Re: [time-nuts] Neural net to control oven temperature ?
I will mention that TI has a neural net chip/eval board now for as I recall $99. Like so many things maybe it makes sense. Regards Paul WB8TSL On Tue, Jul 9, 2019 at 11:02 PM Chase Turner wrote: > Hi Glen, > > This is actually something I know a little about. > > Neural nets are most useful for feature selection, that is, finding the > important x that is a function of y, in a very large sea of x variables. In > this case, we already know what's important, which is temperature > stability. So, a neural net would be a bit much when we already know what > feature is important for function. Additionally, unless I'm mistaken, oven > control is probably a linear relationship of some sort or another, and > neural nets are much better suited for examining and revealing insights > about non-linear data. > > If you have a method by which you can collect the necessary data that has a > bearing on the oven functionality, you'd probably be better off training a > logistic classifier, and using it instead. That said, both methods would be > overkill, imo- I'd use a PID instead. > > Best, > Chase > > On Tue, Jul 9, 2019 at 10:00 PM Glen English VK1XX < > glenl...@pacificmedia.com.au> wrote: > > > Has anyone tried to use a Neural net to control oven tmep, rather than > > the ye olde PID ? > > > > IE the algorithm learns from previous beheviour and successfully > > predicts behaviour (or not). > > > > I'm sure there are a few out there proficient with machine learning > > algorithms. > > > > Might make a good masters thesis I bet. > > > > Given that oven control based on inputs and whatever is not random, > > unlike say flicker etc. > > > > glen > > > > > > > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Neural net to control oven temperature ?
Has anyone tried to use a Neural net to control oven tmep, rather than the ye olde PID ? IE the algorithm learns from previous beheviour and successfully predicts behaviour (or not). I'm sure there are a few out there proficient with machine learning algorithms. Might make a good masters thesis I bet. Given that oven control based on inputs and whatever is not random, unlike say flicker etc. glen ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Advantages of GNSS ???
Hi TCXO’s are very different beasts than OCXO’s. In an OCXO, the crystal is not exposed to any significant temperature change. Bob > On Jul 9, 2019, at 8:05 PM, Mark Goldberg wrote: > > That is the dirty little secret of crystals. Manufacturers will test the > temperature response in one direction, but if you heat and then cool > crystals and measure the frequency, they do exhibit significant hysteresis. > I've not been able to get a supplier of TCXOs for me to characterize this > as I don't buy enough. I just have to test them myself and toss the 10% or > so that don't meet their specs due to the hysteresis. If you cycle the > temperature up and down multiple times, the effect lessens, but after > letting them sit for a while, it comes back. I also saw jumps at particular > temperatures, but that may be due to the TCXO compensation. > > Mark > > > On Tue, Jul 9, 2019 at 4:00 PM Glen English VK1XX < > glenl...@pacificmedia.com.au> wrote: > >> and non monitonicity in the device is the death of a control loops. >> >> My attempts at building good OCXOs using cheap AT crystals in the 90s >> was thwarted by non monotonic bending crystals ! >> >> And everytime they would wake up, the monitonicity would be in a >> different part of the control curve >> >> and they exhibited hysteresis, like defined steps , this seems to be the >> case with most crystals, the harder you looked, the more undesirable >> imperfections you found... >> >> >> >> On 10/07/2019 5:57 AM, David G. McGaw wrote: >>> Leo - >>> >>> I do believe you mean non-monotonic, rather than non-monotonous. Not >>> being monotonous is a good thing. :-) >>> >>> David N1HAC >>> >>> On 7/9/19 1:20 PM, Leo Bodnar wrote: It's not very good, it is highly non-linear and even wor >> >> >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] It is possible to "recharge" a hydrogen maser?
Thank you for the experience / instruction! Em ter, 9 de jul de 2019 12:05, escreveu: > Luiz, > Ch1-75 Hydrogen storage details. > “The compound LaNi5H, is used for storing molecular hydrogen. > The LaHi5H, is characterized by high hydrogen partial pressure (2 to 5 > atmospheres) at +(20-50) degrees C. > 250 grams of the compound contains 18 liters of hydrogen at normal > pressure. > It is sufficient for maser continuous operation for more than 40 000 > hours.” > I believe that the container holding the LaHi5H is heated and > thermostatically controlled to maintain the proper pressure into the > purifier. > First you should be able to power up the maser just far enough so that > the ion pumps can operate. Monitor their current and it should drop down > to almost zero within a few hours. If not you may need to get the ion > pumps rebuilt. > There are commercial outfits that can rebuild them but if there are not > isolation valves to close and isolate the Maser when you remove the ion > pumps you will not be able to proceed! Since the Russian Masers also use > a getter pump in concert with the ion pumps, opening up the vacuum system > will contaminate the getter pump. The process of clearing the getter is > very detailed and involves temperatures of up to 800 degrees C, and > without careful instructions on how to do it you risk damaging other > portions of the Maser! > If the pressure does drop down, then you need to determine if there is > any Hydrogen left. I know that some Russian Masers will give you an alarm > that tells you if you are out, and some have a mechanical pressure gage, > but I’m not sure about the CH1-75. You will need to check the manuals. If > it does not provide an alarm or have a gage then see if the HFO > oscillator is working and if the discharge bulb is lighting up. If it > lights up you are not out of Hydrogen! > If it does not light and you have determined that the lack of Hydrogen > is indeed the problem you will need to locate the LaHi5H container. After > you locate it make sure it is being heated, this could cause an apparent > lack of Hydrogen! Then see how it is connected to the discharge bulb. > Hopefully it will be a threaded connection. This connection is on the > high pressure side of the purifier and can be removed without > compromising the vacuum. You will need to remove the container and > recharge it. I would instead replace it with a small compressed hydrogen > cylinder and regulators. > Use ultra-high purity dry Hydrogen and make sure you purge the line > going to the purifier. The purifier will block other gases from getting > into the Maser but in the process too much “foreign” gas can contaminate > and damage the purifier! > Once you manage to locate the container some pictures on where it’s > hiding would be nice! > Good luck with your efforts! > Cheers, > Corby Dawson > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] odd frequencies
I've seen questions here about GPSDO disciplined frequency sources for = odd frequencies. I recommend the RFZero: http://www.rfzero.net. For $60 US or so, this unit will provide same. Is programmed using the Arduino IDE, several examples provided. All that's needed is a UBLOX compatible patch or other antenna. Disciplined SI oscillator. buffer driver provided, with other goodies. Don -- Dr. Don Latham AJ7LL PO Box 404, Frenchtown, MT, 59834 VOX: 406-626-4304 ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Advantages of GNSS ???
