Re: [time-nuts] +/- TI button on 5370B
Jim, Really annoying feature of HP counters. If you slowly drift from a positive period to a negative one, it will indicate negative numbers for a while. Then almost sudden it will do the jump to 0.9 seconds. I found that adding a phase delay (long cable) helps keep the numbers positive. Or trigger one on the rising, and one on the falling edge to add 50ns delay ( for signals with good 50% duty cycle). Bye, Said On Jun 11, 2013, at 21:13, Jim Palfreyman jim77...@gmail.com wrote: Folks, I'm struggling to understand this button and how it reports intervals. It's supposed to show negative when the Stop is before the Start. When I connect up two clocks sending out 1PPS and say the one connected to Stop is ahead then sometimes I'd get -123.45 ns (say) and sometimes it flips to 999.999... ms. It can't seem to make up its mind which to use. Why is this inconsistent? If I flip it to + TI and make sure the leading clock is on Start - all works well. Thoughts? Jim Palfreyman ___ 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] +/- TI button on 5370B
Hi Another simple solution - If you are using a GPSDO as a PPS source, use the cable delay to offset the pps you are using as a reference by a microsecond. That's worked on every GPSDO I've tried it on. No it really doesn't solve the problem, it just covers it up. Post processing the data is the only real way to straighten things out in the general case. Bob On Jun 12, 2013, at 2:48 AM, Said Jackson saidj...@aol.com wrote: Jim, Really annoying feature of HP counters. If you slowly drift from a positive period to a negative one, it will indicate negative numbers for a while. Then almost sudden it will do the jump to 0.9 seconds. I found that adding a phase delay (long cable) helps keep the numbers positive. Or trigger one on the rising, and one on the falling edge to add 50ns delay ( for signals with good 50% duty cycle). Bye, Said On Jun 11, 2013, at 21:13, Jim Palfreyman jim77...@gmail.com wrote: Folks, I'm struggling to understand this button and how it reports intervals. It's supposed to show negative when the Stop is before the Start. When I connect up two clocks sending out 1PPS and say the one connected to Stop is ahead then sometimes I'd get -123.45 ns (say) and sometimes it flips to 999.999... ms. It can't seem to make up its mind which to use. Why is this inconsistent? If I flip it to + TI and make sure the leading clock is on Start - all works well. Thoughts? Jim Palfreyman ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Phase noise measurement with a scope
Hi all, given that digital scopes have a multichannel ADC for acquisition, which is similar to what a cross-correlating phase noise measurement instrument has, it occurred to me that phase noise measurement might also be possible with a standard digital scope and some post-processing software. The scope usually will have only 8 bits of resolution, but it will have a rather high sampling rate. With oversampling math, one may be able to trade one for the other, at least if the scope's analog frontend is not too bad. Has anyone investigated or tried this? Is it a silly idea to start with? Cheers Stefan Heinzmann attachment: stefan_heinzmann.vcf___ 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] +/- TI button on 5370B
Not only HP counters. I have never seen a TI counter that outputs negative values. I use the cable delay or user delay feature of GPSes to delay one PPS to the other so that the result is always positive. I have seen that only oscilloscopes can handle negative time interval values. Maybe that the Wavecrest counters can handle negative TI, I don't know. On Wed, Jun 12, 2013 at 8:48 AM, Said Jackson saidj...@aol.com wrote: Jim, Really annoying feature of HP counters. If you slowly drift from a positive period to a negative one, it will indicate negative numbers for a while. Then almost sudden it will do the jump to 0.9 seconds. I found that adding a phase delay (long cable) helps keep the numbers positive. Or trigger one on the rising, and one on the falling edge to add 50ns delay ( for signals with good 50% duty cycle). Bye, Said On Jun 11, 2013, at 21:13, Jim Palfreyman jim77...@gmail.com wrote: Folks, I'm struggling to understand this button and how it reports intervals. It's supposed to show negative when the Stop is before the Start. When I connect up two clocks sending out 1PPS and say the one connected to Stop is ahead then sometimes I'd get -123.45 ns (say) and sometimes it flips to 999.999... ms. It can't seem to make up its mind which to use. Why is this inconsistent? If I flip it to + TI and make sure the leading clock is on Start - all works well. Thoughts? Jim Palfreyman ___ 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] Phase noise measurement with a scope
