Re: [time-nuts] NAA experiments as a reference
Paul wrote: OK have been experimenting with a simple vlf receiver for 24 Khz. Using an HP 3335a as the LO. The Tracor 900 d-msk-r circuit. * * * I was hoping to see a 100 Hz somewhat steady signal in phase relationship to my local 100 Hz reference. Thats absolutely not apparent. Sorry Paul. I think this method may be a bust. So what you have is a 100 Hz signal that comes and goes according to the mark/space timing. (Or if you didn't filter the other frequency out you'd have 100 Hz and 300 Hz signals representing mark and space.) Chapters and volumes have been written about carrier recovery with FSK signals. Read up and you'll find more than enough possible solutions to make your head spin. Given what you have so far -- a 100 Hz signal that comes and goes according to the mark/space timing -- you could try using the 100 Hz as the reference to a PLL with a very long time constant (compared to the symbol rate), much the way that color televisions used to keep their color subcarriers locked to the video signal's color burst, or a synchronous AM detector rides out carrier fading. I'm not saying that will be the best you can do with the incoming NAA signal -- for that, read up on carrier recovery -- but it is the next logical step on your current path. Also of note, since the MSK signal is FSK, not binary (180 degree) PSK, the frequency multiplication didn't do anything magical for you (like removing the modulation, which it would have done with a BPSK signal such as WWVB). What it did for Tracor was produce the 100 Hz signal needed by the rest of the box, when the existing LO was adjustable only in 100 Hz increments and the mark and/or space frequencies would, therefore, have been 50 Hz using the existing LO. (Doubling also widened the separation of the mark and space frequencies from a delta of 100 Hz to a delta of 200 Hz, thus making the filtering a bit easier -- but that is not the primary reason for it.) Finally, once you are no longer tied to the Tracor 900 and its existing 100 Hz IF and detector chain, you are free to use whatever LO frequency you want. 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] Is a crystal likely to change frequency by 3% ?
On 13 Sep 2014 01:23, Alexander Pummer alex...@ieee.org wrote: just open the box, look for the wires which going to the magnet which drives the minute hand and measure the period time -- not the frequency, it is to low yes analog quarz clock slows down as the battery get old, you will be surprised, that the driver pulse's period time dos not change, but sometimes the divider chain or the mechanic skips a pulse, as the battery voltage drops further suddenly the clock mechanic or the electronic will stop working, takes less current so the battery recovers a bit, because the magnet did not used power for a while, and will run again for a while, the pause between two run time will be larger and larger so the clock looks like going slower 73 Alex So if it the mechanics skips a pulse, one really needs some method of measuring the position of the hands and recording that. In any case, the explanation you give is different to Dave McGuire. Maybe the second hand is more likely to slip if trying to fight gravity (between 30 and 0 seconds) and less likely when gravity helps (between 0 and 30 seconds) It would be interesting to see a detailed study of this. Dave ___ 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] Is a crystal likely to change frequency by 3% ?
On 13 Sep 2014 04:39, David McGaw n1...@dartmouth.edu wrote: The battery probably was going weak and the oscillator coming out of full control by the crystal. The tuning-fork crystal used in RTCs is not as high-Q as a MHz crystal. I have noticed clocks using these can go quite slow at low voltage. The crystal acts more like an inductor in this case and resonates with the increased junction capacitance at low voltage. David Two very different explanations from two different people about why clocks slow when the battery gets old. BTW Dave, please reply by my private email about whether you want the loads measured before I send them, given the VNA is at Keysight for calibration. Dave ___ 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] Is a crystal likely to change frequency by 3% ?
On Sat, Sep 13, 2014 at 8:08 AM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: So if it the mechanics skips a pulse, one really needs some method of measuring the position of the hands and recording that. Better modern quartz movements, have circuitry in the pulse driver that senses reluctance during the drive and will adjust the drive level down to save battery power if mechanical drag is low, and when the drag level is high (maybe fighting against gravity) even re-do the failed advances. The mechanical WWVB movements also have sensors for calibrating position of hour/minute/second hands (usually at a single fixed point on the dial). Tim. ___ 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] Is a crystal likely to change frequency by 3% ?
Hi In this era of “everything runs at GHz” it’s a bit tough to reach back to the sort of process used for watch IC’s. The idea is to optimize for low power / low leakage. They make enough of them that an application specific process can be used. The divide side of the chip may have an Fmax of 60 KHz at full battery voltage. By the time the battery gets to 1/2 voltage, the Fmax may have dropped to 30 KHz. The boundary is never an exact thing. It’s a “probability of working” kind of limit. Lots of possibilities. Bob On Sep 12, 2014, at 6:52 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: Dr David Kirkby Managing Director Kirkby Microwave Ltd Registered office: Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3 6DT, United Kingdom Registered in England and Wales as company number 08914892 http://www.kirkbymicrowave.co.uk/ Tel 07910 441670 / +44 7910 441670 (0900-2100 GMT) On 12 Sep 2014 12:18, Bob Camp kb...@n1k.org wrote: Hi Hi, If this is an RTC, it’s probably running off of a battery when the machine is powered down. It is far more likely that the oscillator is dropping out (stopping) rather than shifting frequency. Good point, I never thought of that. I have however noticed that analogue quartz clocks slow as the battery goes flat. But maybe too they stop and start. It would make an interesting experiment to check it, but one would need some method of logging the time from the hands. Conceptually that is not difficult, but it needs more work than I want to do. One could do it with a video camera and a fair bit of work writing the software. Probably easier is logging battery voltage and current as that should show if it starts and stops. ___ 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] Is a crystal likely to change frequency by 3% ?