That is the dirty little secret of crystals. Manufacturers will test the temperature response in one direction, but if you heat and then cool crystals and measure the frequency, they do exhibit significant hysteresis. I've not been able to get a supplier of TCXOs for me to characterize this as I don't buy enough. I just have to test them myself and toss the 10% or so that don't meet their specs due to the hysteresis. If you cycle the temperature up and down multiple times, the effect lessens, but after letting them sit for a while, it comes back. I also saw jumps at particular temperatures, but that may be due to the TCXO compensation. Mark On Tue, Jul 9, 2019 at 4:00 PM Glen English VK1XX < glenl...@pacificmedia.com.au> wrote: > and non monitonicity in the device is the death of a control loops. > > My attempts at building good OCXOs using cheap AT crystals in the 90s > was thwarted by non monotonic bending crystals ! > > And everytime they would wake up, the monitonicity would be in a > different part of the control curve > > and they exhibited hysteresis, like defined steps , this seems to be the > case with most crystals, the harder you looked, the more undesirable > imperfections you found... > > > > On 10/07/2019 5:57 AM, David G. McGaw wrote: > > Leo - > > > > I do believe you mean non-monotonic, rather than non-monotonous. Not > > being monotonous is a good thing. :-) > > > > David N1HAC > > > > On 7/9/19 1:20 PM, Leo Bodnar wrote: > >> It's not very good, it is highly non-linear and even wor > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Advantages of GNSS ???
Hi Well, if you ever get back into it: You play games with varicap diodes to straighten out the curve. You may bias them, you might put them in parallel, you might put a coil or a cap across them. You can get the curve plenty flat enough for a control loop. Hopping / discrete steps generally means you have to much drive on the crystal or some other circuit gotcha. The crystal its self and the tuning diode have no steps in them. They just aren’t complex enough devices to get into stepwise behavior. Drive power on an OCXO will pretty much always be below a milli-watt. A typical design will be in the range of 1/10 to 1/100 of that power level. Bob > On Jul 9, 2019, at 5:36 PM, Glen English VK1XX > wrote: > > and non monitonicity in the device is the death of a control loops. > > My attempts at building good OCXOs using cheap AT crystals in the 90s was > thwarted by non monotonic bending crystals ! > > And everytime they would wake up, the monitonicity would be in a different > part of the control curve > > and they exhibited hysteresis, like defined steps , this seems to be the case > with most crystals, the harder you looked, the more undesirable imperfections > you found... > > > > On 10/07/2019 5:57 AM, David G. McGaw wrote: >> Leo - >> >> I do believe you mean non-monotonic, rather than non-monotonous. Not >> being monotonous is a good thing. :-) >> >> David N1HAC >> >> On 7/9/19 1:20 PM, Leo Bodnar wrote: >>> It's not very good, it is highly non-linear and even wor > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Recommendations for time beginner?
