Re: [time-nuts] Another atomic clock question
Junk crystals are good thermometers. Ballpark is 1 ppm/degree-C albertson.ch...@gmail.com said: So does this mean I can epoxy a sandstone power resister to a junk crystal and keep the frequency exactly perfect by varying the power in the resister? Sure, for some values of perfect and such. I've occasionally thought about building something like this, just for the hell of it to see what happens and/or what I learn, and or how good I/we can get on a low budget. I think there are two problem areas. One is sensors and control algorithms. The other is board layout. Where is the sweet spot on complexity vs accuracy? I'm looking for science-fair level of goodness rather than super-expensive to get another 0 or two. What's the best low-cost way to measure temperature? Many of the obvious choices are only good to 0.1 C. That's great if you are trying to measure room temperature or or want to keep your CPU from melting, but it's probably leaving a lot on the table if you are interested in the frequency from a crystal. My straw man would be a thermistor and OP-Amp feeding into the ADC on your favorite uProc. Maybe the other side of a bridge would be adjustable. How much power do you need to keep things warm? I'm assuming something like a watt or 2 with something like a PWM from the uProc. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Another atomic clock question
Hi The simple approach is to use an op amp, a thermistor, and a couple of resistors. No need for anything digital. You can easily get all the gain possible (before oscillation) out of a very simple circuit. The net result will be about a 1C stability when you run it over temperature (say 0 to 50 C) in a lab chamber. You can tweak it a bit to get the thermal gain up to a few hundred if you have a chamber to give you feedback on your changes. Bob On Mar 3, 2014, at 5:18 AM, Hal Murray hmur...@megapathdsl.net wrote: Junk crystals are good thermometers. Ballpark is 1 ppm/degree-C albertson.ch...@gmail.com said: So does this mean I can epoxy a sandstone power resister to a junk crystal and keep the frequency exactly perfect by varying the power in the resister? Sure, for some values of perfect and such. I've occasionally thought about building something like this, just for the hell of it to see what happens and/or what I learn, and or how good I/we can get on a low budget. I think there are two problem areas. One is sensors and control algorithms. The other is board layout. Where is the sweet spot on complexity vs accuracy? I'm looking for science-fair level of goodness rather than super-expensive to get another 0 or two. What's the best low-cost way to measure temperature? Many of the obvious choices are only good to 0.1 C. That's great if you are trying to measure room temperature or or want to keep your CPU from melting, but it's probably leaving a lot on the table if you are interested in the frequency from a crystal. My straw man would be a thermistor and OP-Amp feeding into the ADC on your favorite uProc. Maybe the other side of a bridge would be adjustable. How much power do you need to keep things warm? I'm assuming something like a watt or 2 with something like a PWM from the uProc. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why using HP5370 ext-ref is (maybe) a bad idea
Hi *IF* I understand the plot (and that’s a big if, it’s early and I’ve had limited coffee): The period is shifting with phase. We trust the 3336 to be on frequency. The likely answer is that the trigger point must be changing. The question is whether it’s changing because the 3336 is doing something (small waveform changes) or because the 5370 is doing something. I would make up / dig up a coax cable that is 8 degrees at 10 MHz. Something around 1/2 meter long should do the job. If you see the same period shift when you use it, the problem is more likely in the 5370 than in the 3336. Next step would be some sort of filtering between the 3336 and the 5370. That would help rule out harmonics and spurs from the generator as the source of the problem. I’d try a lowpass filter first since I have them in my junk box. My junk box and yours may not be stocked with the same stuff :) My only concern is that we spend time chasing 5370 issues and not subtle gotcha’s with the signal source. I’m looking for some quick / easy / cheap ways to narrow things down. If you have a toggle switch based line stretcher, by all means use it instead of making up a cable. Bob On Mar 3, 2014, at 2:26 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message e7a494f6-78f1-4568-8bd3-d94a32deb...@rtty.us, Bob Camp writes: Do you have any idea how 'clean' your 200 MHz signal is? The manual suggests getting it to -65 dbc for subs using a spectrum analyzer. That's pretty far down. I seem to recall the adjustment process being a bit tedious (lots of back and forth). My estimate is that all harmonics are at least -50 and most probably -60 down. The 10MHz is probably the worst. My Lab is not really set up for RF work, so this is probably an area where one of the hams could do lot more competent job than me. I've attached a plot of one of the runs yesterday, beause things are more complicated than I initially thought. The vertical bars are AVG +/- STDDEV of 1000 sample TI on a 10MHz from my HP3336 in start-com mode. The X-axis is the phase offset set on the HP3336 in degrees, and represents the phase difference between the ext-ref and start+stop signals on the HP5370 plus some arbitrary offset due to cables etc. Obviously, the phase difference has no systematic meaning for the red bars, since it is free running on the OCXO at some frequency offset from the input signal. Yet, it is quite evident that there still is a periodicity in the data, which peaks around 0, 5, 10 and 15 degrees. The green bars however... The initial artifact I noticed when I just plotted the STDDEV is still there, around 9 degrees where both the average and the stddev take a hop. But that blib is peanuts relative to the 3-degree periodicity for which I have absolutely no explanation, and the equally evident 18-degree periodicity. The 3-degree periodicity cannot be a simple harmonic, it it were it would be a 1.2 GHz signal. (360/3 * 10 MHz = 1200 MHz) But what then ? As in a canonical scientific paper, I have to conclude that more research is clearly needed, and I'd really love to see what results other people might get. In the meantime, run you 5370 on internal clock, and rely on the law of big numbers. Poul-Henning -- 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. intext.png ___ 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] Why using HP5370 ext-ref is (maybe) a bad idea
In message c542adee-19dd-4dab-a1bf-fb842c077...@rtty.us, Bob Camp writes: The likely answer is that the trigger point must be changing. Yes that would be my first theory as well. The question is whether it's changing because the 3336 is doing something (small waveform changes) or because the 5370 is doing something. Yes, and obviously there are many experiments that can be performed to flesh out the details of that: Changing the 3336 output amplitude. Exchanging the signals, so the 3336 feeds ext-ref, and lab-standard feeds start+stop. Using a different lab-standard. Measuring opposite polarity etc. I would make up / dig up a coax cable that is 8 degrees at 10 MHz. Something around 1/2 meter long should do the job. As I said, I'm not really kitted out for RF work, so my selection of coax isn't that versatile and I don't have the crimp-tools or routine to make my own. Next step would be some sort of filtering between the 3336 and the 5370. That would help rule out harmonics and spurs from the generator as the source of the problem. The 3336 delivers pretty clean output, so I expect a couple of sanity checks will exonerate it. Unfortunately my HP33120 does not have an external clock input, so I can't use that for the experiment. Anybody with a HP3325 or later HP33* with an external clock input can participate in this game... But to be honest, I'm not sure how much more work is really warranted for me, given that I don't think I can tune the 200MHz multipliers filters much better than they presently are. The really interesting experiments, in my mind, would be to ditch the 200MHz multiplier and feed 200MHz from a good generator with high purity instead. But then again: It is so much easier to just run the HP5370 on the internal clock and that solve^H^H^H^H^Hhides all the problems. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why using HP5370 ext-ref is (maybe) a bad idea
What about replacing the 3336 external reference with something like an HP 10811 and checking what difference, if any, that makes? Regards Nigel GM8PZR In a message dated 03/03/2014 13:42:33 GMT Standard Time, p...@phk.freebsd.dk writes: In message c542adee-19dd-4dab-a1bf-fb842c077...@rtty.us, Bob Camp writes: The likely answer is that the trigger point must be changing. Yes that would be my first theory as well. The question is whether it's changing because the 3336 is doing something (small waveform changes) or because the 5370 is doing something. Yes, and obviously there are many experiments that can be performed to flesh out the details of that: Changing the 3336 output amplitude. Exchanging the signals, so the 3336 feeds ext-ref, and lab-standard feeds start+stop. Using a different lab-standard. Measuring opposite polarity etc. I would make up / dig up a coax cable that is 8 degrees at 10 MHz. Something around 1/2 meter long should do the job. As I said, I'm not really kitted out for RF work, so my selection of coax isn't that versatile and I don't have the crimp-tools or routine to make my own. Next step would be some sort of filtering between the 3336 and the 5370. That would help rule out harmonics and spurs from the generator as the source of the problem. The 3336 delivers pretty clean output, so I expect a couple of sanity checks will exonerate it. Unfortunately my HP33120 does not have an external clock input, so I can't use that for the experiment. Anybody with a HP3325 or later HP33* with an external clock input can participate in this game... But to be honest, I'm not sure how much more work is really warranted for me, given that I don't think I can tune the 200MHz multipliers filters much better than they presently are. The really interesting experiments, in my mind, would be to ditch the 200MHz multiplier and feed 200MHz from a good generator with high purity instead. But then again: It is so much easier to just run the HP5370 on the internal clock and that solve^H^H^H^H^Hhides all the problems. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] Why using HP5370 ext-ref is (maybe) a bad idea