there is only one magnet, which drives the fastest moving arm -- the pointer for the seconds -- the other arms are connected via gears, by the way that case with the weak periodically recovering battery is an observed one, I connected a paper chart recorder to the clock and recorded the battery voltage change and the driver pulses of the magnet -- the recorder was not able to follow the individual pulses, but the envelope 73 Alex On 9/13/2014 5:08 AM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote: On 13 Sep 2014 01:23, Alexander Pummer alex...@ieee.org wrote: just open the box, look for the wires which going to the magnet which drives the minute hand and measure the period time -- not the frequency, it is to low yes analog quarz clock slows down as the battery get old, you will be surprised, that the driver pulse's period time dos not change, but sometimes the divider chain or the mechanic skips a pulse, as the battery voltage drops further suddenly the clock mechanic or the electronic will stop working, takes less current so the battery recovers a bit, because the magnet did not used power for a while, and will run again for a while, the pause between two run time will be larger and larger so the clock looks like going slower 73 Alex So if it the mechanics skips a pulse, one really needs some method of measuring the position of the hands and recording that. In any case, the explanation you give is different to Dave McGuire. Maybe the second hand is more likely to slip if trying to fight gravity (between 30 and 0 seconds) and less likely when gravity helps (between 0 and 30 seconds) It would be interesting to see a detailed study of this. Dave ___ 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] Is a crystal likely to change frequency by 3% ?
Interesting topic! Of course I no longer wear a watch since such a habit after advancing well into retirement seems pointless but I did want to point out that perhaps you could include the Bulova Accutron in your studies. Long ago I fell on ice and landed on my wrist with the result that my space model accutron never ran again . But a year ago I asked my wife where it was and she produced it which was then entrusted to a local horologist who studied it and said he couldn't get the parts to repair it. But after he had examined it I found that it did, indeed, start running again--for a time. But then it stopped and I gave up since others skilled in the art simply wanted more for a repair than I wanted to give. But I will still admit that from time to time a watch is a good thing and I find that the seven dollar models I can buy today keep time much better than the old Accutron ever did! Encouraging regards, Lee - Original Message - From: Alexander Pummer alex...@ieee.org To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, September 13, 2014 6:44 AM Subject: Re: [time-nuts] Is a crystal likely to change frequency by 3% ? there is only one magnet, which drives the fastest moving arm -- the pointer for the seconds -- the other arms are connected via gears, by the way that case with the weak periodically recovering battery is an observed one, I connected a paper chart recorder to the clock and recorded the battery voltage change and the driver pulses of the magnet -- the recorder was not able to follow the individual pulses, but the envelope 73 Alex ___ 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] NAA experiments as a reference
Charles I literally just sat down to do some math. What you say is the same thoughts I have. The information I have on NAA says that for 200bit msk its a total of a 100 hz shift +/-50 Hz. That makes no sense I would think it would be at least +/- 100 Hz. They had in the past run a 100 bit msk. I somewhat wonder about the documentation accuracy in the tracor manual and the net. Hey it has to be true on the internet. Agree the whole tracor d-msk-rs goal is to recreate a 100 Hz signal for the PLL. The signal is only there when its on one of the signals so again you are right and that was expected. I had very high hopes that without going to the next step I would get a clue as to the quality of the underlying NAA reference to better understand if the next step had value. The jitter is so high the answers not apparent. Regards Paul WB8TSL On Sat, Sep 13, 2014 at 12:56 AM, Charles Steinmetz csteinm...@yandex.com wrote: Paul wrote: OK have been experimenting with a simple vlf receiver for 24 Khz. Using an HP 3335a as the LO. The Tracor 900 d-msk-r circuit. * * * I was hoping to see a 100 Hz somewhat steady signal in phase relationship to my local 100 Hz reference. Thats absolutely not apparent. Sorry Paul. I think this method may be a bust. So what you have is a 100 Hz signal that comes and goes according to the mark/space timing. (Or if you didn't filter the other frequency out you'd have 100 Hz and 300 Hz signals representing mark and space.) Chapters and volumes have been written about carrier recovery with FSK signals. Read up and you'll find more than enough possible solutions to make your head spin. Given what you have so far -- a 100 Hz signal that comes and goes according to the mark/space timing -- you could try using the 100 Hz as the reference to a PLL with a very long time constant (compared to the symbol rate), much the way that color televisions used to keep their color subcarriers locked to the video signal's color burst, or a synchronous AM detector rides out carrier fading. I'm not saying that will be the best you can do with the incoming NAA signal -- for that, read up on carrier recovery -- but it is the next logical step on your current path. Also of note, since the MSK signal is FSK, not binary (180 degree) PSK, the frequency multiplication didn't do anything magical for you (like removing the modulation, which it would have done with a BPSK signal such as WWVB). What it did for Tracor was produce the 100 Hz signal needed by the rest of the box, when the existing LO was adjustable only in 100 Hz increments and the mark and/or space frequencies would, therefore, have been 50 Hz using the existing LO. (Doubling also widened the separation of the mark and space frequencies from a delta of 100 Hz to a delta of 200 Hz, thus making the filtering a bit easier -- but that is not the primary reason for it.) Finally, once you are no longer tied to the Tracor 900 and its existing 100 Hz IF and detector chain, you are free to use whatever LO frequency you want. 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. ___ 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] NAA experiments as a reference
On 9/13/14, 7:33 AM, paul swed wrote: Charles I literally just sat down to do some math. What you say is the same thoughts I have. The information I have on NAA says that for 200bit msk its a total of a 100 hz shift +/-50 Hz. That makes no sense I would think it would be at least +/- 100 Hz. They had in the past run a 100 bit msk. I somewhat wonder about the documentation accuracy in the tracor manual and the net. Hey it has to be true on the internet. As I recall, MSK is FSK with the shift being half the symbol rate. I assume they're doing gaussian minimum shift keying GMSK. The mod index is typically 0.5 with gmsk. ___ 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] FRK/M100 Lamps for sale!
