Re: [time-nuts] Making a HP 10811 better
Ah well. Just a thought. I was thinking of simply dumping the whole thing into a picnic jug full of baby oil :-) Sorta scatterbrained, but I have seen mentioned on the list a basement sized steel block ... Don ed breya > One last thing regarding oil-filling. My previous comment was made > picturing oil inside the oscillator block only - not outside, or > between the outer parts - if there is a resistance wire heater (I > think it's heated with Qs only on the 10811) it is held together with > various tapes and adhesives that could soften or dissolve. Also, the > insulation would not insulate very well of saturated with oil, and > could possibly soften or break down somehow. I would not recommend > dunking the whole thing in a vat of oil. > > And one final, final note: If oil is somehow effectively contained in > the oscillator block, then a void (bubble) of some sort, or an > expansion facility or vent would be needed to relieve the pressure > changes during warmup. Otherwise, when started up, the expanding oil > would have to either leak out, or deform (or damage) something. This > would be equivalent to dramatically increasing barometric pressure, > and certainly effect the oscillator frequency. > > Ed > > > ___ > 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. > -- "Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind." R. Bacon "If you don't know what it is, don't poke it." Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ 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] Making a HP 10811 better
One last thing regarding oil-filling. My previous comment was made picturing oil inside the oscillator block only - not outside, or between the outer parts - if there is a resistance wire heater (I think it's heated with Qs only on the 10811) it is held together with various tapes and adhesives that could soften or dissolve. Also, the insulation would not insulate very well of saturated with oil, and could possibly soften or break down somehow. I would not recommend dunking the whole thing in a vat of oil. And one final, final note: If oil is somehow effectively contained in the oscillator block, then a void (bubble) of some sort, or an expansion facility or vent would be needed to relieve the pressure changes during warmup. Otherwise, when started up, the expanding oil would have to either leak out, or deform (or damage) something. This would be equivalent to dramatically increasing barometric pressure, and certainly effect the oscillator frequency. Ed ___ 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] Synchronisizing a 100MHz TCXO with Tbold
I know I do it all the time. That's what I spend most my time on. Bert In a message dated 9/19/2011 9:08:25 P.M. Eastern Daylight Time, saidj...@aol.com writes: Bert, one would typically limit the loop bandwidth to something much lower than 10KHz. Say 100Hz. This way at 10KHz the ADF4001 would have no effect on phase noise, it would be almost entirely determined by the TCXO itself. This is because a 10MHz reference would have to have to be better than -170dBc/Hz at 10KHz to not affect the output phase noise if the loop bandwidth is >10KHz. This is due to the 20log(100/10) noise effect. The loop bandwith should be set where the reference OCXO phase noise floor with added 20dB noise intersects the TCXO phase noise floor. This will typically be <<1KHz. bye, Said In a message dated 9/19/2011 18:01:26 Pacific Daylight Time, ewkeh...@aol.com writes: Peter, it will be difficult to degrade -138dBc/10kHz using a ADF 4001. I have PLL's using selected $ 1.00 Xtals getting better than -153dBc/10kHz. .Axtal has units with -174dBC but out of most price ranges but I thought you were looking at below -150,very doable with ADF 4001. Bert In a message dated 9/19/2011 5:53:22 P.M. Eastern Daylight Time, krengelda...@gmx.de writes: Thank you all for your suggestions. @ Attila: I think your suggestion would be "a little bit" too complicated. I dont want to write a dissertation :)) My idea was to simply get a low jitter out of the 100MHz TCXO clocking the FPGA etc.. The fine TCXO I like to use is a AXLE20-12 from AXTAL. I think its expensive enough for my experiments (about 100,- EUR) and it also got a electronic frequency control input as well as a even much more expensive OCXO which would cost me 180,- EUR or more. As I said as the ADCs are working in cascade they have to be enabled and disabled as exact as possible to avoid sampling errors. A jittering clock would do a bad job in that circuit while long time stability is not a problem. ___ 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] Synchronisizing a 100MHz TCXO with Tbold
Bert, one would typically limit the loop bandwidth to something much lower than 10KHz. Say 100Hz. This way at 10KHz the ADF4001 would have no effect on phase noise, it would be almost entirely determined by the TCXO itself. This is because a 10MHz reference would have to have to be better than -170dBc/Hz at 10KHz to not affect the output phase noise if the loop bandwidth is >10KHz. This is due to the 20log(100/10) noise effect. The loop bandwith should be set where the reference OCXO phase noise floor with added 20dB noise intersects the TCXO phase noise floor. This will typically be <<1KHz. bye, Said In a message dated 9/19/2011 18:01:26 Pacific Daylight Time, ewkeh...@aol.com writes: Peter, it will be difficult to degrade -138dBc/10kHz using a ADF 4001. I have PLL's using selected $ 1.00 Xtals getting better than -153dBc/10kHz. .Axtal has units with -174dBC but out of most price ranges but I thought you were looking at below -150,very doable with ADF 4001. Bert In a message dated 9/19/2011 5:53:22 P.M. Eastern Daylight Time, krengelda...@gmx.de writes: Thank you all for your suggestions. @ Attila: I think your suggestion would be "a little bit" too complicated. I dont want to write a dissertation :)) My idea was to simply get a low jitter out of the 100MHz TCXO clocking the FPGA etc.. The fine TCXO I like to use is a AXLE20-12 from AXTAL. I think its expensive enough for my experiments (about 100,- EUR) and it also got a electronic frequency control input as well as a even much more expensive OCXO which would cost me 180,- EUR or more. As I said as the ADCs are working in cascade they have to be enabled and disabled as exact as possible to avoid sampling errors. A jittering clock would do a bad job in that circuit while long time stability is not a problem. ___ 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] Making a HP 10811 better
Bob Camp wrote: > Hi > > If you make a "true SC" the precision required in blank manufacture is > quite tight for turns at HP10811 oven temperatures. The operation off turn > is more a financial decision than an engineering choice. The part met spec > with the crystals. Shipping stuff instead of scrapping it always makes the > finance types happy . > > Bob > This is a perfect description of how HP and specifically the Santa Clara Division was run. Money was always an issue. Engineering was done on a "good enough" basis. Many decisions were pragmatic. What would Bill and Dave have done? The HP Way. Objective #1: make a profit. Etc. Rick ___ 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] Synchronisizing a 100MHz TCXO with Tbold
