[time-nuts] OT: xtal osc PN
Hello all, sorry for the OT, but the electronic expertise of the group is too good :-) I'm looking for ideas and directions (articles and so on) to realize very good phase noise xtal oscillator, in the range 20-50 MHz for high performance frequency conversion. I would like to understand what circuits can be realized (not requiring too much professional and modern equipment, test eq. from the 70s-80s is ok) and what is the contribution of the active oscillator device, the xtal itself and the following buffers. Another idea that came on my mind was using digital oscillator (square wave, cmos) and then filtering for sine output, if this makes sense for a low PN point of view. Is there any way to measure the close-in PN of oscillators with an amateur setup? Thanks in advance Frank IZ8DWF ___ 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] OT: xtal osc PN
sorry for the OT, but the electronic expertise of the group is too good :-) I'm looking for ideas and directions (articles and so on) to realize very good phase noise xtal oscillator, in the range 20-50 MHz for high performance frequency conversion. I would like to understand what circuits can be realized (not requiring too much professional and modern equipment, test eq. from the 70s-80s is ok) and what is the contribution of the active oscillator device, the xtal itself and the following buffers. Another idea that came on my mind was using digital oscillator (square wave, cmos) and then filtering for sine output, if this makes sense for a low PN point of view. Is there any way to measure the close-in PN of oscillators with an amateur setup? A couple of good links from someone who faced a similar problem: http://www.xs4all.nl/~martein/pa3ake/hmode/ http://www.xs4all.nl/~martein/pa3ake/hmode/dds_pmnoise_pll.html Also see the links in the last FAQ entry at http://www.ke5fx.com/gpib/faq.htm . -- john, KE5FX ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT: xtal osc PN
On 09/18/2010 09:48 AM, francesco messineo wrote: Hello all, sorry for the OT, but the electronic expertise of the group is too good :-) I'm looking for ideas and directions (articles and so on) to realize very good phase noise xtal oscillator, in the range 20-50 MHz for high performance frequency conversion. I would like to understand what circuits can be realized (not requiring too much professional and modern equipment, test eq. from the 70s-80s is ok) and what is the contribution of the active oscillator device, the xtal itself and the following buffers. Another idea that came on my mind was using digital oscillator (square wave, cmos) and then filtering for sine output, if this makes sense for a low PN point of view. Is there any way to measure the close-in PN of oscillators with an amateur setup? First of all I think you need to quantify what you mean by high performance frequency conversion and what stability measures you are seeking as there are many degrees of excessiveness to attempt, and many of them may be well beyond what you need. Remember, we are time-nuts... :) You can pick up a lot on the theory and measurement side if you look at Enrico Rubiolas material: http://www.femto-st.fr/~rubiola/ I do recommend his book Phase noise and frequency stability in oscillators which is aimed in a theoretical way on oscillators, essentially driving in the point of what the Leeson theorem actually means. This establish the system parameter rules for oscillator design. Rubiola has a bunch of measurement tricks in his sleeve and those is spread over various articles and presentations on the homepage. Since Rubiolas focus isn't on actual oscillator-design but on theory and practical measurement setups on oscillators you will not be satisfied only with that. Wenzel has a series of online articles which usually is a very good read: http://www.wenzel.com/library1.htm Further, fellow time-nut Bruce has collected a number of design ideas on his pages: http://www.ko4bb.com/~bruce/ There is naturally more, but that should get you going in about the right direction. Concept-wise, Leeson theorem explain how the amplifier noise in the oscillation loop wraps itself around the frequency corner shaped by the oscillators Q-value. Assuming that the Q-value is fixed, the phase noise is shaped by the amounts of white and flicker noise in the amplifier. Additional output buffer noise will then add ontop of that to form the complete phase-noise. So good oscillator performance is tied to achieving low white and flicker noise in amplifiers. Additional contributions then comes from environmental and drift noise sources, so additional care is to be expected there if long-term stability is of interest. For some applications isolational amplifiers is badly needed. So, there is some initial pointers. There is much more, but should be of some use to you. 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] OT: xtal osc PN