Hi, I have a small quantity of good used FRK/M100 lamps I am getting rid of. Offering here prior to eBay. $45.00 each which includes shipping in USA. Contact me off list. Cheers, Corby ___ 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] NAA experiments as a reference
The underlying NAA reference is UTC(USNO). How close they track it I don't know. -- 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] Correcting jitter on the 1 PPS signal from a GPS receiver.
I have 2 Trimble Resolution T receivers and I have compared the 1 PPS signal between the 2 units. They are spec'ed at 15 nS accuracy.I am seeing about 80 nS of jitter between the two. This is with about 6 satellites in view. I was thinking about ways to improve this. Since this is a stationary installation, can you use the jitter in the reported location (latitude and longitude) to correct for the 1 PPS jitter? The location data is derived using the internal GPS disciplined oscillator so both pieces of information should show the same jitter error. If you compare the reported location with the known fixed location you should be able to use that error to correct for the 1 PPS error. Does this make sense or am I missing something? Pete. ___ 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] Correcting jitter on the 1 PPS signal from a GPS receiver.
Hi Have they both completed a survey and does the survey make sense? Bob On Sep 13, 2014, at 10:41 AM, Peter Reilley pe...@reilley.com wrote: I have 2 Trimble Resolution T receivers and I have compared the 1 PPS signal between the 2 units. They are spec'ed at 15 nS accuracy.I am seeing about 80 nS of jitter between the two. This is with about 6 satellites in view. I was thinking about ways to improve this. Since this is a stationary installation, can you use the jitter in the reported location (latitude and longitude) to correct for the 1 PPS jitter? The location data is derived using the internal GPS disciplined oscillator so both pieces of information should show the same jitter error. If you compare the reported location with the known fixed location you should be able to use that error to correct for the 1 PPS error. Does this make sense or am I missing something? Pete. ___ 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] Help understanding an ADEV
Hi Andrew, Yeah, it was a pretty dumb mistake, but I think I learned my lesson. At the very least, my scripts now allow me to skip as many initial samples as I like before the data is plotted. And, the PWM version of the chip is in. It's orders of magnitude more stable than the audio DAC in the one I've been posting about. So, I'm doing testing and tuning, and will be back with still more questions. But, I'm finally starting to get reasonable results. Bob - AE6RV From: Andrew Rodland and...@cleverdomain.org To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Cc: Tom Van Baak t...@leapsecond.com Sent: Friday, September 12, 2014 4:29 PM Subject: Re: [time-nuts] Help understanding an ADEV Your intuition isn't completely wrong -- the law of averages still applies. As you provide more and more good data it will eventually overwhelm the initial bad data, and the result will get closer to correct. But it will take a *lot* of data to overwhelm even a few data points that have a deviation a hundred thousand times as large as the deviation you're trying to measure. You would probably have to run for months before you could trust the plot out to tau = 1s. Removing the bad data is a superior alternative, if you ask me :) Andrew On Thu, Sep 11, 2014 at 5:21 PM, Bob Stewart b...@evoria.net wrote: Hi Tom, And thank you very much for taking the time to look at this. No, I don't know what the heck a lot of this means, and it's no surprise that I used the wrong tool. I had noticed the first few seconds of bad data, but didn't think it would matter over long sample sessions. I'll take some time to get this together properly and see what I can find out. The new PIC arrives tomorrow, so I'll know pretty quickly if there is a big improvement in the noise. Thank you again, and everyone else who has taken even a moment of time to help me during this project! Bob From: Tom Van Baak t...@leapsecond.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, September 11, 2014 3:53 PM Subject: Re: [time-nuts] Help understanding an ADEV I've been wondering if it would be better to look in the frequency domain. I'll have to look at Tom's site to see if he has code to do that. Bob Hi Bob, Ok, I think I found the problem with your plot. There's one mistake, one misunderstanding, and a miscalibration. 1) It appears you're allowing bogus DAC readings to pollute the ADEV calculation. Based on the raw data you kindly sent, your nominal DAC value is about 2.1 volts and your DAC voltage typically changes by tens or low hundreds of microvolts. However the first couple of data points are 0.0 and 1.0 volts. The ADEV calculation is therefore seeing changes of millions (!) of microvolts. This completely messes up every ADEV calculation at every tau of your plot. You must feed clean data into any ADEV calculation. Either fix your instrumentation, or put checks in your scripts, or visually examine time series data before you blindly feed it into a statistical formula or a tool. I don't know why the plotting package you used does not show these points. Those four bogus points should have been an instant red flag. 2) Realize that we normally make ADEV plots only from phase data or from frequency data. Phase data is the net time difference (or time interval) between the DUT and the REF. Units are seconds. Frequency data is the (normalized) relative frequency difference between the DUT and the REF. This is unitless. Now in your case, you want to make an ADEV plot from DAC data. This is ok, since DAC voltage is essentially a proxy for frequency offset. But you can't feed DAC or frequency data into the adev1 tool, since that tool expects phase data only. Make sense? The details are that ADEV is based on the 2nd difference in phase, which is the 1st difference in frequency. You have accidentally feed frequency data into a phase calculation and the result is some sort of 3rd difference! This is not what you want. The solution is either to integrate your DAC or frequency data so it looks like phase. Or, just use a tool that will take frequency data instead of phase data. Stable32 and TimeLab offer this option. Or you can use adev1f.exe (www.leapsecond.com/tools/) which I just made for you. 3) To get an accurate ADEV plot you must scale your arbitrary DAC voltage to real Hz. Use the known or measured EFC offset and gain to convert absolute voltage to relative voltage to relative frequency error. This data can then be given to Stable32 (Data Type: Freq), or TimeLab (File data: Frequency difference), or feed directly to the new tool, adev1f. Let me know if you have any questions. /tvb ___ time-nuts mailing list
Re: [time-nuts] Correcting jitter on the 1 PPS signal from a GPSreceiver.