Hello, given that digital scopes have a multichannel ADC for acquisition, which is similar to what a cross-correlating phase noise measurement instrument has, it occurred to me that phase noise measurement might also be possible with a standard digital scope and some post-processing software. The scope usually will have only 8 bits of resolution, but it will have a rather high sampling rate. With oversampling math, one may be able to trade one for the other, at least if the scope's analog frontend is not too bad. Has anyone investigated or tried this? Is it a silly idea to start with? yes, did it last week. I think it may have a sense with 1Gsps scope with good quality guts (should check with LC584AL at work). I have tried it with a very cheap one, Rigol 2-channel, originally 50MHz, reflashed to 100MHz. 2 signals, refmeasured, into Ch1, Ch2. Waveforms (2x500Msps) acquired, sinc() interpolated. Results: short-term single-shot jitter around 100ps RMS. Long-term was of no interest for my purpose now, so no observations here. Therefore, it is almost of no use at all for higher precision needs. Regards, Marek ___ 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] Ovenaire OSC 49-61C
Anybody have service, schematics or experience for one of these OCXO? They are commonly seen in early HP 8566A spectrum analysers. It is out of adjustable range. Fortunately I had a spare OSC 49-61C floating about and replaced this off frequency reference with it. However the replacement tends to wander about a fair bit. By removing the 4 bottom screws and the 2 top screws, applying a little heat with a heat gun around the bottom to melt the glue, the oven came apart with little protest. I was able to carefully access the top 2 boards and there is no sign of component failure there so it maybe something inside the oven itself. I have stopped here until I get further information. -marki ___ 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] Phase noise measurement with a scope
I would think that considering the amount of time it takes to get the data out of the scope (particularly on the cheap scopes) would be a major impediment to that method regardless of the cleanliness of whatever data you eventually get, since you will only be able to analyze a small fraction of the available data (small aperture window). Regarding the quality of the data, scopes are not particularly low noise. As long as the noise is not objectionable on screen, it is good enough for a scope, probably not time-nut standard. Didier Marek Peca ma...@duch.cz wrote: Hello, given that digital scopes have a multichannel ADC for acquisition, which is similar to what a cross-correlating phase noise measurement instrument has, it occurred to me that phase noise measurement might also be possible with a standard digital scope and some post-processing software. The scope usually will have only 8 bits of resolution, but it will have a rather high sampling rate. With oversampling math, one may be able to trade one for the other, at least if the scope's analog frontend is not too bad. Has anyone investigated or tried this? Is it a silly idea to start with? yes, did it last week. I think it may have a sense with 1Gsps scope with good quality guts (should check with LC584AL at work). I have tried it with a very cheap one, Rigol 2-channel, originally 50MHz, reflashed to 100MHz. 2 signals, refmeasured, into Ch1, Ch2. Waveforms (2x500Msps) acquired, sinc() interpolated. Results: short-term single-shot jitter around 100ps RMS. Long-term was of no interest for my purpose now, so no observations here. Therefore, it is almost of no use at all for higher precision needs. Regards, Marek ___ 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. -- Sent from my Motorola Droid Razr 4G LTE wireless tracker while I do other things. ___ 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] Phase noise measurement with a scope
