Communications: directive radio wave systems and devices (e.g. – Directive – Including a satellite
Patent
1995-10-06
1998-04-07
Tarcza, Thomas H.
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a satellite
342352, 342378, H04B 7185, G01S 502, G01S 316
Patent
active
057369615
ABSTRACT:
A global position system receiver recovers the L1 and L2 carriers, the C/A-code measurements and the L1 and L2 P-code measurements by (a) producing an estimate of the L1 carrier phase angle and synchronizing a locally generated C/A-code with the L1 signal using an L1 delay lock loop and controlling, based on the locally generated C/A code, an L1 P-code generator that produces a synchronized version of the P-code; (b) initializing an L2 P-code generator based on the phase of the P-code generated by the L1 P-code generator; (c) determining, for the L2 signal, an estimate of signal power that is adjusted to compensate for noise; (d) determining an L2 carrier phase angle; (e) tracking the L2 P-code by adjusting an L2 P-code generator until the estimate of signal power is maximized. The GPS receiver also resolves a 1/2 cycle ambiguity in tracking the L2 P-code by comparing demodulated L1 P-code bits and L2 P-code bits. If the bits do not match in the majority of instances, the receiver determines that it is tracking the L2 P-code with 1/2 cycle error and adjusts its estimate of the P-code phase accordingly. The receiver may determine the reliability of the independently tracked L2 signal, by determining an associated carrier-to-noise ratio.
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Fenton Patrick C.
Petersen Walter D.
NovAtel Inc.
Sayadian Hrayr A.
Tarcza Thomas H.
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