Yes, both have completed their surveys. During the survey process I was getting up to 150 uS of error between the PPS pulses. Pete. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Saturday, September 13, 2014 4:33 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Correcting jitter on the 1 PPS signal from a GPSreceiver. Hi Have they both completed a survey and does the survey make sense? Bob On Sep 13, 2014, at 10:41 AM, Peter Reilley pe...@reilley.com wrote: I have 2 Trimble Resolution T receivers and I have compared the 1 PPS signal between the 2 units. They are spec'ed at 15 nS accuracy.I am seeing about 80 nS of jitter between the two. This is with about 6 satellites in view. I was thinking about ways to improve this. Since this is a stationary installation, can you use the jitter in the reported location (latitude and longitude) to correct for the 1 PPS jitter? The location data is derived using the internal GPS disciplined oscillator so both pieces of information should show the same jitter error. If you compare the reported location with the known fixed location you should be able to use that error to correct for the 1 PPS error. Does this make sense or am I missing something? Pete. ___ 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] Correcting jitter on the 1 PPS signal from a GPSreceiver.
I have 2 Trimble Resolution T receivers and I have compared the 1 PPS signal between the 2 units. They are spec'ed at 15 nS accuracy.I am seeing about 80 nS of jitter between the two. This is with about 6 satellites in view. That sounds like too much. Are you also comparing to a reference (e.g., Rb or Cs)? I was thinking about ways to improve this. Since this is a stationary installation, can you use the jitter in the reported location (latitude and longitude) to correct for the 1 PPS jitter? In theory, yes. This is essentially how DGPS (US Coast Guard Differential GPS) and how Common View GPS work. But for proper results the calculations must be done on a per-satellite basis rather than at the final navigation (NMEA output) or timing (1PPS output) level. The location data is derived using the internal GPS disciplined oscillator so both pieces of information should show the same jitter error. You'd think so. But it turns out much of the jitter is due to the antenna and receiver itself. Remember it's trying to detect and track a signal that's so weak you can't see the waveform for the noise. And it has an imperfect internal clock. Consequently, much of the error you see in the nav and timing solutions is not correlated between two (or more) receivers. Just how much I can't say, but it would be nice if you were able to measure this. If you compare the reported location with the known fixed location you should be able to use that error to correct for the 1 PPS error. Again, read up on how DGPS and CV-GPS work; also RINEX. It's good stuff. AFAIK the Resolution-T can output the necessary per-SV raw data that you need to pull this off. The Motorola VP also does. The T versions of ublox too. Of course, all the fancy expensive geodetic receivers support this. /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] Help understanding an ADEV
On 11 Sep 2014 04:35, Bob Stewart b...@evoria.net wrote: I've ordered the PWM version of the PIC, and hopefully, since it's the motor control version (as opposed to the audio version) it will have much better noise performance. I don't know the PIC but I would have thought chips for audio would be optimised for low noise far less than one for driving motors. Dr David Kirkby Managing Director Kirkby Microwave Ltd Registered office: Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3 6DT, United Kingdom Registered in England and Wales as company number 08914892 http://www.kirkbymicrowave.co.uk/ Tel 07910 441670 / +44 7910 441670 (0900-2100 GMT) ___ 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] Help understanding an ADEV
OOPS! CORRECTION. I don't know the PIC but I would have thought chips for audio would be optimised for low noise far MOOR than one for driving motors. Ears are more sensitive to a bit of noise than motors. I assume I have misunderstood you. Dave ___ 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] Help understanding an ADEV
Hi David, It's an odd situation. From the datasheet: Note: The DAC module is designed specifically for audio applications and is not recommended for control type applications. I had hoped that it wouldn't be a problem for driving an OCXO, but my mistake. The datasheet also notes that the DAC has 16-bit resolution but only 14-bit accuracy. It didn't seem to have even that at DC. The PWM version doesn't have any escape clauses. You set x parameters and it's supposed to be 16-bits wide. Maybe audio means within the human auditory passband? Bob From: Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, September 13, 2014 4:27 PM Subject: Re: [time-nuts] Help understanding an ADEV On 11 Sep 2014 04:35, Bob Stewart b...@evoria.net wrote: I've ordered the PWM version of the PIC, and hopefully, since it's the motor control version (as opposed to the audio version) it will have much better noise performance. I don't know the PIC but I would have thought chips for audio would be optimised for low noise far less than one for driving motors. Dr David Kirkby Managing Director Kirkby Microwave Ltd Registered office: Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3 6DT, United Kingdom Registered in England and Wales as company number 08914892 http://www.kirkbymicrowave.co.uk/ Tel 07910 441670 / +44 7910 441670 (0900-2100 GMT) ___ 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] Looking for the spec on a chokering
AeroAntenna AT27751995 https://plus.google.com/u/0/photos/111617808980322733757/albums/6058672650441867201 -pete ___ 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] Correcting jitter on the 1 PPS signal from a GPS receiver.
