[time-nuts] Advantages of differential oscillator structures?
Hi, While reading up on oscillator circuits i stumbled over differential oscillator structures (see [1] for example). But sofar i have been unable to figure out what the exact advantages of a differential oscillator strucutre in general are. Would someone here be so kind and give me some hints where to look? Thanks in advance Attila Kinali [1] A High-Stability, Ultra-Low-Power Differential Oscillator Circuit for Demanding Radio Applications, by David Ruffieux, 2002 http://www.imec.be/esscirc/ESSCIRC2002/PDFs/C02.01.pdf http://www.imec.be/esscirc/ESSCIRC2002/presentations/Slides/C02.01.pdf -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] Advantages of differential oscillator structures?
Hi Attila, I gather you did not fully read the paper ? In normal CMOS circuits, the higher the oscillator frequency the higher the amount of current drawn to reach that higher frequency. So, the two oscillator system was used to keep time and wake up the higher frequency oscillator (for example the 12.8 MHz) when the radio was in operation. When not in operation just the lower frequency oscillator (32 KHz) was used to keep time and provide a wake of the microprocessor and the higher frequency oscillator needed for the radio operation. This paper presents a circuit topography that allows the low current operation at a high frequency (12.8 MHz) thus reducing complexity. This in turn allows the design and manufacture of a radio system using one crystal oscillator at a frequency of 12.8 MHz (example in the paper) with the low power advantage that previously required two oscillators. BillWB6BNQ Attila Kinali wrote: Hi, While reading up on oscillator circuits i stumbled over differential oscillator structures (see [1] for example). But sofar i have been unable to figure out what the exact advantages of a differential oscillator strucutre in general are. Would someone here be so kind and give me some hints where to look? Thanks in advance Attila Kinali [1] A High-Stability, Ultra-Low-Power Differential Oscillator Circuit for Demanding Radio Applications, by David Ruffieux, 2002 http://www.imec.be/esscirc/ESSCIRC2002/PDFs/C02.01.pdf http://www.imec.be/esscirc/ESSCIRC2002/presentations/Slides/C02.01.pdf ___ 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] Advantages of differential oscillator structures?
On Sat, 10 Aug 2013 02:39:35 -0700 wb6bnq wb6...@cox.net wrote: I gather you did not fully read the paper ? I did, but... This paper presents a circuit topography that allows the low current operation at a high frequency (12.8 MHz) thus reducing complexity. This in turn allows the design and manufacture of a radio system using one crystal oscillator at a frequency of 12.8 MHz (example in the paper) with the low power advantage that previously required two oscillators. That's one advantage, and not a small one, but differential oscillators have been in use earlier and even in places where power consumption did not matter much. It pops up in crystal oscillator designs now and then but without any mention why this architecture was choosen. So i started to wonder whether there was any additional advantage than just lower power consumption and being able to work with less headroom, like better phase noise or better long term stability or less harmonics. Attila Kinali -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] Modified Extron DA [WAS: Rb video]
Bob wrote: For a reasonable standard distribution, you probably want one input and many outputs. One in / eight out or one in / 12 out are fairly common. At least the video gizmo we've been dissecting has trouble past one in / 4 out. It has 6 CLC409s, each of which drives 3 BNCs, for 18 outputs. Even if you have all 50 ohm loads and only use 2 outputs per op-amp, that's still 12 outputs. If you cascade them you are at one in to 3 useful outputs. to get to eight you do a lot of jumping from here to there. Each op amp adds it's noise in a cascade. You don't need to cascade anything, because you hardwire the inputs in the configuration you want (1x18, 1x12 + 1x6, or 1x6 + 1x6 + 1x6) (which becomes 1x12, 1x8 + 1x4, or 1x4 + 1x4 + 1x4, assuming again that all of your loads are 50 ohms so you use only two outputs per op-amp). Since most of us have few 50 ohm loads and lots of ~1k ohm loads to feed, the current limit of the CLC409s will not matter as long as we distribute the 50 ohm loads among the op-amps. When I used the Extron, I had it set up to be switchable between 1x18 and 1x12 + 1x6. If you are going to run -185 dbc/Hz phase noise signals, none of these solutions will work. For that stuff you want a totally different approach. The same is true if you are after ADEV at 1x10^-15 at 1 second. Agreed. Also, if you need 120 dB of isolation from output to output or output to input. All of these solutions are for feeding the external reference inputs of various test equipment, radios, etc., not for buffering and isolating signals for serious phase noise or ADEV analysis. All I'm really trying to say here is that the alternative isn't all that tough. You can do it cheap with common parts and not a lot of effort. The time to hack up an existing video box (and do it right) may not be much less than the time to do something much simpler from scratch. One person's not that tough is another person's I don't know how I'd do that. I hacked up a video DA (and did it right, within the limits of re-using the CLC409s) in a couple of hours. I have since built my own DA that has much lower phase noise and ADEV than any source I have or am likely ever to have. By the time you design a PC card and have it made, you are way, way beyond not a lot of effort for lots of people, to say nothing of the metalwork (even if it is just making new front and back plates for an existing Extron box). I can do all of that, and I did, but it appears from the on-list interest in video DAs that a lot of time nuts would rather not be bothered. Best regards, Charles ___ 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] Modified Extron DA [WAS: Rb video]
