Re: [time-nuts] Best reason
On Thu, Mar 29, 2012 at 08:43, Hal Murray hmur...@megapathdsl.net wrote: I think of GPS as a bunch of satellites broadcasting I'm Bob, my orbit parameters are XXX, my clock says YYY. If you hear 4 of those, you have 4 equations to work out 4 unknowns. The unknowns are your position: X, Y, Z, and T. But, but, but, they told you the value of Y three times. Why don't they say: I'm Bob, my orbit parameters are X,Y,Z, my clock says T. Nothing to solve :-) And GPS jamming would work by other people calling you with: Hi, Hal, ignore that guy, _I_ am the genuwine Bob. (For those who see this in a list archive many years from now: I am NOT serious, please). -- Sanjeev Gupta, the person formerly known as Bob +65 98551208 http://www.linkedin.com/in/ghane ___ 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] CW12-TIM vs M12M and the world
Thomas, The sawtooth error on the Motorola M12+ is about +/- 25ns, while the CW12-TIM has a sawtooth error of +/- 2 ns, so correcting for the sawtooth error is not as critical with the CW12-TIM. The first claim The sawtooth error on the Motorola M12+ is about +/- 25ns is correct but are you absolutely sure that the second claim is correct too? It would mean a factor 10 improvement of the CW12-TIM against the M12 which is hardly believeable. Best regards Ulrich Bangert -Ursprungliche Nachricht- Von: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Im Auftrag von Tom Knox Gesendet: Mittwoch, 28. Marz 2012 20:42 An: Time-Nuts Betreff: [time-nuts] CW12-TIM vs M12M and the world I spoke with Navsync about some of the issues we are discussing and this was their response. I just received mine and will try to test it over the weekend. 1. Is CW12-TIM compatible with Motorola M12 ? The CW12 is designed to be compatible with the M12 although there are some differences. The main hardware differences are listed on page 7 of the CW12 User Manual (http://www.navsync.com/docs/cw12-tim_um.pdf). 2. According to the customer, M12 has a Sawtooth Correction Error Hanging Bridge Error? Does CW12 have a solution for these type of errors? How these errors are taken care of in CW12? The Hanging Bridge Error is a pattern seen in the sawtooth error that occurs as the local clock frequency changes. The standard Motorola Binary software for the CW12-TIM does not have the sawtooth correction field in the @@Hn command implemented, but NavSync is currently developing this and it will be available in future standard releases. The sawtooth error on the Motorola M12+ is about +/- 25ns, while the CW12-TIM has a sawtooth error of +/- 2 ns, so correcting for the sawtooth error is not as critical with the CW12-TIM. Thomas Knox ___ 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] CW12-TIM vs M12M and the world
The sawtooth error on the Motorola M12+ is about +/- 25ns, while the CW12-TIM has a sawtooth error of +/- 2 ns, so correcting for the sawtooth error is not as critical with the CW12-TIM. The first claim The sawtooth error on the Motorola M12+ is about +/- 25ns is correct but are you absolutely sure that the second claim is correct too? It would mean a factor 10 improvement of the CW12-TIM against the M12 which is hardly believeable. The 25 ns probably comes from period of the the free running clock they are using. It doesn't seem unreasonable to me to get 10x better if they use a GPSDO for the local clock so they can get the PPS edge right where they want it. -- These are my opinions, not necessarily my employer's. 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] Best reason
I'm currently have to convince management that our 6-1/2 DMM (0.01% uncertainty) can't be used to test the 0.1ppm DC Source that we're repairing. Don't bother, just send it to me (once you've fixed it natch) :) On a more serious note what it this DC source that can manage 0.1ppm - the only thing I can think of that achieve that level of accuracy has to be a Josephson junction array. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Best reason
Yes, and moreover: what kind of test can be done on that DC source if no DMM is able to show that accuracy? On Thu, Mar 29, 2012 at 9:53 AM, David C. Partridge david.partri...@perdrix.co.uk wrote: I'm currently have to convince management that our 6-1/2 DMM (0.01% uncertainty) can't be used to test the 0.1ppm DC Source that we're repairing. Don't bother, just send it to me (once you've fixed it natch) :) On a more serious note what it this DC source that can manage 0.1ppm - the only thing I can think of that achieve that level of accuracy has to be a Josephson junction array. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] CW12-TIM vs M12M and the world
We (that is my company) use the CW12-TIM (NMEA version) and its PPS wonders as usual, nothing different from a uBlox LEA-5T or the M12M. On Thu, Mar 29, 2012 at 9:32 AM, Hal Murray hmur...@megapathdsl.net wrote: The sawtooth error on the Motorola M12+ is about +/- 25ns, while the CW12-TIM has a sawtooth error of +/- 2 ns, so correcting for the sawtooth error is not as critical with the CW12-TIM. The first claim The sawtooth error on the Motorola M12+ is about +/- 25ns is correct but are you absolutely sure that the second claim is correct too? It would mean a factor 10 improvement of the CW12-TIM against the M12 which is hardly believeable. The 25 ns probably comes from period of the the free running clock they are using. It doesn't seem unreasonable to me to get 10x better if they use a GPSDO for the local clock so they can get the PPS edge right where they want it. -- These are my opinions, not necessarily my employer's. 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.