On Sat, Sep 13, 2014 at 1:33 PM, Bob Camp kb...@n1k.org wrote: Hi Have they both completed a survey and does the survey make sense? Are all of the cables the same length? That includes the cables from antenna to receiver and the cable carrying the 1PPS from the receiver to where you are measuring. And also are you SURE you are measuring the correct end of the pulse, you want the raising edge. It is easy to invert the pulse and therefore measure the falling edge. 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] Correcting jitter on the 1 PPS signal from a GPSreceiver.
Hi When you read back the survey location do they make sense? If the antennas are X m apart on at an angle of Y, how close do the locations agree with this? Often the survey process is not adequate to ensure a good fix with this or that antenna. Bob On Sep 13, 2014, at 5:00 PM, Peter Reilley pe...@reilley.com wrote: Yes, both have completed their surveys. During the survey process I was getting up to 150 uS of error between the PPS pulses. Pete. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Saturday, September 13, 2014 4:33 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Correcting jitter on the 1 PPS signal from a GPSreceiver. Hi Have they both completed a survey and does the survey make sense? Bob On Sep 13, 2014, at 10:41 AM, Peter Reilley pe...@reilley.com wrote: I have 2 Trimble Resolution T receivers and I have compared the 1 PPS signal between the 2 units. They are spec'ed at 15 nS accuracy.I am seeing about 80 nS of jitter between the two. This is with about 6 satellites in view. I was thinking about ways to improve this. Since this is a stationary installation, can you use the jitter in the reported location (latitude and longitude) to correct for the 1 PPS jitter? The location data is derived using the internal GPS disciplined oscillator so both pieces of information should show the same jitter error. If you compare the reported location with the known fixed location you should be able to use that error to correct for the 1 PPS error. Does this make sense or am I missing something? Pete. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Correcting jitter on the 1 PPS signal from a GPS receiver.
Hi Where are you getting the “15 ns accuracy” number from? When I look at the Trimble spec’s they have a number of errors described (like sawtooth) that are larger than 15 ns. Bob On Sep 13, 2014, at 10:41 AM, Peter Reilley pe...@reilley.com wrote: I have 2 Trimble Resolution T receivers and I have compared the 1 PPS signal between the 2 units. They are spec'ed at 15 nS accuracy.I am seeing about 80 nS of jitter between the two. This is with about 6 satellites in view. I was thinking about ways to improve this. Since this is a stationary installation, can you use the jitter in the reported location (latitude and longitude) to correct for the 1 PPS jitter? The location data is derived using the internal GPS disciplined oscillator so both pieces of information should show the same jitter error. If you compare the reported location with the known fixed location you should be able to use that error to correct for the 1 PPS error. Does this make sense or am I missing something? Pete. ___ 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] Looking for the spec on a chokering
Look for AERAT2775_42+CR at http://www.ngs.noaa.gov/ANTCAL/Antennas.jsp?manu=AeroAntenna http://www.ngs.noaa.gov/ANTCAL/LoadImage?name=AERAT2775_42%2BCR%2BNONE.gif Even if the phase offsets are different from what is printed on your chokering, they do look similar. Do you have the antenna also, or only the chokering? What spec's are you looking for? /Björn AeroAntenna AT27751995 https://plus.google.com/u/0/photos/111617808980322733757/albums/6058672650441867201 -pete ___ 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] NAA experiments as a reference
Thats what I am trying to understand. How good is good. Is it a useful replacement for wwvb. Certainly kicks butt in signal strength. Regards Paul WB8TSL On Sat, Sep 13, 2014 at 2:03 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: The underlying NAA reference is UTC(USNO). How close they track it I don't know. -- 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] Looking for the spec on a chokering
I have just two of the rings that look like this. Sadly the spec sheets are missing from the box. -pete On Sat, Sep 13, 2014 at 3:38 PM, Björn Gabrielsson b...@lysator.liu.se wrote: Look for AERAT2775_42+CR at http://www.ngs.noaa.gov/ANTCAL/Antennas.jsp?manu=AeroAntenna http://www.ngs.noaa.gov/ANTCAL/LoadImage?name=AERAT2775_42%2BCR%2BNONE.gif Even if the phase offsets are different from what is printed on your chokering, they do look similar. Do you have the antenna also, or only the chokering? What spec's are you looking for? /Björn AeroAntenna AT27751995 https://plus.google.com/u/0/photos/111617808980322733757/albums/6058672650441867201 -pete ___ 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] Correcting jitter on the 1 PPS signal from a GPSreceiver.
I see in the Trimble Resolution T data sheet that they say that the PPS signal is within 15 nS to GPS or UTC (1 Sigma) when using an over determined solution in stationary mode.. I take this to mean that the PPS signal should be within 15 nS and that comparing 2 units that there should be no more than 30 nS between the two edges. This is comparing the rising edges. Pete. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Saturday, September 13, 2014 6:26 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Correcting jitter on the 1 PPS signal from a GPSreceiver. Hi Where are you getting the 15 ns accuracy number from? When I look at the Trimble spec's they have a number of errors described (like sawtooth) that are larger than 15 ns. Bob On Sep 13, 2014, at 10:41 AM, Peter Reilley pe...@reilley.com wrote: I have 2 Trimble Resolution T receivers and I have compared the 1 PPS signal between the 2 units. They are spec'ed at 15 nS accuracy.I am seeing about 80 nS of jitter between the two. This is with about 6 satellites in view. I was thinking about ways to improve this. Since this is a stationary installation, can you use the jitter in the reported location (latitude and longitude) to correct for the 1 PPS jitter? The location data is derived using the internal GPS disciplined oscillator so both pieces of information should show the same jitter error. If you compare the reported location with the known fixed location you should be able to use that error to correct for the 1 PPS error. Does this make sense or am I missing something? Pete. ___ 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] Correcting jitter on the 1 PPS signal from a GPSreceiver.
