3 ms·

The majority of GPS satellites do not have one rubidium clock on board, they have four. For a discussion of the experimental time sync system planned for QZSS s

by dfc 13y ago

The majority of GPS satellites do not have one rubidium clock on board, they have four. For a discussion of the experimental time sync system planned for QZSS see: http://web.archive.org/web/20130411122243/http://unsworks.unsw.edu.au/fapi/datastream/unsworks:4274/SOURCE02 http://web.archive.org/web/20130411122243/http://unsworks.un... I am curious before reading my comment did you think that GPS would continue to work without navy.mil and af.mil?

rm445 13y ago
I would have done. Having once convinced myself that four satellites shouting out the (accurate) time is sufficient to locate oneself in three dimensions, I assumed that was all there is to it.
rasz_pl 13y ago
Hell yes I did. Whole point of Rubidium clocks is you dont have to correct them. I was hoping GPS would stay up for at least 5-10 years - I assumed all they needed was periodic orbit corrections. Well, there goes my GPS to the rescue Zombie survival plan :/. Time to learn how to read stars, or better yet - find android app that does it automagically from a picture :)
- sliverstorm 13y ago
  Or you could learn to use a map and compass. I know, I know, antique and all that, but reliable.
  - dfc 13y ago
    That is going to take the party out of Tactical Air Control Party.
cnvogel 13y ago
According to this "Fact Sheet", the latest GPS generation currently in orbit (Block IIF) has two Rb and one Cs. http://www.losangeles.af.mil/library/factsheets/factsheet.asp?id=18670 http://www.losangeles.af.mil/library/factsheets/factsheet.as... The next generation (III) will take away the Cs and only rely on (three) Rb: http://www.losangeles.af.mil/library/factsheets/factsheet.asp?id=18830 http://www.losangeles.af.mil/library/factsheets/factsheet.as... The current GPS constellation status can be seen here, Plane/Slot describes the position in orbit, SVN is the "Space Vehicle Number", "PRN" is typically the "Sattelite Number" as displayed on a GPS receiver, because it describes the "Pseudorandom number (sequence)" used to decode signals of this particular satellite. Clock is just for information what the satellite right now uses as a timebase. As of 2014-04-27 http://www.navcen.uscg.gov/?Do=constellationStatus http://www.navcen.uscg.gov/?Do=constellationStatus

by dfc 13y ago

rm445 13y ago

I would have done. Having once convinced myself that four satellites shouting out the (accurate) time is sufficient to locate oneself in three dimensions, I assumed that was all there is to it.

rasz_pl 13y ago

Hell yes I did. Whole point of Rubidium clocks is you dont have to correct them. I was hoping GPS would stay up for at least 5-10 years - I assumed all they needed was periodic orbit corrections. Well, there goes my GPS to the rescue Zombie survival plan :/. Time to learn how to read stars, or better yet - find android app that does it automagically from a picture :)

sliverstorm 13y ago
Or you could learn to use a map and compass. I know, I know, antique and all that, but reliable.
- dfc 13y ago
  That is going to take the party out of Tactical Air Control Party.

cnvogel 13y ago

According to this "Fact Sheet", the latest GPS generation currently in orbit (Block IIF) has two Rb and one Cs. http://www.losangeles.af.mil/library/factsheets/factsheet.asp?id=18670 http://www.losangeles.af.mil/library/factsheets/factsheet.as... The next generation (III) will take away the Cs and only rely on (three) Rb: http://www.losangeles.af.mil/library/factsheets/factsheet.asp?id=18830 http://www.losangeles.af.mil/library/factsheets/factsheet.as... The current GPS constellation status can be seen here, Plane/Slot describes the position in orbit, SVN is the "Space Vehicle Number", "PRN" is typically the "Sattelite Number" as displayed on a GPS receiver, because it describes the "Pseudorandom number (sequence)" used to decode signals of this particular satellite. Clock is just for information what the satellite right now uses as a timebase. As of 2014-04-27 http://www.navcen.uscg.gov/?Do=constellationStatus http://www.navcen.uscg.gov/?Do=constellationStatus