I wrote: All of these solutions are for feeding the external reference inputs of various test equipment, radios, etc., not for buffering and isolating signals for serious phase noise or ADEV analysis. By the time you design a PC card and have it made, you are way, way beyond not a lot of effort for lots of people, to say nothing of the metalwork (even if it is just making new front and back plates for an existing Extron box). I can do all of that, and I did, but it appears from the on-list interest in video DAs that a lot of time nuts would rather not be bothered. I guess what I'm saying is if one is going to the effort to build a DA from scratch, why build something that is just adequate to distribute a reference signal to test equipment and radios? Why not really do it right, and build something that *is* capable of buffering and isolating signals for serious phase noise and ADEV analysis? Best regards, Charles ___ 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] Modified Extron DA [WAS: Rb video]
Hi If you are buying NPO caps that are +/- 20%, get another supplier…. Bob On Aug 9, 2013, at 10:27 PM, briana als...@nc.rr.com wrote: A cap marked 82pf might indeed be 79pf or any value 15-20% either side of the marked value. Depends upon what cap type you use. If you really need 79pf, buy a couple dozen 82 pf caps and select one based upon measurement. Be aware that the measure may be off by 10% too. Regards, Brian On 8/9/2013 8:08 PM, Robert LaJeunesse wrote: Thanks. Might end up more useful than the Pi-network approach I've used a few times before. I appreciate knowing of more tools that can be called upon to help with a design. I just wish the calculators had some way to deal with standard values (like TI's FilterPro). Its frustrating getting a 79pF result and wondering how an 82pF part works. Well, I guess that's what Spice is for... Bob LaJeunesse From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, August 9, 2013 6:41 PM Subject: Re: [time-nuts] Modified Extron DA [WAS: Rb video] Hi The simplest way to design it is to do a T matching network. Two inductors in the top of the T and one cap to ground. Weather it's a filter or a match, it's the standard three element T lowpass. The logic gate wants to see an inductor at high frequency. The T has an input inductor and that keeps it happy (so would a step up L). Since it's a three element match, you get to pick Z in, Z out, and Q. (with an L network you just would get Z in and Z out). Simply design it for a low Q. Q of three isn't a bad number. Anything up to 5 is practical with rational parts (no tuning). The narrower bandwidth of the higher Q design will increase it's sensitivity to temperature. The lower Q will have a smaller coil / lower impedance above cutoff. If you have 18 to 20 dbm out, you can put a 6 to 8 db pad on it. That will improve the broadband match into the cable. If you want to design it as a filter, everything still works pretty much the same. It's still Zin / Zout and one other number with a three element network. If you want to go to more elements, you can indeed get better filtering at the cost of higher temperature sensitivity. With three elements the harmonics are down 60 db. That's plenty good enough…. LC match calculators (there are many others): http://www.changpuak.ch/electronics/calc_18.php http://home.sandiego.edu/~ekim/e194rfs01/jwmatcher/matcher2.html Filter calculator: http://www.calculatoredge.com/electronics/bw%20tee%20low%20pass.htm If you plug the numbers into the calculators you can see what the match does for you in terms of the inductor value. Why not design a flat passband filter? You are only interested in passing 10 MHz. Attenuating other frequencies is not a problem and may be beneficial. The bandwidth is not going to be small enough (with a low Q) to give you trouble. The peaking of the filter gives you a steeper cutoff at harmonic frequencies. It rolls off just like any filter, but it starts from a higher peak. With the T you can do any Zin / Zout ratio provided the Q is high enough. If you want to do low power, set it up as a 100 ohm to 50 ohm or 200 ohm to 50 ohm match. It's a pretty simple solution to the problem that is flexible enough to get the job done. Bob On Aug 9, 2013, at 5:24 PM, Robert LaJeunesse rlajeune...@sbcglobal.net wrote: Bob, I need some education. For a low-pass filter I think series L and shunt C. For two inductors that normally means 2-3 capacitors. If you use only one shunt capacitor is the second L in series with it (as a harmonic trap)? Can you point me to a design tool (or equation set) somewhere that shows how to choose values best to match the impedances? thanks, Bob LaJeunesse From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, August 9, 2013 4:57 PM Subject: Re: [time-nuts] Modified Extron DA [WAS: Rb video] I still think that a distribution amp based on logic ic's is cheaper / simpler / lower power / higher performance. A pair of NC7SZ125's will dump 20 dbm into 50 ohms all day long running at 5.5 volts. Good isolation as well. Do the lowpass filter right and the harmonics are not an issue. Two coils / one cap plus dc blocking does it quite nicely. ___ 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] Modified Extron DA [WAS: Rb video]