Re: [time-nuts] CW12-TIM vs M12M and the world
I just posted what I was sent for the manufacturer, warts and all. I did notice they were comparing to the M12+ or M12. I hope the specs are correct. I purchased one and will pass on measurement when I get a chance to test it. Thomas Knox To: time-nuts@febo.com From: hmur...@megapathdsl.net Date: Thu, 29 Mar 2012 00:32:13 -0700 Subject: Re: [time-nuts] CW12-TIM vs M12M and the world The sawtooth error on the Motorola M12+ is about +/- 25ns, while the CW12-TIM has a sawtooth error of +/- 2 ns, so correcting for the sawtooth error is not as critical with the CW12-TIM. The first claim The sawtooth error on the Motorola M12+ is about +/- 25ns is correct but are you absolutely sure that the second claim is correct too? It would mean a factor 10 improvement of the CW12-TIM against the M12 which is hardly believeable. The 25 ns probably comes from period of the the free running clock they are using. It doesn't seem unreasonable to me to get 10x better if they use a GPSDO for the local clock so they can get the PPS edge right where they want it. -- These are my opinions, not necessarily my employer's. 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.
Re: [time-nuts] CW12-TIM vs M12M and the world
OK been only slightly paying attention. But I see in the US several sellers for a operational board at $84-89. Maybe I have the wrong unit but it does say 5ns or less timing error Regards Paul WB8TSL On Thu, Mar 29, 2012 at 11:50 AM, Ed Palmer ed_pal...@sasktel.net wrote: On 3/29/2012 12:54 AM, Ulrich Bangert wrote: Thomas, The sawtooth error on the Motorola M12+ is about +/- 25ns, while the CW12-TIM has a sawtooth error of +/- 2 ns, so correcting for the sawtooth error is not as critical with the CW12-TIM. The first claim The sawtooth error on the Motorola M12+ is about +/- 25ns is correct but are you absolutely sure that the second claim is correct too? It would mean a factor10 improvement of the CW12-TIM against the M12 which is hardly believeable. Believe it. I've made multiple test runs where I use an HP 5372A to measure 1000 pulses of the CW12. The Standard Deviation is always 5 ns with a max-min range of 30 ns. That's without any type of error correction - straight from the GPS receiver to the 5372A. A clue to the performance is a line in the datasheet that says the clock speed is up to 120 MHz. Maybe not fast enough to justify +/- 2 ns., but in the ball park. I am rather surprised that they're adding sawtooth correction. This unit has been around for some years. The Motorola firmware isn't even a standard offering anymore. You have to ask for it. It'll be interesting to see what they come up with considering that the datasheet says that the resolution on the 1 PPS signal is 5 ns. There doesn't seem to be much room for correction there. Ed Best regards Ulrich Bangert -Ursprungliche Nachricht- Von: time-nuts-boun...@febo.com [mailto:time-nuts-bounces@**febo.com time-nuts-boun...@febo.com] Im Auftrag von Tom Knox Gesendet: Mittwoch, 28. Marz 2012 20:42 An: Time-Nuts Betreff: [time-nuts] CW12-TIM vs M12M and the world I spoke with Navsync about some of the issues we are discussing and this was their response. I just received mine and will try to test it over the weekend. 1. Is CW12-TIM compatible with Motorola M12 ? The CW12 is designed to be compatible with the M12 although there are some differences. The main hardware differences are listed on page 7 of the CW12 User Manual (http://www.navsync.com/docs/**cw12-tim_um.pdfhttp://www.navsync.com/docs/cw12-tim_um.pdf). 2. According to the customer, M12 has a Sawtooth Correction Error Hanging Bridge Error? Does CW12 have a solution for these type of errors? How these errors are taken care of in CW12? The Hanging Bridge Error is a pattern seen in the sawtooth error that occurs as the local clock frequency changes. The standard Motorola Binary software for the CW12-TIM does not have the sawtooth correction field in the @@Hn command implemented, but NavSync is currently developing this and it will be available in future standard releases. The sawtooth error on the Motorola M12+ is about +/- 25ns, while the CW12-TIM has a sawtooth error of +/- 2 ns, so correcting for the sawtooth error is not as critical with the CW12-TIM. Thomas Knox __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] CW12-TIM vs M12M and the world