In message 834d5.64e2b237.4045e...@aol.com, gandal...@aol.com writes: What about replacing the 3336 external reference with something like an HP 10811 and checking what difference, if any, that makes? The internal reference is an 10811 already ? The point is not what delivers the reference, but if it is synchronized to the input signals being measured. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Another atomic clock question
On 3/3/14 2:18 AM, Hal Murray wrote: Junk crystals are good thermometers. Ballpark is 1 ppm/degree-C albertson.ch...@gmail.com said: So does this mean I can epoxy a sandstone power resister to a junk crystal and keep the frequency exactly perfect by varying the power in the resister? Sure, for some values of perfect and such. I've occasionally thought about building something like this, just for the hell of it to see what happens and/or what I learn, and or how good I/we can get on a low budget. I think there are two problem areas. One is sensors and control algorithms. The other is board layout. Where is the sweet spot on complexity vs accuracy? I'm looking for science-fair level of goodness rather than super-expensive to get another 0 or two. What's the best low-cost way to measure temperature? Many of the obvious choices are only good to 0.1 C. That's great if you are trying to measure room temperature or or want to keep your CPU from melting, but it's probably leaving a lot on the table if you are interested in the frequency from a crystal. My straw man would be a thermistor and OP-Amp feeding into the ADC on your favorite uProc. Maybe the other side of a bridge would be adjustable. A number of microcontrollers have onchip temperature sensors (Freescale Kinetis, for instance). If the controller were bonded to the crystal housing, that might be enough coupling. Could you hold 0.1 or 0.001 degree? the chip has a 16 bid ADC, although I wouldn't trust the bottom bit or two because of noise. But in any case 1 LSB is 3.3/64k or about 50 microvolts. The temperature sensor slope is 1.715 mV/C, so that's in the 0.03 C/LSB range.. On a good day, you *might* be able to hold 0.1 degree, assuming there's no systematic errors. How much power do you need to keep things warm? I'm assuming something like a watt or 2 with something like a PWM from the uProc. ___ 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] Why using HP5370 ext-ref is (maybe) a bad idea
Sorry, I must have missunderstood. I realise the internal reference is already a 10811, but I thought there was some concern that just the use of the external reference facility might be in some way responsible, so if that was the case then perhaps using an external 10811 might also be expected to cause the same problem?. If it did then that would potentially rules out any issues with the 3336. Regards Nigel GM8PZR In a message dated 03/03/2014 14:12:38 GMT Standard Time, p...@phk.freebsd.dk writes: In message 834d5.64e2b237.4045e...@aol.com, gandal...@aol.com writes: What about replacing the 3336 external reference with something like an HP 10811 and checking what difference, if any, that makes? The internal reference is an 10811 already ? The point is not what delivers the reference, but if it is synchronized to the input signals being measured. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why using HP5370 ext-ref is (maybe) a bad idea
In message 107931.7dbf8887.4045e...@aol.com, gandal...@aol.com writes: I realise the internal reference is already a 10811, but I thought there was some concern that just the use of the external reference facility might be in some way responsible, [...] No, I see no signs of that anywhere in my experiments. The issue is if the HP5370 internal signals are synchronized to the signals you're trying to measure, then you're in trouble. I saw the same kind of phenomena running the HP5370 on its internal OCXO and feeding the HP3336 ref-in from HP5370-ref-out. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why using HP5370 ext-ref is (maybe) a bad idea
Uncorrelated noise improves resolution in certain systems, even mechanical ones... it´s called dither: http://en.wikipedia.org/wiki/Dither Daniel Em 03/03/2014 11:35, Poul-Henning Kamp escreveu: In message 107931.7dbf8887.4045e...@aol.com, gandal...@aol.com writes: I realise the internal reference is already a 10811, but I thought there was some concern that just the use of the external reference facility might be in some way responsible, [...] No, I see no signs of that anywhere in my experiments. The issue is if the HP5370 internal signals are synchronized to the signals you're trying to measure, then you're in trouble. I saw the same kind of phenomena running the HP5370 on its internal OCXO and feeding the HP3336 ref-in from HP5370-ref-out. ___ 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] Wildwood Loran
Wildwood is up as of 1300 Z March 3, 2014. We are in the middle of a lot of snow! Estimated to receive a foot or so. Yippie... 73, Bill, WA2DVU Cape May ___ 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] GPSDO module connections
Hello, I am looking for the advise: what will be the better method to connect GPSDO module by short extension cable to put its antenna input on front or back panel ? Lets say, GPSDO module has female “F” connector. And I would like to have BNC connector on back panel of my project. Manufacturer of GPSDO recommend to use RG-59 cable for antenna connection. Is it OK if I'll take some RG-59 from CCTV, cut 6 or 12 of it, connect one end to GPSDO (let say this cable has compression type connector) and solder other end to BNC on the panel ? Or its better to use adapters and no soldering ? Like F connector-to-BNC adapter , then short BNC-to-BNC cable connected to BNC panel connector ? And other question: is it worth to use RF cable to connect 1PPS output from GPSDO to distribution amplifier ? Or regular AWG-22 could do that job ? Thanks ! -- WBW, V.P. ___ 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] GPSDO module connections
RG-59 cable is fine but soldering wires is not a good idea for 1.6GHz. Use a panel-mount BNC crimp connector made for RG-59 such as the Amphenol 31-343-RFX. I presume you want to use regular 50 ohm BNC types rather than the 75 ohm variant. It is preferred to use coax for the 1 PPS as any reflections will degrade its risetime. Good luck, David On 3/3/14 1:01 PM, d0ct0r wrote: Hello, I am looking for the advise: what will be the better method to connect GPSDO module by short extension cable to put its antenna input on front or back panel ? Lets say, GPSDO module has female “F” connector. And I would like to have BNC connector on back panel of my project. Manufacturer of GPSDO recommend to use RG-59 cable for antenna connection. Is it OK if I'll take some RG-59 from CCTV, cut 6 or 12 of it, connect one end to GPSDO (let say this cable has compression type connector) and solder other end to BNC on the panel ? Or its better to use adapters and no soldering ? Like F connector-to-BNC adapter , then short BNC-to-BNC cable connected to BNC panel connector ? And other question: is it worth to use RF cable to connect 1PPS output from GPSDO to distribution amplifier ? Or regular AWG-22 could do that job ? Thanks ! ___ 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] GPSDO module connections
Is it OK if I'll take some RG-59 from CCTV, cut 6 or 12 of it, connect one end to GPSDO (let say this cable has compression type connector) and solder other end to BNC on the panel ? Or its better to use adapters and no soldering ? Like F connector-to-BNC adapter , then short BNC-to-BNC cable connected to BNC panel connector ? The fewer adapters the better, and it is best to avoid solder-type panel connectors entirely (if what you mean is a non-coaxial connection with the center conductor soldered to the center pin and the shield separated and attached to the panel or the connector body). Best to keep it coaxial all the way. So, the best solution would be a piece of RG-59 with a male F connector on one end and a female, rear-mounting, panel mount BNC on the other end. If you do not have the facilities to make up your own coaxial cables with crimp or compression terminations, there are a number of ebay vendors who will do it for very reasonable cost (or you may well find the pigtail cable you need already made). Alternatively, you could use a cable with a male F connector at one end and a male BNC at the other end, connecting to a female-to-female bulkhead connector at the panel. But that is one more connection, which is better avoided. One further consideration is whether the shield of the panel-mount connector should be galvanically connected to the panel, or insulated from it. If you have problems with ground loops, insulating it may help. If you do insulate it, the shield should be bypassed to the panel right at the connector with (for example) a 0.01uF capacitor paralleled by, say, a 1k ohm resistor. is it worth to use RF cable to connect 1PPS output from GPSDO to distribution amplifier ? Or regular AWG-22 could do that job ? The PPS signal has a tendency to leak everywhere because it is a short pulse with fast edges. If you bring it out of the box you definitely need to use coax. Good, quad-shielded coax. Really, you should use triaxial cable, but that is enough hassle that few people do it. If you don't have a pressing use for the PPS signal, it is best to leave it inside the box. You can mitigate the leakage by slowing down the edges, but that may compromise the utility of the pps by increasing jitter in the trigger circuitry of whatever you feed with it. If you bring the PPS out of the box, you will need to make sure it is properly terminated to preserve the pulse shape. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why using HP5370 ext-ref is (maybe) a bad idea