Marek Peca wrote: Hello, given that digital scopes have a multichannel ADC for acquisition, which is similar to what a cross-correlating phase noise measurement instrument has, it occurred to me that phase noise measurement might also be possible with a standard digital scope and some post-processing software. The scope usually will have only 8 bits of resolution, but it will have a rather high sampling rate. With oversampling math, one may be able to trade one for the other, at least if the scope's analog frontend is not too bad. Has anyone investigated or tried this? Is it a silly idea to start with? yes, did it last week. I think it may have a sense with 1Gsps scope with good quality guts (should check with LC584AL at work). I have tried it with a very cheap one, Rigol 2-channel, originally 50MHz, reflashed to 100MHz. 2 signals, refmeasured, into Ch1, Ch2. Waveforms (2x500Msps) acquired, sinc() interpolated. Results: short-term single-shot jitter around 100ps RMS. Long-term was of no interest for my purpose now, so no observations here. Therefore, it is almost of no use at all for higher precision needs. I was thinking about using a 4-channel scope with cross-spectrum averaging. Look at the Timepod by John Miles for an example of the method. I'm trying to guesstimate if the RS RTO scope, perhaps with the aid of the I/Q option, is capable of doing such measurements, and with what kind of performance. Cheers Stefan attachment: stefan_heinzmann.vcf___ 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] Ovenaire OSC 49-61C
Hi Mark, I am not sure about the design of your OCXO but recently I repaired an Ovenaire from a Cushman 5510 service monitor. I found that there was a bad trimmer pot in the oven control circuit. This wasn't apparent until I started monitoring the current drawn by the unit while trying to adjust the trimmer pot. I found that if I barely touched the adjustment screw, the current would vary greatly. The temperature swing of the crystal made it impossible to adjust the oscillator trimmer cap properly. These problems disappeared after I replaced the trimmer pot. To get the new pot to a reasonably close starting, I measured the setting of the old one after I removed it and duplicated that on the new one before installing it. I had to make an extra hole in the outer case to access the pot adjustment. Although there was a hole in the internal foam to access the pot, there was no corresponding one in the outer can. I adjusted the pot for the minimal variation in oven current while monitoring the output frequency for minimal frequency swing. Now, based on observations conducted over a few days, the OCXO barely wanders and I would guess is within what Cushman required at the time the 5510 was built. Good luck with yours. Fred On 6/12/2013 7:48 AM, Mark C. Stephens wrote: Anybody have service, schematics or experience for one of these OCXO? They are commonly seen in early HP 8566A spectrum analysers. It is out of adjustable range. Fortunately I had a spare OSC 49-61C floating about and replaced this off frequency reference with it. However the replacement tends to wander about a fair bit. By removing the 4 bottom screws and the 2 top screws, applying a little heat with a heat gun around the bottom to melt the glue, the oven came apart with little protest. I was able to carefully access the top 2 boards and there is no sign of component failure there so it maybe something inside the oven itself. I have stopped here until I get further information. -marki ___ 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] Ovenaire OSC 49-61C
Hi Fred, Also, I neglected to ask, you wouldn't have the OXCO pin outs would you? -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Frederick Bray Sent: Thursday, 13 June 2013 2:01 AM To: time-nuts@febo.com Subject: Re: [time-nuts] Ovenaire OSC 49-61C Hi Mark, I am not sure about the design of your OCXO but recently I repaired an Ovenaire from a Cushman 5510 service monitor. I found that there was a bad trimmer pot in the oven control circuit. This wasn't apparent until I started monitoring the current drawn by the unit while trying to adjust the trimmer pot. I found that if I barely touched the adjustment screw, the current would vary greatly. The temperature swing of the crystal made it impossible to adjust the oscillator trimmer cap properly. These problems disappeared after I replaced the trimmer pot. To get the new pot to a reasonably close starting, I measured the setting of the old one after I removed it and duplicated that on the new one before installing it. I had to make an extra hole in the outer case to access the pot adjustment. Although there was a hole in the internal foam to access the pot, there was no corresponding one in the outer can. I adjusted the pot for the minimal variation in oven current while monitoring the output frequency for minimal frequency swing. Now, based on observations conducted over a few days, the OCXO barely wanders and I would guess is within what Cushman required at the time the 5510 was built. Good luck with yours. Fred On 6/12/2013 7:48 AM, Mark C. Stephens wrote: Anybody have service, schematics or experience for one of these OCXO? They are commonly seen in early HP 8566A spectrum analysers. It is out of adjustable range. Fortunately I had a spare OSC 49-61C floating about and replaced this off frequency reference with it. However the replacement tends to wander about a fair bit. By removing the 4 bottom screws and the 2 top screws, applying a little heat with a heat gun around the bottom to melt the glue, the oven came apart with little protest. I was able to carefully access the top 2 boards and there is no sign of component failure there so it maybe something inside the oven itself. I have stopped here until I get further information. -marki ___ 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] Phase noise measurement with a scope