Yes, it is: the CW12 has the PPS derived from the 100MHz clock and that's why you have that PPS granularity with no need for a sawtooth correction. On Thu, Mar 29, 2012 at 7:18 PM, paul swed paulsw...@gmail.com wrote: OK been only slightly paying attention. But I see in the US several sellers for a operational board at $84-89. Maybe I have the wrong unit but it does say 5ns or less timing error Regards Paul WB8TSL On Thu, Mar 29, 2012 at 11:50 AM, Ed Palmer ed_pal...@sasktel.net wrote: On 3/29/2012 12:54 AM, Ulrich Bangert wrote: Thomas, The sawtooth error on the Motorola M12+ is about +/- 25ns, while the CW12-TIM has a sawtooth error of +/- 2 ns, so correcting for the sawtooth error is not as critical with the CW12-TIM. The first claim The sawtooth error on the Motorola M12+ is about +/- 25ns is correct but are you absolutely sure that the second claim is correct too? It would mean a factor10 improvement of the CW12-TIM against the M12 which is hardly believeable. Believe it. I've made multiple test runs where I use an HP 5372A to measure 1000 pulses of the CW12. The Standard Deviation is always 5 ns with a max-min range of 30 ns. That's without any type of error correction - straight from the GPS receiver to the 5372A. A clue to the performance is a line in the datasheet that says the clock speed is up to 120 MHz. Maybe not fast enough to justify +/- 2 ns., but in the ball park. I am rather surprised that they're adding sawtooth correction. This unit has been around for some years. The Motorola firmware isn't even a standard offering anymore. You have to ask for it. It'll be interesting to see what they come up with considering that the datasheet says that the resolution on the 1 PPS signal is 5 ns. There doesn't seem to be much room for correction there. Ed Best regards Ulrich Bangert -Ursprungliche Nachricht- Von: time-nuts-boun...@febo.com [mailto:time-nuts-bounces@**febo.com time-nuts-boun...@febo.com] Im Auftrag von Tom Knox Gesendet: Mittwoch, 28. Marz 2012 20:42 An: Time-Nuts Betreff: [time-nuts] CW12-TIM vs M12M and the world I spoke with Navsync about some of the issues we are discussing and this was their response. I just received mine and will try to test it over the weekend. 1. Is CW12-TIM compatible with Motorola M12 ? The CW12 is designed to be compatible with the M12 although there are some differences. The main hardware differences are listed on page 7 of the CW12 User Manual (http://www.navsync.com/docs/**cw12-tim_um.pdf http://www.navsync.com/docs/cw12-tim_um.pdf). 2. According to the customer, M12 has a Sawtooth Correction Error Hanging Bridge Error? Does CW12 have a solution for these type of errors? How these errors are taken care of in CW12? The Hanging Bridge Error is a pattern seen in the sawtooth error that occurs as the local clock frequency changes. The standard Motorola Binary software for the CW12-TIM does not have the sawtooth correction field in the @@Hn command implemented, but NavSync is currently developing this and it will be available in future standard releases. The sawtooth error on the Motorola M12+ is about +/- 25ns, while the CW12-TIM has a sawtooth error of +/- 2 ns, so correcting for the sawtooth error is not as critical with the CW12-TIM. Thomas Knox __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nuts 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] Yahoo group not receiving emal
On Wed, 28 Mar 2012 10:26:55 -0700 (PDT) CORNACCHIA salc...@rogers.com wrote: I have been a member of the group for a long time yahoo is not sending email. Thank You If you are using yahoo as your webmail, change! quickly! As someone who has been administrating quite a few mailinglists for years, i can tell you that no other free mail provider was so difficult to work with as yahoo. It is basically impossible to resolve any problems with them. They don't read your emails, they reply with canned junk after letting you wait for a couple of days, and treat you like you are an complete idiot who has been using a computer for the first time... even if you tell them that you are a system administrator in each and every mail... Heck! Even hotmail in its worst times has never been this bad! Attila Kinali PS: the problem is most likely that yahoo thinks that this mailinglist is sending spam, thus rejects the mails from half of their mail servers (yes, only half!). Most mailinglist solutions react badly to such a treatment. -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] Pulsar Source?