Peter, it will be difficult to degrade -138dBc/10kHz using a ADF 4001. I have PLL's using selected $ 1.00 Xtals getting better than -153dBc/10kHz. .Axtal has units with -174dBC but out of most price ranges but I thought you were looking at below -150,very doable with ADF 4001. Bert In a message dated 9/19/2011 5:53:22 P.M. Eastern Daylight Time, krengelda...@gmx.de writes: Thank you all for your suggestions. @ Attila: I think your suggestion would be "a little bit" too complicated. I dont want to write a dissertation :)) My idea was to simply get a low jitter out of the 100MHz TCXO clocking the FPGA etc.. The fine TCXO I like to use is a AXLE20-12 from AXTAL. I think its expensive enough for my experiments (about 100,- EUR) and it also got a electronic frequency control input as well as a even much more expensive OCXO which would cost me 180,- EUR or more. As I said as the ADCs are working in cascade they have to be enabled and disabled as exact as possible to avoid sampling errors. A jittering clock would do a bad job in that circuit while long time stability is not a problem. @ Chuck: A good idea in principle but I only have one tbold which controlles all my measurement equipment like spectrum analyzer, signal generators a.s.o. I also dont know whether a synchronisation of the 100MHz TCXO to the tbold will really give me a better noise figure than running the TCXO stand alone. The TCXO I like to use gives me a low noise of -138dBc/10kHz and as far as I know tbold comes with -142 or even better. So the main question is whether a synchronisation will give better results or not. If so an additional effect would be the fact that all equipment is then working synchronous. The ADCs I use will get a part of a homemade 1GHz DSO. @ Bert: Thank you for the hint. I think to use a ADF4001 is an easy task so I like to start my experience first using your idea. Again thank you for even more suggestions. Regards Peter, DG4EK ___ 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] Making a HP 10811 better
Don Latham wrote: > I have to ask again. Is there anything in the 10811 that would be > degraded by mineral oil? No condensation, even temperature distribution > throughout, or at least small gradients. The only downside I see is that > there might be some components that might be chemically degraded. > > Don The piston trimmer is extremely intolerant of any oil. In the early days of the 10811, they encountered a bad aging problem that we traced back to the piston trimmer. It turned out that the trimmer was lubricated with some oil that slowly migrated. The fix was to go to a different trimmer that didn't have oil lubrication. Rick ___ 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] Making a HP 10811 better
The SC cut has turnover points located symmetrically above and below the "inflection temperature". The 10811 crystals are cut to pull these turnovers close to the inflection point, or they merge and you don't even have a turnover technically. The E1938A crystals we just like the 10811 crystals, only in a lower height package, except that the cut was changed slightly to give turnovers of over 100 degrees, to allow 85 degree ambient operation. There was also a lower turnover around 70 degrees. I'm not aware of there being any turnover below room temperature. Rick Tom Van Baak wrote: >> This is mentioned in the HPJ article on the 10811. >> (Required reading for anyone playing with 10811's). >> >> Rick Karlquist N6RK > > Indeed. For the rest of you please note the cover photo is > worth it even if you don't read the article: > > "SC-Cut Oscillator Offers Improved Performance" > http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1981-03.pdf > > --- > > IIRC this is one of the articles that mentions in passing that > the 10811 (SC-cut) isn't actually operated at the turn-over > point, something, I think, that was more important for AT cuts. > I'm looking for the other paper I read recently that discussed > this aspect of the SC-cut. > > --- > > Speaking of turn-over points. Some crystal cuts have both a > low temperature and high temperature turn-over point. Does > anyone know of a crystal oscillator that is specifically operated > at the low temperature point (and I'm not talking about exotic > cryo sapphire here)? Maybe something around -20 C. In the > range of a TEC cooler at least. > > The reason for the interest is that it seems to me some of the > oscillator characteristics (such as drift or phase noise) might > be related to temperature, in which case a well-below ambient > temperature is better than a well-above ambient temperature, > even if it complicates the packaging or thermal regulation. > > /tvb > > > ___ > 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] Making a HP 10811 better
I think mineral oil would be just fine thermally and chemically - the problem would be in keeping it where it belongs, leak-free. Some things may need modification or adjustment, since the higher dielectric constant would cause all inter-node capacitances to increase, compared to air. The trim cap(s) for the oscillator would especially be affected, presuming the oil can get inside every "open" component. Also, any bubbles or voids in the oil fill that can move may cause slight effects related to orientation. Ed ___ 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] Making a HP 10811 better
I have to ask again. Is there anything in the 10811 that would be degraded by mineral oil? No condensation, even temperature distribution throughout, or at least small gradients. The only downside I see is that there might be some components that might be chemically degraded. Don ed breya > Yes, running everything chilled would be better if low temperature > crystal turnovers were available. It is more complicated to chill > than heat, of course, even today, but way back when they started > temperature stabilizing things it was nearly impossible on a small > scale - or at least very impractical, until the advent of TECs. It's > also trickier to do both because there's that crossover region where > the mode has to shift and you can get dead zones in the control > function. Doing heating or cooling only is like a Class-A amplifier - > much simpler to keep linear. > > I think the main problem with chilling though, is that you get > condensation, depending on the humidity (or dewpoint), so you can't > go very low in temperature to take advantage of lower noise and > bias/leakage currents in devices, without encountering the > condensation problem. For example, one of my projects involves making > a very stable voltage standard that has the guts inside a TEC-chilled > (or warmed) aluminum block. I plan to run it somewhere around 15-20 > deg C or so, or as low as I can without having condensation under > most conditions, since the guts aren't going to be hermetically > sealed inside (but maybe have a rechargeable dessicant). Another > project involves building a log attoammeter with the input amplifier > TEC-chilled as far down as possible (-40 to -50 deg C or so) to > minimize bias current. This one has to be specially guarded, and with > the cold block inside a hermetically vacuum sealed enclosure, as any > condensation whatsoever - inside or out - could defeat the whole > purpose. > > Ed > > > ___ > 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. > -- "Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind." R. Bacon "If you don't know what it is, don't poke it." Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ 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] Making a HP 10811 better
Yes, running everything chilled would be better if low temperature crystal turnovers were available. It is more complicated to chill than heat, of course, even today, but way back when they started temperature stabilizing things it was nearly impossible on a small scale - or at least very impractical, until the advent of TECs. It's also trickier to do both because there's that crossover region where the mode has to shift and you can get dead zones in the control function. Doing heating or cooling only is like a Class-A amplifier - much simpler to keep linear. I think the main problem with chilling though, is that you get condensation, depending on the humidity (or dewpoint), so you can't go very low in temperature to take advantage of lower noise and bias/leakage currents in devices, without encountering the condensation problem. For example, one of my projects involves making a very stable voltage standard that has the guts inside a TEC-chilled (or warmed) aluminum block. I plan to run it somewhere around 15-20 deg C or so, or as low as I can without having condensation under most conditions, since the guts aren't going to be hermetically sealed inside (but maybe have a rechargeable dessicant). Another project involves building a log attoammeter with the input amplifier TEC-chilled as far down as possible (-40 to -50 deg C or so) to minimize bias current. This one has to be specially guarded, and with the cold block inside a hermetically vacuum sealed enclosure, as any condensation whatsoever - inside or out - could defeat the whole purpose. Ed ___ 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] Synchronisizing a 100MHz TCXO with Tbold, pse help
