Method and apparatus for civilian receiver operation with P(Y) code in satellite positioning system receiver
AssigneeTrimble Navigation Limited
InventorGary R. Lennen
Life of this patent
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Abstract
The system and method of allowing the civilian GPS receivers to utilize the satellite transmitted P(Y) code signal without requiring the detailed P(Y) code to be revealed inside the receiver are disclosed. This is done by using the W code generator inside the civilian receiver, by integrating the W code signal across the W period, and by delaying the integrated signal to protect against the possible spoofing attack. The generator of the integrated and delayed W code signal is placed inside the tamper-proof container.
Claims17
A system for employing certain characteristics of the P(Y) code in the civilian Satellite Positioning System (SATPS) receiver, said system comprising:
- a RECEIVING MEANS for receiving a known C/A code modulated on L1 carrier frequency, for receiving an unknown Y code modulated on L1 carrier frequency signal, and for receiving an unknown Y code modulated on L2 carrier frequency signal from at least one satellite;
- wherein said received L1, and L2 signals contain propagation noise;
- and wherein said Y code comprises a known P code and an unknown W code;
- and
- at least one DIGITAL CHANNEL PROCESSING MEANS for:
- (1) locally generating replica of said C/A code modulated on L1 carrier frequency signal;
- (2) locally generating replica of said P code modulated on L1 carrier frequency signal;
- (3) locally generating replica of said P code modulated on L2 carrier frequency signal;
- (4) locally generating replica of a L1 G code whose power spectrum characteristics are similar to the unknown W code modulated on L1 carrier frequency signal;
- (5) locally generating replica of a L2 G code whose power spectrum characteristics are similar to the unknown W code modulated on L2 carrier frequency signal;
- (6) correlating a locally generated replica of C/A code with the received L1 code for obtaining an estimate of L1 group delay (L1 pseudo-range) and L1 carrier phase;
- and
- (7) demodulating the satellite data stream.
A method for utilizing the satellite-transmitted P(Y) signal without requiring the detailed P(Y) code to be revealed inside the receiver, said method comprising the steps of:
- receiving a known C/A code modulated on L1 carrier frequency;
- receiving an unknown Y code modulated on L1 carrier frequency signal;
- receiving an unknown Y code modulated on L2 carrier frequency signal from at least one satellite;
- wherein said received L1, and L2 signals contain propagation noise;
- and wherein said Y code comprises a known P code and an unknown W code;
- locally generating replica of said C/A code modulated on L1 carrier frequency signal;
- locally generating replica of said P code modulated on L1 carrier frequency signal;
- locally generating replica of said P code modulated on L2 carrier frequency signal;
- locally generating replica of a L1 G code whose power spectrum characteristics are similar to the unknown W code modulated on L1 carrier frequency signal;
- locally generating replica of a L2 G code whose power spectrum characteristics are similar to the unknown W code modulated on L2 carrier frequency signal;
- correlating a locally generated replica of C/A code with the received L1 code for obtaining an estimate of L1 group delay (L1 pseudo-range) and L1 carrier phase;
- and
- demodulating of the satellite data stream.
Dependencies are inferred from the claim text.