On Wed, 28 Mar 2012 16:20:49 -0700 Hal Murray hmur...@megapathdsl.net wrote: All that is of course correct. But ultimately the pulsars are a better source, I see it as an application question, could it be utilized? Perhaps building an algorithm and basing corrections on multiple pulsars x-ray pulses like a GPS constellation for the next generation of conventional GPS. I think modern atomic clocks are better than Pulsars. Unfortunately, I don't have a good reference handy. I think the theorists have several ideas for why the period of Pulsars change. See [1] for a short overview and pointers to more literature Attila Kinali [1] http://www.astro.oma.be/IAU/COM31/pdf/JD6/JD06_Kopeikinx.pdf -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] SimpleLink CC44000 GPS Development Kit
From http://www.ti.com/tool/cc4000gpsem GNS TC6000GN module and EM board At the GNS site I was able to get a TC6000GN-P1 data sheet and design guide. Bob LaJeunesse From: Attila Kinali att...@kinali.ch To: armstr...@sedsystems.ca; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thu, March 29, 2012 3:51:24 PM Subject: Re: [time-nuts] SimpleLink CC44000 GPS Development Kit On Wed, 28 Mar 2012 10:57:57 -0600 David Armstrong armstr...@sedsystems.ca wrote: It appears that TI has entered the GPS market. I don't know if this would make a good start on a GPSDO or not? Comments? https://estore.ti.com/SimpleLink-CC44000-GPS-Development-Kit-P2945C159.aspx Any idea how those modules work internally? What chips they use? I cannot find anything on either the GNS nor on the TI homepage. Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] Yahoo group not receiving emal
I agree and it is unfortunate, because of all the email accounts I have (and that's quite a few), I like their web mail client the best. Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: Attila Kinali att...@kinali.ch Sender: time-nuts-boun...@febo.com Date: Thu, 29 Mar 2012 21:16:35 To: CORNACCHIAsalc...@rogers.com; Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Yahoo group not receiving emal On Wed, 28 Mar 2012 10:26:55 -0700 (PDT) CORNACCHIA salc...@rogers.com wrote: I have been a member of the group for a long time yahoo is not sending email. Thank You If you are using yahoo as your webmail, change! quickly! As someone who has been administrating quite a few mailinglists for years, i can tell you that no other free mail provider was so difficult to work with as yahoo. It is basically impossible to resolve any problems with them. They don't read your emails, they reply with canned junk after letting you wait for a couple of days, and treat you like you are an complete idiot who has been using a computer for the first time... even if you tell them that you are a system administrator in each and every mail... Heck! Even hotmail in its worst times has never been this bad! Attila Kinali PS: the problem is most likely that yahoo thinks that this mailinglist is sending spam, thus rejects the mails from half of their mail servers (yes, only half!). Most mailinglist solutions react badly to such a treatment. -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] Yahoo group not receiving emal
Interesting. I use yahoo mail to receive email from this list and as far as I am aware I have not had any issues. (Ie. in following threaded conversations it's never been apparent to me that I have missed any of the messages.) ___ 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] Pulsar Source?
