Understanding data on Garmin hiking gps

[MjLsscala]

I have a gpsmap64 . On the satellite page of the setup menu what do the numbers under each satellite represent? Are they "svn", " prn", Gold codes, or something else? Also why do some of the satellites turn from green to gray?

Thanks

 

[Nuvi-Nebie]

The numbers displayed against satellites on Garmin units are their garmin NMEA numbers, Note the first 32 NMEA numbers are identicle to the PRN numbers and relate to the orginal USA owned 'GPS' constellation, see the list here :-

https://www.gpsrchive.com/Shared/Satellites/Satellites.html

As you can see in the Satellite Identification section the GLONASS constellation has numbers derived from it's slot number + 64

Green (or multi-coloured) satellites are being used to calculate current position, grey satellites are still 'visible' to the GPS unit but are not being used to calculated current position due to either incompleted data or inferior position in the sky