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 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.