Hi Poul-Henning, On 02/03/14 23:29, Poul-Henning Kamp wrote: I have spent another evening playing around with the 5370 and the conclusion is pretty ironclad now: Running a 5370 with ext-ref locked to input frequencies is simply a bad idea and should not be done. Running it on the internal OCXO works fine. Running it on another frequency *not* locked to the input frequenc also works fine. In both cases the errors are statistically well-behaved, and can be treated with normal statistical methods, including the built-in STD-DEV function. But feeding ext-ref a frequency which is locked to the input frequencies causes the errors to become systematic, and they can no longer be treated as statistically well-behaved. This comes as no surprise to me. I've expected this to be true for essentially all counters for ages. The relative timing of reference and trigger inputs interact with each others. Running one of the input synchronous to the reference may not only create a maximum but also a minimum in noise. When inputs is asynchronous it is the average of this systematic pattern which is experienced. For instance: The length of the coax to ext-ref suddenly affect your TI measurements, because it shifts the phase between the 200MHz and the input signal. I tried tuning up the A21 200MHz synthesizer to the best of my ability, and it clearly made a difference, the phase pattern of errors shifted around, but the errors did not get any smaller, they just moved. Which then gives support to your theory that it is the 200 MHz itself rather than systematics of the synthesizer as I was theorizing about. Thus, as you tune the synthesizer you only phase-shift around the transitions. OK. Fair enough, that is expected to happen too. The synthesizer probably needs to be very badly trimmed to cause systematics as I theorized. I also tried disconnecting the 10 MHz present circuit, that didn't change the magnitude of the errors either, but did shift the phase of the peak noise a couple of degrees. I used it to clean of the 5 MHz overtones and systematics. Looking at some old notes from years past which just didn't make sense, does now. Good that things becomes clearer. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why using HP5370 ext-ref is (maybe) a bad idea
On 03/03/14 14:14, Bob Camp wrote: Hi *IF* I understand the plot (and that’s a big if, it’s early and I’ve had limited coffee): The period is shifting with phase. We trust the 3336 to be on frequency. The likely answer is that the trigger point must be changing. The question is whether it’s changing because the 3336 is doing something (small waveform changes) or because the 5370 is doing something. I would make up / dig up a coax cable that is 8 degrees at 10 MHz. Something around 1/2 meter long should do the job. If you see the same period shift when you use it, the problem is more likely in the 5370 than in the 3336. Next step would be some sort of filtering between the 3336 and the 5370. That would help rule out harmonics and spurs from the generator as the source of the problem. I’d try a lowpass filter first since I have them in my junk box. My junk box and yours may not be stocked with the same stuff :) My only concern is that we spend time chasing 5370 issues and not subtle gotcha’s with the signal source. I’m looking for some quick / easy / cheap ways to narrow things down. If you have a toggle switch based line stretcher, by all means use it instead of making up a cable. Well, considering that you make 6 cycles in 18 degrees of the 10 MHz, this means that you have 6*20=120 cycles over 10 MHz or 1,2 GHz. Another approach would be to consider it as the 6th overtone of the 200 MHz signal. Poul-Henning, you sure have given us something to think about! :) YES! :) I think I will have to figure out how to duplicate your measurement. Realize that I need to work on getting some GPIB programming done so I can get some scripts going. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO module connections
It might also be worth noting that whilst manufacturers such as Trimble do recommend the use of RG59 or similar 75 ohm cable for GPS module antenna connections this is based on its lower loss compared with 50 ohm equivalents such as RG58. The connector itself on the GPS module, in most cases if not all, will still be a 50 ohm connector but it's considered that the lower cable attenuation will more than compensate for any mismatch effects. In overall cable loss terms it isn't going to make any difference whether 75 ohm RG59 pigtails are used for the internal connections or whether 50 ohm RG58 is used instead, it will just shift the position of the mismatch we're planning to ignore anyway:-) However, RG58 does tend to be better quality, particularly when it comes to the braided screen, some RG59 has a very open weave indeed, and this does generally make the RG58 easier to work with and might also ensure a more reliable connection. If it were me I would maintain the 50 ohms impedance within the unit and then switch to 75 ohms externally, assuming of course that's what I chose to do rather than stay with 50 ohms right through. Regards Nigel GM8PZR In a message dated 03/03/2014 19:42:38 GMT Standard Time, n1...@dartmouth.edu writes: RG-59 cable is fine but soldering wires is not a good idea for 1.6GHz. Use a panel-mount BNC crimp connector made for RG-59 such as the Amphenol 31-343-RFX. I presume you want to use regular 50 ohm BNC types rather than the 75 ohm variant. It is preferred to use coax for the 1 PPS as any reflections will degrade its risetime. Good luck, David On 3/3/14 1:01 PM, d0ct0r wrote: Hello, I am looking for the advise: what will be the better method to connect GPSDO module by short extension cable to put its antenna input on front or back panel ? Lets say, GPSDO module has female “F” connector. And I would like to have BNC connector on back panel of my project. Manufacturer of GPSDO recommend to use RG-59 cable for antenna connection. Is it OK if I'll take some RG-59 from CCTV, cut 6 or 12 of it, connect one end to GPSDO (let say this cable has compression type connector) and solder other end to BNC on the panel ? Or its better to use adapters and no soldering ? Like F connector-to-BNC adapter , then short BNC-to-BNC cable connected to BNC panel connector ? And other question: is it worth to use RF cable to connect 1PPS output from GPSDO to distribution amplifier ? Or regular AWG-22 could do that job ? Thanks ! ___ 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] Why using HP5370 ext-ref is (maybe) a bad idea
Hi Poul-Henning, On 03/03/14 14:41, Poul-Henning Kamp wrote: In message c542adee-19dd-4dab-a1bf-fb842c077...@rtty.us, Bob Camp writes: The likely answer is that the trigger point must be changing. Yes that would be my first theory as well. Cross-talk and ground-bounce through common inductor is known to cause this issue. Seems to recall that Bruce mentioned such a note on the 5370, which I think I have lying around here somewhere. I know that one vendor found out that putting input channel comparators in separate ICs reduced ground-bounce through power-leads between signals. A big issue as you try to get further down the precision scale. The question is whether it's changing because the 3336 is doing something (small waveform changes) or because the 5370 is doing something. Yes, and obviously there are many experiments that can be performed to flesh out the details of that: Changing the 3336 output amplitude. Exchanging the signals, so the 3336 feeds ext-ref, and lab-standard feeds start+stop. Using a different lab-standard. Measuring opposite polarity etc. All good ideas. I have some more below. I would make up / dig up a coax cable that is 8 degrees at 10 MHz. Something around 1/2 meter long should do the job. As I said, I'm not really kitted out for RF work, so my selection of coax isn't that versatile and I don't have the crimp-tools or routine to make my own. Next step would be some sort of filtering between the 3336 and the 5370. That would help rule out harmonics and spurs from the generator as the source of the problem. The 3336 delivers pretty clean output, so I expect a couple of sanity checks will exonerate it. Unfortunately my HP33120 does not have an external clock input, so I can't use that for the experiment. Anybody with a HP3325 or later HP33* with an external clock input can participate in this game... Got a HP3325B, HP5370B/C/D but also 5359A and SR535. Another approach is to set a rubidium for a *slow* scan over phase-relationships. But to be honest, I'm not sure how much more work is really warranted for me, given that I don't think I can tune the 200MHz multipliers filters much better than they presently are. If that is where the issue is. The really interesting experiments, in my mind, would be to ditch the 200MHz multiplier and feed 200MHz from a good generator with high purity instead. Those with a high quality RF generator could force-feed a 200 MHz into the counter and see if it makes any major difference. BTW, have someone looked at how the 200 MHz is then used? Sure that no interesting interaction happens there? But then again: It is so much easier to just run the HP5370 on the internal clock and that solve^H^H^H^H^Hhides all the problems. Yes, but Poul-Henning, we are time-nuts, we dive deep just for the fun of it, to see what we can learn. :D Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why using HP5370 ext-ref is (maybe) a bad idea