Forrest, Thanks very much for the extensive comments, they're greatly helpful. I thought I might say a little more about my goals, and add some notes on points that you made. As mentioned, my main focus at this point is measurement of HF radio signals, with a goal of 1 millihertz accuracy. At 10 MHz that would involve stability of 1 part in 10^10. 1 part in 10^11 would be ideally desirable for reference. I have some oscillators (oven-controlled, double-oven-controlled, etc) but have been told that these won't be able to achieve the stability I'm looking for, and it's been suggested that I think in terms of GPSDOs and/or devices using radioactive sources. I've been told that a GPSDO will maintain 1 part in 10^12 if powered on, locked and left to stabilize for a few months, whereas unlocked they vary with temperature by about 10 PPB, drifting perhaps 5 PPB per day. My first thought on a GPSDO to act as a backup to the Thunderbolt was one of Leo Bodnar's units, either the Precision GPS Reference Clock or the Mini Precision GPS Reference Clock. It appears that the primary difference between these is that the first unit outputs two reference clocks, whereas the mini outputs one. I don't need two clocks, so if their specs are otherwise the same the mini should be fine for me. The BG7TBL GPSDO sounds interesting; my main concern about going in that direction is the variation you mentioned in different editions due to parts availability. I have very poor view of the sky immediately outside the room my gear is located in, so for the Trimble I've been using a run of about 50 feet of coax to an active GPS antenna. If I run multiple GPSDOs I hope I can use an antenna splitter rather than putting up multiple antennas. One topic I'd like to understand better is how GPSDO stability is related to run time. Is it a geometric curve, with stability improvement the greatest in the first hours and days after being powered on, with later improvement less pronounced? If a GPSDO stays powered-on without interruption but loses lock for some reason (for example, the antenna is disconnected), does its stability hold reasonably steady or does it start over from scratch? I haven't yet seen or worked with a cesium or rubidium source, but am very interested in them. I'm told that, like the replicants in Blade Runner, they are high-performance but have limited lifespans -- i.e. they achieve better than 1 PPB and don't require the extended run-times of GPSDOs to achieve optimal stability, but due to the decay of their sources they will not last forever. For educational purposes if nothing else it would be very interesting to experiment with one of these, if I can find one that isn't too expensive and is in decent shape. I do incidentally have a nice Siglent two-channel oscilloscope, so that's available for trimming purposes. Thanks for the caveat about noise. My ultimate goal is accuracy of frequency measurement, but precision may be a higher priority for selection of a clock source. I need to spend time understanding better the relationship between these in the measurement procedures I'm looking at using. One other note -- even with decent gear I realize there will be other factors such as atmospheric Doppler that introduce larger errors than the ones mentioned above. I'll certainly have to deal with those too. If I have anything wrong, or if any of the above suggests any further comments or suggestions (from any one on the list), I'll be very interested. Thanks again, Frank On 7/8/19 6:32 PM, Forrest Christian wrote: Long winded answer to your question: I'm sort of an "Advanced beginner" time-nut or maybe a bit beyond that. In relation to your question: It really depends on your goals. The following is a high level overview of your options, and is intentionally lacking and/or simplifying some details. There are lots of twists and turns one can go down on each of these options. And there's a few spots which I'm making generalizations which may or may not be exact. In the way of "precision" 10Mhz clock sources, I have 2 thunderbolts, a PRS-10 rubidium oscillator, and a BG7TBL GPSDO. Oh and a couple/few OCXO's which are undisciplined. I want a cesium clock but haven't happened to end up with one yet. You're somewhat familiar with the thunderbolts, let me compare the others first. The OCXO's are undisciplined, but aren't that bad of a 10Mhz reference. Especially if you can trim them to a good quality reference - such as your thunderbolt. Depending on your needs, this might be good enough for you. Generally, once the OCXO is warmed up you can adjust it to match the reference, then as long as it isn't shut off it should stay very close to the same frequency. Of course it will drift over time and perhaps as a result of other external forces (temperature, humidity, voltage, vibration, etc). Of course you can then re-trim it to the right frequency. How
Re: [time-nuts] Advantages of GNSS ???
and non monitonicity in the device is the death of a control loops. My attempts at building good OCXOs using cheap AT crystals in the 90s was thwarted by non monotonic bending crystals ! And everytime they would wake up, the monitonicity would be in a different part of the control curve and they exhibited hysteresis, like defined steps , this seems to be the case with most crystals, the harder you looked, the more undesirable imperfections you found... On 10/07/2019 5:57 AM, David G. McGaw wrote: Leo - I do believe you mean non-monotonic, rather than non-monotonous. Not being monotonous is a good thing. :-) David N1HAC On 7/9/19 1:20 PM, Leo Bodnar wrote: It's not very good, it is highly non-linear and even wor ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Advantages of GNSS ???
HI Actually a monotonous ( = un-exciting) GPSDO is a *really* good thing :) Having one that does exciting stuff from time to time is *not* at all what you are after :) Now we get to find out what auto spell check did to all of that …... Bob > On Jul 9, 2019, at 3:57 PM, David G. McGaw > wrote: > > Leo - > > I do believe you mean non-monotonic, rather than non-monotonous. Not > being monotonous is a good thing. :-) > > David N1HAC > > On 7/9/19 1:20 PM, Leo Bodnar wrote: >> It's not very good, it is highly non-linear and even worse - nonmonotonous. >> It sometimes produces runt pulse glitches when you roll time backwards. >> I have used them in GPS clocks for many years but never enabled them for end >> user mode. >> It's really a very primitive delay line series and I don't regret seeing it >> gone. On top of this it is Maxim, doh! >> Leo >> >> Chris Caudle wrote: >>> The original is not, there is a close variant still in production: >>> >>> https://nam05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.maximintegrated.com%2Fen%2Fproducts%2Fanalog%2Fclock-generation-distribution%2FDS1124.htmldata=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7C6a86facc79d243f1cd2308d7049fba48%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636982956387678192sdata=TmHZH%2FJQpSatDlFqHcbQp%2BPHrS9CGjFHe5oPNYzHbRQ%3Dreserved=0 >>> >>> "The DS1124 is an 8-bit programmable timing element similar in function to >>> the DS1021-25. The 256-delay intervals are programmed by using a 3-wire >>> serial interface. With a 0.25ns step size, the DS1124 can provide a delay >>> time from 20ns up to 84ns with an integral nonlinearity of ±3ns. " >>> >>> Small package, would be a little difficult to prototype by hand, but not >>> impossible. >>> >>> -- >>> Chris Caudle >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> https://nam05.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.febo.com%2Fmailman%2Flistinfo%2Ftime-nuts_lists.febo.comdata=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7C6a86facc79d243f1cd2308d7049fba48%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636982956387678192sdata=NQVVBCHNCkD3Ze5J7z6OXfR70zcz0nx3wj1XseqA7Jo%3Dreserved=0 >> and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Advantages of GNSS ???