Hi On Aug 10, 2013, at 6:29 AM, Charles Steinmetz csteinm...@yandex.com wrote: I wrote: All of these solutions are for feeding the external reference inputs of various test equipment, radios, etc., not for buffering and isolating signals for serious phase noise or ADEV analysis. By the time you design a PC card and have it made, you are way, way beyond not a lot of effort for lots of people, to say nothing of the metalwork (even if it is just making new front and back plates for an existing Extron box). I can do all of that, and I did, but it appears from the on-list interest in video DAs that a lot of time nuts would rather not be bothered. I guess what I'm saying is if one is going to the effort to build a DA from scratch, why build something that is just adequate to distribute a reference signal to test equipment and radios? Why not really do it right, and build something that *is* capable of buffering and isolating signals for serious phase noise and ADEV analysis? Hi A couple of reasons: 1) You have already gone into or towards the don't know / can't do region with a simple pcb and putting a dozen or so holes in a Hammond box. If you add the complexity of a full blown uber circuit you are much further into that area. If you have lost the entire crowd with an afternoon project, there's little use in talking about a two week project. 2) To do an apples to apples type comparison. The super circuits come up and get compared to the modified DA's. The real comparison circuit is much less complex and pretty easy to design. 3) In general you have one best source for phase noise and another for ADEV. Except in the case of a Cs, and tau's 100 seconds, I've never seen them used as the house standard. The standard gets run to things like counters and signal generators mostly to keep them on frequency. In the case of a Cs, the ones I use have multiple outputs already. 4) Overkill is an issue here. Even if it's TimeNuts, there is a point where good enough is indeed a measurable quantity. A counter only needs a standard that's good to some level, past that it does no better. The same is true of everything I have hooked up to my standard lines. I have a *lot* of standard lines running around the basement …. Bob Best regards, Charles ___ 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] Advantages of differential oscillator structures?
Hi A couple of observations: 1) There are *way* more low stability oscillators out there than high stability ones. A lot of the papers are focused on applications that are not TimeNuts grade. 2) There are way more oscillator circuits out there than time to list them. Given a couple of days, you could probably invent a new circuit. 3) Most circuits you see are grounding or buffering variations of each other. Grounding / layout / component selection can be important. Some circuits are easier to layout with this or that technology. 4) There are some classic debates about add on stuff. AGC's are the best example. In loop / out of loop buffers are another. There are several others. They really don't change the basic circuit, but they do impact how it does what it does. Past that (with one exception) the world has pretty much settled on topologies that have one device as the active element. The reasoning is pretty simple - fewer active devices means less impact of active device noise and tempco. The one exception is the HP bridge circuit that Rick Karlquist came up with. There the idea is to have no active devices in the loop, with some impact on Q. There is another exception to the one active device rule, but it's not seen in precision oscillators. As you go lower in frequency, crystal loss goes up. There are cases where you simply can't get enough gain out of a practical circuit using one active device. Since you are at low frequency, the impact of the second active stage is not as great as it would be at HF. The circuit shown in the paper is one of the classic ways to get a low frequency crystal going. It's also a very simple audio square wave oscillator. The paper stuff at the links does indeed go into this issue in some detail. Bob On Aug 10, 2013, at 4:22 AM, Attila Kinali att...@kinali.ch wrote: Hi, While reading up on oscillator circuits i stumbled over differential oscillator structures (see [1] for example). But sofar i have been unable to figure out what the exact advantages of a differential oscillator strucutre in general are. Would someone here be so kind and give me some hints where to look? Thanks in advance Attila Kinali [1] A High-Stability, Ultra-Low-Power Differential Oscillator Circuit for Demanding Radio Applications, by David Ruffieux, 2002 http://www.imec.be/esscirc/ESSCIRC2002/PDFs/C02.01.pdf http://www.imec.be/esscirc/ESSCIRC2002/presentations/Slides/C02.01.pdf -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] Advantages of differential oscillator structures?