(..) I have tried it with a very cheap one, Rigol 2-channel, originally 50MHz, reflashed to 100MHz. 2 signals, refmeasured, into Ch1, Ch2. Waveforms (2x500Msps) acquired, sinc() interpolated. Results: short-term single-shot jitter around 100ps RMS. Long-term was of no interest for my purpose now, so no observations here. Therefore, it is almost of no use at all for higher precision needs. I was thinking about using a 4-channel scope with cross-spectrum averaging. Look at the Timepod by John Miles for an example of the method. I'm trying to guesstimate if the RS RTO scope, perhaps with the aid of the I/Q option, is capable of doing such measurements, and with what kind of performance. My point was, that DSO is basically an ADC. Therefore, there is some amount of noise, nonlinearity and drift, limiting the jitter measurement. Do you think any method can dig more information from given data than sinc() interpolation and zero-crossing computation? Regards, Marek ___ 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] Unit tests for time calculations
On Sun, Jun 9, 2013 at 11:29 PM, Bill Hawkins b...@iaxs.net wrote: Hi, Thanks in advance. Since this is a list for precise things, could you make your questions more precise? What sort of test cases? What sort of calculations? Do you mean conversions? What do you mean by catching an error - where would you catch it? What do T1 and T2 have to do with it? What do you mean by timescale? Is a timescale a neighborhood? The work involved in clarifying those questions may make the answers clear to you. Best regards, Are you familiar with the concept of a unit test? I can clariy those questions but I am not sure how that is going to make the answer clear to me. I am writing some software that reads input from users and a number of disparate systems and I have no control over the incoming time formats. I would like to make sure that my time calculatoins/conversions work and continue to work after i make changes during development. T1 and T2 are example time date strings. Calculations: T1(UTC) - T2(EST) = Time delta in seconds 12/31/1998 00:00:00 EST + 5184001 seconds = Time Date in UTC Conversions: 01/01/1991 11:01 AM EST = XX/XX/ XX:XX UTC As far as what do you mean by catching an error - where would you catch it I cant tell if you are being snide. By catching an error I mean identifying that the calculation my program made was incorrect. Maybe you are unfamiliar with unit tests? What was unclear about what catch errors? What else came to mind when you read the sentence. Has anyone ever used time scale to describe a neighborhood? ___ 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] Phase noise measurement with a scope
Marek Peca wrote: (..) I have tried it with a very cheap one, Rigol 2-channel, originally 50MHz, reflashed to 100MHz. 2 signals, refmeasured, into Ch1, Ch2. Waveforms (2x500Msps) acquired, sinc() interpolated. Results: short-term single-shot jitter around 100ps RMS. Long-term was of no interest for my purpose now, so no observations here. Therefore, it is almost of no use at all for higher precision needs. I was thinking about using a 4-channel scope with cross-spectrum averaging. Look at the Timepod by John Miles for an example of the method. I'm trying to guesstimate if the RS RTO scope, perhaps with the aid of the I/Q option, is capable of doing such measurements, and with what kind of performance. My point was, that DSO is basically an ADC. Therefore, there is some amount of noise, nonlinearity and drift, limiting the jitter measurement. Do you think any method can dig more information from given data than sinc() interpolation and zero-crossing computation? The cross-spectrum averaging does indeed do just that, relying on two ADCs to produce uncorrelated noise, which can be averaged out. Or am I misunderstanding your point? Cheers Stefan attachment: stefan_heinzmann.vcf___ 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] Spectracom 8170 Time of Day grief...
