Re: [time-nuts] Speaking of Costas loops
Hi If the WAAS sats were purpose designed to provide a high accuracy carrier, then yes there are ways to do it. The fundamental design concept of a bent pipe is that you don't do any of that. You do not care what's going through the bird, it just maps the input frequencies to the output and amplifies them (a lot). Again, the WAAS signal is simply piggybacking on existing hardware. The conversion oscillator is not locked to the GPS carrier (or to any other carrier). It's simply a free running quartz based oscillator, running into a synthesizer to get the appropriate microwave frequency. Bob On Jul 3, 2013, at 5:21 PM, Dennis Ferguson dennis.c.fergu...@gmail.com wrote: On 3 Jul, 2013, at 11:47 , Bob Camp li...@rtty.us wrote: The pipe in this case is up on one frequency and down on another. The conversion oscillator on satellite that's the weak link, no matter how good the signal from the ground happens to be. That's certainly true but it doesn't seem like a problem that the presence of a high stability free-running oscillator, like a rubidium, would help. The oscillator on a geostationary satellite has a continuous frequency reference to lock to (the uplink carrier) and hence only needs short term stability sufficient to track this and transfer it accurately to the downlink. It seems like this is the kind of problem that quartz excels at. Dennis Ferguson ___ 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] Speaking of Costas loops
On 7/3/13 12:42 PM, Azelio Boriani wrote: Sure about the bent pipe? If so it seems that much power is required at the transmitting ground station... Much equivalent power is required. If you have a 20 meter or so antenna, it doesn't take much to get a pretty high EIRP. ___ 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] Speaking of Costas loops
Hi On Jul 3, 2013, at 3:51 PM, jmfra...@cox.net wrote: http://www.navipedia.net/index.php/WAAS_Signal_Structure Doppler Shift: The Doppler shift, as perceived by a stationary user, on the signal broadcast by WAAS GEOs is less than 40 meters per second (≈210 Hz at L1) So unless you can measure and correct for the doppler, you are at a few hundred Hz at 1.5 GHz. 150 Hz would be 0.1 ppm. That's not very accurate. in the worst case (at the end of life of the GEOs). The Doppler shift is due to the relative motion of the GEO. Carrier Frequency Stability: The short term stability of the carrier frequency (square root of the Allan Variance) at the input of the user´s receiver antenna will be better than 5x10-11 over 1 to 10 seconds, excluding the effects of the ionosphere and Doppler. Polarization: The broadcast signal is right-handed circularly polarized. The ellipticity will be no worse than 2 dB for the angular range of ±9.1o from boresight. Code/Carrier Frequency Coherence: The lack of coherence between the broadcast carrier phase and the code phase shall be limited. The short term (10sec) fractional frequency difference between the code phase rate and the carrier frequency shall be less than 5x10-11 (one sigma). Over the long term (100 sec), the difference between the change in the broadcast code phase (convert to carrier cycles) and the change in the broadcast carrier phase shall be within one carrier cycle (one sigma). Once you are past 100 seconds, there's essentially no spec. One cycle per 100 sec is a lot, even at 1.5 GHz Correlation Loss: Correlation loss is defined as the ratio of output powers from a perfect correlator for two cases: 1) the actual receiver WAAS signal correlated against a perfect unfiltered PN reference, or 2) a perfect unfiltered PN signal normalized to the same total power as the WAAS signal in case 1. The correlation loss resulting from modulation imperfections and filtering inside the WAAS satellite payload is less than 1 dB. If you are only after the carrier, the code stuff pretty much does not matter. Bob John WA4WDL Bob Camp li...@rtty.us wrote: Hi The pipe in this case is up on one frequency and down on another. The conversion oscillator on satellite that's the weak link, no matter how good the signal from the ground happens to be. Bob On Jul 3, 2013, at 1:48 PM, Attila Kinali att...@kinali.ch wrote: On Wed, 3 Jul 2013 08:29:02 -0400 Bob Camp li...@rtty.us wrote: There are two batches of GPS / WAAS sats up there: 1) The ones with numbers above 100 that are geosync and that only do WAAS 2) The ones with numbers = 32 that do nav. These are not geosync. I believe the only ones with corrected / high stab clocks on board are those in the second group. The stuff in the first group aren't dedicated sats, just leased transponders on conventional multipurpose geosync birds. I don't know about WAAS, but AFAIK the EGNOS signals are generated on ground using Cs references and retransmitted by the satelites using a bend pipe. Ie. the signals should be of time-nut quality even without high accuracy frequency standards in the birds themselves. (Sorry, i'm not able to find where i read about that, so no references today) Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown ___ 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] Speaking of Costas loops