First of all, thanks to John and Magnus for inputs and links, makes a very good start! On 9/18/10, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 09/18/2010 09:48 AM, francesco messineo wrote: Hello all, sorry for the OT, but the electronic expertise of the group is too good :-) I'm looking for ideas and directions (articles and so on) to realize very good phase noise xtal oscillator, in the range 20-50 MHz for high performance frequency conversion. I would like to understand what circuits can be realized (not requiring too much professional and modern equipment, test eq. from the 70s-80s is ok) and what is the contribution of the active oscillator device, the xtal itself and the following buffers. Another idea that came on my mind was using digital oscillator (square wave, cmos) and then filtering for sine output, if this makes sense for a low PN point of view. Is there any way to measure the close-in PN of oscillators with an amateur setup? First of all I think you need to quantify what you mean by high performance frequency conversion and what stability measures you are seeking as there are many degrees of excessiveness to attempt, and many of them may be well beyond what you need. Remember, we are time-nuts... :) Ok, let's say as good as practically and economically feasible for single prototype and homebuilder. I already chosed not to use a Si570 because I really need only few (2-4) fixed frequencies and I'm assuming that carefully made xtal oscillators can beat the Si570 phase noise performance. The conversion is obviously for a receiver, not for the classic HF bands, but for the lower VHF amateur bands (50-70 MHz) where IMD3 performance of the receiver has to be the best possible, as these bands are used for TV and radio broadcasts in many nearby countries around here. Of course a very good frontend BPF, amplifier and mixer are needed, but these are less of a problem for me to chose (and are simpler to evaluate with standard test equipment too). Unfortunately I know very few low-VHF-nuts and very few of them (if any) realize their setup performance are so far distant from what can be achieved nowadays. Thanks again Frank IZ8DWF ___ 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] OT: xtal osc PN
On 09/18/2010 02:41 PM, francesco messineo wrote: First of all, thanks to John and Magnus for inputs and links, makes a very good start! On 9/18/10, Magnus Danielsonmag...@rubidium.dyndns.org wrote: On 09/18/2010 09:48 AM, francesco messineo wrote: Hello all, sorry for the OT, but the electronic expertise of the group is too good :-) I'm looking for ideas and directions (articles and so on) to realize very good phase noise xtal oscillator, in the range 20-50 MHz for high performance frequency conversion. I would like to understand what circuits can be realized (not requiring too much professional and modern equipment, test eq. from the 70s-80s is ok) and what is the contribution of the active oscillator device, the xtal itself and the following buffers. Another idea that came on my mind was using digital oscillator (square wave, cmos) and then filtering for sine output, if this makes sense for a low PN point of view. Is there any way to measure the close-in PN of oscillators with an amateur setup? First of all I think you need to quantify what you mean by high performance frequency conversion and what stability measures you are seeking as there are many degrees of excessiveness to attempt, and many of them may be well beyond what you need. Remember, we are time-nuts... :) Ok, let's say as good as practically and economically feasible for single prototype and homebuilder. I already chosed not to use a Si570 because I really need only few (2-4) fixed frequencies and I'm assuming that carefully made xtal oscillators can beat the Si570 phase noise performance. The conversion is obviously for a receiver, not for the classic HF bands, but for the lower VHF amateur bands (50-70 MHz) where IMD3 performance of the receiver has to be the best possible, as these bands are used for TV and radio broadcasts in many nearby countries around here. Of course a very good frontend BPF, amplifier and mixer are needed, but these are less of a problem for me to chose (and are simpler to evaluate with standard test equipment too). Unfortunately I know very few low-VHF-nuts and very few of them (if any) realize their setup performance are so far distant from what can be achieved nowadays. One