GPS

GLONASS

BeiDou

Number of sat.

31

24

14 (5 GEO, 5 IGSO, 4 MEO)

Number of nominal satellite

24

24

35 (5 GEO, 3 IGSO, 27 MEO)

Number of orbital plan

6

3

3 (MEO)

Inclinaison plan

55˚

65˚

55˚ (MEO & IGSO)

Altitude (km)

20,180

19,100

21,530 (MEO)

Orbital period

11 h 58 m

11 h 16 m

12 h 50 m (MEO)

Time scale

GPST UTC(USNO)

UTC(SU)

BDT UTC(NTSC)

Coord. system

WGS 84

PZ 90

CGCS 2000

Ephemerides

Kepler Elements and temporal variations

Geocentric Cartesian Coord. and temporal variations

Kepler Elements and temporal variations

Ephemeris update

every 2 h

every 30 min

every 1 h

Message length

12.5 min

2.5 min

12 min (and 6 min)