On 03/03/14 16:16, Daniel Mendes wrote: Uncorrelated noise improves resolution in certain systems, even mechanical ones... it´s called dither: http://en.wikipedia.org/wiki/Dither ... as used in the HP5328A with option 40. Got it. :) PS. Still wish I had the GPIB for it. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why using HP5370 ext-ref is (maybe) a bad idea
In message 5314e957.30...@rubidium.dyndns.org, Magnus Danielson writes: Realize that I need to work on getting some GPIB programming done so I can get some scripts going. I've mentioned it before, but I'll plug it again: https://github.com/bsdphk/pylt The script I used for the plots I sent look like this: #!/usr/bin/env python from __future__ import print_function import time import socket import hp3336c # Use TCP/IP to Johns ARM board s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((hp5370, 5370)) s.send(ST9\r\n) s.send(MD2\r\n) s.send(SS3\r\n) # Purge whatever is buffered s.settimeout(1) while True: try: x = s.recv(40) except socket.timeout: break print(x) s.settimeout(None) g = hp3336c.hp3336c() print(ID, g.id) # Setup frequency and amplitude manually, this only reports... print(Freq: %.11e Hz %.1f dBm % (g.read_freq(), g.read_dbm())) fo = open(/tmp/_q, w) ph = 0 for m in range(180): ph += 1 g.wr(PH%.1fDE % (.1*ph)) time.sleep(.1) s.send(\n) data = s.recv(80).strip() data += | + s.recv(80).strip() print(%4d % m, %5.1f % (.1 * ph), data) fo.write(%4d % ph + %5.3f % (.1 * ph + j * .005) + data + \n) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why using HP5370 ext-ref is (maybe) a bad idea
In message 5314ef87.1020...@rubidium.dyndns.org, Magnus Danielson writes: Got a HP3325B, HP5370B/C/D but also 5359A and SR535. Another approach is to set a rubidium for a *slow* scan over phase-relationships. Hmm, I have a 5359A as well, I din't consider that as a possible input source. Detuning a Rb is obviously feasible, but being able to key in the phase you want on 0.1deg units is so much more convenient and repeatable. But to be honest, I'm not sure how much more work is really warranted for me, given that I don't think I can tune the 200MHz multipliers filters much better than they presently are. If that is where the issue is. Well, seeing how the pattern changed after I tuned A21, I'm pretty certain that a lot of issues are there, but maybe not all. It would be really interesting if the plot can be displayed in something approaching real time, so it would become feasible to try to tune A21 based on this plot, rather than a spectrum analyzer. Havn't quite figured out how to do that, but using Fast Binary mode on the 5370 and a 10,000,000.1 Hz signal from the HP3336 should be able to do it in half a second... The one sensible idea I have on the 1.2GHz is that it comes from the BBB. A run with the original CPU can resolve that. Absent that the 1.2GHz signal simply doesn't make any sense, there are no frequencies that high in the 5370 anywere, it must be aliasing of a subharmonic somewhere. Those with a high quality RF generator could force-feed a 200 MHz into the counter and see if it makes any major difference. Yes, that would be an interesting experiment. BTW, have someone looked at how the 200 MHz is then used? Sure that no interesting interaction happens there? It's squared up to ECL and fed to the digital side of things. If anybody have a capable HP82xx that might also be an option. But then again: It is so much easier to just run the HP5370 on the internal clock and that solve^H^H^H^H^Hhides all the problems. Yes, but Poul-Henning, we are time-nuts, we dive deep just for the fun of it, to see what we can learn. :D Yes, but there is so much to learn, and so little time... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Another atomic clock question
Hal, For science-fair level accuracy try a $2 PTC-60 thermistor heater one component oven for minimal complexity. I tried this with a small box and insulating foam and it gives surprisingly good results. Leave it to the ham radio guys to come up with a low cost solution. http://www.setileague.org/askdr/xtaloven.htm Richard Junk crystals are good thermometers. Ballpark is 1 ppm/degree-C albertson.ch...@gmail.com said: So does this mean I can epoxy a sandstone power resister to a junk crystal and keep the frequency exactly perfect by varying the power in the resister? Sure, for some values of perfect and such. I've occasionally thought about building something like this, just for the hell of it to see what happens and/or what I learn, and or how good I/we can get on a low budget. I think there are two problem areas. One is sensors and control algorithms. The other is board layout. Where is the sweet spot on complexity vs accuracy? I'm looking for science-fair level of goodness rather than super-expensive to get another 0 or two. What's the best low-cost way to measure temperature? Many of the obvious choices are only good to 0.1 C. That's great if you are trying to measure room temperature or or want to keep your CPU from melting, but it's probably leaving a lot on the table if you are interested in the frequency from a crystal. My straw man would be a thermistor and OP-Amp feeding into the ADC on your favorite uProc. Maybe the other side of a bridge would be adjustable. How much power do you need to keep things warm? I'm assuming something like a watt or 2 with something like a PWM from the uProc. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO module connections
As a rule I'd say to minimize the number of connectors. The ideal is to use one long cable but you can't do that. Soldering to connectors is fine but it is really hard to do correctly with that double shielded cable. The compression fitting are very good and even water proof. I would use those. Custom cables that have the correct ends on them minimize the number of adapters. Note that there are TWO TYPES of BNC connectors, 50 and 75 ohm. Use whatever matches the cable you are using. Also think again if you really plan to connect and disconnect the antenna more then once every few years. A rubber grommet might be better than a BNC. It would save two connectors. All that said It may not matter at all, the antenna has an amplifier in it and you may have dBs to spare. Trimble even says in their manual that impedance mis matches between 50 and 75 oms don't matter. For the PPS it hardly matters if we are talking about a 12 to 18 inch cable. But if you are going 50 or 100 feet you want the coax AND you want to properly terminate it. On Mon, Mar 3, 2014 at 10:01 AM, d0ct0r t...@patoka.org wrote: Hello, I am looking for the advise: what will be the better method to connect GPSDO module by short extension cable to put its antenna input on front or back panel ? Lets say, GPSDO module has female F connector. And I would like to have BNC connector on back panel of my project. Manufacturer of GPSDO recommend to use RG-59 cable for antenna connection. Is it OK if I'll take some RG-59 from CCTV, cut 6 or 12 of it, connect one end to GPSDO (let say this cable has compression type connector) and solder other end to BNC on the panel ? Or its better to use adapters and no soldering ? Like F connector-to-BNC adapter , then short BNC-to-BNC cable connected to BNC panel connector ? And other question: is it worth to use RF cable to connect 1PPS output from GPSDO to distribution amplifier ? Or regular AWG-22 could do that job ? Thanks ! -- WBW, V.P. ___ 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. -- Chris Albertson Redondo Beach, California ___ 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] ADEV from phase or frequency measurement
Volker, On 03/03/14 00:50, Volker Esper wrote: Sorry for the time delay... TIC: SR620 with Z3805 as external reference; signal source Nortel/Trimble GPSTM (GPSDO) 10MHz output Enclosed two plots (SW: Plotter): - one is sigma(tau) calculated from phase samples (SR620 TIME mode), - the other one is sigma(tau) from frequency data (SR620 FREQ mode) Whole equipment had a power up time of several days/weeks. Room temperature was stable over both measurements (within about 2 degrees C). The SR620 uses a bit different path through the logic when doing TI and FREQ measurements. The frequency measurement has a feature that means that the time error between start and stop signal needs to be calibrated out. This can be done using the calibration routines given in the manual. This should not affect the ADEV measure, but as a precaution. Try doing a pair of noise-floor measurements. That is, feed the reference 10 MHz to the A input for the frequency noise measurement. Then, for the TI noise-floor measurement, put a T on the A input, put it in high-Z mode and then use a 1 m cable to put the signal onto the B input which is terminating. You indeed have a higher level. Your initial shape makes me wonder. I would really like to get the TimeLab measurement files and eye-ball them closer. If you plot the phase or frequency, it may be easier to spot systematic wobbles. TDEV would also help, as it provides a general *tau scaling to the ADEV plot. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why using HP5370 ext-ref is (maybe) a bad idea