On 03/29/2012 01:50 AM, Jim Palfreyman wrote: Folks, I'm currently writing my thesis on pulsars, but I need to spend time on it rather than here. :-) But since a lot of this discussion is right at the front of my brain, here's a summary. Some pulsars glitch or speed up. The Vela pulsar (PSR J0835-4510) does this (this is the pulsar I've been studying) and yes these type of pulsars are bad clocks. A jump of its pulse rate of the order of 10^-6 s/s randomly every few years is not good. It does nearly settle back to its original rate after a few months. The nature of these glitches (in Vela at least) is not well understood, but three theories have been put forward: - An orbiting planet - but this has been discarded due to their irregularity. - Star quakes caused by a separation of the crust on the surface of the neutron star from its super-fluid interior. (Not very popular any more) - The effects of tiny micro vortices in the internal super-fluid. (If you can understand this paper - good luck to you!) Now faster pulsars, in particular millisecond pulsars (~700 Hz from memory is the fastest) are quite good clocks and they do rival atomic clocks. The hunt is on to find as many of these as they can, well spread across the sky, so they can look at the effects of gravitational waves on the beams of these super accurate clocks. This is one proposed method to detect gravitational waves. The main problem I see from the original suggestion is that most pulsars are quite faint and you need a very decent telescope to see individual pulses. Vela is very bright, and the 26m telescope I used can only just see the average pulse. I'm studying bright pulses and we can see those easily. So to dedicate a massive radio telescope (or two) pointing at a millisecond pulsar just so we can re-transmit it, is probably not sensible. However, studies of these remarkable pulsars is ongoing. Hmm, wouldn't the space-located antenna have a good chance of better S/N as the antenna sees cold space and could be kept cold itself? I was also thinking antenna size would be a limitation. Then I was thinking about what WMAP has achieved in measuring the background temperature and look back at the very early years of the universe. Cheers, Magnus 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] Pulsar Source?
On 3/29/12 3:17 PM, Magnus Danielson wrote: just so we can re-transmit it, is probably not sensible. However, studies of these remarkable pulsars is ongoing. Hmm, wouldn't the space-located antenna have a good chance of better S/N as the antenna sees cold space and could be kept cold itself? I was also thinking antenna size would be a limitation. Then I was thinking about what WMAP has achieved in measuring the background temperature and look back at the very early years of the universe. Yes and no.. depending on the frequency. A reasonably high gain dish antenna that is under illuminated (i.e. the feed doesn't see the earth behind the antenna) is basically looking at cold space anyway. One reason that Cassegrain and similar designs are possible.. the primary feed is looking at space with the secondary reflector in the way, so spillover is going towards the sky. (moisture in the air is the big factor here.. it's easy to tell when there are clouds overhead with a microwave radiometer) Cryogenically cooled feeds are pretty standard items and not particularly expensive (compared to the cost of even the smallest launch vehicle). Cryocoolers, not dewars of LHe, by the way. As the frequency goes up, though, the atmospheric loss rises, and eventually, it's worth it to get above the atmosphere (Mauna Kea and Atacama are pretty close, but there's still moisture above them). In the mm wave and far IR is where it's really worth while, so you have things like SIRTF and JWST. The latter is a good example of high cost, though.. ___ 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] Pulsar Source?