For the best performance you might look at using the divider from an ADF4001 or 4002, but with a mixer instead of the CMOS phase detector. That way you wouldn't be in the position of feeding 10 MHz to a digital comparator that would really prefer to see a faster edge. If the 1/f noise of the ADF400x chip is better than that of your ADC, then the mixer would be of debatable value. Since you are looking to build a relatively narrow loop and you have an FPGA already, it could be worthwhile to try implementing a divider in the existing gate array first, then move to a dedicated PLL/counter chip if that's too noisy. For that matter you could start with an XOR-type phase detector built on the FPGA as well. It would come down to how much time/desire you have to experiment, and what equipment is available to measure the outcome. I wouldn't bother trying any FPGA-based loop components unless you have a way to measure its actual performance, but if you do, it could potentially save you some money and board space. Since your noise-optimization effort is aimed at clocking an ADC, it should be easy enough to tell if its performance is being degraded and that's an argument in favor of trying the cheap/free solutions first. Architecturally you need to clock the ADC directly rather than routing the clock through the FPGA, but you probably knew that already... -- john, KE5FX > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts- > boun...@febo.com] On Behalf Of ewkeh...@aol.com > Sent: Monday, September 19, 2011 4:04 AM > To: time-nuts@febo.com > Subject: Re: [time-nuts] Synchronisizing a 100MHz TCXO with Tbold, pse > help > > Peter > I would use a PLL like the ADF 4001 because of its low noise floor and > depending of which Tbolt, its phase noise is very good. The advantage is > that > you can pick the filter response in such a way that you take advantage of > the individual Osc. parameters. > > Bert Kehren > > > In a message dated 9/18/2011 9:52:29 P.M. Eastern Daylight Time, > krengelda...@gmx.de writes: > > Hello group, > I like to synchronisize a fine 100MHz TCXO with the > 10MHz output of the Tbold. The TCXO has a EFC input. > I know this can be done > using a PLL but I do not want to add noise > to the very good noise parameters of the TCXO > cause the 100MHz signal is to be used to clock > a FPGA which controlles fast cascaded ADCs. > Has anybody a circuit diagram to use? > Thank you in advance > regards > Peter, DG4EK > > > > ___ > 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] LightSquared on FOX
Folks (on both sides of the political aisle), we're getting way off charter here. Lightsquared has been discussed on the list in multiple threads ad infinitum so let's give it a rest unless/until there's some actual news. Everyone, please keep in mind that time-nuts has over 1,000 subscribers so every message is going to a broad audience. Let's try to keep the SNR at a reasonable level. Thanks, John ___ 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] Making a HP 10811 better
Hi If you make a "true SC" the precision required in blank manufacture is quite tight for turns at HP10811 oven temperatures. The operation off turn is more a financial decision than an engineering choice. The part met spec with the crystals. Shipping stuff instead of scrapping it always makes the finance types happy…. Bob On Sep 19, 2011, at 6:53 PM, Tom Van Baak wrote: >> This is mentioned in the HPJ article on the 10811. >> (Required reading for anyone playing with 10811's). >> Rick Karlquist N6RK > > Indeed. For the rest of you please note the cover photo is > worth it even if you don't read the article: > > "SC-Cut Oscillator Offers Improved Performance" > http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1981-03.pdf > > --- > > IIRC this is one of the articles that mentions in passing that > the 10811 (SC-cut) isn't actually operated at the turn-over > point, something, I think, that was more important for AT cuts. > I'm looking for the other paper I read recently that discussed > this aspect of the SC-cut. > > --- > > Speaking of turn-over points. Some crystal cuts have both a > low temperature and high temperature turn-over point. Does > anyone know of a crystal oscillator that is specifically operated > at the low temperature point (and I'm not talking about exotic > cryo sapphire here)? Maybe something around -20 C. In the > range of a TEC cooler at least. > > The reason for the interest is that it seems to me some of the > oscillator characteristics (such as drift or phase noise) might > be related to temperature, in which case a well-below ambient > temperature is better than a well-above ambient temperature, > even if it complicates the packaging or thermal regulation. > > /tvb > > > ___ > 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] From Sundials to Atomic Clocks
Thank you, sir, it is very kind of you to scan. Could you please send me the larger file version. Thank you. Don Lewis dlewis6...@austin.rr.com -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Peter Vince Sent: Monday, September 19, 2011 4:16 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] From Sundials to Atomic Clocks Hello all, I have just scanned the copy I bought from Amazon the other day (second revised edition, 1999). It makes quite a large file, so uploaded it to Flickr - which seems to insist on resizing it! The largest size is at: http://farm7.static.flickr.com/6156/6163603871_fa6d44a623_b.jpg but I have higher resolution versions I can email to anyone who wants it. Regards, Peter On 19 September 2011 19:07, Azelio Boriani wrote: > Rob, > is it possible to scan the asides? The PDF from NIST has the asides too dark > to be readable (the last one is really difficult/impossible to read). > Thank you ___ 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] Synchronisizing a 100MHz TCXO with Tbold (3)
Hi I suspect you can find a part with significantly better noise floor. "Very good" is around -170 dbc / Hz at a 10 KHz offset. There's a lot of room between that and -135. Best guess is that you start rolling up at 1 KHz on a part like that. More or less you would get: 100 Hz -125 dbc / Hz 10 Hz -105 1 Hz-85 At the phase detector, you would have -85 - 20 log(100/10) = -95 dbc / Hz. At 10 Hz you would have -125. In both cases the TBolt is lower noise than the divided TCXO. A PLL with a 3db loop bandwidth of around 20 Hz should work just fine. Parts values on a loop like that should be very rational. The resulting combination of TCXO + TBolt would be more quiet than the TBolt alone. For that matter, your 10 KHz noise works out to -155 at 10MHz. You could lock anywhere inside 10 KHz and likely the TBolt + TCXO would still be more quiet than the TCXO alone. The problem there would be the noise floor of the divider and detector …. Bob On Sep 19, 2011, at 6:19 PM, Peter Krengel wrote: > @Tom > Unfortunately there are no free ADC channels in the concept > and there is a fixed adjustment (calibration) software routine > which I cannot change. Complete FPGA software is calculated > for a 100MHz clock. There is no possibility to change that. > So I dont have to fix a frequency- but a jittering problem. > But thank you anyway for the good idea. > Maybe I can use it in a later hardware & software version. I will > discuss this with the programmer of the FPGA. > > @Bob > The TCXO I'm using is a AXTAL AXLE20-12 which comes with -135dBc/10kHz. > Unfortunately I havent any closer noise data. The TCXO has a electronic > frequency control input which works from 0.3 to 3V giving it a fdelta of > +-5ppm. > The initial freq. tolerance is +-2ppm and aging is +-1ppm/year. > As you suggested I also thought of giving it a narrow lowpass filter cause the > only thing I need is a very low jitter on the edges of the 100MHz HCMOS > signal. > As we are using an intitial calibration routine (thats the one I cannot > change easily) and an additional working-calibration routine, a very slow > shifting in phase > isnt a problem as the w-calibration can be done quickly everytime before a > measurement (a sampling) will be taken. So the w-calibration will overwrite > the initial > calibration which datas have been copied at boottime to RAM before > programming the FPGA for operation. > > Regards > Peter, DG4EK > > ___ > 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] Making a HP 10811 better