Leo - I do believe you mean non-monotonic, rather than non-monotonous. Not being monotonous is a good thing. :-) David N1HAC On 7/9/19 1:20 PM, Leo Bodnar wrote: > It's not very good, it is highly non-linear and even worse - nonmonotonous. > It sometimes produces runt pulse glitches when you roll time backwards. > I have used them in GPS clocks for many years but never enabled them for end > user mode. > It's really a very primitive delay line series and I don't regret seeing it > gone. On top of this it is Maxim, doh! > Leo > > Chris Caudle wrote: >> The original is not, there is a close variant still in production: >> >> https://nam05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.maximintegrated.com%2Fen%2Fproducts%2Fanalog%2Fclock-generation-distribution%2FDS1124.htmldata=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7C6a86facc79d243f1cd2308d7049fba48%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636982956387678192sdata=TmHZH%2FJQpSatDlFqHcbQp%2BPHrS9CGjFHe5oPNYzHbRQ%3Dreserved=0 >> >> "The DS1124 is an 8-bit programmable timing element similar in function to >> the DS1021-25. The 256-delay intervals are programmed by using a 3-wire >> serial interface. With a 0.25ns step size, the DS1124 can provide a delay >> time from 20ns up to 84ns with an integral nonlinearity of ±3ns. " >> >> Small package, would be a little difficult to prototype by hand, but not >> impossible. >> >> -- >> Chris Caudle > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > https://nam05.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.febo.com%2Fmailman%2Flistinfo%2Ftime-nuts_lists.febo.comdata=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7C6a86facc79d243f1cd2308d7049fba48%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636982956387678192sdata=NQVVBCHNCkD3Ze5J7z6OXfR70zcz0nx3wj1XseqA7Jo%3Dreserved=0 > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Advantages of GNSS ???
It's not very good, it is highly non-linear and even worse - nonmonotonous. It sometimes produces runt pulse glitches when you roll time backwards. I have used them in GPS clocks for many years but never enabled them for end user mode. It's really a very primitive delay line series and I don't regret seeing it gone. On top of this it is Maxim, doh! Leo Chris Caudle wrote: > The original is not, there is a close variant still in production: > > https://www.maximintegrated.com/en/products/analog/clock-generation-distribution/DS1124.html > > "The DS1124 is an 8-bit programmable timing element similar in function to > the DS1021-25. The 256-delay intervals are programmed by using a 3-wire > serial interface. With a 0.25ns step size, the DS1124 can provide a delay > time from 20ns up to 84ns with an integral nonlinearity of ±3ns. " > > Small package, would be a little difficult to prototype by hand, but not > impossible. > > -- > Chris Caudle ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Advantages of GNSS ???
RobertThat was my wrong take, since as long as I have messed with timing GPS receivers the difference was price and the fact that saw tooth data was present in hardware. Juerg did his first M12/Dallas/Maxim in 2004 driving a PRS 10 only replacing it when he bought a Tbolt through TARP.Working 10 years ago with Richard Mc Corkle his GPS MAX used also a PIC to read M12 data adding it up for the time constant and adding the sum to his filter calculation. He also did a PIC for me using the D/M chip.Since something happened to Richard I set out to do a board to be used for our GPSDO. Tests did not show ant improvements. Did a Furuno board without saw tooth because it is only 4 nsec. Works great. In all cases the PIC also generated the survey command in order to work without a computer. The Furuno T does on power up an automatic survey. The N version also works great and is available at Berklin for 1/3 the price of T but does not survey. Only other one also with 1 pps. Looks like Berklin has a problem selling them, that why the price drop. All other ones more expensive.Bert Kehren In a message dated 7/9/2019 11:05:39 AM Eastern Standard Time, lajeune...@mail.com writes: Bert, My take on the issue is that Mark Sims had not seen manufacturer documentation on how specifically to use the sawtooth correction value. You posted a picture of what we now know was an implementation of a use of the correction value. Did you have manufacturer documentation on how the value was to be used before you did your design? If so, that's what Mark is looking for. Like me, Dana was confused by your picture of a GPS assembly, which was not an answer to Mark. Knowing Dana personally I'm not surprised he started down the 20 question path, and I doubt he was actually offended by your post. respectfully, Robert LaJeunesse > Sent: Tuesday, July 09, 2019 at 6:26 AM > From: "ew via time-nuts" > To: time-nuts@lists.febo.com > Cc: ew > Subject: Re: [time-nuts] Advantages of GNSS ??? > > Dana > This was in response to Mark Sins " I don't think that I have ever seen what > to do with the sawtooth