My good old Spectracom 8170 is not setting time. I don't use it for frequency, just as a clock for my Hazetorium. I live about 20 minutes north of downtown Los Angles in Glendale. The antenna I'm using is the Ferrite Rod loop in PVC that came with the 8170. It's located on my back porch just laying on the floor with its maximum pickup direction towards Boulder, Colorado. It has worked reliably for many years in that location. The symptoms are... One day about a month ago I noticed that it seemed to be in the start mode, that is, the far left digit was flashing between 0, 1, 2, and a lot of 4's, and the left most digits were counting time since an apparent restart. Zeros and ones are the logical data states, two is a place holder and four indicates data errors. I'm not aware of it having lost primary power, but it's not on a UPS. In a week's time it did not give me time sync, but shows a green locked light most of the time. This happened several years ago and a fellow at Spectracom told me to change all the electrolytics on the one board that has only 4 electrolytics on it. I did and it started to work just peachy-keen. The caps I put in then were of good quality, but I decided to change them again. This did not solve the problem. The power supply voltages are all well within limits and they look clean. I seem to have plenty of, but not too much, signal. By that I mean it doesn't appear to be oscillating. The antenna is about 30' away from the receiver on a piece of coax that appears to look ok. What I do notice is that the signal looks like it's going through quite a bit of turbulence. I do not see anything that looks like interference. I've looked at the output of the filter amp inside the 8170 and what I see is the signal dithering in amplitude quite rapidly and sometimes squaring off for a moment - sort of what you would expect to see during the Diurnal Shift periods of the day. I can see the 10 dB drops, but they're not very clean due to the rapid dithering. I've checked the antenna connections and tried different azimuth headings. The location and azimuth it has been for years still seems to be the best. Looking at the output of what I'm guessing is a Schmitt Trigger, I see the ST's output jumping from 0 to +5, but erratically, which considering the received signal, makes sense. I'm wondering if I'm just in a period of time that's receiving a poor quality signal? It doesn't seem like WWVB's new phase-modulated format should be causing this kind of a problem. All observations, opinions and suggestions are welcome. Thanks, Burt, K6OQK Burt I. Weiner Associates Broadcast Technical Services Glendale, California U.S.A. b...@att.net www.biwa.cc K6OQK ___ 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] Phase noise measurement with a scope
My point was, that DSO is basically an ADC. Therefore, there is some amount of noise, nonlinearity and drift, limiting the jitter measurement. Do you think any method can dig more information from given data than sinc() interpolation and zero-crossing computation? The cross-spectrum averaging does indeed do just that, relying on two ADCs to produce uncorrelated noise, which can be averaged out. Or am I misunderstanding your point? Nothing against that. It depends on what noise level after averaging you require. I only posted my experience with a very low-quality DSO, which has 100psRMS single-shot. Using sinc() interpolation, but my point was, that I suppose there is no way to obtain better single-shot performance than this. To average out 100psRMS to, say, 1psRMS, it would require 10^4 edges (under the assumption, that the 100psRMS is well behaved noise). What performance it could yield with a better scope? I hope I'll try LC584AL some day, I guess it might give sth like 10psRMS single-shot... Regards, Marek ___ 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] Spectracom 8170 Time of Day grief...
