Satellite identifier 90 from Garmin GLO 1 receiver

Discussion in 'Garmin GPS' started by vcaf_user, Feb 25, 2023.

  1. vcaf_user

    vcaf_user

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    I have a Garmin GLO 1 receiver which I use with :-
    Code:
    ultragpslogger.com
    
    application on my LG Stylo 5 Android phone. I can record the NMEA sentences that the receiver is issuing. I did this at a nearby large parking lot for a shopping complex, where there is a clear view of the sky in all directions, with the receiver at a fixed location and recording at the maximum rate for 4 minutes. In the $GPGSV sentences I see 90 & 91 as a satellite numbers. I also see the numbers 90 & 91 in some of the $GPGSA sentences. These two numbers are not shown in the list of GLONASS satellites given at this web location :-
    Code:
    gpsrchive.com/Shared/Satellites/Satellites.html#Track%20GLONASS
    
    I am puzzled & wonder what to make of these two numbers (90 & 91). My guide for interpreting NMEA sentences is at this web address :-
    Code:
    aprs.gids.nl/nmea/#gsa
    
     
    vcaf_user, Feb 25, 2023
    #1
  2. vcaf_user

    Nuvi-Nebie Moderator

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    I would expect sentences that refer to GLONASS to start with either GL or GN, eg :-
    Code:
    Message ID $--GNS
    
    Talker ID can be:
    GA: Galileo
    GB: BeiDou
    GP: GPS
    GL: GLONASS. When more than one constellation is used.
    GN: Combined GNSS position, for example, GPS and GLONASS.
    GQ: QZSS
    
    I would expect GP sentenses to be GPS only, if GP can refer to other constellations then there would have to be an offset so that 1 - 32 refers to GPS and (1 - 32) plus an offset of say 70 would refer GLONASS, so 90 and 91 = 20 and 21 after 70 is subtracted
     
    Nuvi-Nebie, Feb 25, 2023
    #2
  3. vcaf_user

    vcaf_user

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    The Garmin GLO 1 receiver recognizes both GPS and GLONASS satellites, but all its NMEA sentences start with $GP. this website :-
    Code:
    gpsrchive.com/Shared/Satellites/Satellites.html#Satellite%20Identification-PRN
    
    says that the offset for GLONASS identifiers is 64.
     
    vcaf_user, Feb 26, 2023
    #3
  4. vcaf_user

    Nuvi-Nebie Moderator

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    Here is a list of 27 Glonass satellites :-
    https://www.n2yo.com/satellites/?c=21
    Two more than in the list above, I couldn't find COSMOS 2516 (NORAD 41554) or COSMOS 2564 (NORAD 54377) in the list of 25 so maybe they are slot 26 (90 - 64) and slot 27 (91 - 64)
     
    Nuvi-Nebie, Feb 26, 2023
    #4
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