solution would use a stable standard oscillator, say 10 MHz, and then use a bandpass filter to select suitable overtones for first mixdown. You can select several options for selection of overtones, but fixed LC-resonators comes to mind. Another variant is to use a fairly low-noise VCO and then PLL lock it with wide bandwidth to a stable fixed reference (such as a 5 or 10 MHz TCXO or OCXO of your choice, possibly divided down to suitable step-frequency) as the PLL does some interesting things with phase noise... within the PLL bandwidth the reference phase noise will dominate where as outside of the PLL bandwidth the VCO phase noise will dominate. This comes in handy, and for such PLL applications you want the PLL to be wideband. A third alternative is to again let a stable reference of choice drive a modern DDS chip, for instance AD9971 or so. I am not a radio amateur, so I won't be able to say which is the best solution for your needs, but that is at least what I would be looking at if I where to build something like this. The link to Enrico I sent you is more the knowledge of the field, but if you follow the links to Wenzel and Bruce stuff you have some designs to look at. I wonder if you really need to go deep into the field to get satisfied. 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] OT: xtal osc PN
On 09/18/2010 02:41 PM, francesco messineo wrote: First of all, thanks to John and Magnus for inputs and links, makes a very good start! On 9/18/10, Magnus Danielsonmag...@rubidium.dyndns.org wrote: On 09/18/2010 09:48 AM, francesco messineo wrote: Hello all, sorry for the OT, but the electronic expertise of the group is too good :-) I'm looking for ideas and directions (articles and so on) to realize very good phase noise xtal oscillator, in the range 20-50 MHz for high performance frequency conversion. I would like to understand what circuits can be realized (not requiring too much professional and modern equipment, test eq. from the 70s-80s is ok) and what is the contribution of the active oscillator device, the xtal itself and the following buffers. Another idea that came on my mind was using digital oscillator (square wave, cmos) and then filtering for sine output, if this makes sense for a low PN point of view. Is there any way to measure the close-in PN of oscillators with an amateur setup? First of all I think you need to quantify what you mean by high performance frequency conversion and what stability measures you are seeking as there are many degrees of excessiveness to attempt, and many of them may be well beyond what you need. Remember, we are time-nuts... :) Ok, let's say as good as practically and economically feasible for single prototype and homebuilder. I already chosed not to use a Si570 because I really need only few (2-4) fixed frequencies and I'm assuming that carefully made xtal oscillators can beat the Si570 phase noise performance. The conversion is obviously for a receiver, not for the classic HF bands, but for the lower VHF amateur bands (50-70 MHz) where IMD3 performance of the receiver has to be the best possible, as these bands are used for TV and radio broadcasts in many nearby countries around here. Of course a very good frontend BPF, amplifier and mixer are needed, but these are less of a problem for me to chose (and are simpler to evaluate with standard test equipment too). Unfortunately I know very few low-VHF-nuts and very few of them (if any) realize their setup performance are so far distant from what can be achieved nowadays. I just recalled, you do want to check out John Miles (KE5FX) GPIB toolkit, the PN.EXE software will let you use your spectrum analyzer (if supported) to measure phase-noise. For your purpose it should be useful for you. For some of my phase-noise needs my tools isn't sufficient yeat to do some of the phase-noise measurements I want. John's home: http://www.thegleam.com/ke5fx/ John's GPIB toolkit: http://www.thegleam.com/ke5fx/gpib/readme.htm John's TimeLab: http://www.thegleam.com/ke5fx/timelab/readme.htm I was able to contribute support for my spectrum analyzer with some good help from John. Happy to see it being part of the distribution now. 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] OT: xtal osc PN
