Re: [time-nuts] Important parameters for a GPS/GNSS antenna
On Thu, 7 May 2015 14:43:44 -0400 Tim Shoppa wrote: > Gotcha with modulating the PPS onto a RF carrier, is that for time > resolution of 1 nanosecond, you would end up using a Gigahertz of bandwidth. Not really. You are not doing detection in frequency space or of an infintely sharp pulse. As such it is ok if you are bandlimited. Then you just have to ensure that the risinge edge (or whichever you detect) has always the same shape and you detect always at the same level. It is basically the same principle with which we get sup-ns resolution with PPS pulses. The wire isn't good for a bandwidth of >1GHz, usually much less than that (especially the connectors), but as the pulse does not have a very steep edge, it does not need to. Insted the pulse amplitude and the detection level are kept as constant as possible. Of course, any variation in amplitude, detection level or noise degrades the measurement considerably. Attila Kinali -- < _av500_> phd is easy < _av500_> getting dsl is hard ___ time-nuts mailing 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] Important parameters for a GPS/GNSS antenna
tsho...@gmail.com said: > Gotcha with modulating the PPS onto a RF carrier, is that for time > resolution of 1 nanosecond, you would end up using a Gigahertz of bandwidth. You might be able to use near-field antennas. Picture 2 PCBs spaced a few mm apart with circular antennas. It would be interesting to measure all the timing quirks of not having things lined up accurately. -- 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] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
Hi > On May 7, 2015, at 8:02 AM, Pete Stephenson wrote: > > On 5/7/2015 1:22 PM, Bob Camp wrote: >> Hi >> >> I guess on a general level: >> >> 1) How do they generate the Swiss version of UTC (fleet of hydrogen masers >> run into to a .. :) > > According to their website they use an ensemble of commercial cesium > clocks (they show some photos of HP 5071As) and a hydrogen maser. I'll > be sure to ask them for details. > >> 2) How do they link that version of UTC with the rest of the world? (BIH etc) BIH = Bureau International de l’Heure They are the people who (by treaty) decide what time it *really* is. In order to do this they need to be able to evaluate the various time scales around the world. That evaluation process requires some method of direct inter comparison of time scales over very long distances. Typical approaches range from “clock trips” to TWSTT ( or TWSTFT) to GPS based techniques. In addition to the comparison process it’s self, there is also a lot of internal cross checking and analysis that goes into a typical time scale. Often the associated equipment base is pretty substantial. It’s also a good thing to look at to pick up ideas for (lower cost) implementation in a basement lab. Bob > I'm not familiar with that particular acronym (BIH), but I am curious > how they link their version of UTC. > >> Not so much a picture of this or that. More a tour of an entire process. > > Right. > > Cheers! > -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] FE-2294B data
Anyone have specs and a pinout for the Frequency electronics FE-2294B oscillator? Thanks, 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] Important parameters for a GPS/GNSS antenna
On Thu, 7 May 2015 08:18:05 -0700 "Tom Van Baak" wrote: > Attila, > > My thought was to put PHK's proposed experiment entirely on the rotating > table: antenna, receiver, local Cs standard, laptop, and battery. Then you have to be carefull, that the rotation does not modulate the reference. I am pretty sure rotation would at least shift the Cs frequency (atoms fly in an arc) and thus any change in rotation speed would be visible in the measurement. An vapor cell Rb might be better for that case. The periodic shift of the magnetic field would also need to be considered. Maybe the best way would to put the GPS receiver onto the rotating table as well, modulate some laser which points down the middle of the central shaft, and extract that using a small aperture and a photodiode. (The aperture to make sure that only light commming down the exactly in the center is used). This way the reference would be at a stable place, yet the transfer of the signal would be quite stable. > You could > also get interesting data if you slightly offset the antenna from the center. > It would make the ultimate GPS Spirograph. (for those of you under 40, > http://en.wikipedia.org/wiki/Spirograph will explain) Hehe. That would be really cool! Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing 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] Carrier phase wind up (was: Important parameters for a GPS/GNSS antenna)