I thought I might apologize because I didn't explain my idea very well initially, and reiterate my original thoughts on a pulsar timing idea. The basis of my idea was that if problems could be overcome certain pulsars could provide not only Time but also Position info directly to orbiting platforms. First: I assumed from the start that this was not a DIY idea, but mainly an intellectual exercise, far beyond the resources of all but a few governments. And most likely beyond the scope of our current GPS system. But since I have been a TimeNuts I have been constantly amazed by the complex problems that have been taken on and solved by this brilliant group. So I thought I would throw in something purely theoretical. I should have known there would be at least one TimeNuts writing a thesis on Pulsars. It reminds me, I have been very lucky to have worked around some brilliant people, when I am asked about their depth of knowledge I usually reply They are not that smart, I can get coffee for anyone of them and get it right three out of four times. My point is Do you want any coffee. Second: What I was envisoning was collecting data on Ultra stable pulsars including location, motion and timing needed to use them as a defacto GPS constallation for a set of earth based satalites. With this information you could ascertain the exact position of each satellite. This idea has been under investigation for long distance satellite navigation for some time. I see no advantage terrestrially receiving pulsar signals as a atlernative freq standard in place of the USNO since the cool thing about this concept is that the pulsars would provide both time and position directly to the orbiting platform. Third: Does observing these pulsars from space allow reception of signals at levels and in bands that would be blocked by the earth atmosphere. If not could some of the advances in superconductivity provide an amp of sufficient sensitivity to overcome these problems. Forth: The problems I foresee are can an practical algorithm accounting for the complex motion of all these bodies be built, and can Pulsar signals be received at a high enough signal to noise ratio for this system to produce a coherent time source. I have really enjoyed all the topics lately thanks all for the contributions. Clearly Time Nuts; Thomas Knox Date: Fri, 30 Mar 2012 00:17:33 +0200 From: mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] Pulsar Source? On 03/29/2012 01:50 AM, Jim Palfreyman wrote: Folks, I'm currently writing my thesis on pulsars, but I need to spend time on it rather than here. :-) But since a lot of this discussion is right at the front of my brain, here's a summary. Some pulsars glitch or speed up. The Vela pulsar (PSR J0835-4510) does this (this is the pulsar I've been studying) and yes these type of pulsars are bad clocks. A jump of its pulse rate of the order of 10^-6 s/s randomly every few years is not good. It does nearly settle back to its original rate after a few months. The nature of these glitches (in Vela at least) is not well understood, but three theories have been put forward: - An orbiting planet - but this has been discarded due to their irregularity. - Star quakes caused by a separation of the crust on the surface of the neutron star from its super-fluid interior. (Not very popular any more) - The effects of tiny micro vortices in the internal super-fluid. (If you can understand this paper - good luck to you!) Now faster pulsars, in particular millisecond pulsars (~700 Hz from memory is the fastest) are quite good clocks and they do rival atomic clocks. The hunt is on to find as many of these as they can, well spread across the sky, so they can look at the effects of gravitational waves on the beams of these super accurate clocks. This is one proposed method to detect gravitational waves. The main problem I see from the original suggestion is that most pulsars are quite faint and you need a very decent telescope to see individual pulses. Vela is very bright, and the 26m telescope I used can only just see the average pulse. I'm studying bright pulses and we can see those easily. So to dedicate a massive radio telescope (or two) pointing at a millisecond pulsar just so we can re-transmit it, is probably not sensible. However, studies of these remarkable pulsars is ongoing. Hmm, wouldn't the space-located antenna have a good chance of better S/N as the antenna sees cold space and could be kept cold itself? I was also thinking antenna size would be a limitation. Then I was thinking about what WMAP has achieved in measuring the background temperature and look back at the very early years of the universe. Cheers, Magnus Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go
Re: [time-nuts] Pulsar Source?
On 3/28/2012 4:50 PM, Jim Palfreyman wrote: Folks, I'm currently writing my thesis on pulsars, but I need to spend time on it rather than here I'd love to hear more about your thesis (offline question most likely). I thought I'd add in the detail that I found on another site about one pulsar. For example, a pulsar called PSR J1603-7202 is known to have a period of 0.0148419520154668 seconds. However the periods of all radio pulsars are increasing extremely slowly. The period of PSR J1603-7202 increases by just 0.005 seconds every million years! I don't know how close you could get to syncing with a pulsar signal, but this is one to discuss. Thanks Jim http://outreach.atnf.csiro.au/education/everyone/pulsars/ ___ 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] Best reason