Hello Frank, Down East Microwave (DEMI) in Florida will be coming out with a stabilized VHF LO module soon. Should be a single board for 6M, 2M, 222, 432 MHz and possibly beacon duty. Was designed by N5AC. 10 MHz external reference. Hope fully a single programmed board can be jumpered for the fixed LO as needed. How soon is anyone's guess. Contact them. It is a very active project. This board may satisfy most every VHF Nut's discerning needs. The real question is what should be the LO phase noise threshold for effective VHF/UHF ham radio comms work. If the real goal is xtal low phase noise and you can live with the freq stability, than use an external stabilized source as a local beacon, to verify frequency accuracy. Stan, W1LE Cape Cod FN41sr Ok, let's say as good as practically and economically feasible for single prototype and homebuilder. I already chosed not to use a Si570 because I really need only few (2-4) fixed frequencies and I'm assuming that carefully made xtal oscillators can beat the Si570 phase noise performance. The conversion is obviously for a receiver, not for the classic HF bands, but for the lower VHF amateur bands (50-70 MHz) where IMD3 performance of the receiver has to be the best possible, as these bands are used for TV and radio broadcasts in many nearby countries around here. Of course a very good frontend BPF, amplifier and mixer are needed, but these are less of a problem for me to chose (and are simpler to evaluate with standard test equipment too). Unfortunately I know very few low-VHF-nuts and very few of them (if any) realize their setup performance are so far distant from what can be achieved nowadays. Thanks again Frank IZ8DWF ___ 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] OT: xtal osc PN
I just recalled, you do want to check out John Miles (KE5FX) GPIB toolkit, the PN.EXE software will let you use your spectrum analyzer (if supported) to measure phase-noise. For your purpose it should be useful for you. For some of my phase-noise needs my tools isn't sufficient yeat to do some of the phase-noise measurements I want. John's home: http://www.thegleam.com/ke5fx/ John's GPIB toolkit: http://www.thegleam.com/ke5fx/gpib/readme.htm John's TimeLab: http://www.thegleam.com/ke5fx/timelab/readme.htm I was able to contribute support for my spectrum analyzer with some good help from John. Happy to see it being part of the distribution now. Thanks for the plug! The readme for the spectrum-analyzer utility is actually at http://www.ke5fx.com/gpib/pn.htm -- TimeLab (nee' TI.EXE) only talks to counters and ADCs, not SAs. It is also a very unfinished piece of work, to put it kindly. The PN utility in conjunction with a homebrew quadrature PLL is probably going to be the best way to measure crystal oscillators at this point. You'll need to build two oscillators to measure against each other. The cleaner they are, the more care will need to be taken in the design of the quadrature PLL. This technique can give an excellent measurement floor but it does require you to put in some sweat equity. The software is the easy part of the overall problem. -- john, KE5FX ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT: xtal osc PN
On 9/18/10, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 09/18/2010 02:41 PM, francesco messineo wrote: First of all, thanks to John and Magnus for inputs and links, makes a very good start! On 9/18/10, Magnus Danielsonmag...@rubidium.dyndns.org wrote: On 09/18/2010 09:48 AM, francesco messineo wrote: Hello all, sorry for the OT, but the electronic expertise of the group is too good :-) I'm looking for ideas and directions (articles and so on) to realize very good phase noise xtal oscillator, in the range 20-50 MHz for high performance frequency conversion. I would like to understand what circuits can be realized (not requiring too much professional and modern equipment, test eq. from the 70s-80s is ok) and what is the contribution of the active oscillator device, the xtal itself and the following buffers. Another idea that came on my mind was using digital oscillator (square wave, cmos) and then filtering for sine output, if this makes sense for a low PN point of view. Is there any way to measure the close-in PN of oscillators with an amateur setup? First of all I think you need to quantify what you mean by high performance frequency conversion and what stability measures you are seeking as there are many degrees of excessiveness to attempt, and many of them may be well beyond what you need. Remember, we are time-nuts... :) Ok, let's say as good as practically and economically feasible for single prototype and homebuilder. I already chosed not to use a Si570 because I really need only few (2-4) fixed frequencies and I'm assuming that carefully made xtal oscillators can beat the Si570 phase noise performance. The conversion is obviously for a receiver, not for the classic HF bands, but for the lower VHF amateur bands (50-70 MHz) where IMD3 performance of the receiver has to be the best possible, as these bands are used for TV and radio broadcasts in many nearby countries around here. Of