Advanced timing and time transfer for satellite constellations using crosslink ranging and an accurate time source

• US 8,989,652 B2
• Filed: 03/12/2012
• Issued: 03/24/2015
• Est. Priority Date: 09/09/2011
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Whelan, David A., Gutt, Gregory M., Fyfe, Peter M.
• Primary Examiner(s): Nguyen, Hai V
• Application Number:
  US13/418,200
• Publication Number:
  US 20130065514A1
• Time in Patent Office: 1,107 Days
• Field of Search: 455/13.2
• US Class Current: 455/13.2
• CPC Class Codes: G01S 13/765 with exchange of information between interrogator and responder
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: H04B 7/18521 Systems of inter linked satellites, i.e. inter satellite service for optical links between satellites H04B10/118

Abstract

A system, method, and apparatus for advanced timing and time transfer for satellite constellations using crosslink ranging and an accurate time source are disclosed herein. In particular, the present disclosure relates generally to systems for providing improved positioning, navigation, and/or timing information for oscillator calibration and more specifically, to use at least one satellite with accessibility to an accurate time source to calibrate the local oscillator on a crosslink paired satellite. In at least, one embodiment, time synchronization on a subset of satellites with crosslinking capabilities is used to distribute time through a network of crosslinked satellites.

Claims

1. A method for timing for a satellite constellation, the method comprising:

transmitting, by at least one first satellite, at least one crosslink ranging signal to at least one second satellite, wherein at least one of the at least one first satellite and the at least one second satellite is a timing satellite with a synchronization time;

receiving, by the at least one second satellite, the at least one crosslink ranging signal;

calculating at least one ranging measurement from the at least one first satellite to the at least one second satellite by using an amount of time elapsed from the transmitting of the at least one crosslink ranging signal to the receiving of the at least one crosslink ranging signal; and

calculating an estimate of time and frequency for the at least one first satellite and the at least one second satellite relative to each other and to the synchronization time to synchronize the time and the frequency for at least one of the at least one first satellite and the at least one second satellite by using at least one of the at least one ranging measurement and the synchronization time from the at least one timing satellite; and

calculating an estimate of orbital positioning for at least one of the at least one first satellite and the at least one second satellite by using at least one of the at least one ranging measurement, the synchronization time, positioning data from the at least one timing satellite, and at least one positioning ranging measurement.

2. The method of claim 1, wherein the at least one first satellite is a timing satellite with the synchronization time, and the at least one second satellite is a non-timing satellite without the synchronization time.

3. The method of claim 1, wherein the synchronization time is an accurate time.

4. The method of claim 3, wherein the at least one timing satellite obtains the synchronization time via at least one of at least one global positioning system (GPS) signal, at least one global navigation satellite system (GLONASS) signal, at least one Galileo satellite signal, at least one BeiDou Navigation System signal, and an atomic clock.

5. The method of claim 1, wherein the synchronization time is not an accurate time.

6. The method of claim 1, wherein the at least one second satellite is a timing satellite with the synchronization time, and the at least one first satellite is a non-timing satellite without the synchronization time.

7. The method of claim 1, wherein the method further comprises generating at least one correction signal for synchronizing the time and the frequency for at least one of the at least one first satellite and the at least one second satellite;

and

transmitting the at least one correction signal to at least one of the at least one first satellite and the at least one second satellite.

8. The method of claim 1, wherein the at least one first satellite and the at least one second satellite are at least one of a Lower Earth Orbiting (LEO) satellite, a Medium Earth Orbiting (MEO) satellite, and a Geosynchronous Earth Orbiting (GEO) satellite.

9. The method of claim 1, wherein the method further comprises:

transmitting, by the at least one timing satellite, at least one positioning signal to at least one reference station;

receiving, by the at least one reference station, the at least one positioning signal; and

calculating the at least one positioning ranging measurement from the at least one timing satellite to the at least one reference station by using an amount of time elapsed from the transmitting of the at least one positioning signal to the receiving of the at least one positioning signal.

