Re: [time-nuts] Wikipedia and Residual Phase Noise
Dear Ulrich, Nice performance on your 10 GHz oscillator then! I was not aware of that level of performance from a more regular oscillator source. Wish you luck with solving the power amplifier stage phase noise issue. The FSWP is indeed a nice new box for the task. Wish I had one. Already the FSUP was nice. These use dual channels and cross-correlation techniques to the best of my knowledge. I think maybe my point did not come through right. The residual phase noise term refers more to the measurement setup rather than the addition of noise. The term is troubled in that way. I wonder if additive phase noise is the best term, but it is indeed better. Also, as you say, we have noise conversion even in passive devices. Cheers, Magnus On 07/14/2015 02:32 AM, ka2...@aol.com wrote: Dear Magnus, With your kind permission I (totally ) disagree with you . We make 10 GHz oscillators which are almost getting close to the Poseidon Sapphire , but the post power amplifier at 10 Ghz has a much higher noise floor then the source . I have not yet solved the problem My new FSWP (RS) Analyzer can measure down to - 190dBc/Hz . Wish me luck, Ulrich In a message dated 7/13/2015 5:29:50 P.M. Eastern Daylight Time, mag...@rubidium.dyndns.org writes: Dear Ulrich, Indeed. I think it's really not meaningful of saying it is additive, just as it is not meaningful to say residual. Any buffering/amplifying stage will add phase noise (and amplitude noise). We will have conversion between AM and PM to some degree. For higher quality stuff, the levels are very low such that qualitative measurements becomes very hard, at least compared to oscillator measurements, also it is to it's nature a differential measurement, so the topology will be different. The most sensitive measurements I've seen use interferometric or cross-correlation techniques, as Enrico shown. You have any further insights? Cheers, Magnus On 07/13/2015 03:10 PM, KA2WEU--- via time-nuts wrote: This is a misnomer, it should be called additivephase noise. Think of a noise free oscillator with a buffer stage. This stage because of AM/PM conversion under large signal condition adds noise, makes the over all system noisier.. Ulrich Rohde In a message dated 7/13/2015 8:31:19 A.M. Eastern Daylight Time, tim...@timeok.it writes: Hi all, I am looking on Wikipedia a description of the Residual Phase Noise but this page do not exist. Can some one of the time-nuts expert write a full description of this physical aspect for Wikipedia? thanks, Luciano tim...@timeok.it www.timeok.it Message sent via Atmail Open - http://atmail.org/ ___ time-nuts mailing 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] Wikipedia and Residual Phase Noise
Dear Magnus, I am writing a doc on my Distribution Amplifier project and I was looking a complete, but simple to understand, description about the Phase Noise introduced, or Added, by a non generative devices. thanks, Luciano On Mon 13/07/15 17:37 , Magnus Danielson mag...@rubidium.dyndns.org wrote: Dear Luciano, What do you need to know? Beefing up Wikipedia articles is indeed a nice thing, but lets hear what you look for. Cheers, Magnus On 07/13/2015 09:20 AM, tim...@timeok.it wrote: Hi all, I am looking on Wikipedia a description of the Residual Phase Noise but this page do not exist. Can some one of the time-nuts expert write a full description of this physical aspect for Wikipedia? thanks, Luciano tim...@timeok.it www.timeok.it [1] Message sent via Atmail Open - http://atmail.org/ [2] ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts [3] 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 [4] and follow the instructions there. Links: -- [1] http://webmail.timeok.it/parse.php?redirect=http://www.timeok.it [2] http://webmail.timeok.it/parse.php?redirect=http://atmail.org/ [3] http://webmail.timeok.it/parse.php?redirect=https://www.febo.com/cgi-bin/ma ilman/listinfo/time-nuts[4] http://webmail.timeok.it/parse.php?redirect=https://www.febo.com/cgi-bin/ma ilman/listinfo/time-nuts Message sent via Atmail Open - http://atmail.org/ ___ time-nuts mailing 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] Loran C returning to a station near you...