course a very good frontend BPF, amplifier and mixer are needed, but these are less of a problem for me to chose (and are simpler to evaluate with standard test equipment too). Unfortunately I know very few low-VHF-nuts and very few of them (if any) realize their setup performance are so far distant from what can be achieved nowadays. One solution would use a stable standard oscillator, say 10 MHz, and then use a bandpass filter to select suitable overtones for first mixdown. You can select several options for selection of overtones, but fixed LC-resonators comes to mind. This is a neat idea, but works only for overtones of the standard, some of my needed frequencies aren't overtone of 10 (or 5) MHz. Another variant is to use a fairly low-noise VCO and then PLL lock it with wide bandwidth to a stable fixed reference (such as a 5 or 10 MHz TCXO or OCXO of your choice, possibly divided down to suitable step-frequency) as the PLL does some interesting things with phase noise... within the PLL bandwidth the reference phase noise will dominate where as outside of the PLL bandwidth the VCO phase noise will dominate. This comes in handy, and for such PLL applications you want the PLL to be wideband. this is also interesting, but again, isn't a PLL overkill for just 4 fixed frequencies? I don't mind building separate oscillators. However the PLL approach could be interesting for other reasons (stability), any pointer? :-) A third alternative is to again let a stable reference of choice drive a modern DDS chip, for instance AD9971 or so. I am not a radio amateur, so I won't be able to say which is the best solution for your needs, but that is at least what I would be looking at if I where to build something like this. the best solution depends on many factors: -) if there were many others with my same needs, we'd probably find better to use a modern DDS (share the pcb making and someone who can do the soldering of such packages), instead, so far the low-VHF people aren't generally aware that better frontends are possible, you find lot of work in the HF receivers and next to nothing in the lower VHF where big signals and intermodulations come from broadcasts and not from other amateur stations! -) if much more than 4 different frequencies would be needed, then PLL would be the best choice anyway; -) if cost was not an issue, probably the best thing would be ordering 4 ready made OCXO from a respectable company :-) The link to Enrico I sent you is more the knowledge of the field, but if you follow the links to Wenzel and Bruce stuff you have some designs to look at. I wonder if you really need to go deep into the field to get satisfied. Probably not that deep, I'm convinced that a well studied and known good xtal oscillator circuit could already do the job, I'm just not able to judge the circuit myself, so I must ask for other's advice (while I try to setup my own PN test bed). Best regards Frank IZ8DWF
Re: [time-nuts] OT: xtal osc PN
A couple of disclaimers here: 1. Leeson's oscillator model was mentioned. That doesn't apply much to crystal oscillators. The close in noise will be limited by the intrinsic noise of the crystal and the far out noise will be limited by the buffer amplifier. Leeson's model never comes into play. BTW, the intrinsic noise of the crystal is higher than the thermal noise corresponding to its ESR, at least below 1 kHz or so. 2. Using crystal filters to clean up after the fact is limited by the intrinsic noise of the crystals in the filters. Hence, this usually only makes sense if you multiply a xtal oscillator then filter, as in the HP8662, and then it only improves the noise floor. Unless you have access to very low noise crystals, you are not going to get very far building your own oscillator. Rick Karlquist N6RK ___ 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] OT: xtal osc PN
On 09/18/2010 04:12 PM, francesco messineo wrote: One solution would use a stable standard oscillator, say 10 MHz, and then use a bandpass filter to select suitable overtones for first mixdown. You can select several options for selection of overtones, but fixed LC-resonators comes to mind. This is a neat idea, but works only for overtones of the standard, some of my needed frequencies aren't overtone of 10 (or 5) MHz. What frequencies you actually needed was not clear to me, so I assumed that 30, 40, 50 and 60 MHz would be useful frequencies, in which case it would be a simple and not very complex approach. It has been used in frequency counters for ages to mix-down the signal and then count the beat frequency. Another variant is to use a fairly low-noise VCO and then PLL lock it with wide bandwidth to a stable