On Thu, 7 May 2015 20:57:56 +0200 "Björn Gabrielsson" wrote: >http://www.navipedia.net/index.php/Carrier_Phase_Wind-up_Effect This page referes to Wu, J., Wu, S., Hajj, G., Bertiguer, W. and Lichten, S., 1993. Effects of Antenna Orientation on GPS Carrier Phase Measurements. Manuscripta Geodaetica. 18, pp. 91-98. Which does not seem to be available online. Does anyone have access to a paper copy of this and would be so kind to scan it? Attila Kinali -- < _av500_> phd is easy < _av500_> getting dsl is hard ___ time-nuts mailing 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] Important parameters for a GPS/GNSS antenna
On 5/7/15 7:23 AM, Attila Kinali wrote: On Sun, 03 May 2015 07:29:30 + "Poul-Henning Kamp" wrote: When you post-process raw GPS data you get to include antenna phase center / gain / az/el corrections for free. Speaking of which... I wonder if anybody ever made a rotating GPS antenna to average out the X-Y phase-center offset ? There is a severe mechanical problem with that. Moving contacts are very hard to keep electrically stable. It works for simple power and digital signal wires, as there the only considerations are resistance over the joint and sparks. If you need to transmit analog signals you generally convert them into a form that does not depend on the amplitude of the signal (either going digital or doing a voltage to frequency conversion). Of course, this does not really work with a gps antenna, unless you put the whole receiver onto the rotary table. But then you shift the problem onto the PPS output (note: amplitude noise translates into phase noise). The best system i know about, for such rotating contacts with analog (possibly high frequency) signals is a small pot with mercury. But i guess you can see the problems that causes. The second best, but which only works with high frequency signals, is to use a hollow waveguide. There you need "only" to ensure that the waveguide walls are properly connected and you have a large area to use for that. If you can ensure that there is only one mode, you can make it such, that there is no current flowing over the gap. They make rotary coax joints as well as waveguide. The coax is an air dielectric type. There is, inevitably, some wow and flutter in S21 (and S11) ___ time-nuts mailing 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] Important parameters for a GPS/GNSS antenna
How about a laser diode and pin photo detector? You should be able to get nanosecond resolution with light. - Original Message - From: "Tim Shoppa" To: "Discussion of precise time and frequency measurement" Sent: Thursday, May 07, 2015 2:43 PM Subject: Re: [time-nuts] Important parameters for a GPS/GNSS antenna Personally I would be happy with PPS time resolution at 10 nanoseconds but others would want better than a nanosecond. Gotcha with modulating the PPS onto a RF carrier, is that for time resolution of 1 nanosecond, you would end up using a Gigahertz of bandwidth. Tim N3QE On Thu, May 7, 2015 at 11:49 AM, John Ackermann N8UR wrote: Just put the GPS antenna, receiver, battery, and a low power RF transmitter modulated by the PPS (wide bandwidth = fast edge time) on the turntable, then use an appropriate receiver to demodulate the PPS and feed it to the rest of the system. Put the RX antenna directly above (or below) the turntable so the path length remains close to constant. Using FM might also remove Doppler effects from the received pulse. On 5/7/2015 11:18 AM, Tom Van Baak wrote: I wonder if anybody ever made a rotating GPS antenna to average out the X-Y phase-center offset ? Of course, this does not really work with a gps antenna, unless you put the whole receiver onto the rotary table. But then you shift the problem onto the PPS output (note: amplitude noise translates into phase noise). Attila, My thought was to put PHK's proposed experiment entirely on the rotating table: antenna, receiver, local Cs standard, laptop, and battery. You could also get interesting data if you slightly offset the antenna from the center. It would make the ultimate GPS Spirograph. (for those of you under 40, http://en.wikipedia.org/wiki/Spirograph will explain) /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. ___ time-nuts mailing 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] Important parameters for a GPS/GNSS antenna