Hi, There is indeed investigations going on about what the cost of receivers would be etc. A benefit of Loran-C is that relative jamming/spoofing resistance can be had without the need of opening up for keyed receivers. This helps for non-military and non-government operations. Now, there is tamper-proof GPS receivers that can use the keyed signal for increased signal stability, but I wonder to what degree they are deployed. Then, naturally the military can have use for these receivers. Work is in progress, but we do not yet know the outcome, but they do ask about what it would cost and what performance one would get. It will be interesting to follow. While LORAN-C is sold as jamming/spooing resistant, that is based on the assumption that nobody would raise a 200 m tower undetected. True, but we now know that it was done for that purpose. The safety is relative, in that it takes quite a bit of more infrastructure compared to the jamming of GPS, and that lies in the wavelength of the signal than anything else. Cheers, Magnus On 07/14/2015 04:56 AM, skipp Isaham via time-nuts wrote: Does anyone know of any other genuinely useful purpose to which the Austron 2100F, SRS FS700, etc receivers can be put in the US since the demise of Loran? I've heard Loran C in some form will be returning. GPS is not jam proof and that seems to have caught the attention of our government. Although some locations have already been dismantled to some large degree, a hold that tiger has been issued as the wheels have started to turn backwards and Loran C starts to make a comeback. cheers, skipp ___ time-nuts mailing 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] Omega counters and Parabolic Variance (PVAR)
Fellow time-nuts, Since I haven't seen any reports on this, I though I would write down a few lines. While normal counters use a pair of phase-samples to estimate the frequency, now called Pi counters (big pi, which has the shape of the weighing function of frequency samples), counter vendors have been figuring out how to improve the precision of the frequency estimation for the given observation time. One approach is to overlay multiple measurements in blocks, which for the frequency estimation looks like a triangle-shape weighing, so this type of counter is referred to as Delta counters (again to resemble the shape). Classical counters of the Pi shape is HP5370A, SR620 etc. Classical counter of the Delta shape is the HP53132A. However, counters using the Linear Regression methodology does not fit into either of those categories. Enrico Rubiola derived the parabolic shape of the weighing function (which I then independently verified after we spoke during EFTF 2014), and he then passed on the results to Francois Vernotte and other colleagues to continue the analysis. The new weighing function is a parabolic, looking like an Omega sign, so that is the name for this type of counter. Counters using the Omega shape is HP5371A, HP5372A, Pendelum CNT-90, CNT-91 etc. These weighing shapes acts like filters, and the block variant of the Pi weighing has no real filtering properties, where as both the Delta and Omega shapes has strong low-pass properties, which is beneficial in that they will suppress white phase noise strongly, and that is the typical measurement limitation of counters. The counter resolution limit also acts like white phase noise even if it is a systematic noise, which can interact in interesting ways as we have seen when signal frequencies has interesting relationships to the reference frequency. However, for cases when this is not true, the weighing helps to reduce that noise too from the measurements. For frequency estimation this is good improvements. This technique was actually introduced in optical measurements, as illustrated by J.J. Snyder in his 1980 and 1981 articles. This inspired further development of the Allan Variance to include the filtering technique of Snyder, and that resulted in the Modified Allan Variance (MVAR). Today we refer to the Snyder technique as the Delta counter. What Rubiola, Vernotte et. al discovered was that using a Linear Regression (LR) type of frequency estimated for variance estimation forms a new measure which they ended up calling Parabolic Variance (PVAR). They have done a complete analysis of PVAR properties (noise response and EDF) and it has benefits over MVAR. Variance made by a Delta counter thus becomes MVAR, but only as a special case. Variance made by a Omega counter becomes PVAR, but only as a special case. This is my main critique of their work, if you have access to the full stream of phase samples, you can form MVAR and PVAR using the two shaping techniques. However, if you use counters that perform these frequency estimations, then you can only correctly estimate variance of the two methods for the tau0 of the measurement result rate (and assuming that you know if they are back to back or