On 03/03/14 22:35, Poul-Henning Kamp wrote: In message 5314ef87.1020...@rubidium.dyndns.org, Magnus Danielson writes: Got a HP3325B, HP5370B/C/D but also 5359A and SR535. Another approach is to set a rubidium for a *slow* scan over phase-relationships. Hmm, I have a 5359A as well, I din't consider that as a possible input source. What you want is a synchronous trigger and means to steer the relative timing with sufficient precision. The 5359A and SR535 is there for exactly this type of exercise with their 50 ps and 5 ps step size. I'm only fear they might have too much noise, but I need to check that. Detuning a Rb is obviously feasible, but being able to key in the phase you want on 0.1deg units is so much more convenient and repeatable. Agreed. Just wanted to widen the scope of feasible solutions for setting up alternative solutions such that a multitude of approaches could get similar enough results. But to be honest, I'm not sure how much more work is really warranted for me, given that I don't think I can tune the 200MHz multipliers filters much better than they presently are. If that is where the issue is. Well, seeing how the pattern changed after I tuned A21, I'm pretty certain that a lot of issues are there, but maybe not all. It would be really interesting if the plot can be displayed in something approaching real time, so it would become feasible to try to tune A21 based on this plot, rather than a spectrum analyzer. Which was what I was proposing earlier. One idea would be to dial in a suitable phase-relationship and then tune until the value goes better on the display and then tune to another phase-relationship. This assumes you just don't shift it around, but can actually work on it to become better. Havn't quite figured out how to do that, but using Fast Binary mode on the 5370 and a 10,000,000.1 Hz signal from the HP3336 should be able to do it in half a second... The one sensible idea I have on the 1.2GHz is that it comes from the BBB. A run with the original CPU can resolve that. Absent that the 1.2GHz signal simply doesn't make any sense, there are no frequencies that high in the 5370 anywere, it must be aliasing of a subharmonic somewhere. Indeed. Let's assume that it's not the BBB causing the issue, but it's inherent to the 5370 design. Did you know that the 200 MHz meets the trigger levels on the A18 board? That's where the DAC for trigger levels of the START and STOP channels is located, as well as coarse counting for N0 occurs. The 200 MHz is fed into a tunable filter, and then into U15 MC10216 which is acting as a three-stage amplifier. Now, there's a high-slew-rate source of 200 MHz at the source-end of the trigger levels. There's filtering through a pi-filter as distributed between the A18 board (10 nF to ground, 680 nH in series) and A3 board (10 nF to ground, via resistor). Would be interesting to sniff near those to see if the 200 MHz creeps into the trigger that way. It would sure explain a lot. Those with a high quality RF generator could force-feed a 200 MHz into the counter and see if it makes any major difference. Yes, that would be an interesting experiment. It's a bit problematic thought, the signal is fed to three different places, A19, A20 (the interpolators) and A22. BTW, have someone looked at how the 200 MHz is then used? Sure that no interesting interaction happens there? It's squared up to ECL and fed to the digital side of things. digital if I may. In these cases, digital is but a side-case of analogue. :) If anybody have a capable HP82xx that might also be an option. I'll see how clean the 200 MHz is on my SIA. But then again: It is so much easier to just run the HP5370 on the internal clock and that solve^H^H^H^H^Hhides all the problems. Yes, but Poul-Henning, we are time-nuts, we dive deep just for the fun of it, to see what we can learn. :D Yes, but there is so much to learn, and so little time... That's why we hunt together and learn from each other. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Wildwood Loran
On 03/03/14 14:23, Bill Riches wrote: Wildwood is up as of 1300 Z March 3, 2014. We are in the middle of a lot of snow! Estimated to receive a foot or so. Yippie... Just don't blame LORAN for the snow. A LORAN tower will sure be far more than a foot or so. Good signal? Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why using HP5370 ext-ref is (maybe) a bad idea
In message 531505bc.4050...@rubidium.dyndns.org, Magnus Danielson writes: On 03/03/14 22:35, Poul-Henning Kamp wrote: In message 5314ef87.1020...@rubidium.dyndns.org, Magnus Danielson writes: Indeed. Let's assume that it's not the BBB causing the issue, but it's inherent to the 5370 design. Charles reminded me of this document in private email: http://www.ko4bb.com/Manuals/06)_App_Notes_-_Proceedings/HP_5370/HP5370-DNL-Mod.pdf It explicitly mentions the 5370A, so I guess a check is in order if the ...B has these changes already. Those with a high quality RF generator could force-feed a 200 MHz into the counter and see if it makes any major difference. Yes, that would be an interesting experiment. It's a bit problematic thought, the signal is fed to three different places, A19, A20 (the interpolators) and A22. I would go for TP1 at A21 ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why using HP5370 ext-ref is (maybe) a bad idea
On 03/03/14 23:59, Poul-Henning Kamp wrote: In message 531505bc.4050...@rubidium.dyndns.org, Magnus Danielson writes: On 03/03/14 22:35, Poul-Henning Kamp wrote: In message 5314ef87.1020...@rubidium.dyndns.org, Magnus Danielson writes: Indeed. Let's assume that it's not the BBB causing the issue, but it's inherent to the 5370 design. Charles reminded me of this document in private email: http://www.ko4bb.com/Manuals/06)_App_Notes_-_Proceedings/HP_5370/HP5370-DNL-Mod.pdf It explicitly mentions the 5370A, so I guess a check is in order if the ...B has these changes already. That's the one I mentioned earlier. I also recall it was fixed in the B. Those with a high quality RF generator could force-feed a 200 MHz into the counter and see if it makes any major difference. Yes, that would be an interesting experiment. It's a bit problematic thought, the signal is fed to three different places, A19, A20 (the interpolators) and A22. I would go for TP1 at A21 ? Well, either you lift R1 and insert the signal into that one, or you lift C15 and insert signal there... and use that amplifier chain. Just inserting on TP1 isn't very smart, even if you unplug the 10 MHz input to the multiplier chain. Think I will sniff with the near-field probe tomorrow. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Another atomic clock question
Hi If you are measuring temperature in a room who’s temperature does not change, then yes you can hold 0.1 C. That of course is based on the “room does not change temperature” and that equates to absolutely no change at all. The only rational way to discus temperature stability is as a response to an external change. It change this amount when the temperature around it changes that amount. Trying to compare something on the table here and the table there is not a very useful exercise. On an OCXO the internal temperature control is always specified with a defined external temperature change. The drift in the set temperature at a constant ambient is essentially “un-measurable” even on some pretty cheap ovens. Bob On Mar 3, 2014, at 9:27 AM, Jim Lux jim...@earthlink.net wrote: On 3/3/14 2:18 AM, Hal Murray wrote: Junk crystals are good thermometers. Ballpark is 1 ppm/degree-C albertson.ch...@gmail.com said: So does this mean I can epoxy a sandstone power resister to a junk crystal and keep the frequency exactly perfect by varying the power in the resister? Sure, for some values of perfect and such. I've occasionally thought about building something like this, just for the hell of it to see what happens and/or what I learn, and or how good I/we can get on a low budget. I think there are two problem areas. One is sensors and control algorithms. The other is board layout. Where is the sweet spot on complexity vs accuracy? I'm looking for science-fair level of goodness rather than super-expensive to get another 0 or two. What's the best low-cost way to measure temperature? Many of the obvious choices are only good to 0.1 C. That's great if you are trying to measure room temperature or or want to keep your CPU from melting, but it's probably leaving a lot on the table if you are interested in the frequency from a crystal. My straw man would be a thermistor and OP-Amp feeding into the ADC on your favorite uProc. Maybe the other side of a bridge would be adjustable. A number of microcontrollers have onchip temperature sensors (Freescale Kinetis, for instance). If the controller were bonded to the crystal housing, that might be enough coupling. Could you hold 0.1 or 0.001 degree? the chip has a 16 bid ADC, although I wouldn't trust the bottom bit or two because of noise. But in any case 1 LSB is 3.3/64k or about 50 microvolts. The temperature sensor slope is 1.715 mV/C, so that's in the 0.03 C/LSB range.. On a good day, you *might* be able to hold 0.1 degree, assuming there's no systematic errors. How much power do you need to keep things warm? I'm assuming something like a watt or 2 with something like a PWM from the uProc. ___ 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] Another atomic clock question
