Method and apparatus for using GPS satellite state computations in GLONASS measurement processing
View Patent ↗The present invention is related to location positioning systems, and more particularly, to a method and apparatus for using satellite state information from two or more different satellite systems in navigation processing. According to one aspect, it makes use of GPS extended ephemeris functionality to produce satellite state vector estimates for GLONASS satellites. These satellite state vector estimates can be used alone or in combination with GPS satellite vectors to provide updates to the receiver's navigation processing. According to further aspects, the GLONASS satellite position and trajectory information is extrapolated with a GPS gravity model rather than the GLONASS model, thereby allowing it to be extrapolated more accurately and for longer periods of time than the GLONASS model allows.
1. A method comprising:
receiving, by a GNSS receiver apparatus, satellite state information for a first satellite in a first satellite positioning system, and for a second satellite in a different second satellite positioning system; and
synthesizing, using a processor in the GNSS receiver apparatus, the satellite state information for both the first and second satellites into a common record format of satellite orbit or ephemeris information by representing the satellite state information received from both the first satellite positioning system and the second satellite positioning system in a same reference frame.
2. A method according to claim 1 , wherein the step of receiving the satellite state information for one or both of the first and second satellites includes retrieving all of the information from stored records.
3. A method according to claim 1 , further comprising decoding all the satellite state information for one or both of the first and second satellites from satellite signals.
4. A method according to claim 1 , further comprising:
using the satellite orbit or ephemeris information from the first and second satellites for satellite signal acquisition and navigation measurement processing.
5. A method according to claim 1 , wherein one of the first and second satellite positioning systems is GPS.
6. A method according to claim 1 , wherein one of the first and second satellite positioning systems is GLONASS.
7. A method according to claim 1 , wherein the common format comprises GPS format ephemeris.
8. A method according to claim 6 , wherein synthesizing the satellite state information for the GLONASS system satellite includes:
converting GLONASS time associated with the satellite state information to GPS time; and
converting GLONASS satellite position and velocity from coordinates in a PZ-90 frame to a GPS ECEF frame.
9. A method according to claim 8 , further comprising:
numerically integrating the synthesized satellite state information to obtain a position trajectory for the GLONASS system satellite at a predicted time.
10. A method according to claim 9 , wherein the numerically integrating step includes applying earth, lunar and solar gravity.
11. A method according to claim 8 , further comprising:
converting the GLONASS satellite position and velocity from coordinates in the GPS ECEF frame to an inertial frame; and
numerically integrating the synthesized satellite state information to obtain a position trajectory for the GLONASS system satellite at a predicted time.
12. A method according to claim 11 , wherein the numerically integrating step includes applying earth, lunar and solar gravity in the inertial frame.
13. A method according to claim 6 , wherein the synthesizing step includes numerically integrating GLONASS system satellite position information using earth, lunar and solar gravity in an inertial frame.
14. A method according to claim 1 , further comprising:
commonly receiving signals from the first satellite and from the second satellite in a single device; and
processing the signals, using the single device, to obtain information corresponding to the satellite state information.
15. An apparatus comprising circuitry that performs the method of claim 1 .
16. An apparatus comprising circuitry that performs the method of claim 8 .
17. An apparatus comprising circuitry that performs the method of claim 14 .
18. An apparatus, comprising:
a common location manager that includes:
an input coupled to receive satellite state information for a first satellite in a first satellite positioning system,
an input coupled to receive satellite state information for a second satellite in a different second satellite positioning system; and
an engine adapted to synthesize the satellite state information for both the first and second satellites into a common record format of satellite orbit or ephemeris information by representing the satellite state information received from both the first satellite positioning system and the second satellite positioning system in a same reference frame.