interlaced, which is a mistake that was done at one time). If you have an Omega counter that produce frequency estimates and then process it further, the parabolic filtering shape does not change with m as it should for propper PVAR. This is exactly the same as using a Delta counter for frequency estimates and then perform variance estimation. For both cases, the counter will provide a fixed filtering bandwidth, but as you increase the m*tau0 for your analysis, the frequencies of your sample series will move into the pass-band of the low-pass filter and eventually the filtering effect is completely lost. The result is the hockey-puck response where the low-tau part of the ADEV/MDEV/PDEV curve first increases and then bends down to the white phase noise of the input as if it was not filtered. While Vernotte et al does not provide guidance for how to extend the PVAR from shorter measurements, I have proposed such a solution to them. Unfortunatly none of the existing counters will support that today. Why then, should one use PVAR? Well, PVAR does give good suppression of white flicker noise, and just as MVAR does has a 1/tau^3 curve rather than 1/tau^2 curve. This means that the measurement noise can be suppressed more effectively and the source noise can be reached for a lower tau. PVAR will have a 3/4 of MVAR for the white phase nosie, so there is a 1.25 dB improvement there. So, while it may read it from their papers that you get the PVAR from Omega counters, it's not the same in their analysis where the filtering function changes with m as you have with a typical counter which runs at fixed m. This is not to say that the PVAR technique is not useful. Getting proper
[time-nuts] Update on Skytraq venus8
Back in January it was reported here that the Venus 8 timing modules from Skytraq as used in the LTE-Lite, had a firmware bug that was causing the leap second to be applied as soon as the warning was seen in the GPS stream. I had bought one from Navspark and once I reported the issue they shipped me a replacement receiver as soon as the F/W update was available. I would have preferred the new F/W, but I got a free receiver as they did not want me to return the bugged one. Anyhow, I just put the bad one in the drawer until today and have reconnected it to see if there were any residual issues now that the warning is gone. Happily all is well, Tue Jul 14 10:12:43 UTC 2015 $GPGGA,101243.000,4847.3695,N,00216.3166,E,0,00,99.9,209.9,M,47.0,M,,*61 Tue Jul 14 10:12:43 UTC 2015 $GPGLL,4847.3695,N,00216.3166,E,101243.000,V,N*45 Tue Jul 14 10:12:43 UTC 2015 $GPGSA,A,1,99.9,99.9,99.9*09 Tue Jul 14 10:12:43 UTC 2015 $GPGSV,3,1,10,25,69,284,37,12,65,058,45,14,46,264,,24,37,134,20*75 Tue Jul 14 10:12:43 UTC 2015 $GPGSV,3,2,10,29,34,197,20,02,26,096,28,06,21,055,40,31,15,306,*79 Tue Jul 14 10:12:43 UTC 2015 $GPGSV,3,3,10,32,04,315,,03,00,352,*7D Tue Jul 14 10:12:43 UTC 2015 $GPRMC,101243.000,V,4847.3695,N,00216.3166,E,000.0,274.2,140715,,,N*77 Tue Jul 14 10:12:43 UTC 2015 $GPVTG,274.2,T,,M,000.0,N,000.0,K,N*01 Tue Jul 14 10:12:43 UTC 2015 $GPZDA,101243.000,14,07,2015,00,00*57 Tue Jul 14 10:12:43 UTC 2015 $PSTI,00,1,1963,4.6,30,0*3D I did not check what happened over the June 30 235959 July 1 00:00:00 transition. I suspect that the device will be OK to use , with the quantization correction, until the next leap warning appears in the data stream which should give us a year at least. So anyone with who got a replacement can dig them out again. Ceux qui sont prêts à abandonner une liberté essentielle pour obtenir une petite et provisoire sécurité, ne méritent ni liberté ni sécurité. Benjimin Franklin ___ time-nuts mailing 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] Loran C returning to a station near you...
Skip It certainly keeps trying to return. It will not be the navigation system formerly known as Loran C (Wasn't that also some singer?) it will be eLoran. Most eLORAN systems add an additional pulse for data. They stick somewhat to the old format to avoid possible interference with operating systems in Europe. But it seems in general LORAN is one big question. I know we shut down LORAN C to save $36M/year. A drop in the bucket. Regards Paul WB8TSL On Mon, Jul 13, 2015 at 10:56 PM, skipp Isaham via time-nuts time-nuts@febo.com wrote: Does anyone know of any other genuinely useful purpose to which the Austron 2100F, SRS FS700, etc receivers can be put in the US since the demise of Loran? I've heard Loran C in some form will be returning. GPS is not jam proof and that seems to have caught the attention of our government. Although some locations have already been dismantled to some large degree, a hold that tiger has been issued as the wheels have started to turn backwards and Loran C starts to make a comeback. cheers, skipp ___ time-nuts mailing 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] Loran C returning to a station near you...