Hi It's certainly a good low power approach - if you can fabricate it in silicon. I'd hate to try to do it with discrete devices. The broad band phase noise isn't going to be anything great, but that's likely not something they are worrying about in their system. Bob On Aug 10, 2013, at 9:19 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 39433ff7-ba50-4e0c-9f11-992aedcd5...@rtty.us, Bob Camp writes: A couple of observations: But you have to admit: 5) Getting into low ppm's at 1 microampere is kind of impressive... There's nothing about phase-noise, so I suspect that's where the trade-off is ? -- 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@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Advantages of differential oscillator structures?
In message 39433ff7-ba50-4e0c-9f11-992aedcd5...@rtty.us, Bob Camp writes: A couple of observations: But you have to admit: 5) Getting into low ppm's at 1 microampere is kind of impressive... There's nothing about phase-noise, so I suspect that's where the trade-off is ? -- 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@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Advantages of differential oscillator structures?
On 08/10/2013 12:10 PM, Attila Kinali wrote: On Sat, 10 Aug 2013 02:39:35 -0700 wb6bnq wb6...@cox.net wrote: I gather you did not fully read the paper ? I did, but... This paper presents a circuit topography that allows the low current operation at a high frequency (12.8 MHz) thus reducing complexity. This in turn allows the design and manufacture of a radio system using one crystal oscillator at a frequency of 12.8 MHz (example in the paper) with the low power advantage that previously required two oscillators. That's one advantage, and not a small one, but differential oscillators have been in use earlier and even in places where power consumption did not matter much. It pops up in crystal oscillator designs now and then but without any mention why this architecture was choosen. So i started to wonder whether there was any additional advantage than just lower power consumption and being able to work with less headroom, like better phase noise or better long term stability or less harmonics. Well, at least from this paper they have not analyzed that. Here they only use it for it's benefits in power, which is obvious from the Abstract. If you wish to know other benefits, they need to be analyzed separately, which by itself might prove an interesting paper. Reducing current drawn should be interesting, as this should reduce 1/f noise in the feedback amp, which should make the 1/f^3 noise lower significantly, which should be beneficial for the stability of the oscillator in noise terms, however it might not be beneficial for the oscillator in systematic frequency drift terms. As always, it's a balance thing. It should not be too hard to build it, try it, measure it and learn from it. Sounds like fun! 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] Advantages of differential oscillator structures?
Hi I think you'll find that the low current amps in their schematic have pretty large 1/f noise. Bob On Aug 10, 2013, at 11:04 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/10/2013 12:10 PM, Attila Kinali wrote: On Sat, 10 Aug 2013 02:39:35 -0700 wb6bnq wb6...@cox.net wrote: I gather you did not fully read the paper ? I did, but... This paper presents a circuit topography that allows the low current operation at a high frequency (12.8 MHz) thus reducing complexity. This in turn allows the design and manufacture of a radio system using one crystal oscillator at a frequency of 12.8 MHz (example in the paper) with the low power advantage that previously required two oscillators. That's one advantage, and not a small one, but differential oscillators have been in use earlier and even in places where power consumption did not matter much. It pops up in crystal oscillator designs now and then but without any mention why this architecture was choosen. So i started to wonder whether there was any additional advantage than just lower power consumption and being able to work with less headroom, like better phase noise or better long term stability or less harmonics. Well, at least from this paper they have not analyzed that. Here they only use it for it's benefits in power, which is obvious from the Abstract. If you wish to know other benefits, they need to be analyzed separately, which by itself might prove an interesting paper. Reducing current drawn should be interesting, as this should reduce 1/f noise in the feedback amp, which should make the 1/f^3 noise lower significantly, which should be beneficial for the stability of the oscillator in noise terms, however it might not be beneficial for the oscillator in systematic frequency drift terms. As always, it's a balance thing. It should not be too hard to build it, try it, measure it and learn from it. Sounds like fun! 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. ___ 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] Advantages of differential oscillator structures?