This is mentioned in the HPJ article on the 10811. (Required reading for anyone playing with 10811's). Rick Karlquist N6RK Indeed. For the rest of you please note the cover photo is worth it even if you don't read the article: "SC-Cut Oscillator Offers Improved Performance" http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1981-03.pdf --- IIRC this is one of the articles that mentions in passing that the 10811 (SC-cut) isn't actually operated at the turn-over point, something, I think, that was more important for AT cuts. I'm looking for the other paper I read recently that discussed this aspect of the SC-cut. --- Speaking of turn-over points. Some crystal cuts have both a low temperature and high temperature turn-over point. Does anyone know of a crystal oscillator that is specifically operated at the low temperature point (and I'm not talking about exotic cryo sapphire here)? Maybe something around -20 C. In the range of a TEC cooler at least. The reason for the interest is that it seems to me some of the oscillator characteristics (such as drift or phase noise) might be related to temperature, in which case a well-below ambient temperature is better than a well-above ambient temperature, even if it complicates the packaging or thermal regulation. /tvb ___ 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] LightSquared on FOX
Right! Good luck! Falcone said today that $60M had been set aside for this issue. At $10,000 per 'plane, that fund will cover 6000 planes. Hardly even a token gesture, IMO. -John == > For aircraft-related stuff you may send your official Navigation > Equipment Performance Variance Report form to your illustrious > president o'bama via the FAA Inter-Agency Regulatory Communications > Dept. All other non-military cases go to the FCC Office of Regulatory > Review. You must include proof of the loss of use of the equipment, > proof that said loss of use was due to operations of LightSquared's > communication systems, the purchase date and depreciated value of > said equipment, the amount needed (third party estimate in writing) > to restore use of said equipment, the dates when said loss of use > occurred, and a US$100 application review fee. > > Each case will be evaluated at whim, and there is a remote > possibility that you may receive some reimbursement - if you donated > to The Party, and if there are any funds recovered from the Solyndra case. > > Ed > > > ___ > 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] Synchronisizing a 100MHz TCXO with Tbold, pse help
If your 100 MHz is already at HCMOS levels, then just use a 74AC family decade divider or D-FF for the downconversion to 10 MHz - very straightforward. A small series damping resistor may be needed if the 100 MHz signal has to be carried very far from its source. Ed ___ 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] LightSquared on FOX
For aircraft-related stuff you may send your official Navigation Equipment Performance Variance Report form to your illustrious president o'bama via the FAA Inter-Agency Regulatory Communications Dept. All other non-military cases go to the FCC Office of Regulatory Review. You must include proof of the loss of use of the equipment, proof that said loss of use was due to operations of LightSquared's communication systems, the purchase date and depreciated value of said equipment, the amount needed (third party estimate in writing) to restore use of said equipment, the dates when said loss of use occurred, and a US$100 application review fee. Each case will be evaluated at whim, and there is a remote possibility that you may receive some reimbursement - if you donated to The Party, and if there are any funds recovered from the Solyndra case. Ed ___ 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] Synchronisizing a 100MHz TCXO with Tbold (3)
@Tom Unfortunately there are no free ADC channels in the concept and there is a fixed adjustment (calibration) software routine which I cannot change. Complete FPGA software is calculated for a 100MHz clock. There is no possibility to change that. So I dont have to fix a frequency- but a jittering problem. But thank you anyway for the good idea. Maybe I can use it in a later hardware & software version. I will discuss this with the programmer of the FPGA. @Bob The TCXO I'm using is a AXTAL AXLE20-12 which comes with -135dBc/10kHz. Unfortunately I havent any closer noise data. The TCXO has a electronic frequency control input which works from 0.3 to 3V giving it a fdelta of +-5ppm. The initial freq. tolerance is +-2ppm and aging is +-1ppm/year. As you suggested I also thought of giving it a narrow lowpass filter cause the only thing I need is a very low jitter on the edges of the 100MHz HCMOS signal. As we are using an intitial calibration routine (thats the one I cannot change easily) and an additional working-calibration routine, a very slow shifting in phase isnt a problem as the w-calibration can be done quickly everytime before a measurement (a sampling) will be taken. So the w-calibration will overwrite the initial calibration which datas have been copied at boottime to RAM before programming the FPGA for operation. Regards Peter, DG4EK ___ 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] Synchronisizing a 100MHz TCXO with Tbold
Thank you all for your suggestions. @ Attila: I think your suggestion would be "a little bit" too complicated. I dont want to write a dissertation :)) My idea was to simply get a low jitter out of the 100MHz TCXO clocking the FPGA etc.. The fine TCXO I like to use is a AXLE20-12 from AXTAL. I think its expensive enough for my experiments (about 100,- EUR) and it also got a electronic frequency control input as well as a even much more expensive OCXO which would cost me 180,- EUR or more. As I said as the ADCs are working in cascade they have to be enabled and disabled as exact as possible to avoid sampling errors. A jittering clock would do a bad job in that circuit while long time stability is not a problem. @ Chuck: A good idea in principle but I only have one tbold which controlles all my measurement equipment like spectrum analyzer, signal generators a.s.o. I also dont know whether a synchronisation of the 100MHz TCXO to the tbold will really give me a better noise figure than running the TCXO stand alone. The TCXO I like to use gives me a low noise of -138dBc/10kHz and as far as I know tbold comes with -142 or even better. So the main question is whether a synchronisation will give better results or not. If so an additional effect would be the fact that all equipment is then working synchronous. The ADCs I use will get a part of a homemade 1GHz DSO. @ Bert: Thank you for the hint. I think to use a ADF4001 is an easy task so I like to start my experience first using your idea. Again thank you for even more suggestions. Regards Peter, DG4EK ___ 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] LightSquared on FOX
