half at P+1. > > Does anyone else have experience with these issues? > > Rick N6RK > > > ___ > 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] Programmable clock for BFO use....noise
Another great posting from Attila that keeps the S/N ratio on this list high. On 9/15/2018 3:26 AM, Attila Kinali wrote: possible logic family for the task. Otherwise the harmonics of the switching of the FF will down-mix high frequency white noise down to the signal band (this is the reason for the 10*log(N) noise scaling of digital divider that Egan[1] and Calosso/Rubiola[2] and a few others mentioned). Wow, I never knew this in 45 years of designing synthesizers! I do remember that some of the frequency counter engineers at HP talked about noise aliasing. I think this is another way of describing the same problem. About 10 years ago, the frequency synthesizer chip vendors started talking about a Figure of Merit (FOM) that predicted phase noise floor, and it also included the 10 LOG N noise scaling. An application engineer at ADI told me this was a characteristic of the sampling phase detector that all these chips used. But I always wondered if the frequency divider could come into play. The way FOM is defined, it doesn't distinguish between phase detector and divider noise. At Agilent, we used to make a lot of lab demos using a Centellax (now Microsemi AKA Microchip) frequency divider that could divide by any number between 8 and 511 up to 10 GHz. It was absolutely fabulous for dividing 10 GHz down to 2.5 GHz. But 20 LOG N quit working if I tried to divide down to 50 MHz. Now you have explained it. If you divide by something that is not a power of 2, then it is important that each stage produces an output waveform with a 50% duty cycle. Otherwise flicker noise which has been up-mixed by a previous stage, will be down-mixed into the signal band, increasing the close-in phase-noise. Wow, another thing I never knew. The conventional wisdom was to divide by any number (even or odd) and then follow that divider with a divide by 2 flip flop to get 50%. Now, that is in question. The now correct answer is to us a variable modulus prescaler to divide by P and P+1, controlled by a toggle flip flop to make half the divisions at P and half at P+1. Does anyone else have experience with these issues? Rick N6RK ___ 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] Programmable clock for BFO use....noise
The question was deviding a Rb 20 MHz to 10 that is easy to but how much effort is dependant what it is used for and that in turn determines what to use on the input. We have 4 choices depending on the requirementBert Sent from my Galaxy Tab® A Original message From: Attila Kinali Date: 9/15/18 8:34 AM (GMT-05:00) To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Programmable clock for BFO usenoise Hoi Bert, On Sat, 15 Sep 2018 11:09:18 + (UTC) ew via time-nuts wrote: > What about the application and the trigger circuit Sorry, I don't understand what you mean. Attila Kinali -- The bad part of Zurich is where the degenerates throw DARK chocolate at you. ___ 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] Programmable clock for BFO use....noise
Hoi Bert, On Sat, 15 Sep 2018 11:09:18 + (UTC) ew via time-nuts wrote: > What about the application and the trigger circuit Sorry, I don't understand what you mean. Attila Kinali -- The bad part of Zurich is where the degenerates throw DARK chocolate at you. ___ 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] Programmable clock for BFO use....noise
On Sat, 15 Sep 2018 13:13:40 +0200 Club-Internet Clemgill wrote: > Very interesting, thanks. > I found ref (2) by seems that need to pay or be to registered as a researcher > to get ref (1). > Is there a easier way to get a copy ? Yes, use sci-hub: https://sci-hub.tw/10.1109/58.56498 Attila Kinali -- The bad part of Zurich is where the degenerates throw DARK chocolate at you. ___ 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] Programmable clock for BFO use....noise
Hi Attila, Very interesting, thanks. I found ref (2) by seems that need to pay or be to registered as a researcher to get ref (1). Is there a easier way to get a copy ? Thx, Gilles. > Le 15 sept. 2018 à 12:26, Attila Kinali a écrit : > > On Fri, 14 Sep 2018 21:42:05 + > Bryan _ wrote: > >> I would be interested in hearing more of the more suitable classes of >> logic chips. I have a 20Mhz rubidium that I wanted to divide down to 10Mhz > > Any logic family works, as long as it is fast enough to handle your > input frequency. Due to the non-linear (aka digital) behaviour > of a D-Flipflop style divider, it is recommended to use the slowest > possible logic family for the task. Otherwise the harmonics of the > switching of the FF will down-mix high frequency white noise down > to the signal band (this is the reason for the 10*log(N) noise scaling > of digital divider that Egan[1] and Calosso/Rubiola[2] and a few others > mentioned). > > As a rule of