value > documented in any receiver documentation"I did this 4 years ago it, is a > sawtooth corrected ublox. First pass. Always do a follow on board but never > did any thing with it since there was no interest. We did it part of our > GPSDO work but saw no improvement. Sorry my work offends you.I did the same > with the Furuno GT and GN-87 without sawtooth since it is only 4 nsec. Ole > tested it and we use it with very good results. Again I followed it up with a > later design in case there is interest. I will not post the picture of the > original one so not to offend you.I will not do a board on the ublox 9 since > we are frequency not time nuts and see no need for it. > Bert Kehren > > > In a message dated 7/9/2019 12:05:14 AM Eastern Standard Time, > k8yumdoo...@gmail.com writes: > > One what? I see that it is a Ublox unit, but see no reference to the > interesting > modern units like the 9 series. Also, I note that the only reference on > the board > to "ant" is on the lower right corner, while what I suppose to be the > actual antenna > connector appears to be an SMA near the upper right corner. > > And why does it look like several of the components have been resoldered > or replaced or something? > > Dana > > > On Mon, Jul 8, 2019 at 8:00 PM ew via time-nuts > wrote: > > > Well now you can see one > > Bert Kehren > > > > > > In a message dated 7/8/2019 7:02:07 PM Eastern Standard Time, > > hol...@hotmail.com writes: > > > > A big issue with using the sawtooth correction message from a GPS > > receivers is the issue of just what that sawtooth value is related to and > > how to apply it to the measured PPS value / phase. > > I added the ability to Lady Heather to calculate a sawtooth corrected > > "paper clock" by applying the sawtooth correction message value to the PPS > > output measured by an external counter like the TAPR TICC. > > > > There are around a dozen different combinations of sawtooth value and PPS > > measurements... only one of which minimizes the PPS error. Do you add or > > subtract the sawtooth value to the PPS measurement? Do you apply the > > sawtooth value to the previous/current/next PPS measurement? Do you apply > > the sawtooth correction to the PPS itself or the accumulated phase of the > > PPS? > > I don't think that I have ever seen what to do with the sawtooth value > > documented in any receiver documentation... Heather has default receiver > > dependent correction strategies or lets you specify the correction > > strategy to use.___time-nuts > > mailing list -- time-n...@lists.febo.comTo unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.comand follow > > the instructions there. > > ___ > > time-nuts mailing list --
Re: [time-nuts] Advantages of GNSS ???
In message <8e74832c-58e6-c2ef-f68c-48e116718...@leapsecond.com>, Tom Van Baak writes: >The plot is beautiful. The reason this delay line technique isn't used >much anymore is that AFAIK the Dallas chips are no longer produced. So >almost every uses s/w sawtooth correction now. So... this is where it gets complicated isn't it ? If you saw-tooth compensate the PPS in hardware, and then use it to latch some digital counter, you may actually have made your performance worse, because you lost the "dithering" of the counter provided by the sawtooth, and all else being equal, just created a new "hanging bridge" problem. If instead you latch your counter on the uncompensated PPS and apply the saw-tooth compensation in software, you most likely dither the +/-1 count noise almost out of existence. Compensating the saw-tooth in hardware only[1] makes sense (IMO) if you feed the compensate PPS into an analog PLL and want to reduce the "hanging bridge" effect to the resolution of your delay-line. And if you implement an analog PLL in time-nuts territory where the timeconstants are measured in minutes and hours, you have far bigger challenges than the hanging bridge from the GPS... [1] Or, I guess, if you want to feed the PPS to your HP5370 without having to postprocess the TI measurements for the sawtooth. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Advantages of GNSS ???
On Tue, July 9, 2019 10:50 am, Tom Van Baak wrote: > chip. Look carefully and see the DS1023-50, which is an 8-bit > programmable delay line (~0 to ~127 ns in 0.5 ns steps). ... > The reason this delay line technique isn't used > much anymore is that AFAIK the Dallas chips are no longer produced. The original is not, there is a close variant still in production: https://www.maximintegrated.com/en/products/analog/clock-generation-distribution/DS1124.html "The DS1124 is an 8-bit programmable timing element similar in function to the DS1021-25. The 256-delay intervals are programmed by using a 3-wire serial interface. With a 0.25ns step size, the DS1124 can provide a delay time from 20ns up to 84ns with an integral nonlinearity of ±3ns. " Small package, would be a little difficult to prototype by hand, but not impossible. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Advantages of GNSS ???