Uh No. Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chuck Forsberg WA7KGX N2469R Sent: Monday, September 19, 2011 3:47 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] LightSquared on FOX My Cessna has a Apollo 2001 GPS receiver which was upgraded to a TSO C129 GPS Sensor around the turn of the century. It is likely this unit, whose design was approved by the Federal Aviation Administration (TSO) will not reject strong signals from LightSquared's proposed cell phone network. It will take $10,000 to $20,000 to replace this unit with a "LightSquared resistant" unit which may become available in several years.Do you think LightSquared will cut me a $20,000 check to cover the costs, not to mention downtime? On 09/19/2011 11:59 AM, Bruce Lane wrote: > The channel didn't earn its multiple nicknames of, among others, > "Faux News" or "Fox Noise" for nothing. ;-) > > Keep the peace(es). > > *** REPLY SEPARATOR *** > > On 19-Sep-11 at 11:32 J. Forster wrote: > >> Phillip Falcone was just on FOX News Channel being grilled. >> >> To hear him tell it GPS interferance is all a political campaign by >> the GPS industry. He said that LightSquared has set aside $60M for >> interferance issues. >> >> Somehow, that seems pitifully inadequate. >> >> First LORAN-C >> Now GPS >> WWV and WWVB next? >> >> -John >> >> = >> >> >> ___ >> 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. >> >> __ Information from ESET Smart Security, version of virus >> signature database 6477 (20110919) __ >> >> The message was checked by ESET Smart Security. >> >> http://www.eset.com > > > > ___ > 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. > -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc "The High Reliability Software" 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] From Sundials to Atomic Clocks
Hello all, I have just scanned the copy I bought from Amazon the other day (second revised edition, 1999). It makes quite a large file, so uploaded it to Flickr - which seems to insist on resizing it! The largest size is at: http://farm7.static.flickr.com/6156/6163603871_fa6d44a623_b.jpg but I have higher resolution versions I can email to anyone who wants it. Regards, Peter On 19 September 2011 19:07, Azelio Boriani wrote: > Rob, > is it possible to scan the asides? The PDF from NIST has the asides too dark > to be readable (the last one is really difficult/impossible to read). > Thank you ___ 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] Synchronisizing a 100MHz TCXO with Tbold, pse help
If the 100 MHz VCTCXO is fundamentally "better" than the 10 MHz VC?XO in the Tbolt, then I would go with Chuck's idea to just use it with a divide by 10 in front, as the main oscillator. You will still have a good 10 MHz signal available from the divider - just buffer it up and maybe harmonic filter it if necessary. If the Tbolt uses an ovenized oscillator, I think you'd be better off keeping it as the main one. In this case, I'd recommend using a 10H ECL decade divider to get the 100 MHz down to 10, and compare it to the Tbolt 10 MHz with a 74HC4046A PLL IC (or higher performance type if necessary), driving the 100 MHz VCTCXO through a very long time constant loop filter. The reference sidebands will be pretty far +/- n*10 MHz out from your 100 MHz, and can be made very small since the filter is a brick wall, comparatively. You would have to optimize the close-in noise performance/loops depending on the relative quality of the two oscillators at various offsets. Another option may be to use a 10H ECL D flip flop as a direct subsampler/phase detector, followed by a differential opamp loop filter, so a separate PLL IC would not be needed, but the loop filter would probably have to be faster to keep up with power supply noise and thermal effects in the D-FF. Yet another way similar to that above, would be to use a classic harmonic mixer topology - with the 100 MHz reacting with the 10th harmonic of a good strong 10 MHz drive to a balanced RF mixer, giving a DC IF that represents phase, low pass filtered and amplified to control the oscillator. Regardless of how the 100 MHz is "synchronized" to something else, you will have a PLL (or FLL) in some form - even manually recalibrating to a standard is a closed loop error correction system - it's just a question of the timeframes involved. Ed ___ 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] question on apparent offset between two Endrun CDMA clocks
At Mon Sep 19 05:23:43 UTC 2011, Hal Murray wrote: > >>I have a minor mystery and if any ready explanation is >>available I would be curious to learn of it. >> >> Have two Endrun CDMA time sources: >> >> ntpd 4.1.1c-rc2 at 1.866 > >That's quite old. Ancient, in fact. :-) But I got it for $300 a couple of years ago. >>'ntpq -pn' and 'ntpdate -q' queries from both systems >>and from other client systems consistently show the >>Praecis Cntp between 30 and 80 microseconds >>ahead of the Praecis Cf device. The median offset >>seems to be about 60 microseconds. > >You might ask Endrun. (If you get a good answer, >>please tell us.) They essentially agreed with my code-path asymmetry amplified by very slow CPU theory along with the possibility that HDX carrier switching on the Cntp might be a distorting factor as well. They told me to check the PseudoNoise Offset (PNO) value and this proved that both CDMA clocks are synced to the same tower and therefore should read within one or two microseconds of each other. >>Round trip time to the Cntp is about 960 microseconds and >>round-trip time to the P4/Cf is about 60 microseconds. >>'ntpdate -d' shows that the Cntp takes a total of 3600 >>microseconds to service a request where the P4 takes 65 >> microseconds. > >[I'm not sure what it means to have 3600 uSec service time with >960 uSec round trip time.] I'm pretty sure it means that it takes ~500 microseconds in each direction for network and IP stack traversal and ~2500 microseconds of CPU time to process the request on the fabulously slow Am5x86-WB 133 MHz processor. >I'm not all that surprised that two similar setups are off by >something like 60 microseconds. 60 out of 3600 is pretty small. Yes. Hence my amplified code-path asymmetry theory. >One likely source of quirks is interrupt coalescing which is >common on Gigabit ethernet chips. (That's probably not >happening if the round trip time is only 60 microseconds.) Nope, disabled: options e1000 InterruptThrottleRate=0,0 FlowControl=0,0 copybreak=2048 >ntpq -p and ntpdate give you two different sorts of data. > >ntpq tells you what the target thinks is going on. >ntpdate tells you the difference between the local clock and the >target clock. Yes, knew that but thanks. >If I wanted more info on this type of quirk, I would >setup ntpd on a monitoring system using both systems >as servers and turn on rawstats. Use the noselect >keyword if you don't really want to use it as a server. Have 'noselect' on everything that is not a precision time source. Doesn't seem to make any difference from stratum 2 relative the two CDMA-synced clocks so there I just have a 'prefer' on the Cntp even though the P4 probably has the better time--it sometimes is busy doing other additional work and may wander. >Set minpoll and maxpoll to get the desired >amount of data. Always lock the local systems to min/max = 4 (16 seconds), except for the Windows boxes which are locked to min/max = 0 (1 second). A quick experiment showed that Windows keeps much better time via the network at one second polling than with 16 second polling of the Ct via a real (not USB) serial port. Didn't bother hacking the Trimble clock driver to poll at one second since it's clear the problem with Windows is the poor stability of the multimedia timer interpolation and that won't ever get fixed. So no point in direct attaching time sources under Windows. >Then graph the results. >(Poke me off-list if you want more details.) > >If you have access to ntp.conf on the servers, turn on >loopstats, peerstats, and clockstats. They might show >something interesting. Have done this in the past; too much trouble at present as I'm pretty sure nothing exciting will appear. Awhile ago the graphs did help find a once-or- twice a day glitch with the Cntp where the departure time-stamp was set before the arrival time stamp. The glitch would biff 'ntpd' into wild jump and oscillation events till I patched it to discard insane replies. -- My present plan is put up a Trimble Palisade (Accutime 2000 actually) running on a third system with PPS for a higher accuracy reference point. Bit of a pain as I don't have the converter box and will have to buy a RS-422 interface, solder up a custom connector, and back-port Rodolfo Giometti's PPS kernel patch to CentOS 5's 2.6.18 (can't abide poor performing newer kernels running on the box best suited for the GPS source). Good project for days when I can't stand doing real work. ___ 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] LightSquared on FOX