thumb, I'd say that the FF should not be more than 10 to 20 > times faster than the input frequency, to limit noise down-mixing. > If your FF is too fast or you want to reduce the noise floor, capacitively > loading and/or having some additional resistance in the Vcc and GND lines > will help slow it down. But ensure that the resistance is still low enough > that the FF's supply stays within specs at all time. Similarly, the > capacitive loading should be low enough that the output current is within > reasonable bounds. > > Alternatively, using the Λ-divider approach[2] and introducing voltage > steps between 0 and 1 will also reduce down-mixing. > > If you divide by something that is not a power of 2, then it is important > that each stage produces an output waveform with a 50% duty cycle. Otherwise > flicker noise which has been up-mixed by a previous stage, will be down-mixed > into the signal band, increasing the close-in phase-noise. > > > Attila Kinali > > [1] "Modeling Phase Noise in Frequency Dividers," by Egan, 1990 > > [2] "The Sampling Theorem in Pi and Lambda Digital Frequency Dividers," > by Calosso and Rubiola 2013 > > -- > The bad part of Zurich is where the degenerates >throw DARK chocolate at you. > > ___ > 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] Programmable clock for BFO use....noise
What about the application and the trigger circuit In a message dated 9/15/2018 6:27:50 AM Eastern Standard Time, att...@kinali.ch writes: On Fri, 14 Sep 2018 21:42:05 + Bryan _ wrote: > I would be interested in hearing more of the more suitable classes of > logic chips. I have a 20Mhz rubidium that I wanted to divide down to 10Mhz Any logic family works, as long as it is fast enough to handle your input frequency. Due to the non-linear (aka digital) behaviour of a D-Flipflop style divider, it is recommended to use the slowest possible logic family for the task. Otherwise the harmonics of the switching of the FF will down-mix high frequency white noise down to the signal band (this is the reason for the 10*log(N) noise scaling of digital divider that Egan[1] and Calosso/Rubiola[2] and a few others mentioned). As a rule of thumb, I'd say that the FF should not be more than 10 to 20 times faster than the input frequency, to limit noise down-mixing. If your FF is too fast or you want to reduce the noise floor, capacitively loading and/or having some additional resistance in the Vcc and GND lines will help slow it down. But ensure that the resistance is still low enough that the FF's supply stays within specs at all time. Similarly, the capacitive loading should be low enough that the output current is within reasonable bounds. Alternatively, using the Λ-divider approach[2] and introducing voltage steps between 0 and 1 will also reduce down-mixing. If you divide by something that is not a power of 2, then it is important that each stage produces an output waveform with a 50% duty cycle. Otherwise flicker noise which has been up-mixed by a previous stage, will be down-mixed into the signal band, increasing the close-in phase-noise. Attila Kinali [1] "Modeling Phase Noise in Frequency Dividers," by Egan, 1990 [2] "The Sampling Theorem in Pi and Lambda Digital Frequency Dividers," by Calosso and Rubiola 2013 -- The bad part of Zurich is where the degenerates throw DARK chocolate at you. ___ 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] Programmable clock for BFO use....noise
Good points, Ulrich Rohde Sent from my iPhone > On Sep 15, 2018, at 6:26 AM, Attila Kinali wrote: > > On Fri, 14 Sep 2018 21:42:05 + > Bryan _ wrote: > >> I would be interested in hearing more of the more suitable classes of >> logic chips. I have a 20Mhz rubidium that I wanted to divide down to 10Mhz > > Any logic family works, as long as it is fast enough to handle your > input frequency. Due to the non-linear (aka digital) behaviour > of a D-Flipflop style divider, it is recommended to use the slowest > possible logic family for the task. Otherwise the harmonics of the > switching of the FF will down-mix high frequency white noise down > to the signal band (this is the reason for the 10*log(N) noise scaling > of digital divider that Egan[1] and Calosso/Rubiola[2] and a few others > mentioned). > > As a rule of thumb, I'd say that the FF should not be more than 10 to 20 > times faster than the input frequency, to limit noise down-mixing. > If your FF is too fast or you want to reduce the noise floor, capacitively > loading and/or having some additional resistance in the Vcc and GND lines > will help slow it down. But ensure that the resistance is still low enough > that the FF's supply stays within specs at all time. Similarly, the > capacitive loading should be low enough that the output current is within > reasonable bounds. > > Alternatively, using the Λ-divider approach[2] and introducing voltage > steps between 0 and 1 will also reduce down-mixing. > > If you divide by something that is not a power of 2, then it is important > that each stage produces an output waveform with a 50% duty cycle. Otherwise > flicker noise which has been up-mixed by a previous stage, will be down-mixed > into the signal band, increasing the close-in phase-noise. > > >Attila Kinali > > [1] "Modeling Phase Noise in Frequency Dividers," by Egan, 1990 > > [2] "The Sampling Theorem in Pi and Lambda Digital Frequency Dividers," > by Calosso and Rubiola 2013 > > -- > The bad part of Zurich is where the degenerates >throw DARK chocolate at you. > > ___ > 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] Programmable clock for BFO use....noise