Let's put the Bert vs. Dana misunderstanding aside. To me the key feature in Bert's photo is the Dallas/Maxim digital delay chip. Look carefully and see the DS1023-50, which is an 8-bit programmable delay line (~0 to ~127 ns in 0.5 ns steps). This is a technique used to remove sawtooth error without requiring a ns or sub-ns TIC and a PC. The trick: before each 1PPS the delay line is latched with the appropriately signed and scaled sawtooth correction number so that when the 1PPS arrives the leading edge is physically (electronically) delayed by exactly the right number of compensating ns. If you look inside one of Rick Hambly's GPS clocks [1] you will see this. Each second a PIC reads the binary sawtooth message from the receiver and programs the delay line just in time for the next 1PPS. The result is a sawtooth-free 1PPS without requiring a TIC or a PC. The idea has been around for 20 years, the era of the Motorola Oncore VP receiver. The performance of this "hardware" solution to sawtooth correction is simpler and nearly as good as the more complex "software" solution that's used today. For comparison plots see page 35 of: https://www.haystack.mit.edu/workshop/TOW2017/files/Seminars/tow-time2017.pdf The plot is beautiful. The reason this delay line technique isn't used much anymore is that AFAIK the Dallas chips are no longer produced. So almost every uses s/w sawtooth correction now. /tvb [1] https://www.cnssys.com/cnsclock/CNSClockII.php ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Advantages of GNSS ???
Bert, My take on the issue is that Mark Sims had not seen manufacturer documentation on how specifically to use the sawtooth correction value. You posted a picture of what we now know was an implementation of a use of the correction value. Did you have manufacturer documentation on how the value was to be used before you did your design? If so, that's what Mark is looking for. Like me, Dana was confused by your picture of a GPS assembly, which was not an answer to Mark. Knowing Dana personally I'm not surprised he started down the 20 question path, and I doubt he was actually offended by your post. respectfully, Robert LaJeunesse > Sent: Tuesday, July 09, 2019 at 6:26 AM > From: "ew via time-nuts" > To: time-nuts@lists.febo.com > Cc: ew > Subject: Re: [time-nuts] Advantages of GNSS ??? > > Dana > This was in response to Mark Sins " I don't think that I have ever seen what > to do with the sawtooth value > documented in any receiver documentation"I did this 4 years ago it, is a > sawtooth corrected ublox. First pass. Always do a follow on board but never > did any thing with it since there was no interest. We did it part of our > GPSDO work but saw no improvement. Sorry my work offends you.I did the same > with the Furuno GT and GN-87 without sawtooth since it is only 4 nsec. Ole > tested it and we use it with very good results. Again I followed it up with a > later design in case there is interest. I will not post the picture of the > original one so not to offend you.I will not do a board on the ublox 9 since > we are frequency not time nuts and see no need for it. > Bert Kehren > > > In a message dated 7/9/2019 12:05:14 AM Eastern Standard Time, > k8yumdoo...@gmail.com writes: > > One what? I see that it is a Ublox unit, but see no reference to the > interesting > modern units like the 9 series. Also, I note that the only reference on > the board > to "ant" is on the lower right corner, while what I suppose to be the > actual antenna > connector appears to be an SMA near the upper right corner. > > And why does it look like several of the components have been resoldered > or replaced or something? > > Dana > > > On Mon, Jul 8, 2019 at 8:00 PM ew via time-nuts > wrote: > > > Well now you can see one > > Bert Kehren > > > > > > In a message dated 7/8/2019 7:02:07 PM Eastern Standard Time, > > hol...@hotmail.com writes: > > > > A big issue with using the sawtooth correction message from a GPS > > receivers is the issue of just what that sawtooth value is related to and > > how to apply it to the measured PPS value / phase. > > I added the ability to Lady Heather to calculate a sawtooth corrected > > "paper clock" by applying the sawtooth correction message value to the PPS > > output measured by an external counter like the TAPR TICC. > > > > There are around a dozen different combinations of sawtooth value and PPS > > measurements... only one of which minimizes the PPS error. Do you add or > > subtract the sawtooth value to the PPS measurement? Do you apply the > > sawtooth value to the previous/current/next PPS measurement? Do you apply > > the sawtooth correction to the PPS itself or the accumulated phase of the > > PPS? > > I don't think that I have ever seen what to do with the sawtooth value > > documented in any receiver documentation... Heather has default receiver > > dependent correction strategies or lets you specify the correction > > strategy to use.___time-nuts > > mailing list -- time-n...@lists.febo.comTo unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.comand follow > > the instructions there. > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] It is possible to "recharge" a hydrogen maser?