On Mon, Mar 3, 2014 at 2:18 AM, Hal Murray hmur...@megapathdsl.net wrote: Junk crystals are good thermometers. Ballpark is 1 ppm/degree-C albertson.ch...@gmail.com said: So does this mean I can epoxy a sandstone power resister to a junk crystal and keep the frequency exactly perfect by varying the power in the resister? Sure, for some values of perfect and such. There is only one value of perfect. The goal is to keep the frequency spot-on the marked 10MHz If this system works the crystal never moves off it's design value. We are not using het to push or pull the crystal off it's fundamental design point but maybe we say to push or pull it back to center. I've occasionally thought about building something like this, just for the hell of it to see what happens and/or what I learn, and or how good I/we can get on a low budget. That is my goal too. I'm never impressed that people with unlimited budget do good work. But doing the same with recycled junk parts really is impressive. I think there are two problem areas. One is sensors and control algorithms. The other is board layout. Where is the sweet spot on complexity vs accuracy? I'm looking for science-fair level of goodness rather than super-expensive to get another 0 or two. What's the best low-cost way to measure temperature? Many of the obvious choices are only good to 0.1 C. That's great if you are trying to measure room temperature or or want to keep your CPU from melting, but it's probably leaving a lot on the table if you are interested in the frequency from a crystal. Why are you measuring temperature. Just let it be whatever. You measure the frequent and then adult the current in the heater to keep the frequency constant. I assume that if the crystal really is a good thermometer then frequency is all you need to measure. One can make the control easier by adding some thermal mass. A big chunk of metal would add some stability. -- Chris Albertson Redondo Beach, California ___ 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] Another atomic clock question
In message ab202da8-82bd-4861-af15-abbf92779...@rtty.us, Bob Camp writes: If you are measuring temperature in a room who's temperature does not change, then yes you can hold 0.1 C. That would make you quite famous, since the current best measurement of Bolzmans constant has a relative uncertainty of 0.71e-6. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Another atomic clock question
The OCXO maker is forced to use a temperature sensor because he does not have access to a frequency reference. If do have an external frequency reference then the crystal itself makes a good thermometer. So why not use THAT thermometer to control the heat added by the resister.Such a system would respond to changes in ambient temperature by adjusting the power in the resister. We don't even have to care if the crystal's temp-co is nonlinear because we are using a very small temperature range, so small it looks linear. I'll build it.Can you or anyone else subject a simple XCO schematic? Hopefully SIMPLE. What I need is a design that can be pulled down a few PPM so that I can raise it back with a bit of heat. I will have to be kept at a temperer above the hottest it will ever get inside the house, maybe 100F. On Mon, Mar 3, 2014 at 3:18 PM, Bob Camp li...@rtty.us wrote: Hi If you are measuring temperature in a room who's temperature does not change, then yes you can hold 0.1 C. That of course is based on the room does not change temperature and that equates to absolutely no change at all. The only rational way to discus temperature stability is as a response to an external change. It change this amount when the temperature around it changes that amount. Trying to compare something on the table here and the table there is not a very useful exercise. On an OCXO the internal temperature control is always specified with a defined external temperature change. The drift in the set temperature at a constant ambient is essentially un-measurable even on some pretty cheap ovens. Bob On Mar 3, 2014, at 9:27 AM, Jim Lux jim...@earthlink.net wrote: On 3/3/14 2:18 AM, Hal Murray wrote: Junk crystals are good thermometers. Ballpark is 1 ppm/degree-C albertson.ch...@gmail.com said: So does this mean I can epoxy a sandstone power resister to a junk crystal and keep the frequency exactly perfect by varying the power in the resister? Sure, for some values of perfect and such. I've occasionally thought about building something like this, just for the hell of it to see what happens and/or what I learn, and or how good I/we can get on a low budget. I think there are two problem areas. One is sensors and control algorithms. The other is board layout. Where is the sweet spot on complexity vs accuracy? I'm looking for science-fair level of goodness rather than super-expensive to get another 0 or two. What's the best low-cost way to measure temperature? Many of the obvious choices are only good to 0.1 C. That's great if you are trying to measure room temperature or or want to keep your CPU from melting, but it's probably leaving a lot on the table if you are interested in the frequency from a crystal. My straw man would be a thermistor and OP-Amp feeding into the ADC on your favorite uProc. Maybe the other side of a bridge would be adjustable. A number of microcontrollers have onchip temperature sensors (Freescale Kinetis, for instance). If the controller were bonded to the crystal housing, that might be enough coupling. Could you hold 0.1 or 0.001 degree? the chip has a 16 bid ADC, although I wouldn't trust the bottom bit or two because of noise. But in any case 1 LSB is 3.3/64k or about 50 microvolts. The temperature sensor slope is 1.715 mV/C, so that's in the 0.03 C/LSB range.. On a good day, you *might* be able to hold 0.1 degree, assuming there's no systematic errors. How much power do you need to keep things warm? I'm assuming something like a watt or 2 with something like a PWM from the uProc. ___ 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. -- Chris Albertson Redondo Beach, California ___ 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] Another atomic clock question
Hi The crystal as normally cut makes a very poor thermometer compared to a thermistor. Bob On Mar 3, 2014, at 6:46 PM, Chris Albertson albertson.ch...@gmail.com wrote: The OCXO maker is forced to use a temperature sensor because he does not have access to a frequency reference. If do have an external frequency reference then the crystal itself makes a good thermometer. So why not use THAT thermometer to control the heat added by the resister.Such a system would respond to changes in ambient temperature by adjusting the power in the resister. We don't even have to care if the crystal's temp-co is nonlinear because we are using a very small temperature range, so small it looks linear. I'll build it.Can you or anyone else subject a simple XCO schematic? Hopefully SIMPLE. What I need is a design that can be pulled down a few PPM so that I can raise it back with a bit of heat. I will have to be kept at a temperer above the hottest it will ever get inside the house, maybe 100F. On Mon, Mar 3, 2014 at 3:18 PM, Bob Camp li...@rtty.us wrote: Hi If you are measuring temperature in a room who's temperature does not change, then yes you can hold 0.1 C. That of course is based on the room does not change temperature and that equates to absolutely no change at all. The only rational way to discus temperature stability is as a response to an external change. It change this amount when the temperature around it changes that amount. Trying to compare something on the table here and the table there is not a very useful exercise. On an OCXO the internal temperature control is always specified with a defined external temperature change. The drift in the set temperature at a constant ambient is essentially un-measurable even on some pretty cheap ovens. Bob On Mar 3, 2014, at 9:27 AM, Jim Lux jim...@earthlink.net wrote: On 3/3/14 2:18 AM, Hal Murray wrote: Junk crystals are good thermometers. Ballpark is 1 ppm/degree-C albertson.ch...@gmail.com said: So does this mean I can epoxy a sandstone power resister to a junk crystal and keep the frequency exactly perfect by varying the power in the resister? Sure, for some values of perfect and such. I've occasionally thought about building something like this, just for the hell of it to see what happens and/or what I learn, and or how good I/we can get on a low budget. I think there are two problem areas. One is sensors and control algorithms. The other is board layout. Where is the sweet spot on complexity vs accuracy? I'm looking for science-fair level of goodness rather than super-expensive to get another 0 or two. What's the best low-cost way to measure temperature? Many of the obvious choices are only good to 0.1 C. That's great if you are trying to measure room temperature or or want to keep your CPU from melting, but it's probably leaving a lot on the table if you are interested in the frequency from a crystal. My straw man would be a thermistor and OP-Amp feeding into the ADC on your favorite uProc. Maybe the other side of a bridge would be adjustable. A number of microcontrollers have onchip temperature sensors (Freescale Kinetis, for instance). If the controller were bonded to the crystal housing, that might be enough coupling. Could you hold 0.1 or 0.001 degree? the chip has a 16 bid ADC, although I wouldn't trust the bottom bit or two because of noise. But in any case 1 LSB is 3.3/64k or about 50 microvolts. The temperature sensor slope is 1.715 mV/C, so that's in the 0.03 C/LSB range.. On a good day, you *might* be able to hold 0.1 degree, assuming there's no systematic errors. How much power do you need to keep things warm? I'm assuming something like a watt or 2 with something like a PWM from the uProc. ___ 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. -- Chris Albertson Redondo Beach, California ___ 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] Another atomic clock question