Burt There is nothing wrong with your 8170. WWVB no longer allows it to work correctly because of the phase modulation. They went to all psk about 1 month ago. They had been reverting back twice a day for things like the 8170. So the ole 8170 is dead. You need to build something like the d-psk-r to get it going though I have not had time to actually add the am phase flipper precisely for the likes of a 8170. I have one also. Sorry Paul WB8TSL On Wed, Jun 12, 2013 at 5:35 PM, Burt I. Weiner b...@att.net wrote: My good old Spectracom 8170 is not setting time. I don't use it for frequency, just as a clock for my Hazetorium. I live about 20 minutes north of downtown Los Angles in Glendale. The antenna I'm using is the Ferrite Rod loop in PVC that came with the 8170. It's located on my back porch just laying on the floor with its maximum pickup direction towards Boulder, Colorado. It has worked reliably for many years in that location. The symptoms are... One day about a month ago I noticed that it seemed to be in the start mode, that is, the far left digit was flashing between 0, 1, 2, and a lot of 4's, and the left most digits were counting time since an apparent restart. Zeros and ones are the logical data states, two is a place holder and four indicates data errors. I'm not aware of it having lost primary power, but it's not on a UPS. In a week's time it did not give me time sync, but shows a green locked light most of the time. This happened several years ago and a fellow at Spectracom told me to change all the electrolytics on the one board that has only 4 electrolytics on it. I did and it started to work just peachy-keen. The caps I put in then were of good quality, but I decided to change them again. This did not solve the problem. The power supply voltages are all well within limits and they look clean. I seem to have plenty of, but not too much, signal. By that I mean it doesn't appear to be oscillating. The antenna is about 30' away from the receiver on a piece of coax that appears to look ok. What I do notice is that the signal looks like it's going through quite a bit of turbulence. I do not see anything that looks like interference. I've looked at the output of the filter amp inside the 8170 and what I see is the signal dithering in amplitude quite rapidly and sometimes squaring off for a moment - sort of what you would expect to see during the Diurnal Shift periods of the day. I can see the 10 dB drops, but they're not very clean due to the rapid dithering. I've checked the antenna connections and tried different azimuth headings. The location and azimuth it has been for years still seems to be the best. Looking at the output of what I'm guessing is a Schmitt Trigger, I see the ST's output jumping from 0 to +5, but erratically, which considering the received signal, makes sense. I'm wondering if I'm just in a period of time that's receiving a poor quality signal? It doesn't seem like WWVB's new phase-modulated format should be causing this kind of a problem. All observations, opinions and suggestions are welcome. Thanks, Burt, K6OQK Burt I. Weiner Associates Broadcast Technical Services Glendale, California U.S.A. b...@att.net www.biwa.cc K6OQK __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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] Spectracom 8170 Time of Day grief...
Burt One other tidbit the phase mod will exactly cause what you see. Spectracom used phase tracking to demodulate the AM time signal. Thats why its nuts. On Wed, Jun 12, 2013 at 5:49 PM, paul swed paulsw...@gmail.com wrote: Burt There is nothing wrong with your 8170. WWVB no longer allows it to work correctly because of the phase modulation. They went to all psk about 1 month ago. They had been reverting back twice a day for things like the 8170. So the ole 8170 is dead. You need to build something like the d-psk-r to get it going though I have not had time to actually add the am phase flipper precisely for the likes of a 8170. I have one also. Sorry Paul WB8TSL On Wed, Jun 12, 2013 at 5:35 PM, Burt I. Weiner b...@att.net wrote: My good old Spectracom 8170 is not setting time. I don't use it for frequency, just as a clock for my Hazetorium. I live about 20 minutes north of downtown Los Angles in Glendale. The antenna I'm using is the Ferrite Rod loop in PVC that came with the 8170. It's located on my back porch just laying on the floor with its maximum pickup direction towards Boulder, Colorado. It has worked reliably for many years in that location. The symptoms are... One day about a month ago I noticed that it seemed to be in the start mode, that is, the far left digit was flashing between 0, 1, 2, and a lot of 4's, and the left most digits were counting time since an apparent restart. Zeros and ones are the logical data states, two is a place holder and four indicates data errors. I'm not aware of it having lost primary power, but it's not on a UPS. In a week's time it did not give me time sync, but shows a green locked light most of the time. This happened several years ago and a fellow at Spectracom told me to change all the electrolytics on the one board that has only 4 electrolytics on it. I did and it started to