On Fri, 14 Sep 2018 21:42:05 + Bryan _ wrote: > I would be interested in hearing more of the more suitable classes of > logic chips. I have a 20Mhz rubidium that I wanted to divide down to 10Mhz Any logic family works, as long as it is fast enough to handle your input frequency. Due to the non-linear (aka digital) behaviour of a D-Flipflop style divider, it is recommended to use the slowest possible logic family for the task. Otherwise the harmonics of the switching of the FF will down-mix high frequency white noise down to the signal band (this is the reason for the 10*log(N) noise scaling of digital divider that Egan[1] and Calosso/Rubiola[2] and a few others mentioned). As a rule of thumb, I'd say that the FF should not be more than 10 to 20 times faster than the input frequency, to limit noise down-mixing. If your FF is too fast or you want to reduce the noise floor, capacitively loading and/or having some additional resistance in the Vcc and GND lines will help slow it down. But ensure that the resistance is still low enough that the FF's supply stays within specs at all time. Similarly, the capacitive loading should be low enough that the output current is within reasonable bounds. Alternatively, using the Λ-divider approach[2] and introducing voltage steps between 0 and 1 will also reduce down-mixing. If you divide by something that is not a power of 2, then it is important that each stage produces an output waveform with a 50% duty cycle. Otherwise flicker noise which has been up-mixed by a previous stage, will be down-mixed into the signal band, increasing the close-in phase-noise. Attila Kinali [1] "Modeling Phase Noise in Frequency Dividers," by Egan, 1990 [2] "The Sampling Theorem in Pi and Lambda Digital Frequency Dividers," by Calosso and Rubiola 2013 -- The bad part of Zurich is where the degenerates throw DARK chocolate at you. ___ 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] Programmable clock for BFO use....noise
Depending on the cost of those mems devices, a microcontroller can be so trivial that you can just consider it as a smart eprom. Like Tom's PICDIV dividers, which act more like perfect-for-pupose division chip than a micro. On Sat, Sep 15, 2018 at 4:31 AM, Forrest Christian (List Account) < li...@packetflux.com> wrote: > Would a mems oscillator such as a dsc6183 possibly work for you? I'm > uncertain if the characteristics of a mems oscillator is compatible with > your application. > > For odd frequencies I often head toward a mems oscillator since many can be > programmed to any reasonable frequency. For example one can buy dsc6183 > blanks and use a programmer to program it to your desired frequency. > > The dsc61xx series happens to be one time programmable so you only get one > shot at it per blank. The programmer is relatively inexpensive, but might > be more than one would want to pay for a one off. I have found that having > a collection of blanks and a programmer is very useful since it allows me > to generate any frequency oscillator I need. > > There are other mems oscillator models out there, with various specs and > programming (or not) options. > > > > > > > On Fri, Sep 14, 2018, 11:16 AM wrote: > > > Off topic for this list, but you guys are experts in oscillator noise! > > > > Playing with some mechanical filters. Need USB and LSB crystals for the > > BFO. No one seems to make crystals anymore, especially in the 253 KHz > > range! > > > > Looking at the DigiKey Cardinal programmable oscillators. Cheap and > > available: CPPC1LZ A5B6 > > > > Anyone have an idea how noisy these would be after a division by 4 to get > > them in range? > > > > Thanks, > > > > N0UU > > ___ > > 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] Programmable clock for BFO use....noise Thanks to all
Somebody send me the URL to that board thank you On Fri, Sep 14, 2018, 9:21 PM wrote: > Got a whole bunch of answers all with useful info. I think I will go > with Hans' 4 output board to see if the project works at all and go from > there. Off on a three week tour of Italy to Malta and should have the > parts when I get back. This is one of those weird design things so maybe > the oscillators won't be the problem! > > N0UU > ___ > 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] Programmable clock for BFO use....noise Thanks to all