fixed reference (such as a 5 or 10 MHz TCXO or OCXO of your choice, possibly divided down to suitable step-frequency) as the PLL does some interesting things with phase noise... within the PLL bandwidth the reference phase noise will dominate where as outside of the PLL bandwidth the VCO phase noise will dominate. This comes in handy, and for such PLL applications you want the PLL to be wideband. this is also interesting, but again, isn't a PLL overkill for just 4 fixed frequencies? I don't mind building separate oscillators. However the PLL approach could be interesting for other reasons (stability), any pointer? :-) A simple PLL is not that complex these days. As long as you have fairly high comparator frequency after dividing down the VCO and reference you could get away fairly easilly. Standard programmable dividers in the TTL family and a single chip for phase-comparator will work fairly well. There is gazillions of examples among hams for this approach. A third alternative is to again let a stable reference of choice drive a modern DDS chip, for instance AD9971 or so. I am not a radio amateur, so I won't be able to say which is the best solution for your needs, but that is at least what I would be looking at if I where to build something like this. the best solution depends on many factors: -) if there were many others with my same needs, we'd probably find better to use a modern DDS (share the pcb making and someone who can do the soldering of such packages), instead, so far the low-VHF people aren't generally aware that better frontends are possible, you find lot of work in the HF receivers and next to nothing in the lower VHF where big signals and intermodulations come from broadcasts and not from other amateur stations! Maybe the DDS board from the DMTD project would fit your needs? -) if much more than 4 different frequencies would be needed, then PLL would be the best choice anyway; Actually, a DDS beats PLL on number of frequency any day of the week. -) if cost was not an issue, probably the best thing would be ordering 4 ready made OCXO from a respectable company :-) Certainly, it would be easy, but you would not learn anything. The link to Enrico I sent you is more the knowledge of the field, but if you follow the links to Wenzel and Bruce stuff you have some designs to look at. I wonder if you really need to go deep into the field to get satisfied. Probably not that deep, I'm convinced that a well studied and known good xtal oscillator circuit could already do the job, I'm just not able to judge the circuit myself, so I must ask for other's advice (while I try to setup my own PN test bed). John's and Bruce's pages alongside Wenzel should be the place to start then. 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] OT: xtal osc PN
On 09/18/2010 04:28 PM, Richard (Rick) Karlquist wrote: A couple of disclaimers here: 1. Leeson's oscillator model was mentioned. That doesn't apply much to crystal oscillators. The close in noise will be limited by the intrinsic noise of the crystal and the far out noise will be limited by the buffer amplifier. Leeson's model never comes into play. BTW, the intrinsic noise of the crystal is higher than the thermal noise corresponding to its ESR, at least below 1 kHz or so. Actually, I did mention the output buffer noise explicitly. The crystal noise adds ontop of the amplifiers noise, yes... but the crystal noise will also be feedback to the crystal through the amplifier, right? 2. Using crystal filters to clean up after the fact is limited by the intrinsic noise of the crystals in the filters. Hence, this usually only makes sense if you multiply a xtal oscillator then filter, as in the HP8662, and then it only improves the noise floor. Essentially only useful as relatively narrow filters. Unless you have access to very low noise crystals, you are not going to get very far building your own oscillator. Agreed. There is a danger in expecting any spare AT-cut crystal laying around being able to provide the ultra high performance if only stabilized and perfect design of amplifiers. But for the purpose at hand it may suffice. 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] OT: xtal osc PN