So does this mean I can epoxy a sandstone power resister to a junk crystal and keep the frequency exactly perfect by varying the power in the resister? Sure. In fact you can loosely phase lock it to GPS that way. Your xtal doesn't need to have an EFC pin. You are using external temperature as a replacement for EFC. Call it TFC (temperature frequency control) instead. You can't get much simpler than that. Make sure to use a plain XO (not a TCXO or OCXO). I used a resistor heater to bust hanging-bridges: http://leapsecond.com/pages/vp/heater.htm /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] SR620 binary dump
Has anyone used the binary dump feature of the SR620 (command BDMP) or the x1000 feature (command EXPD)? If you have, please send me email off-list. If you haven't, I will post a report to time-nuts later this week. Thanks, /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] Wildwood Loran
Yes LORAN is sounding fine in Boston. Have a number of receivers on Autrons SRS etc and checking local references. Good to hear the signal. Also testing a fellow Time-Nuts LORAN C SDR that was posted about a month ago. Regards Paul WB8TSL On Mon, Mar 3, 2014 at 5:46 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 03/03/14 14:23, Bill Riches wrote: Wildwood is up as of 1300 Z March 3, 2014. We are in the middle of a lot of snow! Estimated to receive a foot or so. Yippie... Just don't blame LORAN for the snow. A LORAN tower will sure be far more than a foot or so. Good signal? Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Another atomic clock question
Tom, That's a pretty interesting idea. It makes me wonder if it would be worth it to switch perhaps a 1/2W heat source (random number) off and on over the XO in the UT+ say every minute or so. Bob From: Tom Van Baak t...@leapsecond.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, March 3, 2014 6:40 PM Subject: Re: [time-nuts] Another atomic clock question Sure. In fact you can loosely phase lock it to GPS that way. Your xtal doesn't need to have an EFC pin. You are using external temperature as a replacement for EFC. Call it TFC (temperature frequency control) instead. You can't get much simpler than that. Make sure to use a plain XO (not a TCXO or OCXO). I used a resistor heater to bust hanging-bridges: http://leapsecond.com/pages/vp/heater.htm /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] Another atomic clock question
On Mon, Mar 3, 2014 at 4:51 PM, Charles Steinmetz csteinm...@yandex.com wrote: What you are proposing is a disciplined oscillator using the oven setpoint as the control input. What I want to try is building a GPSDO for say $25 for everything except the GPS. A fun contest would be to adopt some low budget, like $20 and see who can make the best ADEV numbers. A rules would have to be only fair market prices for components, not fair if you buys $1 rubidium clock. It would have to be prices that anyone could get any day. Or you fix the task and lowest priced design wins. Say the test is a lab 10MHz reference good to 11 digits then see who can do the job at lowest cost. Thanks that schematic looks to be the exact one I was looking for, I've got most of the rest of what's needed to connect it to a GPS. -- Chris Albertson Redondo Beach, California ___ 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] Time transfer, internationally before GPS
My apologies to the list if this has been posted before but I found it fascinating. I'm guessing this was early 60's. I wonder if this practice continued until the advent of GPS? I be interested to know if there was an interim technology and what it was. http://youtu.be/SXV4c5eVkE4 Jim... N5SPE ___ 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] Time transfer, internationally before GPS
I think there were a couple of steps in between things like time-mation satellites and such precursors to GPS. But I believe that CS references were trucked around for a long time. Regards Paul WB8TSL On Mon, Mar 3, 2014 at 8:17 PM, Jimmy Burrell jimmydb...@gmail.com wrote: My apologies to the list if this has been posted before but I found it fascinating. I'm guessing this was early 60's. I wonder if this practice continued until the advent of GPS? I be interested to know if there was an interim technology and what it was. http://youtu.be/SXV4c5eVkE4 Jim... N5SPE ___ 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] Another atomic clock question
Hi So I can use the scrap (zero value) 5 MHz 3rd OT HC-40 package SC’s that are sitting in a pile in the basement right ? Bob On Mar 3, 2014, at 8:47 PM, Chris Albertson albertson.ch...@gmail.com wrote: On Mon, Mar 3, 2014 at 4:51 PM, Charles Steinmetz csteinm...@yandex.com wrote: What you are proposing is a disciplined oscillator using the oven setpoint as the control input. What I want to try is building a GPSDO for say $25 for everything except the GPS. A fun contest would be to adopt some low budget, like $20 and see who can make the best ADEV numbers. A rules would have to be only fair market prices for components, not fair if you buys $1 rubidium clock. It would have to be prices that anyone could get any day. Or you fix the task and lowest priced design wins. Say the test is a lab 10MHz reference good to 11 digits then see who can do the job at lowest cost. Thanks that schematic looks to be the exact one I was looking for, I've got most of the rest of what's needed to connect it to a GPS. -- Chris Albertson Redondo Beach, California ___ 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] Time transfer, internationally before GPS
Hi Jim, Nice video. I had not see that old one before. Someone at NPL must be going through archives. That's very nice of them to post it. Did anyone spot the date of the filming? My understanding is that the era of traveling clocks gradually ended as various methods of satellite time transfer began. However people still use traveling clocks today as a backup for GPS, or to double check GPS, or in places where GPS cannot be received, or when one needs accurate results quickly without waiting for GPS averaging or post-processing. So the practice is not dead. Most recently we all saw it used to validate the neutrino timing experiments. Traveling clocks can also be used to demonstrate time dilation: http://leapsecond.com/great2005/ For more info on the traveling clock era make sure to read these four HPJ articles: World-Wide Time Synchronization, 1966 http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1966-08.pdf, page 13 A New Performance of the Flying Clock Experiment http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1964-07.pdf, page 1 Correlating Time from Europe to Asia with Flying Clocks http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1965-04.pdf, page 1 'Flying Clock' Comparisons Extended to East Europe, Africa and Australia http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1967-12.pdf /tvb - Original Message - From: Jimmy Burrell jimmydb...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, March 03, 2014 5:17 PM Subject: [time-nuts] Time transfer, internationally before GPS My apologies to the list if this has been posted before but I found it fascinating. I'm guessing this was early 60's. I wonder if this practice continued until the advent of GPS? I be interested to know if there was an interim technology and what it was. http://youtu.be/SXV4c5eVkE4 Jim... N5SPE ___ 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] Time transfer, internationally before GPS
Hi A traveling clock process is still the only way to fully validate a local time setup. The NIST modems can get close, but a clock (second opinion) is the only way to be sure. Bob On Mar 3, 2014, at 9:09 PM, Tom Van Baak t...@leapsecond.com wrote: Hi Jim, Nice video. I had not see that old one before. Someone at NPL must be going through archives. That's very nice of them to post it. Did anyone spot the date of the filming? My understanding is that the era of traveling clocks gradually ended as various methods of satellite time transfer began. However people still use traveling clocks today as a backup for GPS, or to double check GPS, or in places where GPS cannot be received, or when one needs accurate results quickly without waiting for GPS averaging or post-processing. So the practice is not dead. Most recently we all saw it used to validate the neutrino timing experiments. Traveling clocks can also be used to demonstrate time dilation: http://leapsecond.com/great2005/ For more info on the traveling clock era make sure to read these four HPJ articles: World-Wide Time Synchronization, 1966 http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1966-08.pdf, page 13 A New Performance of the Flying Clock Experiment http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1964-07.pdf, page 1 Correlating Time from Europe to Asia with Flying Clocks http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1965-04.pdf, page 1 'Flying Clock' Comparisons Extended to East Europe, Africa and Australia http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1967-12.pdf /tvb - Original Message - From: Jimmy Burrell jimmydb...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, March 03, 2014 5:17 PM Subject: [time-nuts] Time transfer, internationally before GPS My apologies to the list if this has been posted before but I found it fascinating. I'm guessing this was early 60's. I wonder if this practice continued until the advent of GPS? I be interested to know if there was an interim technology and what it was. http://youtu.be/SXV4c5eVkE4 Jim... N5SPE ___ 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] Time transfer, internationally before GPS