On 7/3/13 2:21 PM, Dennis Ferguson wrote: On 3 Jul, 2013, at 11:47 , Bob Camp li...@rtty.us wrote: The pipe in this case is up on one frequency and down on another. The conversion oscillator on satellite that's the weak link, no matter how good the signal from the ground happens to be. That's certainly true but it doesn't seem like a problem that the presence of a high stability free-running oscillator, like a rubidium, would help. The oscillator on a geostationary satellite has a continuous frequency reference to lock to (the uplink carrier) and hence only needs short term stability sufficient to track this and transfer it accurately to the downlink. It seems like this is the kind of problem that quartz excels at. Kind of depends on what the transponder on the satellite looks like. For deep space, we use a very narrow band loop filter to recover the received carrier. The synthesis approach for the downlink is designed to cancel any variations in the local crystal oscillator (e.g. it's typically a ratio.. for X band, 880/749) ___ 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] PIN define of VECTRON OCXO 217-8422
Dear Group: I just got a VECTRON 5Mhz OCXO the model is 217-8422, does anyone have its datasheet or PIN define? Thanks a lot. Hui ___ 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 low-power system for gps ntp timekeeping NANOSG20
One possibility is that the CPU is getting turned off when idle to save power. If that includes the stuff normally used for timekeeping, things could get screwed up when it gets turned back on. It has to reset the time, probably getting it from the RTC. I don't think this is the case. Look at how well the system to sync'd with other NTP servers. It is only the local GPS ref. clocks that are not doing well. Also you might check the NMEA output by some other means, some Garmin units are really bad. If you can turn off all the un-needed NMEA sentences it might help. Simply watching the NMEA output in a terminal window is a good enough check. You can see by eye if there is a one second error -- 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] looking for low-power system for gps ntptimekeeping NANOSG20
From: Chris Albertson The computer itself and the NTP installation are OK because we can see it syncing to other NTP servers. Likely you have a problem in the way the GPS using is connected. Some common errors is an inverted PPS, just flip it ad see if you gets better, it is really hard to see a 1Hz signal on a scope. = Any 'scope should be able to see a pule which is high for 100 ms and low for 900 ms! Modern digital scopes even make it easy to see a 100 ns pulse repeated at 1 second intervals. Best investment I made recently was a Rigol DS1052E 'scope - so useful for time-nuts type work. It was /just/ affordable, and it may be even a lower cost now as a newer model is out. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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 low-power system for gps ntp timekeeping NANOSG20
Oh for convenience. I need to patch ntpd to use linux pps (afaik) and on other systems I successfully run gpsd with ntpd (read: low jitter). Using gpsd with ntpd reduces the jitter versus just using ntpd by itself? No I meant that running that combination is successfully because I see low jitter. Folkert van Heusden -- Multitail est un outil permettant la visualisation de fichiers de journalisation et/ou le suivi de l'exécution de commandes. Filtrage, mise en couleur de mot-clé, fusions, visualisation de différences (diff-view), etc. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] BPSK decoder for WWVB
On Wed, 03 Jul 2013 19:15:40 + Brian Alsop als...@nc.rr.com wrote: Apparently this modulation scheme is less prone to jammers. There is is British station which jams east coast WWVB. The way WWVB implements BPSK does not make it less prone to jammers or noise. The idea, to get higher SNR would be to encode a known signal onto the carrier which you can correlate against. WWVB does not do that. The phase switches every second according to the bit to be transmitted. As the bits are unkown (safe the 12 sync bits) you have no additional information what the phase/signal is, actually you have even less knowledge compared to a fixed phase signal (aka AM only modulation), hence lower SNR (= less jamming protection). Compare this modulation scheme to what DCF77 or GPS does. Both modulate a long pseudorandom, but known bit string over the carrier against which you can correlate. The effective data bitrate is much lower. And just for clarity: The jamming resistance of such modulation schemes is not inherent in the known signal, but comes from spreading the signal over a larger bandwidth. White noise and random narrow band noise (the two most common noise sources over the air) can be averaged out by the modulation if the bitstring is known. If designed right, you can detect a signal that is several dB below the thermal noise limit, like GPS. TL;DR version: The way how BPSK modulation is implemented in WWVB makes it more prone to jammers and noise instead of less. Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ 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] Speaking of Costas loops
