Real-time data aiding for enhanced GPS performance

• US 20050159891A1
• Filed: 06/22/2004
• Published: 07/21/2005
• Est. Priority Date: 01/15/2004
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Gutt, Greg, Ferrell, Bart, Whelan, David, Cohen, Clark
• Granted Patent: US 7,904,243 B2
• Time in Patent Office: Days
• US Class Current: 701/213
• CPC Class Codes: G01S 19/06 employing an initial estimate of the location of the receiver as aiding data or in generating aiding data
• CPC Class Codes: G01S 19/21 Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
• CPC Class Codes: H04K 3/255 based on redundancy of transmitted data, transmission path or transmitting source
• CPC Class Codes: H04K 3/90 related to allowing or preventing navigation or positioning, e.g. GPS

Abstract

Data from GPS satellites within the field of view of a ground station are retransmitted to LEO satellites, such as Iridium satellites, and cross-linked if necessary before being transmitted to a user. The user is then able to combine the fed-forward data with data received directly from GPS satellites in order to resolve errors due to interference or jamming. Iridium and data aiding thus provides a means for extending GPS performance under a variety of data-impaired conditions because it can provide certain aiding information over its data link in real time.

Claims

1. A method for determining a position for a user using GPS satellite signals, comprising:

receiving a real-time GPS data stream transmitted from a GPS satellite;

receiving, from a LEO satellite, a feed-forward GPS data stream originating from the GPS satellite;

processing the real-time and feed forward signals such that the feed forward signals supplement the real-time data at least where the real-time data is impaired; and

determining a position for the user based on the processed signals.

2. The method of claim 1, wherein the real-time data is impaired as a result of at least one of jamming, RF interference, or structural interference.

3. The method of claim 1, wherein the step of processing comprises accumulation and time synchronization buffering.

4. The method of claim 1, wherein the step of processing comprises demodulation of the feed-forward data stream.

5. The method of claim 1, further comprising accessing an inertial reference unit before determining a position.

6. The method of claim 1, further comprising receiving at least one additional real-time GPS data stream, and receiving, from the LEO satellite, and at least one additional feed-forward GPS data stream.

7. The method of claim 1, wherein the feed-forward GPS data stream is cross linked to the LEO satellite and broadcast to the user.

8. A device for determining a position for a user based on GPS signals, comprising:

a first receiver configured to process a first real-time GPS signal received from a first GPS satellite; and

a second receiver coupled to the first receiver, the second receiver configured to process a first LEO signal transmitted from a LEO satellite, the first LEO signal comprising a first feed-forward GPS signal corresponding to the first real-time GPS signal and originating from the first GPS satellite, the second receiver further configured to send to the first receiver GPS aiding data;

whereby the first receiver is configured to acquire a more accurate GPS signal by supplementing the first real-time GPS signal with the first feed-forward GPS signal.

9. The device of claim 8, wherein the first receiver further comprises a synchronization buffer configured to synchronize the first real-time GPS signal with the first feed forward GPS signal.

10. The device of claim 9, further comprising a common clock coupled to the first 10 receiver and the second receiver.

11. The device of claim 10, further comprising an antenna adapted to receive transmissions from the first GPS satellite and from the first LEO satellite.

12. The device of claim 11, further comprising a filter in signal communication with the antenna, and a pre-amplifier in signal communication with the filter and the first and second receiver.

13. The device of claim 10, further comprising an inertial reference unit coupled to the first receiver, whereby the first receiver is configured to use inertial aiding data from the inertial reference unit to determine the position of the user.

14. The device of claim 13, wherein the first receiver further comprises a digital signal processor and a memory coupled to the digital signal processor.

21. The device of claim 13, wherein the first processing means further comprises a digital signal processor and a memory coupled to the digital signal processor.

15. A device for determining a position for a user based on GPS signals, comprising:

a first means for processing a first real-time GPS signal received from a first GPS satellite; and

a second means for processing a first LEO signal transmitted from a LEO satellite to produce first GPS aiding data, the first LEO signal comprising a first feed-forward GPS signal corresponding to the first real-time GPS signal and originating from the first GPS satellite; and

a means for determining the position of the user as a function of the first real-time GPS signal and the GPS aiding data.

16. The device of claim 15, wherein the first processing means comprises a synchronization buffer configured to synchronize the first real-time GPS signal with the first feed forward GPS signal.

17. The device of claim 16, further comprising a common clock coupled to the first processing means and the second processing means.

18. The device of claim 17, further comprising an antenna adapted to receive transmissions from the first GPS satellite and from the first LEO satellite.

19. The device of claim 18, further comprising a filter in signal communication with the antenna, and a pre-amplifier in signal communication with the filter and the first processing means and the second processing means.

20. The device of claim 19, further comprising an inertial reference unit coupled to the first processing means, whereby the first processing means is configured to use inertial aiding data from the inertial reference unit to determine the position of the user.

22. A system for determining the position of a user based on GPS signals, comprising:

a plurality of GPS satellites, each of the plurality of GPS satellites configured to transmit real-time GPS signals to the user;

a first LEO satellite configured to receive signals transmitted from the earth, to optionally cross-link the signals to a plurality of additional LEO satellites, and to broadcast the signals to users;

a monitoring and control station configured to receive the real-time GPS signals from at least one of the plurality of GPS satellites and to transmit feed-forward GPS signals based on the real-time GPS signals to the first LEO satellite; and

a user receiver configured to receive the real-time GPS signals and the feed-forward GPS signals from one of the first LEO satellite or the plurality of additional LEO satellites, whereby the user receiver uses the real-time GPS signals and the feed-forward GPS signals to determine the position of the user.

23. The system of claim 22, wherein the user receiver further comprises:

a first receiver configured to process the real-time GPS signal; and

a second receiver coupled to the first receiver, the second receiver configured to process the LEO feed-forward GPS signal and to send to the first receiver GPS aiding data;

whereby the first receiver is configured to acquire a more accurate GPS signal by supplementing the first real-time GPS signal with the first feed-forward GPS signal.

24. The system of claim 23, wherein the first receiver further comprises a synchronization buffer configured to synchronize the real-time GPS signal with the feed forward GPS signal.

25. The system of claim 24, further comprising a common clock coupled to the first receiver and the second receiver.

26. The system of claim 25, further comprising an antenna adapted to receive transmissions from at least one of the plurality of GPS satellites and from at least one of the first LEO satellite and the plurality of additional LEO satellites.

27. The system of claim 26, further comprising a filter in signal communication with the antenna, and a pre-amplifier in signal communication with the filter and the first and second receiver.

28. The system of claim 27, further comprising an inertial reference unit coupled to the first receiver, whereby the first receiver is configured to use inertial aiding data from the inertial reference unit to determine the position of the user.

29. The system of claim 28, wherein the first receiver further comprises a digital signal processor and a memory coupled to the digital signal processor.

30. The system of claim 29, wherein the first LEO satellite and the plurality of additional LEO satellites comprise Iridium satellites.