Luiz, Ch1-75 Hydrogen storage details. The compound LaNi5H, is used for storing molecular hydrogen. The LaHi5H, is characterized by high hydrogen partial pressure (2 to 5 atmospheres) at +(20-50) degrees C. 250 grams of the compound contains 18 liters of hydrogen at normal pressure. It is sufficient for maser continuous operation for more than 40 000 hours. I believe that the container holding the LaHi5H is heated and thermostatically controlled to maintain the proper pressure into the purifier. First you should be able to power up the maser just far enough so that the ion pumps can operate. Monitor their current and it should drop down to almost zero within a few hours. If not you may need to get the ion pumps rebuilt. There are commercial outfits that can rebuild them but if there are not isolation valves to close and isolate the Maser when you remove the ion pumps you will not be able to proceed! Since the Russian Masers also use a getter pump in concert with the ion pumps, opening up the vacuum system will contaminate the getter pump. The process of clearing the getter is very detailed and involves temperatures of up to 800 degrees C, and without careful instructions on how to do it you risk damaging other portions of the Maser! If the pressure does drop down, then you need to determine if there is any Hydrogen left. I know that some Russian Masers will give you an alarm that tells you if you are out, and some have a mechanical pressure gage, but Im not sure about the CH1-75. You will need to check the manuals. If it does not provide an alarm or have a gage then see if the HFO oscillator is working and if the discharge bulb is lighting up. If it lights up you are not out of Hydrogen! If it does not light and you have determined that the lack of Hydrogen is indeed the problem you will need to locate the LaHi5H container. After you locate it make sure it is being heated, this could cause an apparent lack of Hydrogen! Then see how it is connected to the discharge bulb. Hopefully it will be a threaded connection. This connection is on the high pressure side of the purifier and can be removed without compromising the vacuum. You will need to remove the container and recharge it. I would instead replace it with a small compressed hydrogen cylinder and regulators. Use ultra-high purity dry Hydrogen and make sure you purge the line going to the purifier. The purifier will block other gases from getting into the Maser but in the process too much foreign gas can contaminate and damage the purifier! Once you manage to locate the container some pictures on where its hiding would be nice! Good luck with your efforts! Cheers, Corby Dawson ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] verifying synchronization with PPS
I wrote: > I'm guessing there are some time nuts here who might be able > to give me some pointers. And there were! Thanks for the suggestions & comments. Dana Whitlow wrote: > in the absence of a PPS or other electrical output from your > "computer", what is the nature of the time "output"? It's collecting data and coordinating activities among several other systems, each with their own clocks, some connected by serial ports and some by ethernet, some on NTP and some not, some with PPS feeds and some not, but obviously the goal is, by hook or by crook, to keep all the clocks well synchronized so that timestamped data is commensurate -- and then to positively *demonstrate* that they're well synchronized. > why not view the light output of the seconds digit with a photocell. Because I had never thought of such a thing. I could pretty easily implement, in a diagnostic window somewhere, a nice fat 1 Hz spot that would be trivial for even a crude photocell to "see". There'd be some latency, but it'd be much better than nothing. Thanks very much for the suggestion! Graham wrote: > What level of accuracy do you mean by "synchronized"? I think we'd be happy with 1 ms. > Plotting a lightly loaded Linux box, which is extracting time from > the network via timesyncd, against a GPS 1PPS signal, I observe... So it sounds like you're already doing more or less what I want to do! I'd be curious to hear more about the setup you use to make those plots. > The owner of this list has designed an excellent dual input timing > device called the TICC, which can compare two PPS signals... Ha! Thought so. Thanks for the pointer. David Taylor wrote: > Folkert van Heusden has a driver for NTP which includes PPS output: > https://vanheusden.com/time/rpi_gpio_ntp/ Great! I will read that. Hal Murray wrote: > There is code in the Linux kernel to generate a PPS output. Huh! I should have noticed that. (I'd been thinking of adding it, if I had to.) > I think it uses the printer port... But it shouldn't be too hard to modify it to use a GPIO pin. > If I wanted to try something, I would write a user-level hack > to flap a modem line and compare that to a PPS signal. That would probably be fine for my current purposes. The latent time-nut in me worries about scheduling and latency and jitter, of course, tempting me to chase an overkill solution which is not only in the kernel, but implemented in a brute-force, special- cased way, eschewing the extra function calls and indirections (and hence latency) which a properly general-purpose solution might involve. Thanks again for all the replies; this has been very helpful. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] A Research Proposal
On 7/8/19 8:33 PM, Hal Murray wrote: jim...@earthlink.net said: Free space propgation delay for 5500 m is 18.5 milliseconds - compared to 16.67 millisecond period of 60Hz. A velocity factor of about 90% Neat. Thanks. What's going on? I'm used to calculating the velocity from the dielectric constant. Power lines have no obvious non-air dielectric. Is the dielectric-constant only calculation ignoring some things that are significant in a power line? If so, what? Dielectric affects the C per unit length, which affects the propagation constant. The telegrapher's equation (now the "transmission line equation") was developed back in the days of open wire lines with essentially no dielectric. It gets really interesting when looking at three phase power lines, because you have to calculate not only the C relative to ground, but the C between the wires. And the L for the wire by itself, and the mutual L between wires. Fortunately, it is a linear system and superposition holds (until there's a fault) This is the big challenge with stabilizing large grids - you have these long transmission lines with "springy" generators and loads. Transients can take a long time to die out, as they bounce back and forth along a 1000km long line, with lots of impedance discontinuities. So you wind up with synchronous condensers and switched reactive components along the line. The real value of DC links is that they're MUCH easier to stabilize. Measuring the phase along such a line could be really interesting, especially if you had a source of switching events information. The power companies have all this, and direct connections to do the measurements. The intriguing thing is to do it "non-contact" and see what you can figure out. I suspect, also, that the local power distribution company probably doesn't care much about it - to them, it's all loads, and what they watch is overall power factor - in a residential area, I'd bet the PF is very close to 1 (resistive loads). In industrial areas, there are lots of motors and magnetic ballasts for lighting, so you get a lagging PF, but I'll bet with all the variable speed drives and electronic ballasts, not to say LED lighting, things are changing. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Advantages of GNSS ???