Also consider phase wind up. http://www.navipedia.net/index.php/Carrier_Phase_Wind-up_Effect Sure there are also some papers on rotating antennas. http://www.researchgate.net/profile/Simon_Banville/publication/257945217_Antenna_Rotation_and_Its_Effects_on_Kinematic_Precise_Point_Positioning/links/0deec5266c9c6ac71800.pdf "Due to the polarization of GPS signals, carrier-phase measurements made by GPS receivers are affected by the orientation of the antenna. " "On the other hand, code measurements are not affected by this effect. " -- Björn > I'm curious whether it would need 360 degree rotation? Would simply > cycling about 120 degrees on the end of a short arm be just as good and > could be done without a rotary joint? I understand that now the RX is > moving but within a small radius would it be unbearable? Or would 300 > degrees around the axis be sufficient? > > From Tom Holmes, N8ZM > > >> On May 7, 2015, at 11:49 AM, John Ackermann N8UR wrote: >> >> Just put the GPS antenna, receiver, battery, and a low power RF >> transmitter modulated by the PPS (wide bandwidth = fast edge time) on >> the turntable, then use an appropriate receiver to demodulate the PPS >> and feed it to the rest of the system. Put the RX antenna directly >> above (or below) the turntable so the path length remains close to >> constant. Using FM might also remove Doppler effects from the received >> pulse. >> >> On 5/7/2015 11:18 AM, Tom Van Baak wrote: > I wonder if anybody ever made a rotating GPS antenna to average out > the > X-Y phase-center offset ? >>> Of course, this does not really work with a gps antenna, unless you put the whole receiver onto the rotary table. But then you shift the problem onto the PPS output (note: amplitude noise translates into phase noise). >>> >>> Attila, >>> >>> My thought was to put PHK's proposed experiment entirely on the >>> rotating table: antenna, receiver, local Cs standard, laptop, and >>> battery. You could also get interesting data if you slightly offset the >>> antenna from the center. It would make the ultimate GPS Spirograph. >>> (for those of you under 40, http://en.wikipedia.org/wiki/Spirograph >>> will explain) >>> >>> /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. > ___ > time-nuts mailing 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] Important parameters for a GPS/GNSS antenna
Personally I would be happy with PPS time resolution at 10 nanoseconds but others would want better than a nanosecond. Gotcha with modulating the PPS onto a RF carrier, is that for time resolution of 1 nanosecond, you would end up using a Gigahertz of bandwidth. Tim N3QE On Thu, May 7, 2015 at 11:49 AM, John Ackermann N8UR wrote: > Just put the GPS antenna, receiver, battery, and a low power RF > transmitter modulated by the PPS (wide bandwidth = fast edge time) on the > turntable, then use an appropriate receiver to demodulate the PPS and feed > it to the rest of the system. Put the RX antenna directly above (or below) > the turntable so the path length remains close to constant. Using FM might > also remove Doppler effects from the received pulse. > > > On 5/7/2015 11:18 AM, Tom Van Baak wrote: > >> I wonder if anybody ever made a rotating GPS antenna to average out the X-Y phase-center offset ? >>> >> Of course, this does not really work with a gps antenna, unless you >>> put the whole receiver onto the rotary table. But then you shift >>> the problem onto the PPS output (note: amplitude noise translates >>> into phase noise). >>> >> >> Attila, >> >> My thought was to put PHK's proposed experiment entirely on the rotating >> table: antenna, receiver, local Cs standard, laptop, and battery. You could >> also get interesting data if you slightly offset the antenna from the >> center. It would make the ultimate GPS Spirograph. (for those of you under >> 40, http://en.wikipedia.org/wiki/Spirograph will explain) >> >> /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. > ___ time-nuts mailing 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] Important parameters for a GPS/GNSS antenna