In message 55a4ac81.1030...@rubidium.dyndns.org, Magnus Danielson writes: The safety is relative, in that it takes quite a bit of more infrastructure compared to the jamming of GPS, and that lies in the wavelength of the signal than anything else. If the goal is a reliable backup for GPS, there are smarter ways to use the 100kHz band than Loran-C pulses, and there really isn't much reason to stay compatible with Loran-C receivers. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Loran C returning to a station near you...
Poul-Henning, On 07/14/2015 06:16 PM, Poul-Henning Kamp wrote: In message 55a4ac81.1030...@rubidium.dyndns.org, Magnus Danielson writes: The safety is relative, in that it takes quite a bit of more infrastructure compared to the jamming of GPS, and that lies in the wavelength of the signal than anything else. If the goal is a reliable backup for GPS, there are smarter ways to use the 100kHz band than Loran-C pulses, and there really isn't much reason to stay compatible with Loran-C receivers. True. I would look at PRN-codes if I where to do such a system today. What may be an issue is the amount of sidebands allowed, as it would put limits on the chipping-rate of PRN-codes or for that matter other forms of modulations. I think another approach was being considered for the LORAN-rebuild in the US. I don't remember from the top of my head when it was discussed or link to the article. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Omega counters and Parabolic Variance (PVAR)
Hi Chuck, On 07/14/2015 07:46 PM, Chuck Harris wrote: Hi Magnus, Am I understanding correctly that the difference between Pi, Delta, and Omega is basically one of software processing after the sample is made? Correct! If so, how can this be best leveraged by those of us that have 5370A/B counters that are running John Seamon's enhanced BBB processor in place of the original 5370 Motorola processor? I would stream the raw samples over to the computer and do processing there. Doing the Delta/Lambda estimation works if the computer side does the right post-processing (which they rarely do). Implementing this for frequency only in the BBB would not be too hard if you like to do that. I need to install my BBB board one of these days. Cheers, Magnus Thanks! -Chuck Harris Magnus Danielson wrote: Fellow time-nuts, Since I haven't seen any reports on this, I though I would write down a few lines. While normal counters use a pair of phase-samples to estimate the frequency, now called Pi counters (big pi, which has the shape of the weighing function of frequency samples), counter vendors have been figuring out how to improve the precision of the frequency estimation for the given observation time. One approach is to overlay multiple measurements in blocks, which for the frequency estimation looks like a triangle-shape weighing, so this type of counter is referred to as Delta counters (again to resemble the shape). Classical counters of the Pi shape is HP5370A, SR620 etc. Classical counter of the Delta shape is the HP53132A. However, counters using the Linear Regression methodology does not fit into either of those categories. Enrico Rubiola derived the parabolic shape of the weighing function (which I then independently verified after we spoke during EFTF 2014), and he then passed on the results to Francois Vernotte and other colleagues to continue the analysis. ___ time-nuts mailing 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] Omega counters and Parabolic Variance (PVAR)
Hi Magnus, Am I understanding correctly that the difference between Pi, Delta, and Omega is basically one of software processing after the sample is made? If so, how can this be best leveraged by those of us that have 5370A/B counters that are running John Seamon's enhanced BBB processor in place of the original 5370 Motorola processor? Thanks! -Chuck Harris Magnus Danielson wrote: Fellow time-nuts, Since I haven't seen any reports on this, I though I would write down a few lines. While normal counters use a pair of phase-samples to estimate the frequency, now called Pi counters (big pi, which has the shape of the weighing function of frequency samples), counter vendors have been figuring out how to improve the precision of the frequency estimation for the given observation time. One approach is to overlay multiple measurements in blocks, which for the frequency estimation looks like a triangle-shape weighing, so this type of counter is referred to as Delta counters (again to resemble the shape). Classical counters of the Pi shape is HP5370A, SR620 etc. Classical counter of the Delta shape is the HP53132A. However, counters using the Linear Regression methodology does not fit into either of those categories. Enrico Rubiola derived the parabolic shape of the weighing function (which I then independently verified after we spoke during EFTF 2014), and he then passed on the results to Francois Vernotte and other colleagues to continue the analysis. ___ time-nuts mailing 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] Omega counters and Parabolic Variance (PVAR)