My Cessna has a Apollo 2001 GPS receiver which was upgraded to a TSO C129 GPS Sensor around the turn of the century. It is likely this unit, whose design was approved by the Federal Aviation Administration (TSO) will not reject strong signals from LightSquared's proposed cell phone network. It will take $10,000 to $20,000 to replace this unit with a "LightSquared resistant" unit which may become available in several years.Do you think LightSquared will cut me a $20,000 check to cover the costs, not to mention downtime? On 09/19/2011 11:59 AM, Bruce Lane wrote: The channel didn't earn its multiple nicknames of, among others, "Faux News" or "Fox Noise" for nothing. ;-) Keep the peace(es). *** REPLY SEPARATOR *** On 19-Sep-11 at 11:32 J. Forster wrote: Phillip Falcone was just on FOX News Channel being grilled. To hear him tell it GPS interferance is all a political campaign by the GPS industry. He said that LightSquared has set aside $60M for interferance issues. Somehow, that seems pitifully inadequate. First LORAN-C Now GPS WWV and WWVB next? -John = ___ 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. __ Information from ESET Smart Security, version of virus signature database 6477 (20110919) __ The message was checked by ESET Smart Security. http://www.eset.com ___ 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. -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc "The High Reliability Software" 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] Making a HP 10811 better
WarrenS wrote: > > The test took a while, but I finally got around to testing the effect of > setting a HP10811's inner oven to the xtral's EXACT turn over temperature. > Short answer is NO Help. > I did not see any improvement in freq stability with environmental > temperature changes. You have reconfirmed what was established decades ago. The 10811 oven has high thermal gain only at the location of the crystal. The oscillator transistor is ovenized at a much lower level of stability. As explained in my 1997 paper, the 10811 frequency is quite sensitive to the transistor temperature. The non-hermetic versions of the 10811 are also quite sensitive to humidity for some other unknown reason. The oscillator transistor is hermetic. (BTW, the transistor is a 2N5179 selected for minimum fT at 30 mA, to assure that the oscillator starts). It is also worth noting that about half the 10811 crystals do NOT have a turnover, rather they have a very low, but not zero, tempco from 80 to 84 degrees. The ones that do have a turnover, have a very shallow turnover, not like an AT cut. The 10811 uses two transistors as point source heaters, making a zero gradient oven an impossibility (see my 1997 paper on zero gradient ovens for why this is important). The reason for the transistors was to avoid the PWM oven controller used in its predecessor, the 10544, which had wire heaters. The E1938A uses linear control transistors to control the current in flex circuit heaters. This gives the best oven performance, but wastes a fair amount of power in the linear regulators, which are outside the oven. This extra thermal load is not a big problem because it decreases at higher temperatures, since the oven current is dropping off. At HP, we looked at making improvements to the 10811 and were never able to come up with any modifications that made sense. It's not that you can't make a better oscillator than the 10811, it is just that the existing design has pretty well been beat to death, and you need to start over with a clean sheet of paper to do better. If you want to get serious about tinkering with the 10811 oven, you need to convert the oscillator to run in mode B, which is very temperature sensitive. Then you can really see what the oven is doing, at the crystal blank. This is mentioned in the HPJ article on the 10811. (Required reading for anyone playing with 10811's). 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] LightSquared on FOX
You might want to investigate Solyndra's technology, excluding the politics. It is not competitive today, however it is a low energy to produce product. That is, it will produce the amount of energy it took to produce must faster than conventional photovoltaics, which takes about 20 years. Ultimately thin film solar cells will be the dominant technology. Remember, Fox News lost money for a decade. It takes time to build a business. The US portion of the investment in Solyndra is about 2 to 3 days of either of Bush's unfinanced, off the books, illegal wars. ___ 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] LightSquared on FOX
The channel didn't earn its multiple nicknames of, among others, "Faux News" or "Fox Noise" for nothing. ;-) Keep the peace(es). *** REPLY SEPARATOR *** On 19-Sep-11 at 11:32 J. Forster wrote: >Phillip Falcone was just on FOX News Channel being grilled. > >To hear him tell it GPS interferance is all a political campaign by the >GPS industry. He said that LightSquared has set aside $60M for >interferance issues. > >Somehow, that seems pitifully inadequate. > >First LORAN-C >Now GPS >WWV and WWVB next? > >-John > >= > > >___ >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. > >______ Information from ESET Smart Security, version of virus >signature database 6477 (20110919) __ > >The message was checked by ESET Smart Security. > >http://www.eset.com ___ 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] LightSquared on FOX
I never said they were. And, this is no longer an EE story. It is now political, and has been so for many months. If it were a purely EE story, LightSquared would be bust, like Solyndra. Another also-ran. -John = > Fox News may be Fair and Balanced, but their on air talent are not EEs. > > http://www.gpsworld.com/gnss-system/news/rally-organized-protest-potential-gps-band-interference-lightsquared-12073 > > On 09/19/2011 11:32 AM, J. Forster wrote: >> Phillip Falcone was just on FOX News Channel being grilled. >> >> To hear him tell it GPS interferance is all a political campaign by the >> GPS industry. He said that LightSquared has set aside $60M for >> interferance issues. >> >> Somehow, that seems pitifully inadequate. >> >> First LORAN-C >> Now GPS >> WWV and WWVB next? >> >> -John >> >> = >> >> >> ___ >> 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. >> > > -- > Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com > Developer of Industrial ZMODEM(Tm) for Embedded Applications >Omen Technology Inc "The High Reliability Software" > 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 > > ___ 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] From Sundials to Atomic Clocks