Got a whole bunch of answers all with useful info. I think I will go with Hans' 4 output board to see if the project works at all and go from there. Off on a three week tour of Italy to Malta and should have the parts when I get back. This is one of those weird design things so maybe the oscillators won't be the problem! N0UU ___ 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] Programmable clock for BFO use....noise
Would a mems oscillator such as a dsc6183 possibly work for you? I'm uncertain if the characteristics of a mems oscillator is compatible with your application. For odd frequencies I often head toward a mems oscillator since many can be programmed to any reasonable frequency. For example one can buy dsc6183 blanks and use a programmer to program it to your desired frequency. The dsc61xx series happens to be one time programmable so you only get one shot at it per blank. The programmer is relatively inexpensive, but might be more than one would want to pay for a one off. I have found that having a collection of blanks and a programmer is very useful since it allows me to generate any frequency oscillator I need. There are other mems oscillator models out there, with various specs and programming (or not) options. On Fri, Sep 14, 2018, 11:16 AM wrote: > Off topic for this list, but you guys are experts in oscillator noise! > > Playing with some mechanical filters. Need USB and LSB crystals for the > BFO. No one seems to make crystals anymore, especially in the 253 KHz > range! > > Looking at the DigiKey Cardinal programmable oscillators. Cheap and > available: CPPC1LZ A5B6 > > Anyone have an idea how noisy these would be after a division by 4 to get > them in range? > > Thanks, > > N0UU > ___ > 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] Programmable clock for BFO use....noise
The beauty of a $2 arduino and a drop of code snitched from Engineer google. OK enough of that back to the thread. Regards Paul WB8TSL On Fri, Sep 14, 2018 at 8:04 PM, Mike Feher wrote: > Not when I built them in the late 60's and early 70's. All discrete. 73 - > Mike > > > > Mike B. Feher, N4FS > > 89 Arnold Blvd. > > Howell NJ 07731 > > 848-245-9115 > > > > -Original Message- > From: time-nuts On Behalf Of Richard > (Rick) Karlquist > Sent: Friday, September 14, 2018 7:15 PM > To: Discussion of precise time and frequency measurement > ; ed breya > Subject: Re: [time-nuts] Programmable clock for BFO usenoise > > > > > > > > Finally, of course, you can use DDS. This is nearly an ideal case for > > > > The trouble with a DDS is that you need a microcontroller with software > just > to baby sit the thing. > > > > Rick N6RK > > > > ___ > > time-nuts mailing list -- <mailto:time-nuts@lists.febo.com> > time-nuts@lists.febo.com To unsubscribe, go to > <http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > 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] Programmable clock for BFO use....noise
Not when I built them in the late 60's and early 70's. All discrete. 73 - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 -Original Message- From: time-nuts On Behalf Of Richard (Rick) Karlquist Sent: Friday, September 14, 2018 7:15 PM To: Discussion of precise time and frequency measurement ; ed breya Subject: Re: [time-nuts] Programmable clock for BFO usenoise > > Finally, of course, you can use DDS. This is nearly an ideal case for The trouble with a DDS is that you need a microcontroller with software just to baby sit the thing. Rick N6RK ___ time-nuts mailing list -- <mailto:time-nuts@lists.febo.com> time-nuts@lists.febo.com To unsubscribe, go to <http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> 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] Programmable clock for BFO use....noise
Rick said: "The trouble with a DDS is that you need a microcontroller with software just to baby sit the thing." Yes, I know what you mean. I wouldn't want to go through all that. I'm picturing more like the small, cheap DDS boards that show up on ebay. Maybe the right stuff could be found that can stand alone, for maybe a tenth the cost of a custom crystal or XO. I've always been kind of frustrated with not being able to readily use most of the cool new technologies in ICs, due to the SMT packaging, and the need for programming them via serial ports. I have saved a number of comparatively old-school, obsolete DDS and PLL devices, because they are parallel controlled, and can be hard-wired for fixed or limited functions. Also, speaking of PLLs, maybe that would be the way to go for the OP - depending on the particular frequencies needed, and the resulting complexity of the divider(s). Ed ___ 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] Programmable clock for BFO use....noise
Finally, of course, you can use DDS. This is nearly an ideal case for The trouble with a DDS is that you need a microcontroller with software just to baby sit the thing. Rick N6RK ___ 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] Programmable clock for BFO use....noise