Build it from discrete parts, of course, what frequency do you suggest to try? 32768Hz, 1MHz? I have nothing in-between... On Sat, Aug 10, 2013 at 5:04 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/10/2013 12:10 PM, Attila Kinali wrote: On Sat, 10 Aug 2013 02:39:35 -0700 wb6bnq wb6...@cox.net wrote: I gather you did not fully read the paper ? I did, but... This paper presents a circuit topography that allows the low current operation at a high frequency (12.8 MHz) thus reducing complexity. This in turn allows the design and manufacture of a radio system using one crystal oscillator at a frequency of 12.8 MHz (example in the paper) with the low power advantage that previously required two oscillators. That's one advantage, and not a small one, but differential oscillators have been in use earlier and even in places where power consumption did not matter much. It pops up in crystal oscillator designs now and then but without any mention why this architecture was choosen. So i started to wonder whether there was any additional advantage than just lower power consumption and being able to work with less headroom, like better phase noise or better long term stability or less harmonics. Well, at least from this paper they have not analyzed that. Here they only use it for it's benefits in power, which is obvious from the Abstract. If you wish to know other benefits, they need to be analyzed separately, which by itself might prove an interesting paper. Reducing current drawn should be interesting, as this should reduce 1/f noise in the feedback amp, which should make the 1/f^3 noise lower significantly, which should be beneficial for the stability of the oscillator in noise terms, however it might not be beneficial for the oscillator in systematic frequency drift terms. As always, it's a balance thing. It should not be too hard to build it, try it, measure it and learn from it. Sounds like fun! 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. ___ 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] Advantages of differential oscillator structures?
Hi I suspect that built from discrete parts you will simply have an audio / square wave oscillator. It's a classic multivibrator circuit…. Bob On Aug 10, 2013, at 11:13 AM, Azelio Boriani azelio.bori...@screen.it wrote: Build it from discrete parts, of course, what frequency do you suggest to try? 32768Hz, 1MHz? I have nothing in-between... On Sat, Aug 10, 2013 at 5:04 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/10/2013 12:10 PM, Attila Kinali wrote: On Sat, 10 Aug 2013 02:39:35 -0700 wb6bnq wb6...@cox.net wrote: I gather you did not fully read the paper ? I did, but... This paper presents a circuit topography that allows the low current operation at a high frequency (12.8 MHz) thus reducing complexity. This in turn allows the design and manufacture of a radio system using one crystal oscillator at a frequency of 12.8 MHz (example in the paper) with the low power advantage that previously required two oscillators. That's one advantage, and not a small one, but differential oscillators have been in use earlier and even in places where power consumption did not matter much. It pops up in crystal oscillator designs now and then but without any mention why this architecture was choosen. So i started to wonder whether there was any additional advantage than just lower power consumption and being able to work with less headroom, like better phase noise or better long term stability or less harmonics. Well, at least from this paper they have not analyzed that. Here they only use it for it's benefits in power, which is obvious from the Abstract. If you wish to know other benefits, they need to be analyzed separately, which by itself might prove an interesting paper. Reducing current drawn should be interesting, as this should reduce 1/f noise in the feedback amp, which should make the 1/f^3 noise lower significantly, which should be beneficial for the stability of the oscillator in noise terms, however it might not be beneficial for the oscillator in systematic frequency drift terms. As always, it's a balance thing. It should not be too hard to build it, try it, measure it and learn from it. Sounds like fun! 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. ___ 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] Advantages of differential oscillator structures?
On 08/10/2013 05:13 PM, Bob Camp wrote: Hi I think you'll find that the low current amps in their schematic have pretty large 1/f noise. True, but if you wanted to fool around a little and see what it could do. For the intended application, it's probably good enough thought. 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] Advantages of differential oscillator structures?
Hi Looking at the picture of the die, I suspect their radio has a VCO on it that they lock up through a (noisy) low frequency PLL. That would mean they really don't care a lot about phase noise of the reference. Bob On Aug 10, 2013, at 11:43 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/10/2013 05:13 PM, Bob Camp wrote: Hi I think you'll find that the low current amps in their schematic have pretty large 1/f noise. True, but if you wanted to fool around a little and see what it could do. For the intended application, it's probably good enough thought. 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. ___ 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] Advantages of differential oscillator structures?
On 08/10/2013 05:55 PM, Bob Camp wrote: Hi Looking at the picture of the die, I suspect their radio has a VCO on it that they lock up through a (noisy) low frequency PLL. That would mean they really don't care a lot about phase noise of the reference. Agree. But I was arguing about looking at it outside of their system limits and see if it could be practical approach otherwise. Then their choice of transistor geometrics etc. is irrelevant. So, given that, could it be potentially interesting? 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] Advantages of differential oscillator structures?