10. The method of claim 9, wherein the at least one timing satellite obtains the positioning data via at least one of at least one global positioning system (GPS) signal, at least one global navigation satellite system (GLONASS) signal, at least one BeiDou Navigation System signal, and at least one Galileo satellite signal.

11. The method of claim 1, wherein the method further comprises:

transmitting, by at least one reference station, at least one positioning signal to the at least one timing satellite;

receiving, by the at least one timing satellite, the at least one positioning signal;

calculating at least one positioning ranging measurement from the at least one reference station to the at least one timing satellite by using an amount of time elapsed from the transmitting of the at least one positioning signal to the receiving of the at least one positioning signal; and

calculating an estimate of orbital positioning for at least one of the at least one first satellite and the at least one second satellite by using at least one of the at least one ranging measurement, the synchronization time, positioning data from the at least one timing satellite, and the at least one positioning ranging measurement.

12. The method of claim 11, wherein the at least one timing satellite obtains the positioning data via at least one of at least one global positioning system (GPS) signal, at least one global navigation satellite system (GLONASS) signal, at least one BeiDou Navigation System signal, and at least one Galileo satellite signal.

13. A method for timing for a satellite constellation, the method comprising:

transmitting, by at least one first satellite, at least one first crosslink ranging signal to at least one second satellite, wherein at least one of the at least one first satellite and the at least one second satellite is a timing satellite with a synchronization time;

receiving, by the at least one second satellite, the at least one first crosslink ranging signal;

transmitting, by the at least one second satellite, at least one second crosslink ranging signal to the at least one first satellite;

receiving, by the at least one first satellite, the at least one second crosslink ranging signal;

calculating at least one first ranging measurement from the at least one first satellite to the at least one second satellite by using an amount of time elapsed from the transmitting of the at least one first crosslink ranging signal to the receiving of the at least one first crosslink ranging signal;

calculating at least one second ranging measurement from the at least one second satellite to the at least one first satellite by using an amount of time elapsed from the transmitting of the at least one second crosslink ranging signal to the receiving of the at least one second crosslink ranging signal

calculating an estimate of time and frequency for the at least one first satellite and the at least one second satellite relative to each other and to the synchronization time to synchronize the time and the frequency for at least one of the at least one first satellite and the at least one second satellite by using at least one of the at least one first ranging measurement, the at least one second ranging measurement, and the synchronization time from the at least one timing satellite; and

calculating an estimate of orbital positioning for at least one of the at least one first satellite and the at least one second satellite by using at least one of the at least one first ranging measurement, the at least one second ranging measurement, the synchronization time, positioning data from the at least one timing satellite, and at least one positioning ranging measurement.

14. A system for timing for a satellite constellation, the system comprising:

at least one first satellite configured to transmit at least one crosslink ranging signal to at least one second satellite;

the at least one second satellite configured to receive the at least one crosslink ranging signal,

wherein at least one of the at least one first satellite and the at least one second satellite is a timing satellite with a synchronization time;

at least one processor configured to calculate at least one ranging measurement from the at least one first satellite to the at least one second satellite by using an amount of time elapsed from the transmitting of the at least one crosslink ranging signal to the receiving of the at least one crosslink ranging signal;

the at least one processor further configured to calculate an estimate of time and frequency for the at least one first satellite and the at least one second satellite relative to each other and to the synchronization time to synchronize the time and the frequency for at least one of the at least one first satellite and the at least one second satellite by using at least one of the at least one ranging measurement and the synchronization time from the at least one timing satellite; and

the at least one processor is further configured to calculate an estimate of orbital positioning for at least one of the at least one first satellite and the at least one second satellite by using at least one of the at least one ranging measurement, the synchronization time, positioning data from the at least one timing satellite, and at least one positioning ranging measurement.

15. The system of claim 14, wherein the at least one first satellite is a timing satellite with the synchronization time, and the at least one second satellite is a non-timing satellite without the synchronization time.

16. The system of claim 14, wherein the synchronization time is an accurate time.

17. The system of claim 16, wherein the at least one timing satellite obtains the synchronization time via at least one of at least one global positioning system (GPS) signal, at least one global navigation satellite system (GLONASS) signal, at least one Galileo satellite signal, at least one BeiDou Navigation System signal, and an atomic clock.