li...@rtty.us said: If the WAAS sats were purpose designed to provide a high accuracy carrier, then yes there are ways to do it. The fundamental design concept of a bent pipe is that you don't do any of that. You do not care what's going through the bird, it just maps the input frequencies to the output and amplifies them (a lot). Again, the WAAS signal is simply piggybacking on existing hardware. The conversion oscillator is not locked to the GPS carrier (or to any other carrier). It's simply a free running quartz based oscillator, running into a synthesizer to get the appropriate microwave frequency. If somebody wanted to use that path for a frequency reference, they could setup a ground station to measure the Doppler and distribute that so people could adjust their expectations. I suspect measuring the Doppler is a common sanity check. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] looking for low-power system for gps ntptimekeeping NANOSG20
I have the same model and the trigger settings are great for capturing those tiny width PPS pulses. I setup the trigger so I see the pulse in the middle of the screen and its updated when the pulse occurs. In a nutshell, as Chris mentioned, The trigger modes are excellent for time nuts. The USB works flawlessly but the network basically only works with a crossover cable to a laptop. The network won't work across routers etc. I recently got them to fix the firmware to auto negotiate the correct speed but alas, it still won't work across routers. The control software is.. mmm.. work in progress.. You can plug a VGA monitor in, but honestly the Scope has a huge screen anyway. Its light, portable and there is a battery pack available if you want to guard ground when working on live switch mode PSU. At the time mine cost less than $300 AUD, but I believe they have gone up in price now. I can honestly admit, this scope has become my main scope on the bench, except for a 400MHz Tek Analogue I use infrequently. -marki -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of David J Taylor Sent: Thursday, 4 July 2013 3:27 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] looking for low-power system for gps ntptimekeeping NANOSG20 From: Chris Albertson The computer itself and the NTP installation are OK because we can see it syncing to other NTP servers. Likely you have a problem in the way the GPS using is connected. Some common errors is an inverted PPS, just flip it ad see if you gets better, it is really hard to see a 1Hz signal on a scope. = Any 'scope should be able to see a pule which is high for 100 ms and low for 900 ms! Modern digital scopes even make it easy to see a 100 ns pulse repeated at 1 second intervals. Best investment I made recently was a Rigol DS1052E 'scope - so useful for time-nuts type work. It was /just/ affordable, and it may be even a lower cost now as a newer model is out. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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] HP 8566A, 8568B and 3585A Noise floor.
I just had a discussion about older spectrum analyser versus the new Rigol type SA. They are saying the Rigol is -80dBc. Unfortunately I don't know what the specs of mine are. Could someone help me out with some noise floor figures for the following? * HP 8566A * HP 8568B * HP 3585A Many thanks, -marki ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Speaking of Costas loops
Hi Ed, On 07/02/2013 08:21 PM, ed breya wrote: Here we go again - the first send didn't seem to get through. This is the second attempt. This talk of Costas loops reminded me of something I wanted to investigate some day. I read somewhere a while back about carrier-phase measurements, and various methods for recovering the GPS carrier frequencies, including the Costas loop, and something with carrier-squaring. Nothing I found showed actual examples or detail of how this is done, only high-order mathematical descriptions. For my needs, I'm more of a frequency-nut - I usually don't care about getting time info, but I'd like perfect 10 MHz for reference. Can using only the carriers lead to simple ways to get the same (or better) frequency stability as a conventional GPSDO, but without the time and location info, or is it pointless to worry about it, and just go with full GPS decoding of everything? Or, is carrier-phase just an enhancement only if you already have the full GPS info? I know that the group could redesign the whole GPS system with tubes if necessary, considering recent philosophical discussions on that, so I think there's plenty of knowledge here about carrier-phase related stuff too. Just using the carrier phase in bare form isn't directly useful, as it will be shifted in frequency by the doppler, creating a 1,57542 GHz +/- 6 kHz. If you decode the message (isn't all that much work) you get the nav messaeg, the detailed orbits and can correct using that, but once you got this far you could just as well do full nav message. 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] HP 8566A, 8568B and 3585A Noise floor.