Hi The stability with two active devices will be worse than with one. That's true of tc, ADEV, and phase noise. Buffering out of the circuit is problematic for a precision application, so that's likely to add to the noise as well. It's a reasonable way to do a cheap oscillator. It's probably not a lot worse than some inverter feedback clocks. It's not a great approach for a TimeNuts stable part. Bob On Aug 10, 2013, at 12:03 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/10/2013 05:55 PM, Bob Camp wrote: Hi Looking at the picture of the die, I suspect their radio has a VCO on it that they lock up through a (noisy) low frequency PLL. That would mean they really don't care a lot about phase noise of the reference. Agree. But I was arguing about looking at it outside of their system limits and see if it could be practical approach otherwise. Then their choice of transistor geometrics etc. is irrelevant. So, given that, could it be potentially interesting? 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. ___ 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] Advantages of differential oscillator structures?
Hi Any bets on weather or not they have actually designed a 12.8 MHz multivibrator that injection locks to the crystal? Pretty hard with discrete parts, but not out of the question with silicon. You'd have to get their spice (or what ever) files to figure it out ... Bob On Aug 10, 2013, at 12:03 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 08/10/2013 05:55 PM, Bob Camp wrote: Hi Looking at the picture of the die, I suspect their radio has a VCO on it that they lock up through a (noisy) low frequency PLL. That would mean they really don't care a lot about phase noise of the reference. Agree. But I was arguing about looking at it outside of their system limits and see if it could be practical approach otherwise. Then their choice of transistor geometrics etc. is irrelevant. So, given that, could it be potentially interesting? 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. ___ 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] Using VNWA3 to compare Frequency Standards
Hi: This is an interesting type of VNA where they independently change the LO and detector DDS clocks to fill in what otherwise would be nulls thus extending the frequency coverage. 20 minutes into the video they talk about comparing two Rb sources. HAMRADIO 2012 DG8SAQ VNWA UK HD (2012) http://www.youtube.com/watch?v=C94J4AutCRc This same video is also available in a number of different languages. http://www.youtube.com/user/TheKurtPoulsen/videos -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html ___ 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] Using VNWA3 to compare Frequency Standards
On 10 August 2013 19:59, Brooke Clarke bro...@pacific.net wrote: Hi: This is an interesting type of VNA where they independently change the LO and detector DDS clocks to fill in what otherwise would be nulls thus extending the frequency coverage. 20 minutes into the video they talk about comparing two Rb sources. HAMRADIO 2012 DG8SAQ VNWA UK HD (2012) http://www.youtube.com/watch?v=C94J4AutCRc An interesting idea, though I am a bit sceptical. At such small phases, things like changes in temperature of cables have an effect on measurements of phase on a VNA. One can measure something as simple as a short circuit, and will see some drift with temperature, yet I use expensive VNA grade cables on a VNA costing much more than the VWNA. The method assumes the only cause of a measured phase difference between the two oscillators is their frequency drift, but there are other reasons too. I sold me 300 kHz to 3 GHz VNA last week. Someone picks it up tommorow. A 10 MHz reference is too low for my 8720D, which covers 50 MHz to 20 GHz. I wonder if this would work on the inevitable harmonics present, or if one put it into something like a mixer which is non-linear. I must admit I have been tempted to buy one of the VWNAs. I see some results on an earler model, and they looked poor above about 600 MHz, when harmonics of the oscillator are used. I belive they have improved things, but in any case it would compliment my HP, so I really only need something below 50 MHz. Brooke Clarke Dave ___ 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] Rb video - UPDATE video for you critics
To the Group, Here is a link of Gerry's update video addressing some of the concerns expressed here and other places. http://gerrysweeney.com/10mhz-rubidium-frequency-standard-and-signal-distribution-amp-follow-up/ BillWB6BNQ ___ 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] Warped back to 1993
Some of the GPS clocks think its 26 Dec 1993. A Z3805A, a Z3815A and 58534A integrated timing antenna all think it's 26 Dec 1993. What happened?! ___ 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] Warped back to 1993
ma...@non-stop.com.au said: A Z3805A, a Z3815A and 58534A integrated timing antenna all think it's 26 Dec 1993. What happened?! ___ Is that off by 1024 weeks? (Looks close, but I haven't checked the details.) There is a week field in the GPS data stream. It's only 10 bits. I had that problem on a Z3801A. It did the right thing after I told it the date. :GPS:INIT:DATE 2011,12,26 -- These are my opinions. I hate spam. ___ 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] Warped back to 1993