On 9/18/10, Magnus Danielson mag...@rubidium.dyndns.org wrote: A simple PLL is not that complex these days. As long as you have fairly high comparator frequency after dividing down the VCO and reference you could get away fairly easilly. Standard programmable dividers in the TTL family and a single chip for phase-comparator will work fairly well. There is gazillions of examples among hams for this approach. sure, but I'd need to at least understand what's low noise and what's not again :-) -) if there were many others with my same needs, we'd probably find better to use a modern DDS (share the pcb making and someone who can do the soldering of such packages), instead, so far the low-VHF people aren't generally aware that better frontends are possible, you find lot of work in the HF receivers and next to nothing in the lower VHF where big signals and intermodulations come from broadcasts and not from other amateur stations! Maybe the DDS board from the DMTD project would fit your needs? maybe, I didn't follow that thread, what DDS chip is used? What's the clock source? In this moment I'd pretty much like it fits my needs, also because of Rick's comment (I would order custom made xtals if it's not going to cost more than the rest of the parts and if I know what to order). Regards Frank IZ8DWF ___ 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] OT: xtal osc PN
Another reference on VHF crystal oscillator circuits (if you can read German) is: http://www.axtal.com/data/buch/Kap6.pdf In particular Figures 6.20 and 6.21 on page 23. Bruce Bruce francesco messineo wrote: On 9/18/10, Magnus Danielsonmag...@rubidium.dyndns.org wrote: A simple PLL is not that complex these days. As long as you have fairly high comparator frequency after dividing down the VCO and reference you could get away fairly easilly. Standard programmable dividers in the TTL family and a single chip for phase-comparator will work fairly well. There is gazillions of examples among hams for this approach. sure, but I'd need to at least understand what's low noise and what's not again :-) -) if there were many others with my same needs, we'd probably find better to use a modern DDS (share the pcb making and someone who can do the soldering of such packages), instead, so far the low-VHF people aren't generally aware that better frontends are possible, you find lot of work in the HF receivers and next to nothing in the lower VHF where big signals and intermodulations come from broadcasts and not from other amateur stations! Maybe the DDS board from the DMTD project would fit your needs? maybe, I didn't follow that thread, what DDS chip is used? What's the clock source? In this moment I'd pretty much like it fits my needs, also because of Rick's comment (I would order custom made xtals if it's not going to cost more than the rest of the parts and if I know what to order). Regards Frank IZ8DWF ___ 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] Homebrew WWVB TX simulator?
Hal, The NIST web page is here: http://www.nist.gov/physlab/div847/grp40/wwvb.cfm [and the iers page and the historic leap second list, in a subsequent message.] I assume you can find the fine print there, but they probably aren't easily machine readable. Yes, sure, I know about those resources. You're right, they're meant for eyeballs, not code. I remember seeing the IERS bulletin taped to the wall at WWVH the first time I visited, back in the late 80s or maybe early 90s. Back then, someone had to drive out to the site on the UTC day before a leap second (typically new year's eve) and flip a toggle switch to insert the :60. And then (harder, given parties and hangovers) the next day to prevent another from happening the next UTC midnight (2PM Hawaiian time). I did a bit more digging on the NIST site, and it appears that you can get the Leap info, DST-pending info and DUT1 (current but not pending) info via ACTS, the modem dialup service. But none of the internet services include those. There is a site name acts.nist.gov in the DNS, but nothing responds on any of the usual ports. So maybe they intend to work on this issue. The NTP package includes a utility to generate the audio for WWV. It's util/tg2.c in any recent NTP source package. Yup. Only tg.c in the production release, but tg2.c is in the development tarball -- hadn't seen the improved version. It looks like it does a good job on the IRIG and IEEE stuff. But the WWV / WWVH is kinda minimal. It says it is intended to test the detector code, but doesn't include the 500, 600 and 440 Hz tones, which it ought to for a proper test. Also, no double ticks for the DUT1, and no voice announcements. My own tcg code does all that, and adjusts for WWV vs WWVH tone schedule and tick frequency. (Not ready to release to the world, though. I should think about that.) This was written back when the RFP went out for the current generators to replace the Audichron drum announcers and add the new code stuff. I built a prototype, then decided it was nuts to submit an actual proposal. Tnx again 73, Bob, K1BC ___ 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] Semi-OT: Hardware for WR-90 waveguide sections?