The cables are not exactly the same lengths. Differences in length will result in a fixed offset. I am not concerned about such fixed errors, only jitter. I am comparing the rising edges which is what the spec defines as the reference edge. Pete. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Saturday, September 13, 2014 6:12 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Correcting jitter on the 1 PPS signal from a GPSreceiver. On Sat, Sep 13, 2014 at 1:33 PM, Bob Camp kb...@n1k.org wrote: Hi Have they both completed a survey and does the survey make sense? Are all of the cables the same length? That includes the cables from antenna to receiver and the cable carrying the 1PPS from the receiver to where you are measuring. And also are you SURE you are measuring the correct end of the pulse, you want the raising edge. It is easy to invert the pulse and therefore measure the falling edge. 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.
[time-nuts] Have some Leica/AeroAntenna Tech Inc Choke Ring antennas for sale
I've acquired a few new in the box Leica/AeroAntennas. Some boxes have been opened. https://plus.google.com/u/0/photos/111617808980322733757/albums/6052074218781475313 The complete assemble is Leica P/N 10147 The 'puck' antenna is P/N 10160 I would like to have Time-Nuts get first dibs Does $100 + shipping sound reasonable ? The box is 16 x 16 x 16 and weighs 11 lbs. -pete ___ 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] Correcting jitter on the 1 PPS signal from a GPSreceiver.
Hi I’m sure they expect you to take out the sawtooth error before you do the comparison. Are you doing that? Bob On Sep 13, 2014, at 6:41 PM, Peter Reilley pe...@reilley.com wrote: I see in the Trimble Resolution T data sheet that they say that the PPS signal is within 15 nS to GPS or UTC (1 Sigma) when using an over determined solution in stationary mode.. I take this to mean that the PPS signal should be within 15 nS and that comparing 2 units that there should be no more than 30 nS between the two edges. This is comparing the rising edges. Pete. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Saturday, September 13, 2014 6:26 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Correcting jitter on the 1 PPS signal from a GPSreceiver. Hi Where are you getting the 15 ns accuracy number from? When I look at the Trimble spec's they have a number of errors described (like sawtooth) that are larger than 15 ns. Bob On Sep 13, 2014, at 10:41 AM, Peter Reilley pe...@reilley.com wrote: I have 2 Trimble Resolution T receivers and I have compared the 1 PPS signal between the 2 units. They are spec'ed at 15 nS accuracy.I am seeing about 80 nS of jitter between the two. This is with about 6 satellites in view. I was thinking about ways to improve this. Since this is a stationary installation, can you use the jitter in the reported location (latitude and longitude) to correct for the 1 PPS jitter? The location data is derived using the internal GPS disciplined oscillator so both pieces of information should show the same jitter error. If you compare the reported location with the known fixed location you should be able to use that error to correct for the 1 PPS error. Does this make sense or am I missing something? Pete. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Have some Leica/AeroAntenna Tech Inc Choke Ring antennas for sale
Forgot .. I'm in Portland, Oregon 97217 -pete On Sat, Sep 13, 2014 at 5:00 PM, Pete Lancashire p...@petelancashire.com wrote: I've acquired a few new in the box Leica/AeroAntennas. Some boxes have been opened. https://plus.google.com/u/0/photos/111617808980322733757/albums/6052074218781475313 The complete assemble is Leica P/N 10147 The 'puck' antenna is P/N 10160 I would like to have Time-Nuts get first dibs Does $100 + shipping sound reasonable ? The box is 16 x 16 x 16 and weighs 11 lbs. -pete ___ 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] Have some Leica/AeroAntenna Tech Inc Choke Ring antennas for sale
Hi Pete, I'll take a couple of these of your hands if possible. I'm in Australia, but using a shipping agent in California, so it'll just be domestic freight. Let me know. david dho...@gmail.com I've acquired a few new in the box Leica/AeroAntennas. Some boxes have been opened. https://plus.google.com/u/0/photos/111617808980322733757/albums/6052074218781475313 The complete assemble is Leica P/N 10147 The 'puck' antenna is P/N 10160 I would like to have Time-Nuts get first dibs Does $100 + shipping sound reasonable ? The box is 16 x 16 x 16 and weighs 11 lbs. -pete ___ 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] Have some Leica/AeroAntenna Tech Inc Choke Ring antennas for sale
Sorry Everyone, I thought I replied only to Pete. david Hi Pete, I'll take a couple of these of your hands if possible. I'm in Australia, but using a shipping agent in California, so it'll just be domestic freight. Let me know. david dho...@gmail.com I've acquired a few new in the box Leica/AeroAntennas. Some boxes have been opened. https://plus.google.com/u/0/photos/111617808980322733757/albums/6052074218781475313 The complete assemble is Leica P/N 10147 The 'puck' antenna is P/N 10160 I would like to have Time-Nuts get first dibs Does $100 + shipping sound reasonable ? The box is 16 x 16 x 16 and weighs 11 lbs. -pete ___ 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] Have some Leica/AeroAntenna Tech Inc Choke Ring antennas for sale