I'm curious whether it would need 360 degree rotation? Would simply cycling about 120 degrees on the end of a short arm be just as good and could be done without a rotary joint? I understand that now the RX is moving but within a small radius would it be unbearable? Or would 300 degrees around the axis be sufficient? >From Tom Holmes, N8ZM > On May 7, 2015, at 11:49 AM, John Ackermann N8UR wrote: > > Just put the GPS antenna, receiver, battery, and a low power RF transmitter > modulated by the PPS (wide bandwidth = fast edge time) on the turntable, then > use an appropriate receiver to demodulate the PPS and feed it to the rest of > the system. Put the RX antenna directly above (or below) the turntable so > the path length remains close to constant. Using FM might also remove > Doppler effects from the received pulse. > > On 5/7/2015 11:18 AM, Tom Van Baak wrote: I wonder if anybody ever made a rotating GPS antenna to average out the X-Y phase-center offset ? >> >>> Of course, this does not really work with a gps antenna, unless you >>> put the whole receiver onto the rotary table. But then you shift >>> the problem onto the PPS output (note: amplitude noise translates >>> into phase noise). >> >> Attila, >> >> My thought was to put PHK's proposed experiment entirely on the rotating >> table: antenna, receiver, local Cs standard, laptop, and battery. You could >> also get interesting data if you slightly offset the antenna from the >> center. It would make the ultimate GPS Spirograph. (for those of you under >> 40, http://en.wikipedia.org/wiki/Spirograph will explain) >> >> /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. ___ time-nuts mailing 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] Important parameters for a GPS/GNSS antenna
Just put the GPS antenna, receiver, battery, and a low power RF transmitter modulated by the PPS (wide bandwidth = fast edge time) on the turntable, then use an appropriate receiver to demodulate the PPS and feed it to the rest of the system. Put the RX antenna directly above (or below) the turntable so the path length remains close to constant. Using FM might also remove Doppler effects from the received pulse. On 5/7/2015 11:18 AM, Tom Van Baak wrote: I wonder if anybody ever made a rotating GPS antenna to average out the X-Y phase-center offset ? Of course, this does not really work with a gps antenna, unless you put the whole receiver onto the rotary table. But then you shift the problem onto the PPS output (note: amplitude noise translates into phase noise). Attila, My thought was to put PHK's proposed experiment entirely on the rotating table: antenna, receiver, local Cs standard, laptop, and battery. You could also get interesting data if you slightly offset the antenna from the center. It would make the ultimate GPS Spirograph. (for those of you under 40, http://en.wikipedia.org/wiki/Spirograph will explain) /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] CM level GPS accuracy in a smartphone
A 300M error is not "just a GPS determination" but is likely the phone using a few extrapolated stale GPS readings maybe combined with some kind (probably wrong kind) of dead reckoning. Automotive dead reckoning applied to pedestrian movement can produce really interesting results! As I walk around my house or yard, my phone keeps on jumping my location to the middle of a 12-lane superhighway a few hundred feet away. Most GPS code is based on automotive dead reckoning algorithms but the cellphone manufacturers also are working on "pedestrian dead reckoning" modes, activated when the inertial sensors indicate walking. Tim N3QE On Thu, May 7, 2015 at 9:32 AM, Attila Kinali wrote: > On Tue, 5 May 2015 22:01:29 + > Mark Sims wrote: > > > Should be fun when it becomes available... they claim they can get > > accurate carrier phase info using a cheap antenna in the phone... > > and in real time. It should also be able to get accurate time. > > http://www.eurekalert.org/pub_releases/2015-05/uota-ncg050415.php > > From what I know about carrier phase measurement, I am not so sure > they can actually deliver this accuracy in urban environments. > > Yes, carrier phase measurement can give you cm level accuracy > (after you solve the integer ambiguity), but the biggest contributor > to dilution of precision is multipath and refraction (in urban > environments). These can easily make up several meters. I have > experienced my cell phone to be off by ~300m for several minutes > in an environment where I "only" had a large tree and some smallish > houses in a residential area. Yes, this was most likely just a fluke > of the gps receiver, but still, the biggest problem in the environment, > where most people would use gps for this kind of thing, is not the > limit of precision due to code-only tracking. > > But anyways. Let's see what they will deliver. > > Attila Kinali > > -- > It is upon moral qualities that a society is ultimately founded. All > the prosperity and technological sophistication in the world is of no > use without that foundation. > -- Miss Matheson, The Diamond Age, Neil Stephenson > ___ > time-nuts mailing 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] Important parameters for a GPS/GNSS antenna