I look forward to the article, Magnus! Don Magnus Danielson Fellow time-nuts, Since I haven't seen any reports on this, I though I would write down a few lines. While normal counters use a pair of phase-samples to estimate the frequency, now called Pi counters (big pi, which has the shape of the weighing function of frequency samples), counter vendors have been figuring out how to improve the precision of the frequency estimation for the given observation time. One approach is to overlay multiple measurements in blocks, which for the frequency estimation looks like a triangle-shape weighing, so this type of counter is referred to as Delta counters (again to resemble the shape). Classical counters of the Pi shape is HP5370A, SR620 etc. Classical counter of the Delta shape is the HP53132A. However, counters using the Linear Regression methodology does not fit into either of those categories. Enrico Rubiola derived the parabolic shape of the weighing function (which I then independently verified after we spoke during EFTF 2014), and he then passed on the results to Francois Vernotte and other colleagues to continue the analysis. The new weighing function is a parabolic, looking like an Omega sign, so that is the name for this type of counter. Counters using the Omega shape is HP5371A, HP5372A, Pendelum CNT-90, CNT-91 etc. These weighing shapes acts like filters, and the block variant of the Pi weighing has no real filtering properties, where as both the Delta and Omega shapes has strong low-pass properties, which is beneficial in that they will suppress white phase noise strongly, and that is the typical measurement limitation of counters. The counter resolution limit also acts like white phase noise even if it is a systematic noise, which can interact in interesting ways as we have seen when signal frequencies has interesting relationships to the reference frequency. However, for cases when this is not true, the weighing helps to reduce that noise too from the measurements. For frequency estimation this is good improvements. This technique was actually introduced in optical measurements, as illustrated by J.J. Snyder in his 1980 and 1981 articles. This inspired further development of the Allan Variance to include the filtering technique of Snyder, and that resulted in the Modified Allan Variance (MVAR). Today we refer to the Snyder technique as the Delta counter. What Rubiola, Vernotte et. al discovered was that using a Linear Regression (LR) type of frequency estimated for variance estimation forms a new measure which they ended up calling Parabolic Variance (PVAR). They have done a complete analysis of PVAR properties (noise response and EDF) and it has benefits over MVAR. Variance made by a Delta counter thus becomes MVAR, but only as a special case. Variance made by a Omega counter becomes PVAR, but only as a special case. This is my main critique of their work, if you have access to the full stream of phase samples, you can form MVAR and PVAR using the two shaping techniques. However, if you use counters that perform these frequency estimations, then you can only correctly estimate variance of the two methods for the tau0 of the measurement result rate (and assuming that you know if they are back to back or interlaced, which is a mistake that was done at one time). If you have an Omega counter that produce frequency estimates and then process it further, the parabolic filtering shape does not change with m as it should for propper PVAR. This is exactly the same as using a Delta counter for frequency estimates and then perform variance estimation. For both cases, the counter will provide a fixed filtering bandwidth, but as you increase the m*tau0 for your analysis, the frequencies of your sample series will move into the pass-band of the low-pass filter and eventually the filtering effect is completely lost. The result is the hockey-puck response where the low-tau part of the ADEV/MDEV/PDEV curve first increases and then bends down to the white phase noise of the input as if it was not filtered. While Vernotte et al does not provide guidance for how to extend the PVAR from shorter measurements, I have proposed such a solution to them. Unfortunatly none of the existing counters will support that today. Why then, should one use PVAR? Well, PVAR does give good suppression of white flicker noise, and just as MVAR does has a 1/tau^3 curve rather than 1/tau^2 curve. This means that the measurement noise can be suppressed more effectively and the source noise can be reached for a lower tau. PVAR will have a 3/4 of MVAR for the white phase nosie, so there is a 1.25 dB improvement there. So, while it may read it from their papers that you get the PVAR from Omega counters, it's not the same in their analysis where the filtering function changes with m as you have with a typical counter which runs at fixed m. This is not to
Re: [time-nuts] Loran C returning to a station near you...