Hi Pete, I'd like to tentatively speak for one. Thanks! Andy ◉ Bardagjy.com ◉ +1-404-964-1641 On Sep 13, 2014, at 5:13 PM, Pete Lancashire p...@petelancashire.com wrote: Forgot .. I'm in Portland, Oregon 97217 -pete On Sat, Sep 13, 2014 at 5:00 PM, Pete Lancashire p...@petelancashire.com wrote: I've acquired a few new in the box Leica/AeroAntennas. Some boxes have been opened. https://plus.google.com/u/0/photos/111617808980322733757/albums/6052074218781475313 The complete assemble is Leica P/N 10147 The 'puck' antenna is P/N 10160 I would like to have Time-Nuts get first dibs Does $100 + shipping sound reasonable ? The box is 16 x 16 x 16 and weighs 11 lbs. -pete ___ 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] Have some Leica/AeroAntenna Tech Inc Choke Ring antennas for sale
I have been told this is the spec sheet, but I can't say for sure since it does not say Leica http://petelancashire.com/pictures/LeicaL1Choke-ring_AT575-90_G.pdf -pete On Sat, Sep 13, 2014 at 5:00 PM, Pete Lancashire p...@petelancashire.com wrote: I've acquired a few new in the box Leica/AeroAntennas. Some boxes have been opened. https://plus.google.com/u/0/photos/111617808980322733757/albums/6052074218781475313 The complete assemble is Leica P/N 10147 The 'puck' antenna is P/N 10160 I would like to have Time-Nuts get first dibs Does $100 + shipping sound reasonable ? The box is 16 x 16 x 16 and weighs 11 lbs. -pete ___ 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] Have some Leica/AeroAntenna Tech Inc Choke Ring antennas for sale
David, I going to limit to one only at this price. Want to make sure as many list members get the chance to have one. Hope you understand -pete On Sat, Sep 13, 2014 at 5:18 PM, davidh dho...@gmail.com wrote: Hi Pete, I'll take a couple of these of your hands if possible. I'm in Australia, but using a shipping agent in California, so it'll just be domestic freight. Let me know. david dho...@gmail.com I've acquired a few new in the box Leica/AeroAntennas. Some boxes have been opened. https://plus.google.com/u/0/photos/111617808980322733757/ albums/6052074218781475313 The complete assemble is Leica P/N 10147 The 'puck' antenna is P/N 10160 I would like to have Time-Nuts get first dibs Does $100 + shipping sound reasonable ? The box is 16 x 16 x 16 and weighs 11 lbs. -pete ___ 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] Correcting jitter on the 1 PPS signal from a GPSreceiver.
Within 15 ns to GPS or UTC (1 Sigma) means that the 1 sigma spread is 30ns. You have two units and assuming completely uncorrelated errors that would mean expected 1 sigma spread between them, of 42ns. Seeing frequent cases of 80ns delta when the 1 sigma spread is 42ns, should not be surprising. Tim N3QE On Sat, Sep 13, 2014 at 6:41 PM, Peter Reilley pe...@reilley.com wrote: I see in the Trimble Resolution T data sheet that they say that the PPS signal is within 15 nS to GPS or UTC (1 Sigma) when using an over determined solution in stationary mode.. I take this to mean that the PPS signal should be within 15 nS and that comparing 2 units that there should be no more than 30 nS between the two edges. This is comparing the rising edges. Pete. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Saturday, September 13, 2014 6:26 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Correcting jitter on the 1 PPS signal from a GPSreceiver. Hi Where are you getting the 15 ns accuracy number from? When I look at the Trimble spec's they have a number of errors described (like sawtooth) that are larger than 15 ns. Bob On Sep 13, 2014, at 10:41 AM, Peter Reilley pe...@reilley.com wrote: I have 2 Trimble Resolution T receivers and I have compared the 1 PPS signal between the 2 units. They are spec'ed at 15 nS accuracy.I am seeing about 80 nS of jitter between the two. This is with about 6 satellites in view. I was thinking about ways to improve this. Since this is a stationary installation, can you use the jitter in the reported location (latitude and longitude) to correct for the 1 PPS jitter? The location data is derived using the internal GPS disciplined oscillator so both pieces of information should show the same jitter error. If you compare the reported location with the known fixed location you should be able to use that error to correct for the 1 PPS error. Does this make sense or am I missing something? Pete. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Have some Leica/AeroAntenna Tech Inc Choke Ringantennas for sale
I'll speak for one of the antennas... Shipping will be to zip code 35750. Let me know the cost and I'll pay immediately. How do you prefer to get payment? Paypal is good for me, or personal check if you desire. dave M Pete Lancashire wrote: I've acquired a few new in the box Leica/AeroAntennas. Some boxes have been opened. https://plus.google.com/u/0/photos/111617808980322733757/albums/6052074218781475313 The complete assemble is Leica P/N 10147 The 'puck' antenna is P/N 10160 I would like to have Time-Nuts get first dibs Does $100 + shipping sound reasonable ? The box is 16 x 16 x 16 and weighs 11 lbs. -pete ___ 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] Correcting jitter on the 1 PPS signal from a GPSreceiver.