Dana This was in response to Mark Sins " I don't think that I have ever seen what to do with the sawtooth value documented in any receiver documentation"I did this 4 years ago it, is a sawtooth corrected ublox. First pass. Always do a follow on board but never did any thing with it since there was no interest. We did it part of our GPSDO work but saw no improvement. Sorry my work offends you.I did the same with the Furuno GT and GN-87 without sawtooth since it is only 4 nsec. Ole tested it and we use it with very good results. Again I followed it up with a later design in case there is interest. I will not post the picture of the original one so not to offend you.I will not do a board on the ublox 9 since we are frequency not time nuts and see no need for it. Bert Kehren In a message dated 7/9/2019 12:05:14 AM Eastern Standard Time, k8yumdoo...@gmail.com writes: One what? I see that it is a Ublox unit, but see no reference to the interesting modern units like the 9 series. Also, I note that the only reference on the board to "ant" is on the lower right corner, while what I suppose to be the actual antenna connector appears to be an SMA near the upper right corner. And why does it look like several of the components have been resoldered or replaced or something? Dana On Mon, Jul 8, 2019 at 8:00 PM ew via time-nuts wrote: > Well now you can see one > Bert Kehren > > > In a message dated 7/8/2019 7:02:07 PM Eastern Standard Time, > hol...@hotmail.com writes: > > A big issue with using the sawtooth correction message from a GPS > receivers is the issue of just what that sawtooth value is related to and > how to apply it to the measured PPS value / phase. > I added the ability to Lady Heather to calculate a sawtooth corrected > "paper clock" by applying the sawtooth correction message value to the PPS > output measured by an external counter like the TAPR TICC. > > There are around a dozen different combinations of sawtooth value and PPS > measurements... only one of which minimizes the PPS error. Do you add or > subtract the sawtooth value to the PPS measurement? Do you apply the > sawtooth value to the previous/current/next PPS measurement? Do you apply > the sawtooth correction to the PPS itself or the accumulated phase of the > PPS? > I don't think that I have ever seen what to do with the sawtooth value > documented in any receiver documentation... Heather has default receiver > dependent correction strategies or lets you specify the correction > strategy to use.___time-nuts > mailing list -- time-n...@lists.febo.comTo unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.comand follow > the instructions there. > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] LT3042, etc. Re: HP E1938A schematics.
In message <20190709053037.2d244406...@ip-64-139-1-69.sjc.megapath.net>, Hal Mu rray writes: >What's the advantage of a PSRR in the MHz range? Is it as simple as reducing >the number and size of the caps needed? The caps have only ever acted as a low-pass filter, to move the noise down in the frequency range of the power-supply regulation. The digital switching noise happens in (pico- and nano-)Coloumbs, not in volts or amps, which means that as the supply voltage decreases, it becomes percentwise larger voltage noise. To deal with that passively you would need bigger caps with better high frequency performance, and lower ESR and more, expensive PCBs (more layers etc.) The trend is therefore to move the corner frequency of the passive low-pass filter higher, that allows you to use ceramic capacitors, instead you must increase the bandwidth of the final power-supply, typically a LDO, and move it physically closer to the load. On high-end kit, it is not uncommon to see a big chip surrounded by a ring of tiny LDO's spaced as little as a centimeter apart along its periphery. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] A Research Proposal
Um, you're quite right that DC lines have no phase angle - unless you call a polarity reversal a 180 degree shift. I was referring to the phase angle of the AC side of an inverter with respect to the average phase angle of the grid that it is connected to. It behaves just like a synchronous machine. Advance the phase angle of the inverter and it pumps energy into the grid. The inverter at the other end of the DC line must be lagging in order to take power from that grid. Conservation of energy says you must take more power than you deliver in order to cover the resistive and corona losses in the DC line and the conversion losses in the inverters. Perhaps the source inverter phase angle is controlled by the DC output voltage, and the load phase angle is controlled by the DC current. Controlling the load inverter phase angle would be like adjusting the steam to a turbine coupled to a generator. I have no knowledge of how control is actually accomplished. Bill Hawkins On Mon, Jul 8, 2019, at 6:12 AM, Hal Murray wrote: > > bill.i...@pobox.com said: > > Since the direction of power flow depends on the phase angle between the > > synchronous source and load, it seems to me that the difference between the > > average phase angle in one region and that in another (at the ends of a DC > > transmission line) will tell you which way power is flowing. > > Nope. The phase angle difference tells you a lot on an AC line, but nothing > on a DC line. For DC, the frequencies can even be different. That means the > phase angle is changing, and it can wrap around while the phase angle on an > AC > system is always small. > > A classic 3 phase synchronous motor is also a generator if you are pushing it > rather than it is pushing you. The sign of the phase angle flips between > motor and generator. In this context, the phase angle is the angle the > magnetic lines make between the rotor and stator. > > > -- > These are my opinions. I hate spam. > > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] LT3042, etc. Re: HP E1938A schematics.
>> Not only are they low noise, but they have spectacularly good HF >> rejection across the regulator up to 10s of MHz. > In the 5071A, I wanted high bandwidth PSRR and stumbled across a designer's > manual (HP internal document) for the MMS Modular Measurement System. They > described a regulator with a common base pass transistor and an op amp, with > a bandwidth approaching 1 MHz. I'm used to thinking that the bypass caps on the board will take care of high frequencies. What's the advantage of a PSRR in the MHz range? Is it as simple as reducing the number and size of the caps needed? In this area, is there a significant difference between analog and digital sections? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