>> I wonder if anybody ever made a rotating GPS antenna to average out the >> X-Y phase-center offset ? > Of course, this does not really work with a gps antenna, unless you > put the whole receiver onto the rotary table. But then you shift > the problem onto the PPS output (note: amplitude noise translates > into phase noise). Attila, My thought was to put PHK's proposed experiment entirely on the rotating table: antenna, receiver, local Cs standard, laptop, and battery. You could also get interesting data if you slightly offset the antenna from the center. It would make the ultimate GPS Spirograph. (for those of you under 40, http://en.wikipedia.org/wiki/Spirograph will explain) /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] Important parameters for a GPS/GNSS antenna
On Sun, 03 May 2015 07:29:30 + "Poul-Henning Kamp" wrote: > >When you post-process raw GPS data you get to include antenna phase > >center / gain / az/el corrections for free. > > Speaking of which... > > I wonder if anybody ever made a rotating GPS antenna to average out the > X-Y phase-center offset ? There is a severe mechanical problem with that. Moving contacts are very hard to keep electrically stable. It works for simple power and digital signal wires, as there the only considerations are resistance over the joint and sparks. If you need to transmit analog signals you generally convert them into a form that does not depend on the amplitude of the signal (either going digital or doing a voltage to frequency conversion). Of course, this does not really work with a gps antenna, unless you put the whole receiver onto the rotary table. But then you shift the problem onto the PPS output (note: amplitude noise translates into phase noise). The best system i know about, for such rotating contacts with analog (possibly high frequency) signals is a small pot with mercury. But i guess you can see the problems that causes. The second best, but which only works with high frequency signals, is to use a hollow waveguide. There you need "only" to ensure that the waveguide walls are properly connected and you have a large area to use for that. If you can ensure that there is only one mode, you can make it such, that there is no current flowing over the gap. Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing 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] Important parameters for a GPS/GNSS antenna
On Sat, 02 May 2015 18:36:30 +0200 Magnus Danielson wrote: > On 04/29/2015 10:43 PM, Attila Kinali wrote: > > Moin, > > > > I recently discovered openEMS[1], which is, very simply put, a fancy > > antenna simulator. I played a little with it and thought about > > trying to optimize an GPS patch antenna design for timing use. > > Will take it for a test-drive to see how it align up to NEC2 and variants. I'm pretty sure that OpenEMS will be more accurate in most cases. OpenEMS uses a more general approach to solving Maxwells equations that works for patterned conductors as well. While NEC2 is known to work well only for wires and cylinders (even tappered antennas cause large inaccuracies). > > My google skills failed to locate any relevant documents on this topic. > > > > Could someone be so kind and give me some pointers, what to search > > for, documents or the like? > > The thing that we care about is: > > 1) LHCP surpression > 2) Directivity/ surpression of signals below say 5 degrees above horizon > 3) Phase stability with regard to azimuth/elevation > 4) Relatively flat gain above 5 degrees Yes. In the meantime I found [1]. I only skimmed over an electronic version so far, but the gist of it seems that multipath supression comes first, before anything else. Ie RHCP/LHCP ratio and supression of everything below 5°-10°. After that, it's phase center stability. Other factors do not seem to matter as much (not sure, it could be that I just didnt read enough of the book) > Do read up on the Novatel pinwheels, as they illustrate the various > concerns and how they do that in a new fashion. I read most of the papers and the patents I found. While enlightening on some aspects, they do not tell much about the tradeoffs. Also I had some facepalm-moments on what is patentable But then, the first pinwheel patent is to expire in 4 years, so that problem solves itself. Attila Kinali [1] "GPS/GNSS Antennas", by Rama Rao, Kunysz, Fante, McDonald, 2012, ISBN: 978-1596931503 -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing 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] Important parameters for a GPS/GNSS antenna