Hi If you add the +/- 20 ns of sawtooth on top of that you can quickly get some pretty big numbers. Bob On Sep 13, 2014, at 8:39 PM, Tim Shoppa tsho...@gmail.com wrote: Within 15 ns to GPS or UTC (1 Sigma) means that the 1 sigma spread is 30ns. You have two units and assuming completely uncorrelated errors that would mean expected 1 sigma spread between them, of 42ns. Seeing frequent cases of 80ns delta when the 1 sigma spread is 42ns, should not be surprising. Tim N3QE On Sat, Sep 13, 2014 at 6:41 PM, Peter Reilley pe...@reilley.com wrote: I see in the Trimble Resolution T data sheet that they say that the PPS signal is within 15 nS to GPS or UTC (1 Sigma) when using an over determined solution in stationary mode.. I take this to mean that the PPS signal should be within 15 nS and that comparing 2 units that there should be no more than 30 nS between the two edges. This is comparing the rising edges. Pete. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Saturday, September 13, 2014 6:26 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Correcting jitter on the 1 PPS signal from a GPSreceiver. Hi Where are you getting the 15 ns accuracy number from? When I look at the Trimble spec's they have a number of errors described (like sawtooth) that are larger than 15 ns. Bob On Sep 13, 2014, at 10:41 AM, Peter Reilley pe...@reilley.com wrote: I have 2 Trimble Resolution T receivers and I have compared the 1 PPS signal between the 2 units. They are spec'ed at 15 nS accuracy.I am seeing about 80 nS of jitter between the two. This is with about 6 satellites in view. I was thinking about ways to improve this. Since this is a stationary installation, can you use the jitter in the reported location (latitude and longitude) to correct for the 1 PPS jitter? The location data is derived using the internal GPS disciplined oscillator so both pieces of information should show the same jitter error. If you compare the reported location with the known fixed location you should be able to use that error to correct for the 1 PPS error. Does this make sense or am I missing something? Pete. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Last of the Leica Choke Ring antennas has been spoken for
There is a slim chance more will show up If still interested I will put your name on a list -pete PHEW .. that was quick ___ 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] Have some Leica/AeroAntenna Tech Inc Choke Ring antennas for sale
The last one has been spoken for. I'll start a list if anyone is still interested, there is a slim chance others may show up. -pete On Sat, Sep 13, 2014 at 5:00 PM, Pete Lancashire p...@petelancashire.com wrote: I've acquired a few new in the box Leica/AeroAntennas. Some boxes have been opened. https://plus.google.com/u/0/photos/111617808980322733757/albums/6052074218781475313 The complete assemble is Leica P/N 10147 The 'puck' antenna is P/N 10160 I would like to have Time-Nuts get first dibs Does $100 + shipping sound reasonable ? The box is 16 x 16 x 16 and weighs 11 lbs. -pete ___ 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] Correcting jitter on the 1 PPS signal from aGPSreceiver.
Pete, Bob, For data on a Resolution-T that I tested see http://leapsecond.com/pages/res-t/ What I found: the raw 1PPS has a standard deviation of about 13 ns; with sawtooth correction that drops to about 6 ns. If that sounds too good to be true, I can double check the raw data, or even re-run the test. I still have the same Trimble board; maybe more than one of them. So my suggestion is to try to duplicate this level of performance first, for each of your two units separately. Only then run the test comparing them against themselves. /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] Correcting jitter on the 1 PPS signal from aGPSreceiver.
Offline Tom, Have you run the same sort of test on a LEA-6T, or do you know off the top of your head what the std deviation is? I had naively expected it to be spot on, but I see jumps every now and then, and I don't know whether it's something on my end, or if that's expected. Bob From: Tom Van Baak t...@leapsecond.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, September 13, 2014 8:42 PM Subject: Re: [time-nuts] Correcting jitter on the 1 PPS signal from aGPSreceiver. Pete, Bob, For data on a Resolution-T that I tested see http://leapsecond.com/pages/res-t/ What I found: the raw 1PPS has a standard deviation of about 13 ns; with sawtooth correction that drops to about 6 ns. If that sounds too good to be true, I can double check the raw data, or even re-run the test. I still have the same Trimble board; maybe more than one of them. So my suggestion is to try to duplicate this level of performance first, for each of your two units separately. Only then run the test comparing them against themselves. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NAA experiments as a reference
Well it doesn't make any sense but by using a LO of + or-150hz I do get a stable signal that at least allows me to get a sense of the stability of the carrier. I am not using the tracor d-msk-r to see this. In fact I need to relook at it may have an issue it does not seem to be doubling. A big change I made is to use a Krohn Hite 5910c arb gen that actually has an amazing stability all by itself. Have never had a manual for it. Though I see the b exists. Its set to 100 hz and putting out a nice clean sine wave. So the math is still nuts. Re-read the tracor documentation and they injected the LO 100 Hz low. So 24 Khz needs a LO of 23.9 Khz. The d-mask-r did not require any change to this setting. If NAA is transmitting 200 baud then I would expect the MSK carrier to be +/- 100 Hz. Not +/-50 Hz. Regards Paul. On Sat, Sep 13, 2014 at 7:18 PM, paul swed paulsw...@gmail.com wrote: Thats what I am trying to understand. How good is good. Is it a useful replacement for wwvb. Certainly kicks butt in signal strength. Regards Paul WB8TSL On Sat, Sep 13, 2014 at 2:03 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: The underlying NAA reference is UTC(USNO). How close they track it I don't know. -- 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] Correcting jitter on the 1 PPS signal from aGPSreceiver.
The cables are not exactly the same lengths. Differences in length will result in a fixed offset. I am not concerned about such fixed errors, only jitter. I am comparing the rising edges which is what the spec defines as the reference edge. Pete. Pete, Correct, the survey position is determined only by the phase center of the antenna, not by cable length. And cable length mismatches should make no difference in your jitter measurements. But one thing to check is how sharp the 1PPS rising edge is -- right at the input to your TI counter. I use a BNC tee with one leg open allowing a 'scope check (set to 1M input). If your risetime is a couple of ns like mine is, then all is well. Slow risetime can be a huge source of timing jitter. Check both 50R and 1M at the counter input. Use DC, not AC coupling. Use fixed trigger, never auto-trigger. Pick a trigger level that matches the maximum slope. Some examples of good/bad GPS 1PPS risetimes: http://leapsecond.com/pages/gpsdo-rise/ /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] NAA experiments as a reference
On 9/13/14, 7:13 PM, paul swed wrote: If NAA is transmitting 200 baud then I would expect the MSK carrier to be +/- 100 Hz. Not +/-50 Hz. I'd expect the total shift to be half the baud rate: 100 Hz.. ___ 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.