I just had a discussion about older spectrum analyser versus the new Rigol type SA. They are saying the Rigol is -80dBc. Unfortunately I don't know what the specs of mine are. Could someone help me out with some noise floor figures for the following? * HP 8566A * HP 8568B * HP 3585A If you could find a baseline phase noise plot for the Rigol you could compare it with these: http://www.ke5fx.com/floors.gif It'll be influenced by various factors, such as the carrier frequency where it's being measured. I don't know what their block diagram looks like so it's hard to say. -- john, KE5FX Miles Design LLC ___ 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] BPSK decoder for WWVB
Please read the WWVB article on this. There is a whole section devoted on how it can provide higher immunity to MSF. I don't think it a false advertising claim. www.jks.com/*wwvb*.pdf Read the Fundamentals of the new protocol section. Don't shoot the messenger please. Brian On 7/4/2013 2:01 AM, Attila Kinali wrote: On Wed, 03 Jul 2013 19:15:40 + Brian Alsop als...@nc.rr.com wrote: Apparently this modulation scheme is less prone to jammers. There is is British station which jams east coast WWVB. The way WWVB implements BPSK does not make it less prone to jammers or noise. The idea, to get higher SNR would be to encode a known signal onto the carrier which you can correlate against. WWVB does not do that. The phase switches every second according to the bit to be transmitted. As the bits are unkown (safe the 12 sync bits) you have no additional information what the phase/signal is, actually you have even less knowledge compared to a fixed phase signal (aka AM only modulation), hence lower SNR (= less jamming protection). Compare this modulation scheme to what DCF77 or GPS does. Both modulate a long pseudorandom, but known bit string over the carrier against which you can correlate. The effective data bitrate is much lower. And just for clarity: The jamming resistance of such modulation schemes is not inherent in the known signal, but comes from spreading the signal over a larger bandwidth. White noise and random narrow band noise (the two most common noise sources over the air) can be averaged out by the modulation if the bitstring is known. If designed right, you can detect a signal that is several dB below the thermal noise limit, like GPS. TL;DR version: The way how BPSK modulation is implemented in WWVB makes it more prone to jammers and noise instead of less. Attila Kinali ___ 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] Speaking of Costas loops
Hi The way doppler is corrected on a normal GPS is by having a large body of orbital data for each sat measured by a bunch of stations and then processed into the almanac. It's not a trivial process. Since the doppler is in the hundred Hz or so range, I'd bet the conversion oscillator was designed to a similar spec. There may also be other issues as well. You would do *much* better for far less money simply using the same data collection process to do common view GPS with normal gear. Bob On Jul 4, 2013, at 3:06 AM, Hal Murray hmur...@megapathdsl.net wrote: li...@rtty.us said: If the WAAS sats were purpose designed to provide a high accuracy carrier, then yes there are ways to do it. The fundamental design concept of a bent pipe is that you don't do any of that. You do not care what's going through the bird, it just maps the input frequencies to the output and amplifies them (a lot). Again, the WAAS signal is simply piggybacking on existing hardware. The conversion oscillator is not locked to the GPS carrier (or to any other carrier). It's simply a free running quartz based oscillator, running into a synthesizer to get the appropriate microwave frequency. If somebody wanted to use that path for a frequency reference, they could setup a ground station to measure the Doppler and distribute that so people could adjust their expectations. I suspect measuring the Doppler is a common sanity check. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] LORAN
Has anybody listened for LORAN in the US lately? -John = ___ 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] Speaking of Costas loops
That works well for transponders with o LY one signal. On commercial satellites, each transponder is shared among multiple signals, so that would not work. Didier Jim Lux jim...@earthlink.net wrote: On 7/3/13 2:21 PM, Dennis Ferguson wrote: On 3 Jul, 2013, at 11:47 , Bob Camp li...@rtty.us wrote: The pipe in this case is up on one frequency and down on another. The conversion oscillator on satellite that's the weak link, no matter how good the signal from the ground happens to be. That's certainly true but it doesn't seem like a problem that the presence of a high stability free-running oscillator, like a rubidium, would help. The oscillator on a geostationary satellite has a continuous frequency reference to lock to (the uplink carrier) and hence only needs short term stability sufficient to track this and transfer it accurately to the downlink. It seems like this is the kind of problem that quartz excels at. Kind of depends on what the transponder on the satellite looks like. For deep space, we use a very narrow band loop filter to recover the received carrier. The synthesis approach for the downlink is designed to cancel any variations in the local crystal oscillator (e.g. it's typically a ratio.. for X band, 880/749) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Sent from my Motorola Droid Razr 4G LTE wireless tracker while I do other things. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 8566A, 8568B and 3585A Noise floor.