Those programmable oscillators look interesting. I went to Cardinal the website to learn more, but they're pretty sparse on details. It looks like they make all sorts of crystals, OC, TC, and VT XO modules, etc, and these programmable ones, which are apparently PLL-based oscillators locked to an XO. They don't say much more, but if you asked, maybe they'd give some usable info. There was also some mention of their own shortcomings with phase noise and jitter, circa 2005, and how the later generations are much improved. I'd say that since the programmed frequency is at least XO-based, then its stability seems to be specified and can be good, but the noise etc of the associated PLL inside does not seem to specified. It may be OK for the application to just pick a certain frequency that would be easier on the PLL (if you knew more about it and the XO frequency they would use), and easy to divide down to your end results. I would wonder what the few-off cost would be for the appropriate base parts and programming. They also seem to have custom crystal building service, which could be very handy, depending on the cost. I've often needed oddball frequencies for various projects, and wished it was easy and cheap to just order some up. Another trick you can try, that I've resorted to a number of times, is to find two "standard" or common (or oddball ones that you happen to already have) crystal frequencies that you can mix to get the desired result. The combinations of various crystals and possible dividing ratios may yield something close enough to tweak in. An EXCEL sheet can help organize the info and choices. Finally, of course, you can use DDS. This is nearly an ideal case for this, since you want to make stuff around 250 kHz, but necessarily must (for lack of in-range XOs) use a clock in the MHz region - maybe ten to a hundred times higher than the output, so easy to get a good sine out. Between the various XO clock frequencies available, and the program choices in the DDS, it should be possible to come up with a nice scheme to make whatever you want down in that range. Ed ___ 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] Programmable clock for BFO use....noise
I would be interested in hearing more of the more suitable classes of logic chips. I have a 20Mhz rubidium that I wanted to divide down to 10Mhz -=Bryan=- From: time-nuts on behalf of Dana Whitlow Sent: September 14, 2018 12:55 PM To: lstosk...@cox.net; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Programmable clock for BFO usenoise Frequency dividers can be pretty low noise, if you choose the right class of logic. I remember that at one time in the distant past, LSTTL was considered king. Unfortunately I've been out of touch with frequency dividers long enough to be ignorant of what works well today. i'd suggest trying something with either HC-series or AC-series CMOS, chances are fair that you'd be happy. Write me off list and I'll tell you which well-known distributor still has an excellent selection of HC and AC parts in stock. Dana On Fri, Sep 14, 2018 at 11:14 AM, wrote: > Off topic for this list, but you guys are experts in oscillator noise! > > Playing with some mechanical filters. Need USB and LSB crystals for the > BFO. No one seems to make crystals anymore, especially in the 253 KHz > range! > > Looking at the DigiKey Cardinal programmable oscillators. Cheap and > available: CPPC1LZ A5B6 > > Anyone have an idea how noisy these would be after a division by 4 to get > them in range? > > Thanks, > > N0UU > ___ > 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] Programmable clock for BFO use....noise
As a suggestion I collaborate with a Canadian ham some 5 years ago using a DDS as a BFO for the HP 3586. Those details were shared on time-nuts if they are still in the archives.That worked really well. I recall he was a VE3??? The 3586 had 2 crystals for the BFO while the entire rest of the system was locked to a single reference. Adding the DDS really reduced the BFO behaviors that we typical hams wouldn't really notice. It also sound very clean. Regards Paul WB8TSL On Fri, Sep 14, 2018 at 4:26 PM, Richard (Rick) Karlquist < rich...@karlquist.com> wrote: > The AC series is really quite good on phase noise; I used it in > the 5071A at 80 MHz. > > Rick N6RK > > On 9/14/2018 12:55 PM, Dana Whitlow wrote: > >> Frequency dividers can be pretty low noise, if you choose the right class >> of logic. I remember that >> at one time in the distant past, LSTTL was considered king. Unfortunately >> I've been out of touch >> with frequency dividers long enough to be ignorant of what works well >> today. >> >> i'd suggest trying something with either HC-series or AC-series CMOS, >> > > ___ > 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] Programmable clock for BFO use....noise