Hal, I can't get it to take, I keep getting E-350 and the time does not change. Did you unplug the antenna or anything while you changed date? -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal Murray Sent: Sunday, 11 August 2013 12:54 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Warped back to 1993 ma...@non-stop.com.au said: A Z3805A, a Z3815A and 58534A integrated timing antenna all think it's 26 Dec 1993. What happened?! ___ Is that off by 1024 weeks? (Looks close, but I haven't checked the details.) There is a week field in the GPS data stream. It's only 10 bits. I had that problem on a Z3801A. It did the right thing after I told it the date. :GPS:INIT:DATE 2011,12,26 -- These are my opinions. I hate spam. ___ 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] Warped back to 1993
Okay this is what worked for me: 1. Removed power and antenna. 2. apply power with no antenna. 3. send :GPS:INIT:DATE 2007,08,11 4. plug antenna back in. For some reason if I used the correct date, the Z3815A warped back to 1993. But I am curious why did this happen today? --marki -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark C. Stephens Sent: Sunday, 11 August 2013 1:06 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Warped back to 1993 Hal, I can't get it to take, I keep getting E-350 and the time does not change. Did you unplug the antenna or anything while you changed date? -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal Murray Sent: Sunday, 11 August 2013 12:54 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Warped back to 1993 ma...@non-stop.com.au said: A Z3805A, a Z3815A and 58534A integrated timing antenna all think it's 26 Dec 1993. What happened?! ___ Is that off by 1024 weeks? (Looks close, but I haven't checked the details.) There is a week field in the GPS data stream. It's only 10 bits. I had that problem on a Z3801A. It did the right thing after I told it the date. :GPS:INIT:DATE 2011,12,26 -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Warped back to 1993
ma...@non-stop.com.au said: Hal, I can't get it to take, I keep getting E-350 and the time does not change. Did you unplug the antenna or anything while you changed date? I don't remember doing anything like that, but it was a long time ago. I may have told it the date while it was doing a survey. The text in the Z3801A manual doesn't say anything about the 1024 week problem. It does say first satellite, so I'd unplug the antenna and power cycle the box and see if that would let you set the date. -- These are my opinions. I hate spam. ___ 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] Warped back to 1993
With the wrong date and time, the GPS should not find almanac data, so will not lock. This was the problem caused by the 1024 week roll over problem. Are we possibly at week 2048?? 73 Glenn WB4UIV At 11:28 PM 8/10/2013, you wrote: ma...@non-stop.com.au said: Hal, I can't get it to take, I keep getting E-350 and the time does not change. Did you unplug the antenna or anything while you changed date? I don't remember doing anything like that, but it was a long time ago. I may have told it the date while it was doing a survey. The text in the Z3801A manual doesn't say anything about the 1024 week problem. It does say first satellite, so I'd unplug the antenna and power cycle the box and see if that would let you set the date. -- These are my opinions. I hate spam. ___ 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] Warped back to 1993
I just checked by Z3801A which is being monitored by SatStat on an old laptop. Mine is showing the correct date and time. Joe Gray W5JG On Sat, Aug 10, 2013 at 8:53 PM, Hal Murray hmur...@megapathdsl.net wrote: ma...@non-stop.com.au said: A Z3805A, a Z3815A and 58534A integrated timing antenna all think it's 26 Dec 1993. What happened?! ___ Is that off by 1024 weeks? (Looks close, but I haven't checked the details.) There is a week field in the GPS data stream. It's only 10 bits. I had that problem on a Z3801A. It did the right thing after I told it the date. :GPS:INIT:DATE 2011,12,26 -- These are my opinions. I hate spam. ___ 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] Warped back to 1993
I have 5 Z3805A and only one had the wrong date. They all have identical GPS modules and firmware so I don't know why just one decided to warp back to 1993. The Z3815A is still stuck at 1993, I can't even set it to 11 Aug 2007. (-1024) even with antenna unplugged and power cycle. I mean, Can set it to 11 Aug 2007, but after the 1st bird it sees it goes back to 1993. I might try a factory default and see how we go. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Joseph Gray Sent: Sunday, 11 August 2013 1:16 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Warped back to 1993 I just checked by Z3801A which is being monitored by SatStat on an old laptop. Mine is showing the correct date and time. Joe Gray W5JG On Sat, Aug 10, 2013 at 8:53 PM, Hal Murray hmur...@megapathdsl.net wrote: ma...@non-stop.com.au said: A Z3805A, a Z3815A and 58534A integrated timing antenna all think it's 26 Dec 1993. What happened?! ___ Is that off by 1024 weeks? (Looks close, but I haven't checked the details.) There is a week field in the GPS data stream. It's only 10 bits. I had that problem on a Z3801A. It did the right thing after I told it the date. :GPS:INIT:DATE 2011,12,26 -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Warped back to 1993