Hi You really need to know a few things about the Rigol spec: 1) Is it simply a noise measure? If so, at what bandwidth and frequency (narrow will always be lower)? 2) Is it a signal spec? If so with what signal level and settings? Does it include / exclude IMD / harmonics? 3) Is it the spec on the number of screen divisions? (yes, I *have* seen that one) 4) Is it the just spec on the SFDR of the ADC? (assuming it's an ADC - FFT beast) Without some qualifiers, the big print spectrum analyzer spec's don't mean a whole lot…. Bob On Jul 4, 2013, at 3:56 AM, Mark C. Stephens ma...@non-stop.com.au wrote: I just had a discussion about older spectrum analyser versus the new Rigol type SA. They are saying the Rigol is -80dBc. Unfortunately I don't know what the specs of mine are. Could someone help me out with some noise floor figures for the following? * HP 8566A * HP 8568B * HP 3585A Many thanks, -marki ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LORAN
A few weeks ago I listened and there was something VERY weak (under 1 uV) from a 150 foot long wire. I've picked up 10+ mV a couple of months ago. Seems like they're still doing testing. On 7/4/2013 9:08 AM, J. Forster wrote: Has anybody listened for LORAN in the US lately? -John = ___ 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. - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3204/5963 - Release Date: 07/04/13 ___ 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
John yes on and off every other week or so. I hear nothing. But its pot luck and if I don't hear it I turn the radio off. It would be easy to miss it. Or perhaps the funding is not going to happen and it really is dead. Regards Paul WB8TSL On Thu, Jul 4, 2013 at 9:08 AM, J. Forster j...@quikus.com wrote: Has anybody listened for LORAN in the US lately? -John = ___ 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
Hi At sub 1uV you may be getting one of the European chains. Bob On Jul 4, 2013, at 10:59 AM, Peter Gottlieb n...@verizon.net wrote: A few weeks ago I listened and there was something VERY weak (under 1 uV) from a 150 foot long wire. I've picked up 10+ mV a couple of months ago. Seems like they're still doing testing. On 7/4/2013 9:08 AM, J. Forster wrote: Has anybody listened for LORAN in the US lately? -John = ___ 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. - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3204/5963 - Release Date: 07/04/13 ___ 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] HP 8566A, 8568B and 3585A Noise floor.