In message 55a53a67.7010...@rubidium.dyndns.org, Magnus Danielson writes: If the goal is a reliable backup for GPS, there are smarter ways to use the 100kHz band than Loran-C pulses, and there really isn't much reason to stay compatible with Loran-C receivers. True. I would look at PRN-codes if I where to do such a system today. What may be an issue is the amount of sidebands allowed, as it would put limits on the chipping-rate of PRN-codes or for that matter other forms of modulations. I would probably stay with the pulses, they have some very desirable properties in terms of transmitter and antenna design and bandwidth. But I would get rid of the current spread-spectrum design and do something like this: We pick a basic period as a prime number of microseconds, for instance 262139µs (just below 2^18) and we define an epoch for this. This means that all transmitters are autonomous based on a local TAI reference. Each transmitter emits an individual PRN-spaced pattern of 32 pulses in the basic period. The exact pulse patterns for a transmitter will be picked based on vectors to neighboring transmitters. The pulse polarity is plus, minus, data where every 3rd pulse is used to implement a serial data-channel which communicates chain-configuration data, TAI/UTC info with some bits left over for civil defence warnings. Using one global GRI means that there no longer any chains. This eliminates a host of failure-modes on the transmitter side and the receivers will automatically be all-in-view. With all transmitters autonomous and independent, RAIM is possible. The basic period is relatively long to attenuate any CW interference for time/frequency purposes but the higher pulse-per-period count compensates this for location purposes. Making the pulse-pattern per transmitter and PRN-like eliminates all the shadow effects (baseline extension etc) and makes for quick (re)acquisition based on pattern-matching. The PRN pattern will also dramatically attenuate the loran-lines which polluted nearby VLF and LF bands. The +/-/data pulse polarity makes it possible to detect the start of the period by tracking where in the potential basic period pulses do not change polarity: 3 doesn't divide 32, so there is a + - + - sequence from all transmitters around the start of the period. But then again, I have spent far more of my life on Loran-C than can ever be justified :-) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Loran C returning to a station near you...
Poul-Henning, The reason to stay with the LORAN C style pulses is very very simple. It allows our time-nuts Austrons and SRS to work. Its the only way I get any of my tax dollars back. :-) The good news is no official government person reads time-nuts. Regards Paul On Tue, Jul 14, 2015 at 12:16 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 55a4ac81.1030...@rubidium.dyndns.org, Magnus Danielson writes: The safety is relative, in that it takes quite a bit of more infrastructure compared to the jamming of GPS, and that lies in the wavelength of the signal than anything else. If the goal is a reliable backup for GPS, there are smarter ways to use the 100kHz band than Loran-C pulses, and there really isn't much reason to stay compatible with Loran-C receivers. -- 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] Loran C returning to a station near you...
Hi Not to be to much of a downer here but ….. Loran for timing and an “Eastern WWVB” are two projects that seem to each have a life of their own. They seem to come up on some sort of cycle related to sun spots. Both have zero (or possibly less than that) percent mind share among those who would need to implement them into systems. Since there is major cost on the systems end, it would take “mandatory use” legislation to get them designed in. Without those design in’s, *having* a backup system is pretty useless. You are talking about billions of dollars and years of effort to hook them up …. If you are talking about “infinite budget” military systems, some of that may happen. I notice in the papers that “infinite budget” does not seem to apply to the US DOD these days. For commercial systems, nobody will significantly cut into profits to do something like this. Should they do this - sure. Will they do it - nope. Bob On Jul 14, 2015, at 4:49 PM, paul swed paulsw...@gmail.com wrote: Poul-Henning, The reason to stay with the LORAN C style pulses is very very simple. It allows our time-nuts Austrons and SRS to work. Its the only way I get any of my tax dollars back. :-) The good news is no official government person reads time-nuts. Regards Paul On Tue, Jul 14, 2015 at 12:16 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 55a4ac81.1030...@rubidium.dyndns.org, Magnus Danielson writes: The safety is relative, in that it takes quite a bit of more infrastructure compared to the jamming of GPS, and that lies in the wavelength of the signal than anything else. If the goal is a reliable backup for GPS, there are smarter ways to use the 100kHz band than Loran-C pulses, and there really isn't much reason to stay compatible with Loran-C receivers. -- 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. ___ time-nuts mailing 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] Loran C returning to a station near you...