Hi Azelio, Unfortunately my original copy is in storage with a lot of other books (I moved recently), so not accessible at present. Maybe someone else can help you out on this. Rob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Azelio Boriani Sent: 19 September 2011 7:07 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] From Sundials to Atomic Clocks Rob, is it possible to scan the asides? The PDF from NIST has the asides too dark to be readable (the last one is really difficult/impossible to read). Thank you On Mon, Sep 19, 2011 at 6:58 PM, Rob Kimberley < timing.consulta...@btinternet.com> wrote: > Some history for you on this... > > The original idea came from Dr Jim Barnes who was head of T&F at NBS > (NIST). > The idea was not well received from some quarters at NBS as it was > "too simplistic", and not "technical enough". > > Jim later worked for Austron and was there as Chief Scientific Officer > when I worked for them in the mid-80s. > > I agree with you, a great read! > > Rob > > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] > On Behalf Of paul swed > Sent: 19 September 2011 4:24 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] From Sundials to Atomic Clocks > > Funny I was just reading the hard copy I have last night. > Great document and funny. > > On Mon, Sep 19, 2011 at 10:38 AM, Rob Kimberley < > timing.consulta...@btinternet.com> wrote: > > > Hi Mike, > > > > I bought a bunch of these when I worked for Austron, and gave them > > out to customers and reps. It was very well received. I have one > > original copy left at home, so thanks for the PDF link. > > > > Rob Kimberley > > > > -Original Message- > > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] > > On Behalf Of Mike Fahmie > > Sent: 07 September 2011 6:27 PM > > To: time-nuts@febo.com > > Subject: [time-nuts] From Sundials to Atomic Clocks > > > > On a visit to NIST Boulder (then known as NBS) many years ago > > (1978), I was presented with a copy of NBS Monograph 155, "From > > Sundials to Atomic Clocks" > > by one of the authors. I found it to be a fantastic read, it > > answers all of those questions about Time & Frequency that you were > > afraid to ask. > > > > I stumbled on it again today in PDF form on the NIST website, it has > > undergone two revisions and this URL points to the most current > > (1999) edition. > > > > http://tf.nist.gov/general/pdf/1796.pdf > > > > -Mike- > > WA6ZTY > > > > > > ___ > > 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. > ___ 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] Synchronisizing a 100MHz TCXO with Tbold, pse help
Hi Tom, Christian Vogel : but of course: Whatever algorithms you put into your after-the-fact software correction will have an influence similar to a hardware PLL. Tom Van Baak : I'm curious about this. What are the inherent limits of each approach? One difference comes to mind -- with a software post-processing solution you get the benefit of being able to see samples in both the past and future. A hardware PLL works in real-time with data from the past. I have to admit that my comment was backed only by my "gut feeling" about how I would implement such a post-processing, which resembles a numerical PLL. But your question about a non-causal correction/filter/... is a very interesting one. I think it would be worthwhile to try and find it out experimentally: Setup a thunderbolt that receives the GPS signal but is undisciplined. Log both the internally measured PPS offset and the measured PPS versus a known good reference. Try to find the algorithm that gives the best estimate of the externally measured PPS offset from the internally measured (serial port logged) thunderbolt data. Greetings, Chris ___ 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] LightSquared on FOX
Fox News may be Fair and Balanced, but their on air talent are not EEs. http://www.gpsworld.com/gnss-system/news/rally-organized-protest-potential-gps-band-interference-lightsquared-12073 On 09/19/2011 11:32 AM, J. Forster wrote: Phillip Falcone was just on FOX News Channel being grilled. To hear him tell it GPS interferance is all a political campaign by the GPS industry. He said that LightSquared has set aside $60M for interferance issues. Somehow, that seems pitifully inadequate. First LORAN-C Now GPS WWV and WWVB next? -John = ___ 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. -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc "The High Reliability Software" 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] LightSquared on FOX
Phillip Falcone was just on FOX News Channel being grilled. To hear him tell it GPS interferance is all a political campaign by the GPS industry. He said that LightSquared has set aside $60M for interferance issues. Somehow, that seems pitifully inadequate. First LORAN-C Now GPS WWV and WWVB next? -John = ___ 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] From Sundials to Atomic Clocks
Rob, is it possible to scan the asides? The PDF from NIST has the asides too dark to be readable (the last one is really difficult/impossible to read). Thank you On Mon, Sep 19, 2011 at 6:58 PM, Rob Kimberley < timing.consulta...@btinternet.com> wrote: > Some history for you on this... > > The original idea came from Dr Jim Barnes who was head of T&F at NBS > (NIST). > The idea was not well received from some quarters at NBS as it was "too > simplistic", and not "technical enough". > > Jim later worked for Austron and was there as Chief Scientific Officer when > I worked for them in the mid-80s. > > I agree with you, a great read! > > Rob > > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of paul swed > Sent: 19 September 2011 4:24 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] From Sundials to Atomic Clocks > > Funny I was just reading the hard copy I have last night. > Great document and funny. > > On Mon, Sep 19, 2011 at 10:38 AM, Rob Kimberley < > timing.consulta...@btinternet.com> wrote: > > > Hi Mike, > > > > I bought a bunch of these when I worked for Austron, and gave them out > > to customers and reps. It was very well received. I have one original > > copy left at home, so thanks for the PDF link. > > > > Rob Kimberley > > > > -Original Message- > > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] > > On Behalf Of Mike Fahmie > > Sent: 07 September 2011 6:27 PM > > To: time-nuts@febo.com > > Subject: [time-nuts] From Sundials to Atomic Clocks > > > > On a visit to NIST Boulder (then known as NBS) many years ago (1978), > > I was presented with a copy of NBS Monograph 155, "From Sundials to > > Atomic Clocks" > > by one of the authors. I found it to be a fantastic read, it answers > > all of those questions about Time & Frequency that you were afraid to > > ask. > > > > I stumbled on it again today in PDF form on the NIST website, it has > > undergone two revisions and this URL points to the most current (1999) > > edition. > > > > http://tf.nist.gov/general/pdf/1796.pdf > > > > -Mike- > > WA6ZTY > > > > > > ___ > > 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. > ___ 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] From Sundials to Atomic Clocks
Some history for you on this... The original idea came from Dr Jim Barnes who was head of T&F at NBS (NIST). The idea was not well received from some quarters at NBS as it was "too simplistic", and not "technical enough". Jim later worked for Austron and was there as Chief Scientific Officer when I worked for them in the mid-80s. I agree with you, a great read! Rob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: 19 September 2011 4:24 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] From Sundials to Atomic Clocks Funny I was just reading the hard copy I have last night. Great document and funny. On Mon, Sep 19, 2011 at 10:38 AM, Rob Kimberley < timing.consulta...@btinternet.com> wrote: > Hi Mike, > > I bought a bunch of these when I worked for Austron, and gave them out > to customers and reps. It was very well received. I have one original > copy left at home, so thanks for the PDF link. > > Rob Kimberley > > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] > On Behalf Of Mike Fahmie > Sent: 07 September 2011 6:27 PM > To: time-nuts@febo.com > Subject: [time-nuts] From Sundials to Atomic Clocks > > On a visit to NIST Boulder (then known as NBS) many years ago (1978), > I was presented with a copy of NBS Monograph 155, "From Sundials to > Atomic Clocks" > by one of the authors. I found it to be a fantastic read, it answers > all of those questions about Time & Frequency that you were afraid to > ask. > > I stumbled on it again today in PDF form on the NIST website, it has > undergone two revisions and this URL points to the most current (1999) > edition. > > http://tf.nist.gov/general/pdf/1796.pdf > > -Mike- > WA6ZTY > > > ___ > 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] Synchronisizing a 100MHz TCXO with Tbold, pse help