On Sat, 2 May 2015 13:25:16 -0400 Bob Camp wrote: > Phase / delay stability over temperature would be an interesting thing > to look at. Probably not a big deal on > a simple antenna. It might be an issue as the antenna interacts with the > preamp and filter. I've seen a couple of papers concerning this. I haven't sorted them in yet (much less read), so i cannot give you the names and doi yet. But if you are interested i can do so over the weekend. Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing 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] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
On 5/7/2015 1:22 PM, Bob Camp wrote: > Hi > > I guess on a general level: > > 1) How do they generate the Swiss version of UTC (fleet of hydrogen masers > run into to a .. :) According to their website they use an ensemble of commercial cesium clocks (they show some photos of HP 5071As) and a hydrogen maser. I'll be sure to ask them for details. > 2) How do they link that version of UTC with the rest of the world? (BIH etc) I'm not familiar with that particular acronym (BIH), but I am curious how they link their version of UTC. > Not so much a picture of this or that. More a tour of an entire process. Right. Cheers! -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] CM level GPS accuracy in a smartphone
On Tue, 5 May 2015 22:01:29 + Mark Sims wrote: > Should be fun when it becomes available... they claim they can get > accurate carrier phase info using a cheap antenna in the phone... > and in real time. It should also be able to get accurate time. > http://www.eurekalert.org/pub_releases/2015-05/uota-ncg050415.php >From what I know about carrier phase measurement, I am not so sure they can actually deliver this accuracy in urban environments. Yes, carrier phase measurement can give you cm level accuracy (after you solve the integer ambiguity), but the biggest contributor to dilution of precision is multipath and refraction (in urban environments). These can easily make up several meters. I have experienced my cell phone to be off by ~300m for several minutes in an environment where I "only" had a large tree and some smallish houses in a residential area. Yes, this was most likely just a fluke of the gps receiver, but still, the biggest problem in the environment, where most people would use gps for this kind of thing, is not the limit of precision due to code-only tracking. But anyways. Let's see what they will deliver. Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing 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] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
Poul-Henning Kamp wrote: Ask them how/why the HBG transmitter screwed up the 2006 leapsecond ? If I remember correctly then the transmitter would have needed to be overhauled, which would have been very expensive. Since the German DCF77 transmitter can also be received in Switzerland and DCF77 receivers were much more common than HBG receivers the decision was taken to finish HBG transmission. Martin ___ time-nuts mailing 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] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
In message <7fa86d93-1c83-4fe8-84a0-ddb7a542a...@n1k.org>, Bob Camp writes: Ask them how/why the HBG transmitter screwed up the 2006 leapsecond ? -- 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] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
Hi I guess on a general level: 1) How do they generate the Swiss version of UTC (fleet of hydrogen masers run into to a .. :) 2) How do they link that version of UTC with the rest of the world? (BIH etc) Not so much a picture of this or that. More a tour of an entire process. Bob > On May 7, 2015, at 5:38 AM, Pete Stephenson wrote: > > Hi all, > > I recently inquired about taking a tour of the METAS time lab[1] and > they said they'd be willing to show me around. > > Is there anything in particular that fellow time-nuts would be > interested in me asking them about or (if possible) photographing? > > Cheers! > -Pete > > [1] http://www.metas.ch/metas/en/home/fabe/zeit-und-frequenz.html > > -- > Pete Stephenson > ___ > time-nuts mailing 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] Microsemi versus Spetracom
