[time-nuts] GPS PRN vs SV...??

Magnus Danielson magnus at rubidium.dyndns.org
Sat Feb 9 05:29:26 EST 2008


From: Rex <rexa at sonic.net>
Subject: Re: [time-nuts] GPS PRN vs SV...??
Date: Sat, 09 Feb 2008 02:16:28 -0800
Message-ID: <47AD7D7C.8090802 at sonic.net>

> Tom Van Baak wrote:
> >> Current status SVNs, PRN etc at:
> >>
> >> http://www.navcen.uscg.gov/navinfo/Gps/ActiveNanu.aspx
> >>
> >> Bruce
> >>     
> >
> > That's a good URL. Thanks.
> >
> > More on the SVN vs. PRN issue...
> >
> > When I mistrust a GPS receiver and want to check where a
> > satellite really is, I use the NASA satellite tracker:
> >
> > http://science.nasa.gov/Realtime/jtrack/3d/JTrack3D.html
> >
> > If any of you haven't heard of, or used this java applet yet,
> > I highly recommend it. After you click on +J-TRACK 3D,
> > click on Satellite->Select and pick any GPS satellite.
> >
> > The only trouble: our SV of interest, GPS BIIA-10 (PRN 32),
> > is missing from the list (perhaps because it is still marked
> > unhealthy?), so we can't get its orbit or ground track. I sent
> > a note to NASA and we'll see if they fix it.
> >
> > If any of you know of another satellite tracking web site that
> > shows SVN23/PRN32, let us know, ok?
> >
> > By the way, if one takes a screen capture of each GPS SV
> > in the Jtrack3D list, you get this cute GPS orbit animation:
> >
> > http://www.leapsecond.com/pages/gps-orbit/
> >
> > /tvb
> >
> >
> >   
> Thanks Tom, I'm trying to follow this discussion with my limited 
> knowledge and see if my HP z3816a with a UT receiver knows about this 
> new satellite. My random looks have seen a 31 PRN but not a 32. So 
> knowing when the new 32 should be visible in N. Cal would help a lot. I 
> tried your link to the nasa.gov jtrack page, but I don't see how I get 
> to anyplace where I can select a GPS satellite to track. Sorry if I 
> missed something obvious.
> 
> Any hints or clarifications on how to predict when any gps satellite 
> should be in view here are appreciated. I think I could get Ham 
> satellite tracking software and find the ephemeris information for the 
> satellites somewhere, but I was hoping for an easy way for just the GPS 
> sats.

Ephemeris data is alread available:
http://www.navcen.uscg.gov/archives/gps/2008/ALMANACS/SEM/039.AL3

32
23
0
 1.44729614257812E-02  9.04464721679688E-03 -2.53930920735002E-09
 5.15345068359375E+03  9.07266139984131E-01 -4.24016833305359E-01
-3.47391366958618E-01  2.25067138671875E-04  1.09139364212751E-11
63
9

Should be sufficient to predict sky-view.

We don't know yeat at what time it is expected to be set operational.
We need to await another NANUS detailing that, as being indicated in NANUS
2008016:
http://www.navcen.uscg.gov/archives/gps/2008/NANUS/2008016.nnu

> Thanks for the heads-up on the new satellite with this binary new-bit 
> PRN. (That is the potential issue with why some receivers may not handle 
> it -- correct?)

Indeed. :)

Cheers,
Magnus



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