Hi How good is the TCXO? Put another way - do you know what it's close in (1 to 100 Hz) phase noise looks like? Even with a hardware loop, you normally can make it narrow enough that most TCXO's are unlikely to be degraded by the TBolt. No matter how you do it, below some cut off frequency the TCXO will have to follow the TBolt... Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Peter Krengel Sent: Sunday, September 18, 2011 9:52 PM To: time-nuts@febo.com Subject: [time-nuts] Synchronisizing a 100MHz TCXO with Tbold, pse help Hello group, I like to synchronisize a fine 100MHz TCXO with the 10MHz output of the Tbold. The TCXO has a EFC input. I know this can be done using a PLL but I do not want to add noise to the very good noise parameters of the TCXO cause the 100MHz signal is to be used to clock a FPGA which controlles fast cascaded ADCs. Has anybody a circuit diagram to use? Thank you in advance regards Peter, DG4EK ___ 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] From Sundials to Atomic Clocks
Funny I was just reading the hard copy I have last night. Great document and funny. On Mon, Sep 19, 2011 at 10:38 AM, Rob Kimberley < timing.consulta...@btinternet.com> wrote: > Hi Mike, > > I bought a bunch of these when I worked for Austron, and gave them out to > customers and reps. It was very well received. I have one original copy > left > at home, so thanks for the PDF link. > > Rob Kimberley > > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of Mike Fahmie > Sent: 07 September 2011 6:27 PM > To: time-nuts@febo.com > Subject: [time-nuts] From Sundials to Atomic Clocks > > On a visit to NIST Boulder (then known as NBS) many years ago (1978), I was > presented with a copy of NBS Monograph 155, "From Sundials to Atomic > Clocks" > by one of the authors. I found it to be a fantastic read, it answers all > of > those questions about Time & Frequency that you were afraid to ask. > > I stumbled on it again today in PDF form on the NIST website, it has > undergone two revisions and this URL points to the most current (1999) > edition. > > http://tf.nist.gov/general/pdf/1796.pdf > > -Mike- > WA6ZTY > > > ___ > 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] Synchronisizing a 100MHz TCXO with Tbold, pse help
but of course: Whatever algorithms you put into your after-the-fact software correction will have an influence similar to a hardware PLL. Chris, I'm curious about this. What are the inherent limits of each approach? One difference comes to mind -- with a software post-processing solution you get the benefit of being able to see samples in both the past and future. A hardware PLL works in real-time with data from the past. /tvb ___ 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] From Sundials to Atomic Clocks
Hi Mike, I bought a bunch of these when I worked for Austron, and gave them out to customers and reps. It was very well received. I have one original copy left at home, so thanks for the PDF link. Rob Kimberley -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Mike Fahmie Sent: 07 September 2011 6:27 PM To: time-nuts@febo.com Subject: [time-nuts] From Sundials to Atomic Clocks On a visit to NIST Boulder (then known as NBS) many years ago (1978), I was presented with a copy of NBS Monograph 155, "From Sundials to Atomic Clocks" by one of the authors. I found it to be a fantastic read, it answers all of those questions about Time & Frequency that you were afraid to ask. I stumbled on it again today in PDF form on the NIST website, it has undergone two revisions and this URL points to the most current (1999) edition. http://tf.nist.gov/general/pdf/1796.pdf -Mike- WA6ZTY ___ 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] Synchronisizing a 100MHz TCXO with Tbold, pse help
Hi Tom,
Would it be possible for your application to let the 100 MHz
TCXO free-run? Then you could use one or two of the ADC
channels to sample the TBolt 10 MHz and 1PPS leaving all
the rest of the channels to do real work.
This would then give you all the information you need to apply
phase adjustments to your ADC readings as an after-the-fact
software correction. Essentially you get all the benefits of GPS
time tagging and accurate reference frequency along with the
low jitter of your TCXO but without any of the additive noise of
a hardware PLL.
but of course: Whatever algorithms you put into your after-the-fact
software correction will have an influence similar to a hardware PLL.
{With the added benefit that you can improve your code at your
leisure and re-iterate without having to repeat your data recording.}
If one doesn't want to sacrifice an ADC channel to sample the reference,
I'd suggest going Chuck's route, divide the 100 MHz down to 10 and let
the thunderbolt discipline the 100 MHz TCXO.
But when business gets serious, you can break the loop and put the
Thunderbolt into holdover manually. It will then keep the control input
of the 100 MHz stable but will still measure the phase and frequency
offset with respect to GPS time. You could then use the data recorded
from the thunderbolt to do phase corrections on your sampled data as
suggested.
Chris
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Re: [time-nuts] Synchronisizing a 100MHz TCXO with Tbold, pse help
Peter, How closely locked to GPS time or frequency does your TCXO need to be? Would it be possible for your application to let the 100 MHz TCXO free-run? Then you could use one or two of the ADC channels to sample the TBolt 10 MHz and 1PPS leaving all the rest of the channels to do real work. This would then give you all the information you need to apply phase adjustments to your ADC readings as an after-the-fact software correction. Essentially you get all the benefits of GPS time tagging and accurate reference frequency along with the low jitter of your TCXO but without any of the additive noise of a hardware PLL. /tvb Hello group, I like to synchronisize a fine 100MHz TCXO with the 10MHz output of the Tbold. The TCXO has a EFC input. I know this can be done using a PLL but I do not want to add noise to the very good noise parameters of the TCXO cause the 100MHz signal is to be used to clock a FPGA which controlles fast cascaded ADCs. Has anybody a circuit diagram to use? Thank you in advance regards Peter, DG4EK ___ 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] Synchronisizing a 100MHz TCXO with Tbold, pse help
Peter I would use a PLL like the ADF 4001 because of its low noise floor and depending of which Tbolt, its phase noise is very good. The advantage is that you can pick the filter response in such a way that you take advantage of the individual Osc. parameters. Bert Kehren In a message dated 9/18/2011 9:52:29 P.M. Eastern Daylight Time, krengelda...@gmx.de writes: Hello group, I like to synchronisize a fine 100MHz TCXO with the 10MHz output of the Tbold. The TCXO has a EFC input. I know this can be done using a PLL but I do not want to add noise to the very good noise parameters of the TCXO cause the 100MHz signal is to be used to clock a FPGA which controlles fast cascaded ADCs. Has anybody a circuit diagram to use? Thank you in advance regards Peter, DG4EK ___ 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] Synchronisizing a 100MHz TCXO with Tbold, pse help
Replace the 10 mHz oscillator with a divide by ten counter driven by the 100 mHz signal. Connect the control voltage from the Tbolt to the 100 mHz oscillator through a low pass filter and voltage divider that provides the minimum signal required for discipline. Tboltmon can set gain etc., even invert the signal. -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc "The High Reliability Software" 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] Difference between Trimble 37265 and 65256
I've ordered a 65256 to replace a failed 37265 clock in one of my Thunderbolts. The pinouts are obviously different, no sweat. What about electrical characteristics? -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc "The High Reliability Software" 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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.