QST did a review of the Rigol DSA815-TG in the February 2013 issue, page 55. The specs were determined to be as specified by Essco Calibration Labratories of Chelmsford Mass. There is a copy here: http://ed31.ref-union.org/Test_RIGOL_QST_February%202013.pdf Bob - AE6RV - Original Message - From: Mark C. Stephens ma...@non-stop.com.au To: time-nuts@febo.com time-nuts@febo.com Cc: Sent: Thursday, July 4, 2013 2:56 AM Subject: [time-nuts] HP 8566A, 8568B and 3585A Noise floor. I just had a discussion about older spectrum analyser versus the new Rigol type SA. They are saying the Rigol is -80dBc. Unfortunately I don't know what the specs of mine are. Could someone help me out with some noise floor figures for the following? * HP 8566A * HP 8568B * HP 3585A Many thanks, -marki ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] BPSK decoder for WWVB
On Thu, 04 Jul 2013 07:59:59 -0500 briana als...@nc.rr.com wrote: Please read the WWVB article on this. There is a whole section devoted on how it can provide higher immunity to MSF. I don't think it a false advertising claim. www.jks.com/*wwvb*.pdf Read the Fundamentals of the new protocol section. I'm not an expert in signal theory, but i call their claims wrong. (Disclaimer: What i write here is based on what i've learned on signal theory ages ago, and forgot most of it. There will be inaccuracies and mistakes in it) Yes, if you argue with the phase state diagram, then you have a larger difference between the old AM and the new BPSK modulation. But: They argue about decoding the bits of the signal, which is something totally different than using WWVB as a frequency or time reference. In the bit decoding case, yes, you get a higher immunity to white noise or burst noise. I am not convinced that a narrow band jamming signal can be correctly substracted from the BPSK signal. Fortunately, they leave all the important details out, how this would be acheived or what the theoretical limits would be. Using WWVB as a frequency reference, you have to substract a previously unknown phase modulation from the signal, hence you lose a bit of noise resilience (it's not much because the bitrate is low). As for timing reference, you gain nothing at all, because the edge where the second begins has still the same properties as with the pure AM modulation: there is only one edge and it is degraded by any noise. Their claim that the DCF77 645Hz spread signal has not the same jamming resiliance because it uses only a +/-13° phase modulation is plain wrong. The jamming and noise resilence is indeed degraded by the low modulation index compared to what could have been acheived using a 180° modulation. But using only +/-13° modulation ensures that people who are phase locking to the DCF77 carrier do not run into the troubles that are well documented on this mailinglist. Also the 645Hz modulation spreads the signal over a wider bandwidth. Instead of the very narrow tone you get a BW of ~1000Hz of the first lobe. And the gain in BW is proportional in gain of SNR you get (roughly and with a lot of simplifications). Compare that to ~1Hz spread you get for the new WWVB signal. And unlike the WWVB signal, where you don't know what the phase modulation signal will be, with DCF77 you exactly know it (pseudo random bit string), hence you can use this knowledge to remove the phase modulation and gain the above mentioned dB's in SNR for better frequency/phase lock (or jamming/noise resilience). When using DCF77 as a timing reference, you get a few hundred additional edges at known positions to figure out when the second exactly began. By using these additonal edges you can average out a lot of noise and hence get a better noise resilience as timing source as well. If they would really have cared about resilience to MSF interfering with WWVB reception, then they would have employed something similar to what DCF77 does, which works the same way as a very well known and tested same frequency transmitter de-jamming tool: CDMA Oh.. and Brian. Dont worry about being shot. My laser gun is ineffective for anything at a distance of more than one meter ;-) Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown ___ 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
Which LORAN system are we talking about? I thought the US stopped LORAN-C back in 2010 and eLORAN plans were cancelled. Are you talking about the European eLORAN system? John On 7/4/2013 8:59 AM, Peter Gottlieb wrote: A few weeks ago I listened and there was something VERY weak (under 1 uV) from a 150 foot long wire. I've picked up 10+ mV a couple of months ago. Seems like they're still doing testing. On 7/4/2013 9:08 AM, J. Forster wrote: Has anybody listened for LORAN in the US lately? -John = ___ 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. - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3204/5963 - Release Date: 07/04/13 ___ 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] HP 8566A, 8568B and 3585A Noise floor.