The AC series is really quite good on phase noise; I used it in the 5071A at 80 MHz. Rick N6RK On 9/14/2018 12:55 PM, Dana Whitlow wrote: Frequency dividers can be pretty low noise, if you choose the right class of logic. I remember that at one time in the distant past, LSTTL was considered king. Unfortunately I've been out of touch with frequency dividers long enough to be ignorant of what works well today. i'd suggest trying something with either HC-series or AC-series CMOS, ___ 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] Programmable clock for BFO use....noise
I encountered these oscillators on a circuit I inherited from another engineer. The spectrum of these is quite dirty and they should only be considered as digital clock oscillators. An additional annoyance is that they are not marked with the frequency they are programmed to, so if you have USB and LSB you'll have to put a dot of paint on them or something to tell them apart. Dividing by 4 or N will reduce spurs by 20 LOG N as any time nut knows. If you get a programmable oscillator at a frequency around 32 MHz and divide it down by 128 to ~253 kHz, you might get enough clean up for your purposes. 20 LOG 128 = 42 dB. Alternately, find a conventional clock oscillator that can be divided by an even integer to hit your BFO frequency. For example, 20 MHz divided by 78 = 256.4 kHz. 20 MHz divided by 80 = 250 kHz. Divide by 39 followed by divide by 2 or divide by 40 followed by divide by 2, in order to get a square wave at the output. Rick N6RK On 9/14/2018 9:14 AM, lstosk...@cox.net wrote: Off topic for this list, but you guys are experts in oscillator noise! Playing with some mechanical filters. Need USB and LSB crystals for the BFO. No one seems to make crystals anymore, especially in the 253 KHz range! Looking at the DigiKey Cardinal programmable oscillators. Cheap and available: CPPC1LZ A5B6 Anyone have an idea how noisy these would be after a division by 4 to get them in range? Thanks, N0UU ___ 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] Programmable clock for BFO use....noise
Frequency dividers can be pretty low noise, if you choose the right class of logic. I remember that at one time in the distant past, LSTTL was considered king. Unfortunately I've been out of touch with frequency dividers long enough to be ignorant of what works well today. i'd suggest trying something with either HC-series or AC-series CMOS, chances are fair that you'd be happy. Write me off list and I'll tell you which well-known distributor still has an excellent selection of HC and AC parts in stock. Dana On Fri, Sep 14, 2018 at 11:14 AM, wrote: > Off topic for this list, but you guys are experts in oscillator noise! > > Playing with some mechanical filters. Need USB and LSB crystals for the > BFO. No one seems to make crystals anymore, especially in the 253 KHz > range! > > Looking at the DigiKey Cardinal programmable oscillators. Cheap and > available: CPPC1LZ A5B6 > > Anyone have an idea how noisy these would be after a division by 4 to get > them in range? > > Thanks, > > N0UU > ___ > 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] Programmable clock for BFO use....noise
I'd look for the appropriate crystals. If it will help, I have a 250.00 kHz one you can have. Wes N7WS On 9/14/2018 9:14 AM, lstosk...@cox.net wrote: Off topic for this list, but you guys are experts in oscillator noise! Playing with some mechanical filters. Need USB and LSB crystals for the BFO. No one seems to make crystals anymore, especially in the 253 KHz range! Looking at the DigiKey Cardinal programmable oscillators. Cheap and available: CPPC1LZ A5B6 Anyone have an idea how noisy these would be after a division by 4 to get them in range? Thanks, N0UU ___ 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] Programmable clock for BFO use....noise
paulsw...@gmail.com said: > I looked at those types of units. I thought they were factory programmed. I > may be wrong but was not of the opinion they were single unit buys. I think the business model is distributor programmed. The distributor stocks a small set of internal xtal frequencies and programs them to order. -- These are my opinions. I hate spam. ___ 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] Programmable clock for BFO use....noise
Not sure it would be the noise divided by 4. Not a useful answer. I looked at those types of units. I thought they were factory programmed. I may be wrong but was not of the opinion they were single unit buys. Regards WB8TSL On Fri, Sep 14, 2018 at 12:14 PM, wrote: > Off topic for this list, but you guys are experts in oscillator noise! > > Playing with some mechanical filters. Need USB and LSB crystals for the > BFO. No one seems to make crystals anymore, especially in the 253 KHz > range! > > Looking at the DigiKey Cardinal programmable oscillators. Cheap and > available: CPPC1LZ A5B6 > > Anyone have an idea how noisy these would be after a division by 4 to get > them in range? > > Thanks, > > N0UU > ___ > 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.
