METHOD OF REDUCING THE GLARE OF A RECEIVER WITHIN A SYSTEM, IN PARTICULAR A GEOLOCATION SYSTEM

• US 20130142272A1
• Filed: 07/01/2011
• Published: 06/06/2013
• Est. Priority Date: 07/01/2010
• Status: Active Grant

• Current Assignee: Institut-Telecom/Telecom Sudparis
• Original Assignee: Institut-Telecom/Telecom Sudparis
• Inventors: Vervisch-Picois, Alexandre, Samama, Nel
• Granted Patent: US 8,929,489 B2
• Time in Patent Office: Days
• US Class Current: 375/284
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• 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: G01S 19/22 Multipath-related issues
• CPC Class Codes: H04B 15/00 Suppression or limitation of noise or interference by means associated with receiver H04B1/10

Abstract

A method of reducing the glare of at least one receiver within a system, in particular a geolocation system, the system including: at least one first emitter emitting at least a first signal modulated by a first code, at least a second emitter emitting at least one second signal modulated by a second code, which is repetitive and potentially variable, and a third signal out of phase with respect to the second signal, the third signal being modulated by the second code delayed by a first delay, and the receiver, the latter being configured so as to detect signals emitted by the first and second emitters and implementing, for the tracking of the first signal, a local signal.

Claims

1. A method for reducing the glare of at least one receiver within a system, the system comprising:

at least one first emitter emitting at least one first signal modulated by a first code,

at least one second emitter emitting at least one second signal modulated by a repetitive and potentially variable second code and a third signal phase-shifted with respect to the second signal, the third signal being modulated by the second code delayed by a first delay, and

the receiver being configured to detect the signals emitted by the first and second emitters and implementing, for the tracking of the first signal, a local signal, wherein

a first correlation quantity is calculated for a correlation between the local signal of the receiver modulated by the first code and a signal resulting from a combination of at least the

a second correlation quantity is calculated for a correlation between the local signal of the receiver, modulated by the first code delayed by the first delay and the signal resulting from the combination of at least the first, second and third signals, and

the first and second correlation quantities are combined to improve the signal/noise ratio of the first signal received by the receiver while reducing the glare of the receiver by the second signal.

2. The method as claimed in claim 1, wherein the second code is periodic.

3. The method as claimed in claim 1, wherein the first delay is equal to within 1% to half the duration of the second code.

4. The method as claimed in claim 1, wherein the phase shift between the second and the third signal is equal to 180°

to within 10%.

5. The method as claimed in claim 1, wherein the ratio between the power of the second signal and the power of the first signal is greater than 24 dB.

6. The method as claimed in claim 1, wherein the second emitter is fixed with respect to the receiver.

7. The method as claimed in claim 1, wherein the first emitter is mobile with respect to the receiver.

8. The method as claimed in claim 1, wherein the first and second signals are emitted simultaneously.

9. The method as claimed in claim 1, wherein the second and third signals are emitted simultaneously.

10. The method as claimed in claim 1, wherein the first, second and third signals have the same carrier frequency.

11. The method as claimed in claim 10, wherein the carrier frequency is a frequency L1 and the first and the second codes are C/A codes.

12. The method as claimed in claim 1, wherein the first emitter is a satellite.

13. The method as claimed in claim 1, being implemented in an outside setting.

14. The method as claimed in claim 1, wherein the local signal used to calculate the first correlation quantity has a local carrier in phase with the local carrier of the local signal used to calculate the second correlation quantity.

15. The method as claimed in claim 1, wherein the local signal used to calculate the second correlation quantity has a local carrier phase-shifted with respect to the phase carrier of the local signal used to calculate the first correlation quantity.

16. The method as claimed in claim 1, wherein the first and second correlation quantities are calculated and/or combined together by the receiver.

17. A system comprising:

a first emitter emitting at least one first signal,

at least one second emitter emitting at least one second signal modulated by a repetitive and potentially variable second code, and

at least one receiver configured to detect the signals emitted by the first and second emitters and utilizing, for the detection of the first signal, a local signal,

the second emitter being configured to emit, the second signal and a third signal phase-shifted with respect to the second signal and modulated by the second code delayed by a first delay.

18. The system as claimed in claim 17, the first delay being equal to within 1% to half the duration of the second code.

19. The system as claimed in claim 17, the phase shift between the second and the third signal being equal to 180°

to within 10%.

20. An emitter, used within the system, as defined in claim 17, said system comprising at least one other emitter and a receiver configured to detect the signals emitted by said emitter and the other emitter, said emitter being configured to:

emit, a signal modulated by a code and another signal phase-shifted with respect to said signal, the other signal being modulated by said code delayed by a delay.

21. A system, as defined in claim 17, said system comprising at least one first emitter emitting at least one first signal modulated by a first code and at least one second emitter emitting at least one second signal modulated by a repetitive and potentially variable second code, the second emitter furthermore emitting, at least one third signal phase-shifted with respect to the second signal and modulated by the second code delayed by a first delay, the receiver being configured to:

detect and demodulate the first signal, the detection of the first signal implementing a local signal of the receiver,

calculate a first correlation quantity for the correlation between the local signal of the receiver modulated by the first code and a signal resulting from a combination of at least the first, second and third signals,

calculate a second correlation quantity for the correlation between the local signal of the receiver modulated by the first code delayed by the first delay and the signal resulting from the combination of at least the first, second and third signals and,

combine the first and second correlation quantities.