Marki... The noise floor spec to compare is the Displayed Average Noise Level (DANL). This will usually be measured at the narrowest Resolution Bandwidth (RBW) and Video Bandwidth (VBW) available. And possibly some trace averaging thrown in and either the Average or Sampling Detector since this is a noise measurement. Some analyzers go to 1 HZ RBW, some only 100 Hz, so beware of apples/oranges. -80 dBc is a measurement relative to a CW signal, which implies a phase noise spec, as I found a specification of -80 dBc/Hz @ 10 kHz offset on their web site. The best Spec Ans available today are specified at around -129 dBc/Hz@ 10 kHz offset (Agilent's PXA). Rigol's best claimed DANL is -135 dBm for the DSA800 series, and -148 dBm for the DSA1000 series. I suspect they get that from having an internal preamp. With the preamp off the number is more likely around -135 dBm. High end units today can achieve very close to -174 dBm DANL, at the cost of a new Corvette. I found a spec for noise sidebands at 10 kHz offset for the 8566B at -108 dBc. But that isn't dBc/Hz, which would be lower when adjusted for the RBW setting. Tom Holmes, N8ZM Tipp City, OH EM79 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark C. Stephens Sent: Thursday, July 04, 2013 3:56 AM To: time-nuts@febo.com Subject: [time-nuts] HP 8566A, 8568B and 3585A Noise floor. I just had a discussion about older spectrum analyser versus the new Rigol type SA. They are saying the Rigol is -80dBc. Unfortunately I don't know what the specs of mine are. Could someone help me out with some noise floor figures for the following? * HP 8566A * HP 8568B * HP 3585A Many thanks, -marki ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Speaking of Costas loops
On 7/4/13 7:33 AM, Didier Juges wrote: That works well for transponders with o LY one signal. On commercial satellites, each transponder is shared among multiple signals, so that would not work. Ah, yes.. if it's a linear transponder/translator.. ___ 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] HP 8566A, 8568B and 3585A Noise floor.
Hi John: How can I make a noise floor plot for my HP 4395A? http://www.prc68.com/I/4395A.shtml Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html John Miles wrote: I just had a discussion about older spectrum analyser versus the new Rigol type SA. They are saying the Rigol is -80dBc. Unfortunately I don't know what the specs of mine are. Could someone help me out with some noise floor figures for the following? * HP 8566A * HP 8568B * HP 3585A If you could find a baseline phase noise plot for the Rigol you could compare it with these: http://www.ke5fx.com/floors.gif It'll be influenced by various factors, such as the carrier frequency where it's being measured. I don't know what their block diagram looks like so it's hard to say. -- john, KE5FX Miles Design LLC ___ 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] Speaking of Costas loops
On 07/03/2013 11:59 AM, Attila Kinali wrote: On Tue, 2 Jul 2013 17:06:47 -0400 jmfra...@cox.net wrote: Valid concerns all. What I am building is a squaring circuit for recovering the carrier from a WAAS GPS satellite. Granted there is still some Doppler and other issues, but the accuracy would not be bad and it just looks like a fun thing to do. Plus, I can use my four foot diameter dish antenna to reduce the number of satellites seen, reduce thermal ground noise, and get some signal gain. Right.. i didnt think about the WAAS/EGNOS satelites. If i'm not mistaken, then you dont have to correct for doppler, as the satelites are stationary relative to you. The only thing you might want to correct for are atmospheric changes, but if you are tracking frequency only, and don't care about the phase relation, respektively can live with some phase noise, then you dont even need to do that. Correcting for atmospheric changes should be fairly simple. You just need to decode the WAAS/EGNOS signal, read the atmosphere/TEC data out and apply a phase shift according to that. You still have doppler on WAAS/EGNOS since the orbit isn't really perfect, but it is less than for normal GPS birds. You would need a pretty good directivity such that not nearby WAAS/EGNOS polutes the squaring. Using code (pretty simple) would allow to surpress nearby birds for cleaner result. 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] Speaking of Costas loops
On 07/03/2013 02:29 PM, Bob Camp wrote: Hi There are two batches of GPS / WAAS sats up there: 1) The ones with numbers above 100 that are geosync and that only do WAAS 2) The ones with numbers= 32 that do nav. These are not geosync. I believe the only ones with corrected / high stab clocks on board are those in the second group. The stuff in the first group aren't dedicated sats, just leased transponders on conventional multipurpose geosync birds. Correct. But the up-link station monitors the signal and makes corrects as I recall it. In fact, there is a whole array of monitoring stations to provide for ionospheric corrections. The orbit is also known and corrected for. WAAS/EGNOS has 100 baud data, using half-rate convolution code. 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] HP 8566A, 8568B and 3585A Noise floor.