When I subscribed to Time Nuts several years ago I felt a little self-concise and purchased a Citizen WWV watch and in all seriousness it has run flawlessly. But I quickly learned that to really fit in I would need a tourbillon movement watch or the TVB mondo wrist watch demonstrated by a professional hand model in the Leapsecond site. Thomas Knox Date: Thu, 29 Mar 2012 21:20:14 +0200 From: att...@kinali.ch To: n1...@alum.dartmouth.org; time-nuts@febo.com Subject: Re: [time-nuts] Best reason On Wed, 28 Mar 2012 13:42:39 -0400 David McGaw n1...@alum.dartmouth.org wrote: Mechanical wristwatches are capable of good precision. I have an inexpensive 40-year old Caravelle (Bulova) that with reasonable adjustment can still keep to a few seconds per day. I never have considered quartz watches to be better unless they can be adjusted, which most cannot. Modern quarz watches use TCXOs and are calibrated. At least my Tissot keeps time to somewhere around 10-20s/half year. Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] FE5680A x-rays
That is a great job. Just looking at the TIFFs. Motivates me to get the better viewers mentioned in the thread. Funny thing. I always though having an xray like this would be quite a help. It reveals the jobs just that much harder. But still fantastic. Regards Paul WB8TSL On Wed, Mar 28, 2012 at 2:54 PM, Rich msima...@sympatico.ca wrote: Nice job. I downloaded them for reference. The original composite was done while repairing my defective 1pps unit and thus I just printed sheets from the original x-rays as needed and eventually decided completing the whole thing with scotch tape. You are right about the down conversion. The composite posted as the example was just a picture of the shop wall with my small camera. That is why I posted the original RAW photos. Actually I hope to have the individual TIFF properly oriented on the web link in a few hours (not quite the res you have as I only have a freeware program to do that) The only reason I did this was to trace the 1pps and lock circuit (turned out the 74act240 was the guilty party). Having lost sight of our objective we will redouble efforts.. I'll post a note when the TIFFs are up. Cheers Richard ___ 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] Pulsar Source?
On 3/29/12 6:19 PM, Tom Knox wrote: I thought I might apologize because I didn't explain my idea very well initially, and reiterate my original thoughts on a pulsar timing idea. The basis of my idea was that if problems could be overcome certain pulsars could provide not only Time but also Position info directly to orbiting platforms. I think that trying to figure out how to use pulsars as as timing source is certainly worthy of contemplation. And as for resources.. who'd have thunk 20 years ago that you could have atomic clocks (real ones, not WWVB receivers) in your house as a hobby using surplus. First: I assumed from the start that this was not a DIY idea, but mainly an intellectual exercise, far beyond the resources of all but a few governments. And most likely beyond the scope of our current GPS system. But since I have been a TimeNuts I have been constantly amazed by the complex problems that have been taken on and solved by this brilliant group. So I thought I would throw in something purely theoretical. I should have known there would be at least one TimeNuts writing a thesis on Pulsars. It reminds me, I have been very lucky to have worked around some brilliant people, when I am asked about their depth of knowledge I usually reply They are not that smart, I can get coffee for anyone of them and get it right three out of four times. My point is Do you want any coffee. Second: What I was envisoning was collecting data on Ultra stable pulsars including location, motion and timing needed to use them as a defacto GPS constallation for a set of earth based satalites. I think that's been done.. At least there is a good list of candidates. With this information you could ascertain the exact position of each satellite. This idea has been under investigation for long distance satellite navigation for some time. I see no advantage terrestrially receiving pulsar signals as a atlernative freq standard in place of the USNO since the cool thing about this concept is that the pulsars would provide both time and position directly to the orbiting platform. and orientation. Sort of like a super star tracker all in one! (You can see why NASA is interested..) Third: Does observing these pulsars from space allow reception of signals at levels and in bands that would be blocked by the earth atmosphere. Certainly yes for X-ray pulsars.. the atmosphere blocks them. For radio pulsars, the attenuation through the atmosphere isn't huge (at least at microwave frequencies, and if you don't pick something like 60GHz where there's an absorption band). If not could some of the advances in superconductivity provide an amp of sufficient sensitivity to overcome these problems. The limiting thing on weak signals is typically noise, and cooling helps. Forth: The problems I foresee are can an practical algorithm accounting for the complex motion of all these bodies be built, Yes. It's just geometry, and probably not more difficult than any other triangulation problem. Surveyors use a form of least squares in some cases, and that's sort of what a Kalman