work just peachy-keen. The caps I put in then were of good quality, but I decided to change them again. This did not solve the problem. The power supply voltages are all well within limits and they look clean. I seem to have plenty of, but not too much, signal. By that I mean it doesn't appear to be oscillating. The antenna is about 30' away from the receiver on a piece of coax that appears to look ok. What I do notice is that the signal looks like it's going through quite a bit of turbulence. I do not see anything that looks like interference. I've looked at the output of the filter amp inside the 8170 and what I see is the signal dithering in amplitude quite rapidly and sometimes squaring off for a moment - sort of what you would expect to see during the Diurnal Shift periods of the day. I can see the 10 dB drops, but they're not very clean due to the rapid dithering. I've checked the antenna connections and tried different azimuth headings. The location and azimuth it has been for years still seems to be the best. Looking at the output of what I'm guessing is a Schmitt Trigger, I see the ST's output jumping from 0 to +5, but erratically, which considering the received signal, makes sense. I'm wondering if I'm just in a period of time that's receiving a poor quality signal? It doesn't seem like WWVB's new phase-modulated format should be causing this kind of a problem. All observations, opinions and suggestions are welcome. Thanks, Burt, K6OQK Burt I. Weiner Associates Broadcast Technical Services Glendale, California U.S.A. b...@att.net www.biwa.cc K6OQK __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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] Update on the d-psk-r schematic costas loop
Good catch by Russ of time-nuttery fame. Wrong ground on the 74hc390. Updated schematic attached. Thanks Rudd Regards Paul WB8TSL WWVB dpskr Costas_Div nu 12Mhz 06122013.sch Description: Binary data ___ 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] Unit tests for time calculations
12/31/1998 00:00:00 EST + 5184001 seconds = Time Date in UTC 01/01/1991 11:01 AM EST = XX/XX/ XX:XX UTC Doug, This is difficult (or impossible) to do right; at a minimum you need a table of all past, current, and future national timezone definitions, DST rules by locale, and leap seconds. Start by defining your problem very explicitly, down to each character, digit, integer, and allowable range. I think there is a timezone mailing list that would better be able to answer your question. They may point you to a number of well tested libraries that already do this sort of thing. /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 to list and GPSDO questions
Hello to the list. I saw on K3PGP's site a mention that the UT-41 GPS receiver had a 10KHz signal on-board so I decided, why not build a GPSDO for my new HP 5334B? Unfortunately the one I bought doesn't have a 10KHz point, and the board doesn't even pull out the 1PPS signal from the chip. So I've had to switch gears and will go with VE2ZAZ's board. I've got a Motorola UT+ on order, but I was wondering about using the board's LED output as a sort of low-rent source of 1PPS. Would the short term accuracy be too bad to even bother with? Has anyone done any tests to see if the LED and 1PPS signals are essentially the same signal on one of these cheapo boards, or at least to find out how often the LED output is corrected? The one I got has a Prolific PL-6313 chip. Bob - AE6RV ___ 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] Unit tests for time calculations
I think it depends on you definition of Unit Test. Some people do a sanity check time test just to verify the function works. Those who want a better test will use a code coverage tool and will add test cases untill every path through the function is exercised. One thing to remember is NO TEST can prove a function correct, you can only prove it wrong. No matter how many tests you do yo only gain confedance that the function is likely not bad. A famous proof goes like this: Can I divide 60 by 1? Yes of course, by 2? yes, by 3, by 4, by 5 , by 6 all yes but this is going to slow so let's try 10, 20 ,30. Ok end of proof: 60 is divisible by all integers. Sady, software unit tests can only be as good as this proof. So just use enough tet cases to exercise every code path and then you will know there is nothing stupid wrong with it. On Wed, Jun 12, 2013 at 8:02 PM, Tom Van Baak t...@leapsecond.com wrote: 12/31/1998 00:00:00 EST + 5184001 seconds = Time Date in UTC 01/01/1991 11:01 AM EST = XX/XX/ XX:XX UTC Doug, This is difficult (or impossible) to do right; at a minimum you need a table of all past, current, and future national timezone definitions, DST rules by locale, and leap seconds. Start by defining your problem very explicitly, down to each character, digit, integer, and allowable range. I think there is a timezone mailing list that would better be able to answer your question. They may point you to a number of well tested libraries that already do this sort of thing. /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. -- 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] Spectracom 8170 Time of Day grief...