Be aware that the early TS2100's have different (SV6) gps receivers than the later (ACE III) ones. Both speak TSIP, but some of the commands are different. Mine went to the boneyard a few months ago. On Wed, May 6, 2015 at 9:28 PM, Sean Gallagher wrote: > > > It's possible that the Heol Design Trimble III replacement cards (N014 & > N024) will correct the 1995 issue. They are sending my company a couple now > for us to test in a trusted time infrastructure which includes 2 TS2100's. > Unfortunately they were not able to get a straight answer from Trimble so > experimenting seems to be the only way to find out. > > > Senr from my Verizon Wireless 4G LTE smartphone > > Original message > From: Andrew Cooper > Date: 05/06/2015 15:58 (GMT-05:00) > To: time-nuts@febo.com > Subject: [time-nuts] Microsemi versus Spetracom > > So, yes, our old TS2100's suffered the 1995 bug over the weekend like all of > the others in the world. Kludged into working for the moment using 1PPS and > two units. > > I do need to buy a couple replacements, good time is critical around an > observatory, looking at a $16K purchase order. We have quoted both the > SecureSync from SpectraCom and the S350 from Microsemi, both fully spec'd out > with IRIG and IEEE1588. > > I am not really a time expert, just an everyday electrical engineer. Thrust > into the problem three days ago. I have learned a bit reading through the > Time Nuts archive... Thanks! > > Anything I should be aware of with these units. Any opinions on this > purchase? > > Thanks for your advice, > Andrew > > Andrew Cooper > Electrical Engineer > W. M. Keck Observatory > 808-881-3862 > mailto:acoo...@keck.hawaii.edu > > ___ > time-nuts mailing 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] TymServe 2100 1995 Issue - A Kludgy Fix
Brian Inglis wrote: The next rollover is about April 2019, but this can happen any time an older receiver's internal date representation used for GPS to UTC conversion overflows. Looks like Tymserve 2100 picked about Sep 1995 for its date epoch so it hits now. Newer GPS receivers support the extra 3 bits added to GPS extended week allowing 8192 weeks (157 years) between rollovers - 2137 is the next big rollover problem, but NavStar will likely not be sending the same data on the same frequency then. There are also GPS receivers out there which use (and have been using) an extended week number internally instead of hardcoded limit for the 10 bit week number. As long as there's a backup battery is OK then there's nothing to do for the user to get the correct epoch. If the backup battery is disconnected or fails then you can just send the current date to the device, and the firmware computes the extended week number, including the epoch of the GPS week number. Martin ___ time-nuts mailing 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] Microsemi versus Spetracom
Look also at Brandywine and Meinberg. /Björn Originalmeddelande Från: Andrew Cooper Datum:2015-05-06 21:58 (GMT+01:00) Till: time-nuts@febo.com Rubrik: [time-nuts] Microsemi versus Spetracom So, yes, our old TS2100's suffered the 1995 bug over the weekend like all of the others in the world. Kludged into working for the moment using 1PPS and two units. I do need to buy a couple replacements, good time is critical around an observatory, looking at a $16K purchase order. We have quoted both the SecureSync from SpectraCom and the S350 from Microsemi, both fully spec'd out with IRIG and IEEE1588. I am not really a time expert, just an everyday electrical engineer. Thrust into the problem three days ago. I have learned a bit reading through the Time Nuts archive... Thanks! Anything I should be aware of with these units. Any opinions on this purchase? Thanks for your advice, Andrew Andrew Cooper Electrical Engineer W. M. Keck Observatory 808-881-3862 mailto:acoo...@keck.hawaii.edu ___ time-nuts mailing 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] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
Hi all, I recently inquired about taking a tour of the METAS time lab[1] and they said they'd be willing to show me around. Is there anything in particular that fellow time-nuts would be interested in me asking them about or (if possible) photographing? Cheers! -Pete [1] http://www.metas.ch/metas/en/home/fabe/zeit-und-frequenz.html -- Pete Stephenson ___ time-nuts mailing 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] Microsemi versus Spetracom