Hi John: How can I make a noise floor plot for my HP 4395A? http://www.prc68.com/I/4395A.shtml Those plots came from my old freeware app ( http://www.ke5fx.com/gpib/pn.htm ). It supports the 4396A but not the 4395A; see http://www.ke5fx.com/4396a.gif for the baseline plot that someone sent me a few years ago. For some reason HP decided to use a different SCPI implementation for the 4395A and 4396A models. I originally thought the same code would run on both, but no such luck. If you want to set up a VNC or Remote Desktop connection to a PC connected to your 4395A, I may be able to add support for it without too much trouble. Email me offline, if so. -- john, KE5FX Miles Design LLC ___ 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] Speaking of Costas loops
Hi I believe the *code* is corrected, but the carrier frequency is not. Without correction it's plenty close enough for any receiver that can handle a normal GPS sat. The intended product is the code rather than the carrier. Even if you tried to correct for doppler, it would only work for a single point. Your velocity to every place else would be either to fast or to slow for the correction (the motion is in 3 dimensions …). Bob On Jul 4, 2013, at 5:23 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 07/03/2013 02:29 PM, Bob Camp wrote: Hi There are two batches of GPS / WAAS sats up there: 1) The ones with numbers above 100 that are geosync and that only do WAAS 2) The ones with numbers= 32 that do nav. These are not geosync. I believe the only ones with corrected / high stab clocks on board are those in the second group. The stuff in the first group aren't dedicated sats, just leased transponders on conventional multipurpose geosync birds. Correct. But the up-link station monitors the signal and makes corrects as I recall it. In fact, there is a whole array of monitoring stations to provide for ionospheric corrections. The orbit is also known and corrected for. WAAS/EGNOS has 100 baud data, using half-rate convolution code. 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] Speaking of Costas loops
On 3 Jul, 2013, at 21:05 , Bob Camp li...@rtty.us wrote: If the WAAS sats were purpose designed to provide a high accuracy carrier, then yes there are ways to do it. The fundamental design concept of a bent pipe is that you don't do any of that. You do not care what's going through the bird, it just maps the input frequencies to the output and amplifies them (a lot). Again, the WAAS signal is simply piggybacking on existing hardware. The conversion oscillator is not locked to the GPS carrier (or to any other carrier). It's simply a free running quartz based oscillator, running into a synthesizer to get the appropriate microwave frequency. I'm not sure about the Again, ... part. All three WAAS satellites are commercial satellites but they were all launched recently enough (2 in 2005, 1 in 2008) to have had WAAS-specific payload added. The solicitation for the 2008 satellite is here https://www.fbo.gov/index?s=opportunitymode=formid=f5aacd4bba2ef67b0c59b586900499b6tab=core_cview=1 and is dated 2002; this isn't looking for service on a satellite already in orbit. For the 2005 satellites, the Telesat one is mentioned here http://www.telesat.com/services/government-services which says Telesat’s Anik F1R includes a specialized payload for the Wide Area Augmentation System while you look at the Orbital Sciences blurb on the last three satellites it built for PanAmSat, here http://www.orbital.com/newsinfo/publications/galaxy_fact.pdf you'll see that they are all exclusively satellite TV things, with 24 active C-band transponders and 8 spares, except for Galaxy 15 which weighs 350 pounds more than the other two and about which it says: The Galaxy 15 satellite, which features a unique hybrid payload configuration, was launched on October 13, 2005. In addition to C-band commercial communications, the spacecraft also broadcasts Global Positioning System (GPS) navigation data using L-band frequencies as part of the Geostationary Communications and Control Segment (GCCS) implemented by Lockheed Martin for the U.S. Federal Aviation Administration (FAA). I don't think they can use any old satellite for WAAS, they added payload for it. Note that when Galaxy 15 went awol it took the WAAS service with it for most of a year even though it was replaced in its orbital slot for TV service by a spare within a week or so (though Wikipedia says the replacement was Galaxy 12 so I guess that's predictable from the blurb above). So I've been assuming that while the WAAS satellites are commercial the WAAS transmitters are specialized to the service and included for its exclusive use. I hence guess they could have been designed to work however they needed to. Dennis Ferguson ___ 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.