The piece didn't say anything about correcting for acceleration. Regards. Max. K 4 O DS. Email: m...@maxsmusicplace.com Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Woodworking site http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html Music site: http://www.maxsmusicplace.com To subscribe to the fun with transistors group send an email to. funwithtransistors-subscr...@yahoogroups.com To subscribe to the fun with tubes group send an email to, funwithtubes-subscr...@yahoogroups.com To subscribe to the fun with wood group send a blank email to funwithwood-subscr...@yahoogroups.com - Original Message - From: Jimmy Burrell jimmydb...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, March 03, 2014 7:17 PM Subject: [time-nuts] Time transfer, internationally before GPS My apologies to the list if this has been posted before but I found it fascinating. I'm guessing this was early 60's. I wonder if this practice continued until the advent of GPS? I be interested to know if there was an interim technology and what it was. http://youtu.be/SXV4c5eVkE4 Jim... N5SPE ___ 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. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.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] Time transfer, internationally before GPS
Hi One of the early relativity confirmation experiments was done with very similar clocks before that film clip was made. There were a number of corrections made as part of the trip. One of them was to re-confirm the traveling Cs once it got back to it’s starting point. You only could “use” the trip if the Cs came back home still on time. There were a *lot* of satellite time transfer experiments in the 60’s and 70’s. They worked well enough to reduce the frequency of clock trips, but not well enough to eliminate them. The GPS common view stuff was the first approach that (with proper calibration) got them to a better level of time transfer than a clock trip. Bob On Mar 3, 2014, at 9:50 PM, Max Robinson m...@maxsmusicplace.com wrote: The piece didn't say anything about correcting for acceleration. Regards. Max. K 4 O DS. Email: m...@maxsmusicplace.com Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Woodworking site http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html Music site: http://www.maxsmusicplace.com To subscribe to the fun with transistors group send an email to. funwithtransistors-subscr...@yahoogroups.com To subscribe to the fun with tubes group send an email to, funwithtubes-subscr...@yahoogroups.com To subscribe to the fun with wood group send a blank email to funwithwood-subscr...@yahoogroups.com - Original Message - From: Jimmy Burrell jimmydb...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, March 03, 2014 7:17 PM Subject: [time-nuts] Time transfer, internationally before GPS My apologies to the list if this has been posted before but I found it fascinating. I'm guessing this was early 60's. I wonder if this practice continued until the advent of GPS? I be interested to know if there was an interim technology and what it was. http://youtu.be/SXV4c5eVkE4 Jim... N5SPE ___ 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. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.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 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] Time transfer, internationally before GPS
The piece didn't say anything about correcting for acceleration. Hi Max, True, but at one point the video mentioned microsecond resolution, and at that level, no relativistic corrections for airplane trips are needed. If you want to get down to nanoseconds, then yes, you will want to apply altitude (gravitational), velocity, and Sagnac corrections. You can use my rel.exe tool (www.leapsecond.com/tools/) to calculate the two relativistic effects: C:\tvb rel 35000ft 500mph 8hr ** Altitude 10668.000 m (35000.000 ft, 6.629 mi) 1.161e-012 blueshift 4181.381949 ps/hour 100.353167 ns/day ** Velocity 223.520 m/s (804.672 km/h, 500.000 mph) -2.779e-013 redshift -1000.607783 ps/hour -24.014587 ns/day ** Net effect (GR+SR) 8.835e-013 shift 3180.774165 ps/hour 76.338580 ns/day ** Duration 28800 seconds (8.000 hours, 0.33 days) 25446.193322 ps total 25.446193 ns total 0.025446 us total So for an 8 hour flight at 500 mph at 35,000 feet the time dilation correction is only about 25 ns. Add to that the Sagnac correction for East-West or West-East travel between USNO and NPL, about +/- 22 ns. /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] new gps sat prn30 svn64
Hi Skip, Your message 30,30 is nearly identical to mine on 3-2-14 2:00mst I just realized I been putting my time stamps as pdt should be pst (pacific standard time). Anyway the supperb time rate from svn64 prn30 changed from execellant to average. Compareable to the other sats on 2/26/2014 01:34:33 pst here is my data. 3.8706945954e-010,-2.7224445300e-01402/25/2014 14:25:20 3.8088047897e-010,-2.8666966126e-01402/25/2014 14:28:50 3.8088047897e-010,-2.8666966126e-01402/25/2014 14:28:50 3.7882484806e-010,-3.0106044610e-01402/25/2014 14:30:20 3.7575403151e-010,-3.0106044610e-01402/25/2014 14:31:50 -7.6402494734e-007,3.6402148657e-01202/26/2014 01:34:33 -7.6389389961e-007,3.6402148657e-01202/26/2014 01:35:33 -7.6336994898e-007,3.6386020065e-01202/26/2014 01:37:33 I'm at somewhat of a loss to explain this change in clock rate (stability). Perhaps the military signal is derived from the better clock ? and the civilians get a less stable clock rate/signal ? I haven't rulled out dopplar shift or my mis-understanding of how gps works and what msg 30 really means. Perhaps the sat is broadcasting the bias and drift every minute and the gps receiver is dummer than I thought ? Here is my data from the approximate time as your data. GeoNav PC Time=1393793993 03/02/2014 12:59:53 30,30,7.5566999e+004,-1.0512244642e+007,-2.0403662041e+007,1.3915637457e+007,1.4887479321e+003,8.9976062727e+002,2.4431245733e+003,1.3331348485e-006,3.6930953087e-012,4,4.096000e+005,1.081600e+004,1.5091755390e+000 I would have thought our messages would be more exact to each other as I've run two receivers from my location running sirf twice on the same pc with both sirf III and sirf IV receivers simotainiously logging and the comparied messages are within 2 or 3 least significant digits of each other.. PRobably are location differences are the reason for a less equal comparison. sunday 3-2-14 the sat passed nearly overhead at my location which would have presented the maximum dopplar shift. but that wouldn't explain the dramitic shift in the clock stability seen on 2-26-14. I will be logging the data daily hoping to see the prn30 clock go back to the better stability. I put and sd card in my laptop pc and now run sirfdemo from the sd card and log to that sd card. I feel it puts less where on my harddrive.. I can easily see prn30 orbit moving westwardly each day across the sat mapping screen. very cool !! I also have written a program to parse out the clock bias and drift. here is its output. prn clk biasclk drift 30sec drift 30sec clk bias next orbit clk bias update utc 01 5.419324e-07 1.939370e-1213 1.350894e-14 2.4980e-10 0714 3.056667e-08 0316 02 4.801467e-04 -6.812491e-13 -2.547918e-14 -7.5000e-12 1332 1.832122e-07 0619 03 3.292035e-04 -7.611533e-14 1.553618e-14 -2.2900e-12 1529 -1.075634e-07 150 14 5.685252e-06 -6.154375e-13 2.511121e-14 -8.2501e-12 1112 5.062425e-08 0459 05 -3.874342e-04 2.121078e-123 8.206977e-15 9.7660e-11 1433 3.457315e-08 0838 06 2.857013e-04 1.634064e-11 5.935703e-14 4.9022e-10 1529 6.195851e-07 1344 07 3.165876e-04 1.958476e-12 5.030264e-15 7.9590e-11 0610 -5.385762e-07 222 08 1.200872e-05 -4.117289e-12 1.142446e-14 -3.7056e-11 0723 -3.790054e-07 234 09 3.072839e-04 5.659474e-125 3.575135e-14 8.4890e-11 0728 3.072825e-04 0025 10 -1.154085e-04 -3.748887e-12 2.945560e-14 -4.8740e-11 1212 -1.017679e-08 075 11 -4.664052e-04 -7.469855e-12 1.838373e-14 -1.1952e-10 0611 -1.192491e-08 021 12 1.880373e-04 3.790502e-12 -6.092783e-15 9.0580e-11 1316 1.010878e-07 0640 13 2.713727e-05 -3.561521e-12 1.282676e-14 -6.0546e-11 0424 2.726619e-05 2116 14 1.961350e-04 -3.153479e-12 1.802226e-14 -9.4600e-11 1529 -2.227599e-07 144 15 -1.645517e-04 -3.145682e-12 1.313034e-14 -7.8620e-11 1529 -1.402962e-08 113 16 -2.304940e-04 3.668937e-125 9.299852e-15 1.0947e-10 1529 5.328928e-08 1304 17 -7.047949e-05 -4.629986e-12 -2.057078e-14 -3.1959e-10 1008 -7.042604e-05 030 18 3.034303e-04 7.149177e-123 -5.420144e-15 2.1093e-10 1529 7.296043e-08 1140 19 -4.404313e-04 -2.519745e-12 1.712601e-13 -9.5182e-10 0445 -1.502963e-08 235 20 1.639282e-04 3.410605e-12 -1.746089e-12 2.3873e-09 0822 8.219745e-08 0635 21 -3.453992e-04 4.039002e-134 -4.799720e-14 1.0840e-11 1529 -1.898633e-07 102 22 2.150482e-04 4.723546e-12 6.304853e-15 1.4105e-10 1529 1.237934e-07 1302 23 1.918922e-06 -6.003539e-12 4.613150e-14 -6.0035e-12 0306 2.001197e-06 1931 24 -2.378059e-05 -1.316009e-12 -5.128276e-16 -3.9554e-11 1529 1.192998e-08 1507 25 1.573178e-05 2.737902e-122 -1.925977e-15 5.2020e-11 1416 6.875391e-08 0820 26 1.577180e-04 -1.734294e-11 2.159037e-14 -4.5705e-10 1521 -7.768384e-08 112 27 -1.932695e-05 -8.357383e-13 1.904347e-15 -2.5027e-11 1529 -3.765017e-08 140 28 3.344866e-04 -3.703717e-13 -8.318476e-14 -3.8030e-11 0842 3.343273e-04 0104 29 5.130142e-04 3.020466e-12 -4.085924e-15 9.0540e-11 1529 1.704589e-07 0854 30