18. The system of claim 14, wherein the synchronization time is not an accurate time.

19. The system of claim 14, wherein the at least one second satellite is a timing satellite with the synchronization time, and the at least one first satellite is a non-timing satellite without the synchronization time.

20. The system of claim 14, wherein the at least one processor is further configured to generate at least one correction signal for synchronizing the time and the frequency for at least one of the at least one first satellite and the at least one second satellite.

21. The system of claim 20, wherein the system further comprises at least one transmitter that is configured to transmit the at least one correction signal to at least one of the at least one first satellite and the at least one second satellite.

22. The system of claim 14, wherein the at least one first satellite and the at least one second satellite are at least one of a Lower Earth Orbiting (LEO) satellite, a Medium Earth Orbiting (MEO) satellite, and a Geosynchronous Earth Orbiting (GEO) satellite.

23. The system of claim 14, wherein the at least one timing satellite is further configured to transmit at least one positioning signal to at least one reference station;

the at least one reference station is configured to receive the at least one positioning signal; and

the at least one processor is further configured to calculate the at least one positioning ranging measurement from the at least one timing satellite to the at least one reference station by using an amount of time elapsed from the transmitting of the at least one positioning signal to the receiving of the at least one positioning signal.

24. The system of claim 23, wherein the at least one timing satellite obtains the positioning data via at least one of at least one global positioning system (GPS) signal, at least one global navigation satellite system (GLONASS) signal, at least one BeiDou Navigation System signal, and at least one Galileo satellite signal.

25. The system of claim 14, wherein the system further comprises:

at least one reference station configured to transmit at least one positioning signal to the at least one timing satellite;

the at least one timing satellite is further configured to receive the at least one positioning inquiry signal; and

the at least one processor is further configured to calculate at least one positioning ranging measurement from the at least one reference station to the at least one timing satellite by using an amount of time elapsed from the transmitting of the at least one positioning signal to the receiving of the at least one positioning signal, and to calculate an estimate of orbital positioning for at least one of the at least one first satellite and the at least one second satellite by using at least one of the at least one ranging measurement, the synchronization time, positioning data from the at least one timing satellite, and the at least one positioning ranging measurement.

26. The system of claim 25, wherein the at least one timing satellite obtains the positioning data via at least one of at least one global positioning system (GPS) signal, at least one global navigation satellite system (GLONASS) signal, at least one BeiDou Navigation System signal, and at least one Galileo satellite signal.

27. A system for timing for a satellite constellation, the system comprising:

at least one first satellite configured to transmit at least one first crosslink ranging signal to at least one second satellite, and to receive at least one second crosslink ranging signal;

the at least one second satellite configured to receive the at least one first crosslink ranging signal, and to transmit the at least one second crosslink ranging signal,

wherein at least one of the at least one first satellite and the at least one second satellite is a timing satellite with a synchronization time;

at least one processor configured to calculate at least one first ranging measurement from the at least one first satellite to the at least one second satellite by using an amount of time elapsed from the transmitting of the at least one first crosslink ranging signal to the receiving of the at least one first crosslink ranging signal;

the at least one processor further configured to calculate at least one second ranging measurement from the at least one second satellite to the at least one first satellite by using an amount of time elapsed from the transmitting of the at least one second crosslink ranging signal to the receiving of the at least one second crosslink ranging signal

the at least one processor further configured to calculate an estimate of time and frequency for the at least one first satellite and the at least one second satellite relative to each other and to the synchronization time to synchronize the time and the frequency for at least one of the at least one first satellite and the at least one second satellite by using at least one of the at least one first ranging measurement, the at least one second ranging measurement, and the synchronization time from the at least one timing satellite; and

the at least one processor further configured to calculate an estimate of orbital positioning for at least one of the at least one first satellite and the at least one second satellite by using at least one of the at least one first ranging measurement, the at least one second ranging measurement, the synchronization time, positioning data from the at least one timing satellite, and at least one positioning ranging measurement.