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

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