System and method for continuous carrier wave reconstruction

• US 9,618,625 B2
• Filed: 04/03/2014
• Issued: 04/11/2017
• Est. Priority Date: 07/06/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Miller, Isaac T., Bencze, William J., Brumley, Robert W., Ledvina, Brent M., Psiaki, Mark L., Holmes, Thomas J., Cohen, Clark E.
• Primary Examiner(s): Liu, Harry
• Application Number:
  US14/244,828
• Publication Number:
  US 20150042511A1
• Time in Patent Office: 1,104 Days
• Field of Search: 34235751, 34235762
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence

Abstract

A system and method of continuous carrier wave reconstruction includes a radio navigation receiver that includes one or more processors, memory coupled to the one or more processors, and an input for receiving a signal from a transmitter. The signal has a phase. The one or more processors are configured to obtain phase lock on the received signal, extract first phase information from the received signal, detect a loss in phase lock on the received signal, and extrapolate second phase information while phase lock is lost using a model of the phase. In some embodiments, the one or more processors are further configured to reconstruct the carrier signal based on the first and second phase information. In some embodiments, the one or more processors are further configured to scale the first and second phase information from a first nominal frequency of the received signal to a different second nominal frequency.

Claims

1. A system comprising:

one or more processors;

memory coupled to the one or more processors; and

a radio navigation receiver for receiving a signal from a transmitter, the signal having a phase;

wherein the one or more processors are configured to perform operations comprising;

obtaining a phase lock on the received signal;

extracting first phase information from the received signal;

detecting a loss in phase lock on the received signal; and

extrapolating second phase information while phase lock is lost using a model of the phase, the extrapolating comprising;

determining a relative velocity between the radio navigation receiver and the transmitter; and

determining the second phase information based at least in part on the relative velocity.

2. The system of claim 1, the operations further comprising:

reconstructing a carrier signal based on the first and second phase information; and

providing the reconstructed carrier signal to a positioning unit.

3. The system of claim 1 wherein:

the received signal has a first nominal frequency; and

the one or more processors are further configured to scale the first and second phase information to a second nominal frequency different from the first nominal frequency.

4. The system of claim 3 wherein the one or more processors are further configured to account for differing ionospheric effects at the first and second nominal frequencies when scaling the first and second phase information.

5. The system of claim 1 wherein the one or more processors are further configured to:

reobtain phase lock on the received signal;

extract third phase information from the received signal; and

correct for a phase difference between the second phase information and the third phase information.

6. The system of claim 5 wherein the one or more processors are further configured to correct the phase difference gradually.

7. The system of claim 6 wherein the one or more processors are further configured to correct the phase difference over at least one cycle of the received signal.

8. The system of claim 5 wherein:

the phase difference includes an arbitrary signal change introduced by the transmitter; and

the one or more processors are further configured to adjust the third phase information to remove the arbitrary signal change.

9. The system of claim 1 wherein the one or more processors are further configured to combine the first and second phase information with additional phase information associated with a second signal received from the transmitter.

10. The system of claim 1 wherein:

the phase model includes a model of a derivative of the phase; and

the one or more processors are further configured to;

determine a position and a velocity of the transmitter;

determine a position and a velocity of the radio navigation receiver;

determine clock drift and bias for the radio navigation receiver;

determine transmission media effects; and

apply the model of the derivative of the phase based on the determined transmitter position and velocity, the radio navigation receiver position and velocity, the radio navigation receiver clock drift and bias, and the transmission media effects.

11. The system of claim 10 wherein determining the transmitter position and velocity is based at least in part on ephemerides.

12. The system of claim 10 wherein the radio navigation receiver position and velocity are determined based at least in part on previous position estimates for the radio navigation receiver.

13. The system of claim 10 wherein:

the radio navigation receiver position is determined based on a previous position estimate for the radio navigation receiver; and

the radio navigation receiver velocity is received from an inertial navigation system.

14. The system of claim 10 wherein the transmission media effects include ionospheric effects.

15. The system of claim 10 wherein the transmission media effects include tropospheric effects.

16. A method for reconstructing a carrier signal in a radio navigation receiver, the method comprising:

receiving a signal from a transmitter, the received signal having a phase;

obtaining phase lock on the received signal;

extracting first phase information from the received signal;

detecting a loss in phase lock on the received signal;

extrapolating second phase information while phase lock is lost using a model of the phase, the extrapolating comprising;

determining a relative velocity between the radio navigation receiver and the transmitter; and

determining the second phase information based at least in part on the relative velocity; and

reconstructing a carrier signal based on the first and second phase information.

17. The method of claim 16, further comprising scaling the first and second phase information to a first nominal frequency different from a second nominal frequency of the received signal.

18. The method of claim 17, wherein the scaling accounts for differing ionospheric effects at the first and second nominal frequencies.

19. The method of claim 16, further comprising:

reobtaining phase lock on the received signal;

extracting third phase information from the received signal;

correcting for a phase difference between the second phase information and the third phase information; and

reconstructing the carrier signal further based on the third phase information.

20. The method of claim 19, further comprising adjusting the third phase information to remove an arbitrary signal change introduced by the transmitter.

21. The method of claim 16, further comprising combining the first and second phase information with additional phase information associated with a second signal received from the transmitter.

22. The method of claim 16, wherein extrapolating the second phase information comprises:

determining clock drift and bias for the radio navigation receiver;

determining transmission media effects; and

applying a model of a derivative of the phase based on the determined transmitter position and velocity, the radio navigation receiver position and velocity, the radio navigation receiver clock drift and bias, and the transmission media effects.

23. A non-transitory machine-readable medium comprising a first plurality of machine-readable instructions which when executed by one or more processors are adapted to cause the one or more processors to perform operations comprising:

receiving, by a radio navigation receiver, a signal from a transmitter, the received signal having a phase;

obtaining a phase lock on the received signal;

extracting first phase information from the received signal;

detecting a loss in phase lock on the received signal;

determining a position and a velocity of the transmitter;

determining a position and a velocity of the radio navigation receiver;

determining clock drift and bias for the radio navigation receiver;

determining transmission media effects;

applying a model of a derivative of the phase based on the determined transmitter position and velocity, the radio navigation receiver position and velocity, the radio navigation receiver clock drift and bias, and the transmission media effects to extrapolate second phase information while phase lock is lost; and

reconstructing a carrier signal based on the first and second phase information.

24. The non-transitory machine-readable medium of claim 23, further comprising a second plurality of machine-readable instructions which when executed by the one or more processors are adapted to cause the one or more processors to perform operations comprising scaling first, second, and third phase information to a first nominal frequency different from a second nominal frequency of the received signal, the scaling accounting for differing ionospheric effects at the first and second nominal frequencies.

25. The non-transitory machine-readable medium of claim 23, further comprising a second plurality of machine-readable instructions which when executed by the one or more processors are adapted to cause the one or more processors to perform a method comprising:

reobtaining phase lock on the received signal;

extracting third phase information from the received signal; and

correcting for a phase difference between the second phase information and the third phase information; and

reconstructing the carrier signal further based on the third phase information.

26. The non-transitory machine-readable medium of claim 25, further comprising a third plurality of machine-readable instructions which when executed by the one or more processors are adapted to cause the one or more processors to perform a method comprising adjusting the third phase information to remove an arbitrary signal change introduced by the transmitter.

27. The non-transitory machine-readable medium of claim 23, further comprising a second plurality of machine-readable instructions which when executed by the one or more processors are adapted to cause the one or more processors to perform a method comprising combining the first and second phase information with additional phase information associated with a second signal received from the transmitter.