It's possible that the Heol Design Trimble III replacement cards (N014 & N024) will correct the 1995 issue. They are sending my company a couple now for us to test in a trusted time infrastructure which includes 2 TS2100's. Unfortunately they were not able to get a straight answer from Trimble so experimenting seems to be the only way to find out. Senr from my Verizon Wireless 4G LTE smartphone Original message From: Andrew Cooper Date: 05/06/2015 15:58 (GMT-05:00) To: time-nuts@febo.com Subject: [time-nuts] Microsemi versus Spetracom So, yes, our old TS2100's suffered the 1995 bug over the weekend like all of the others in the world. Kludged into working for the moment using 1PPS and two units. I do need to buy a couple replacements, good time is critical around an observatory, looking at a $16K purchase order. We have quoted both the SecureSync from SpectraCom and the S350 from Microsemi, both fully spec'd out with IRIG and IEEE1588. I am not really a time expert, just an everyday electrical engineer. Thrust into the problem three days ago. I have learned a bit reading through the Time Nuts archive... Thanks! Anything I should be aware of with these units. Any opinions on this purchase? Thanks for your advice, Andrew Andrew Cooper Electrical Engineer W. M. Keck Observatory 808-881-3862 mailto:acoo...@keck.hawaii.edu ___ time-nuts mailing 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] Lucent KS-24361/Thunderbolt antenna advice
On 5/6/15 3:09 PM, Bob Camp wrote: GPS helix antennas were a really big deal in about 1982. Once people started to get experience with GPS and a variety of designs, they became less of a big deal. I do not know of any modern precision antennas that use a helix. Most precision antennas I've seen recently use some form of a crossed dipole, with drooping elements with a weird shape (to get the match decent at all the frequencies, and to get the relative phase shift right). ___ time-nuts mailing 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] Microsemi versus Spetracom
That's what mine is doing. The hourglass stops and a random ascii character appears overlapped with the top left corner of the hourglass. David and Brian, I'll ping you guys off list so we don't clutter this place up. Thanks, Bob On Wed, May 6, 2015 at 4:58 PM, David & Laura wrote: > I had this happen with my S250. It hangs during boot with the spinning > hourglass stopping, right? > > The problem ended up being that the processor module had come slightly > unseated. The initial boot messages on the display are independent from the > functioning of the processor module. > > Thanks, > > David Slik > VE7FIM > > On Wed, May 6, 2015 at 2:35 PM, Bob Darlington > wrote: > > > My personal S300 died last month but otherwise I've fielded them in hot, > > cold, dusty, wet, and dry environments and they seem to keep going.It > > passes the initial self tetst but won't fully boot. I suspect CF card > > failure. Microsemi won't talk to me without an active support contract. > > > > Due to its death, I'm now working on a BeagleBone Black "cape" > specifically > > for M12+ or Furuno timing receivers. I appreciate COTS hardware, but > I'm a > > hobbyist. Mine will be cheaper, but I can't vouch for more reliable > yet. > > > > -Bob > > > > On Wed, May 6, 2015 at 1:58 PM, Andrew Cooper > > wrote: > > > > > So, yes, our old TS2100's suffered the 1995 bug over the weekend like > all > > > of the others in the world. Kludged into working for the moment using > > 1PPS > > > and two units. > > > > > > I do need to buy a couple replacements, good time is critical around an > > > observatory, looking at a $16K purchase order. We have quoted both the > > > SecureSync from SpectraCom and the S350 from Microsemi, both fully > spec'd > > > out with IRIG and IEEE1588. > > > > > > I am not really a time expert, just an everyday electrical engineer. > > > Thrust into the problem three days ago. I have learned a bit reading > > > through the Time Nuts archive... Thanks! > > > > > > Anything I should be aware of with these units. Any opinions on this > > > purchase? > > > > > > Thanks for your advice, > > > Andrew > > > > > > Andrew Cooper > > > Electrical Engineer > > > W. M. Keck Observatory > > > 808-881-3862 > > > mailto:acoo...@keck.hawaii.edu > > > > > > ___ > > > time-nuts mailing 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] Divider circuit for Rubidium Standard
On 5/6/2015 3:24 PM, Bob Camp wrote: Hi A standard input on a frequency counter is not a very demanding thing in the hierarchy of TimeNut signals. You can drive any of them with some pretty simple logic gate based circuits. No need to spend a lot of money. Bob Logic gate, yes. Comparator, no. Rick ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