Paul, U... What a revolting development this is. My 9150-52054 have a smaller readout out that I can't see without climbing up on my bench, so I suppose I will no longer know what time it is. I've never really had to delve into the 8170 so I wasn't up to speed on how they derived the data from the carrier prior to the new PSK format. I was under the misunderstanding that it was strictly from amplitude variation. I guess it is, except for the manner in which they determine the changes. Please tell me about the d-psk-r you mentioned. Also do you know the times of day WWVB reverts to the old method and for how long? I'll have to go to their site and see. Burt, K6OQK At 04:46 PM 6/12/2013, time-nuts-requ...@febo.com wrote Burt One other tidbit the phase mod will exactly cause what you see. Spectracom used phase tracking to demodulate the AM time signal. Thats why its nuts. On Wed, Jun 12, 2013 at 5:49 PM, paul swed paulsw...@gmail.com wrote: Burt There is nothing wrong with your 8170. WWVB no longer allows it to work correctly because of the phase modulation. They went to all psk about 1 month ago. They had been reverting back twice a day for things like the 8170. So the ole 8170 is dead. You need to build something like the d-psk-r to get it going though I have not had time to actually add the am phase flipper precisely for the likes of a 8170. I have one also. Sorry Paul WB8TSL On Wed, Jun 12, 2013 at 5:35 PM, Burt I. Weiner b...@att.net wrote: My good old Spectracom 8170 is not setting time. I don't use it for frequency, just as a clock for my Hazetorium. I live about 20 minutes north of downtown Los Angles in Glendale. The antenna I'm using is the Ferrite Rod loop in PVC that came with the 8170. It's located on my back porch just laying on the floor with its maximum pickup direction towards Boulder, Colorado. It has worked reliably for many years in that location. The symptoms are... Burt I. Weiner Associates Broadcast Technical Services Glendale, California U.S.A. b...@att.net www.biwa.cc K6OQK ___ 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] Phase noise measurement with a scope
My dim memory says there is some analog way to multiply the phase noise. What does that? Then it might be easier to measure. On Wed, Jun 12, 2013 at 2:36 PM, Marek Peca ma...@duch.cz wrote: My point was, that DSO is basically an ADC. Therefore, there is some amount of noise, nonlinearity and drift, limiting the jitter measurement. Do you think any method can dig more information from given data than sinc() interpolation and zero-crossing computation? The cross-spectrum averaging does indeed do just that, relying on two ADCs to produce uncorrelated noise, which can be averaged out. Or am I misunderstanding your point? Nothing against that. It depends on what noise level after averaging you require. I only posted my experience with a very low-quality DSO, which has 100psRMS single-shot. Using sinc() interpolation, but my point was, that I suppose there is no way to obtain better single-shot performance than this. To average out 100psRMS to, say, 1psRMS, it would require 10^4 edges (under the assumption, that the 100psRMS is well behaved noise). What performance it could yield with a better scope? I hope I'll try LC584AL some day, I guess it might give sth like 10psRMS single-shot... Regards, Marek __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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.