In message cad2jfah+spv23kgizgmnjdh9ea1wksogn03y0icje2edpzt...@mail.gmail.com , paul swed writes: The reason to stay with the LORAN C style pulses is very very simple. It allows our time-nuts Austrons and SRS to work. Its the only way I get any of my tax dollars back. :-) Considering how much better performance you can get with a trivial ARM CPU on a sub $100 development board, I as a time-nut find that an incredibly silly argument... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Loran C returning to a station near you...
Hi On Jul 14, 2015, at 12:35 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Poul-Henning, On 07/14/2015 06:16 PM, Poul-Henning Kamp wrote: In message 55a4ac81.1030...@rubidium.dyndns.org, Magnus Danielson writes: The safety is relative, in that it takes quite a bit of more infrastructure compared to the jamming of GPS, and that lies in the wavelength of the signal than anything else. If the goal is a reliable backup for GPS, there are smarter ways to use the 100kHz band than Loran-C pulses, and there really isn't much reason to stay compatible with Loran-C receivers. True. I would look at PRN-codes if I where to do such a system today. What may be an issue is the amount of sidebands allowed, as it would put limits on the chipping-rate of PRN-codes or for that matter other forms of modulations. If you look at the spectral width of the existing Loran-C (or similar) waveform, it’s a massive thing. You would have a hard time coming up with something that spreads more crud around the VLF range. Bob I think another approach was being considered for the LORAN-rebuild in the US. I don't remember from the top of my head when it was discussed or link to the article. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Loran C returning to a station near you...
The word is that eLoran IS on in the US from Wildwood as of June 19. Has anyone noticed the signal? http://www.pressofatlanticcity.com/news/loran-navigation-signal-back-on-and-better-than-before/article_21d19298-16d0-11e5-9a69-1343edc2e90b.html There is also a bill in the US House to reinstate Loran-C as eLoran. David N1HAC On 7/14/15 6:49 PM, Bob Camp wrote: Hi Not to be to much of a downer here but ….. Loran for timing and an “Eastern WWVB” are two projects that seem to each have a life of their own. They seem to come up on some sort of cycle related to sun spots. Both have zero (or possibly less than that) percent mind share among those who would need to implement them into systems. Since there is major cost on the systems end, it would take “mandatory use” legislation to get them designed in. Without those design in’s, *having* a backup system is pretty useless. You are talking about billions of dollars and years of effort to hook them up …. If you are talking about “infinite budget” military systems, some of that may happen. I notice in the papers that “infinite budget” does not seem to apply to the US DOD these days. For commercial systems, nobody will significantly cut into profits to do something like this. Should they do this - sure. Will they do it - nope. Bob On Jul 14, 2015, at 4:49 PM, paul swed paulsw...@gmail.com wrote: Poul-Henning, The reason to stay with the LORAN C style pulses is very very simple. It allows our time-nuts Austrons and SRS to work. Its the only way I get any of my tax dollars back. :-) The good news is no official government person reads time-nuts. Regards Paul On Tue, Jul 14, 2015 at 12:16 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 55a4ac81.1030...@rubidium.dyndns.org, Magnus Danielson writes: The safety is relative, in that it takes quite a bit of more infrastructure compared to the jamming of GPS, and that lies in the wavelength of the signal than anything else. If the goal is a reliable backup for GPS, there are smarter ways to use the 100kHz band than Loran-C pulses, and there really isn't much reason to stay compatible with Loran-C receivers. -- 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. ___ time-nuts mailing 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] Omega counters and Parabolic Variance (PVAR)
Hi Magnus, John, et al, did such a nice job of making us a hammer for our 5370's, that it has the rest of us searching for nails. Maybe this could be a good place to start? -Chuck Harris Magnus Danielson wrote: Hi Chuck, On 07/14/2015 07:46 PM, Chuck Harris wrote: Hi Magnus, Am I understanding correctly that the difference between Pi, Delta, and Omega is basically one of software processing after the sample is made? Correct! If so, how can this be best leveraged by those of us that have 5370A/B counters that are running John Seamon's enhanced BBB processor in place of the original 5370 Motorola processor? I would stream the raw samples over to the computer and do processing there. Doing the Delta/Lambda estimation works if the computer side does the right post-processing (which they rarely do). Implementing this for frequency only in the BBB would not be too hard if you like to do that. I need to install my BBB board one of these days. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Loran C returning to a station near you...