With the wrong date and time, the GPS should not find almanac data, so will not lock. I don't think that's the right way of describing the problem. The satellites broadcast on a known frequency, but that gets shifted all over the place by Doppler. (All over means a big shift relative to the bandwidth of the signal.) If you have a recent almanac and you know the date/time and location, then you can compute the Doppler and look in the right frequency and find the satellites quickly. In this context, find means hearing a signal at an expected frequency. If you don't hear anything where you expect it, then you get to check nearby frequencies. If you don't find anything nearby, you get to give up and start searching the whole Doppler range. It's the difference between warm start and cold start. Once you do find several satellites, you can figure out the date/time and location and after a while get a new almanac. Assume you have done all that. You still don't really know the date. It's like looking at a clock on the wall. It tells you the time but not the date. (Or looking at a digital display that tells you the month and day but not the year.) The GPS signal tells you the date within a 1024 week epoch, but it doesn't tell you which epoch you are in. Telling it the date has the side effect of telling it the epoch. Real early GPS gear punted this problem. There is no way to tell them the epoch. I don't remember any details, but there have been various discussions about gear that is now useless. (With some simple post processing, you could fix that. That's assuming you have a serial interface rather than a 7-segment display.) -- These are my opinions. I hate spam. ___ 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] Warped back to 1993
Nope, I tried all the resets I could find, I can set the date right but as soon as the Z3815A sees a bird, it jumps back to 1993. How annoying, Anyone else with a Z3815A having problems? --marki -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark C. Stephens Sent: Sunday, 11 August 2013 2:40 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Warped back to 1993 I have 5 Z3805A and only one had the wrong date. They all have identical GPS modules and firmware so I don't know why just one decided to warp back to 1993. The Z3815A is still stuck at 1993, I can't even set it to 11 Aug 2007. (-1024) even with antenna unplugged and power cycle. I mean, Can set it to 11 Aug 2007, but after the 1st bird it sees it goes back to 1993. I might try a factory default and see how we go. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Joseph Gray Sent: Sunday, 11 August 2013 1:16 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Warped back to 1993 I just checked by Z3801A which is being monitored by SatStat on an old laptop. Mine is showing the correct date and time. Joe Gray W5JG On Sat, Aug 10, 2013 at 8:53 PM, Hal Murray hmur...@megapathdsl.net wrote: ma...@non-stop.com.au said: A Z3805A, a Z3815A and 58534A integrated timing antenna all think it's 26 Dec 1993. What happened?! ___ Is that off by 1024 weeks? (Looks close, but I haven't checked the details.) There is a week field in the GPS data stream. It's only 10 bits. I had that problem on a Z3801A. It did the right thing after I told it the date. :GPS:INIT:DATE 2011,12,26 -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Warped back to 1993
Today is start of new epoch. As per: http://adn.agi.com/GNSSWeb/ 1753:0 Full GPS week since 1st epoch : day of week number 729:0 GPS Week since latest epoch : seconds of week at midnight for that day So that explains what happened. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark C. Stephens Sent: Sunday, 11 August 2013 1:19 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Warped back to 1993 Okay this is what worked for me: 1. Removed power and antenna. 2. apply power with no antenna. 3. send :GPS:INIT:DATE 2007,08,11 4. plug antenna back in. For some reason if I used the correct date, the Z3815A warped back to 1993. But I am curious why did this happen today? --marki -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark C. Stephens Sent: Sunday, 11 August 2013 1:06 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Warped back to 1993 Hal, I can't get it to take, I keep getting E-350 and the time does not change. Did you unplug the antenna or anything while you changed date? -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal Murray Sent: Sunday, 11 August 2013 12:54 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Warped back to 1993 ma...@non-stop.com.au said: A Z3805A, a Z3815A and 58534A integrated timing antenna all think it's 26 Dec 1993. What happened?! ___ Is that off by 1024 weeks? (Looks close, but I haven't checked the details.) There is a week field in the GPS data stream. It's only 10 bits. I had that problem on a Z3801A. It did the right thing after I told it the date. :GPS:INIT:DATE 2011,12,26 -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
