[time-nuts] Pulsars make a GPS for the cosmos

Tom Knox actast at hotmail.com
Sat Sep 28 17:49:57 UTC 2013


I am just thinking out loud on this, But it seems you could use carrier phase from plain star light since the light spectrum from stars have spikes and notches which are constant and using the same concept as the Hubble Constant a spacecraft could determine speed, direction, and position. Like the GPS system it will take a very complex algorithm but does not seem beyond today's technologies.
And yes all these sources have some stability issues but if they are linear they can compensated for and if random they can be averaged out. This is why our Cesium, Rubidium, and GPS references have quartz. The bottom line is we have already been able to determine there are a number of Pulsars that rival today's best Cesium clocks and their signals cover vast reaches of space.  So it seems inevitable we will learn to utilize this existing Galactic Positioning System of the gods.

Thomas Knox



> Date: Sat, 28 Sep 2013 09:18:10 -0700
> From: jfor at quikus.com
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] Pulsars make a GPS for the cosmos
> 
> A couple of points:
> 
> Pulsars are pretty faint and the only solution to that is antenna
> aperture. We looked at that while doing SETI a ways back. Receivers are
> now quite close to the theoretical limit as far as noise temperatuse.
> There is very little room for improvement.
> 
> Pulsars are not infrinitely stable. They slowly decay, and, worse,
> randomly undergto 'star quakes' which upset their timing. This was proven
> in the 1960s.
> 
> Best,
> 
> -John
> 
> ====================
> 
> 
> > On 9/28/13 7:32 AM, Hal Murray wrote:
> >>
> >> jimlux at earthlink.net said:
> >>> Scrolling down, it looks like they're getting a whopping 0.5 dB SNR on
> >>> the Crab Nebula pulsar.
> >>
> >> How much of the noise comes from local sources vs thermal or galactic?
> >>
> >
> > These are amateurs, so they're probably not using cryocooled receivers:
> > a good part of the noise is kTB noise in the receiver.
> >
> >>
> >> I'm missing the scale factor for the big picture.  How big a volume does
> >> this
> >> work over before I have to start counting fringes or something like
> >> that?
> >> Wiki says the longest one is 8.5 seconds.  That's small even on the
> >> scale of
> >> the Solar system.
> >
> > You also get direction, so for a "navigation" system, you can figure out
> > where you are.
> >
> > Time wise, you'd have to count ticks.
> >
> >>
> >> Is there some trick I'm missing?  Are there lots and lots of pulsars at
> >> different frequencies so I can beat them against each other to make
> >> larger
> >> synthetic fringes?
> >>
> >> Are X-ray or gamma-ray pulsars (much) slower?
> >>
> >>
> >
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> 
> 
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