How much money was saved by not sending NIST time codes over GOES satellites? I'm sure that was much less than $36M/year to continue, probably not even 1% of that. I'm strongly for high diversity in time distribution. GPS is great, but putting all our eggs in the GPS basket seems very unwise. At the moment I have GPS, CHU, WWV, and WWVB, but more diversity would be better, and I hope I can add some variant of LORAN back to the list soon. Tim N3QE On Tue, Jul 14, 2015 at 9:07 AM, paul swed paulsw...@gmail.com wrote: Skip It certainly keeps trying to return. It will not be the navigation system formerly known as Loran C (Wasn't that also some singer?) it will be eLoran. Most eLORAN systems add an additional pulse for data. They stick somewhat to the old format to avoid possible interference with operating systems in Europe. But it seems in general LORAN is one big question. I know we shut down LORAN C to save $36M/year. A drop in the bucket. Regards Paul WB8TSL On Mon, Jul 13, 2015 at 10:56 PM, skipp Isaham via time-nuts time-nuts@febo.com wrote: Does anyone know of any other genuinely useful purpose to which the Austron 2100F, SRS FS700, etc receivers can be put in the US since the demise of Loran? I've heard Loran C in some form will be returning. GPS is not jam proof and that seems to have caught the attention of our government. Although some locations have already been dismantled to some large degree, a hold that tiger has been issued as the wheels have started to turn backwards and Loran C starts to make a comeback. cheers, skipp ___ time-nuts mailing 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] Wikipedia and Residual Phase Noise
Dear Luciano, While the Phase Noise wikipedia page could do with an upgrade, I do recommend you (and anyone other that want's to learn about amplitude and phase noise) to visit Enrico Rubiolas page http://rubiola.org He has a nice set of presentations and papers. Do consider getting his book, as I've found it a nice, comprehensive and easily accessible summary. A simple model is that an amplifier will add white phase noise and flicker phase noise. A somewhat more complete model will also include amplitude noise to phase noise conversion. Care in amplifier/buffer design can reduce these effects. In the NIST TF archives you can find some material relating to this. Cheers, Magnus On 07/14/2015 08:50 AM, tim...@timeok.it wrote: Dear Magnus, I am writing a doc on my Distribution Amplifier project and I was looking a complete, but simple to understand, description about the Phase Noise introduced, or Added, by a non generative devices. thanks, Luciano On Mon 13/07/15 17:37 , Magnus Danielson mag...@rubidium.dyndns.org wrote: Dear Luciano, What do you need to know? Beefing up Wikipedia articles is indeed a nice thing, but lets hear what you look for. Cheers, Magnus On 07/13/2015 09:20 AM, tim...@timeok.it wrote: Hi all, I am looking on Wikipedia a description of the Residual Phase Noise but this page do not exist. Can some one of the time-nuts expert write a full description of this physical aspect for Wikipedia? thanks, Luciano tim...@timeok.it www.timeok.it [1] Message sent via Atmail Open - http://atmail.org/ [2] ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts [3] 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 [4] and follow the instructions there. Links: -- [1] http://webmail.timeok.it/parse.php?redirect=http://www.timeok.it [2] http://webmail.timeok.it/parse.php?redirect=http://atmail.org/ [3] http://webmail.timeok.it/parse.php?redirect=https://www.febo.com/cgi-bin/ma ilman/listinfo/time-nuts[4] http://webmail.timeok.it/parse.php?redirect=https://www.febo.com/cgi-bin/ma ilman/listinfo/time-nuts Message sent via Atmail Open - http://atmail.org/ ___ time-nuts mailing 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.