Not completely OT, as stable and accurate timebases are very useful in microwave systems... What's the proper hardware to use for connecting WR-90 (10GHz) waveguide sections? I figure 8-32 brass or stainless, avoiding anything magnetic. Bob K6RTM in Silicon Valley ___ 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] Semi-OT: Hardware for WR-90 waveguide sections?
Magnetic is generally irrelevant unless you are working with an isolator or maybe a gas noise source. A magnetic field won't alter the waves propagation inside the guide. Stainless is generally used. -John = Not completely OT, as stable and accurate timebases are very useful in microwave systems... What's the proper hardware to use for connecting WR-90 (10GHz) waveguide sections? I figure 8-32 brass or stainless, avoiding anything magnetic. Bob K6RTM in Silicon Valley ___ 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] Semi-OT: Hardware for WR-90 waveguide sections?
The field is contained entirely within the guide, so, you can use any type of fastener on the flanges. Typically, however, brass or stainless is the most common. It is OK to use ferrous screws/nuts, but they can become magnetized if close to an isolator. If using one of those, then care should be taken regardless, not because of the effects on the performance but the possibility of getting iron shavings into the guide. 73 - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of k6...@comcast.net Sent: Saturday, September 18, 2010 9:17 PM To: time-nuts@febo.com Subject: [time-nuts] Semi-OT: Hardware for WR-90 waveguide sections? Not completely OT, as stable and accurate timebases are very useful in microwave systems... What's the proper hardware to use for connecting WR-90 (10GHz) waveguide sections? I figure 8-32 brass or stainless, avoiding anything magnetic. Bob K6RTM in Silicon Valley ___ 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] OT: xtal osc PN
Hi Is -195 dbc/Hz floor good enough or is it overkill? Is -155 dbc/Hz at 100 Hz offset a requirement or is -40 dbc ok? You need to quantify what you are after before deciding on an approach. Low noise means many different things to each of us. Bob On Sep 18, 2010, at 1:27 PM, francesco messineo francesco.messi...@gmail.com wrote: On 9/18/10, Magnus Danielson mag...@rubidium.dyndns.org wrote: A simple PLL is not that complex these days. As long as you have fairly high comparator frequency after dividing down the VCO and reference you could get away fairly easilly. Standard programmable dividers in the TTL family and a single chip for phase-comparator will work fairly well. There is gazillions of examples among hams for this approach. sure, but I'd need to at least understand what's low noise and what's not again :-) -) if there were many others with my same needs, we'd probably find better to use a modern DDS (share the pcb making and someone who can do the soldering of such packages), instead, so far the low-VHF people aren't generally aware that better frontends are possible, you find lot of work in the HF receivers and next to nothing in the lower VHF where big signals and intermodulations come from broadcasts and not from other amateur stations! Maybe the DDS board from the DMTD project would fit your needs? maybe, I didn't follow that thread, what DDS chip is used? What's the clock source? In this moment I'd pretty much like it fits my needs, also because of Rick's comment (I would order custom made xtals if it's not going to cost more than the rest of the parts and if I know what to order). Regards Frank IZ8DWF ___ 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] Semi-OT: Hardware for WR-90 waveguide sections?
k6...@comcast.net wrote: Not completely OT, as stable and accurate timebases are very useful in microwave systems... What's the proper hardware to use for connecting WR-90 (10GHz) waveguide sections? I figure 8-32 brass or stainless, avoiding anything magnetic. whatever fits through the holes in the flanges. #8 requires a 0.187 hole, #6 requires a 0.156, #4 is 0.125, #2 is 0.109 One reference I have says WR90 has 0.169 holes, so that's #6 hardware. Whether it is magnetic or not doesn't make any difference. ___ 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.
