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Re: Identifying a GEO GNSS Satellite

From: Gary E. Miller
Subject: Re: Identifying a GEO GNSS Satellite
Date: Wed, 28 Apr 2021 11:16:10 -0700

Yo Sanjeev!

On Wed, 28 Apr 2021 12:47:12 +0800
Sanjeev Gupta <> wrote:

> > odd PRN 45 is on the sky view, but not in the sat list?
> >  
> It is, identified as SB132

gpsd should not identify the sat as SB132 in one place and SB45 in
another.  SB132 is not a valid PRN  NMEA that I can see.  The
IS-GPS-200 shows PRN 120 to 158 for SBAS, but the mapping to NMEA is unclear.

AFAIK, only Quectel uses NMEA PRN 101 to 136.

> > IRNSS-1G, PRIN I01 is at 129.5 E.  Maybe that one?  If you can
> > capture u-blox
> > binary, then we can see the PRNs.
> >  
> But 129.5E is *East* of me.  This is to the west.

Sorry, your side of the planet is backwards.  :-)

> I have a ublox (8,I think) at home. Will capture logs.

That would be interesting.  Your sky is changing rapidly.

> > I think all SBAS speak an privately documented GPS dialect.  All
> > GNSS protocols are open, except for SBAS.
> >  
> Ah.  If I understand you correctly, it is possible that my (putative)
> receiver understands WAAS and not EGNOS?

The secret SBAS protocol is maintained the the FAA and ICAO.  WAAS, EGNOS,
MSAS, GAGAN, BDSBAS, KASS, etc. are all SBAS.  They all interoperate.  The
ICAO wanted, and got, a worldwide overlay to GPS.

> Thank you, will try a ublox capture today.  gpspipe?

"gpspipe -R -n 1200 > raw.log"

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703  Tel:+1 541 382 8588

            Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin

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