filter does, as well. That's probably the easy part. and can Pulsar signals be received at a high enough signal to noise ratio for this system to produce a coherent time source. That's the hard part. I have really enjoyed all the topics lately thanks all for the contributions. Clearly Time Nuts; Thomas Knox Date: Fri, 30 Mar 2012 00:17:33 +0200 From: mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] Pulsar Source? On 03/29/2012 01:50 AM, Jim Palfreyman wrote: Folks, I'm currently writing my thesis on pulsars, but I need to spend time on it rather than here. :-) But since a lot of this discussion is right at the front of my brain, here's a summary. Some pulsars glitch or speed up. The Vela pulsar (PSR J0835-4510) does this (this is the pulsar I've been studying) and yes these type of pulsars are bad clocks. A jump of its pulse rate of the order of 10^-6 s/s randomly every few years is not good. It does nearly settle back to its original rate after a few months. The nature of these glitches (in Vela at least) is not well understood, but three theories have been put forward: - An orbiting planet - but this has been discarded due to their irregularity. - Star quakes caused by a separation of the crust on the surface of the neutron star from its super-fluid interior. (Not very popular any more) - The effects of tiny micro vortices in the internal super-fluid. (If you can understand this paper - good luck to you!) Now faster pulsars, in particular millisecond pulsars (~700 Hz from memory is the fastest) are quite good clocks and they do rival atomic clocks. The hunt is on to find as many of these as they can, well spread across the sky, so they can look at the effects of gravitational waves on the beams of these super accurate clocks. This is one proposed method to detect gravitational waves. The
Re: [time-nuts] Yahoo group not receiving emal
On 3/29/2012 3:16 PM, Attila Kinali wrote: If you are using yahoo as your webmail, change! quickly! They're not called yahoos for nothing. But, Microsoft and Google aren't far behind in Internet cluelessness. http://www.merriam-webster.com/dictionary/yahoo ___ 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] Pulsar Source?
Jim, If you look at some atomic clocks, they really do look like they were built in somebody's basement... out of WW II RADAR parts and Home Depot plumbing fittings. -John On 3/29/12 6:19 PM, Tom Knox wrote: I thought I might apologize because I didn't explain my idea very well initially, and reiterate my original thoughts on a pulsar timing idea. The basis of my idea was that if problems could be overcome certain pulsars could provide not only Time but also Position info directly to orbiting platforms. I think that trying to figure out how to use pulsars as as timing source is certainly worthy of contemplation. And as for resources.. who'd have thunk 20 years ago that you could have atomic clocks (real ones, not WWVB receivers) in your house as a hobby using surplus. [snip] ___ 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] Yahoo group not receiving emal
ATT is my Internet provider. ATT does not provide e-mail even though they have .att, sbcglobal.com (or whatever). When you subscribe to ATT e-mail you wind up with Yahoo as the actual e-mail provider along with the Yahoo e-mail servers. I do not like Yahoo and I will agree with Attia's experiences and comments. When I've called Yahoo they treat me like I'm an idiot. My Internet connection from ATT is fine and seldom has problems, however, the e-mail is unreliable. About a year ago Yahoo told me,if you want reliable e-mail service you should get your own servers and do it yourself, you should not be depending on Yahoo for business e-mails. I've taken them to heart and have done that via the hosting company that hosts my website www.biwa.cc My only dilemma is that I cannot take my e-mail address with me. Burt, K6OQK If you are using yahoo as your webmail, change! quickly! As someone who has been administrating quite a few mailinglists for years, i can tell you that no other free mail provider was so difficult to work with as yahoo. It is basically impossible to resolve any problems with them. They don't read your emails, they reply with canned junk after letting you wait for a couple of days, and treat you like you are an complete idiot who has been using a computer for the first time... even if you tell them that you are a system administrator in each and every mail... Heck! Even hotmail in its worst times has never been this bad! Attila Kinali PS: the problem is most likely that yahoo thinks that this mailinglist is sending spam, thus rejects the mails from half of their mail servers (yes, only half!). Most mailinglist solutions react badly to such a treatment. Burt I. Weiner Associates Broadcast Technical Services Glendale, California U.S.A. b...@att.net www.biwa.cc K6OQK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] SimpleLink CC44000 GPS Development Kit
On Thu, 29 Mar 2012 13:14:14 -0700 (PDT) Robert LaJeunesse rlajeune...@sbcglobal.net wrote: From http://www.ti.com/tool/cc4000gpsem GNS TC6000GN module and EM board At the GNS site I was able to get a TC6000GN-P1 data sheet and design guide. Yes, i found the TC6000GN-P1 datasheet from GNS and the module description from TI, but neither tells anything beside the outside features. Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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.
