초록 ▼

A GPS receiver uses the energy of the L1 and L2 GPS satellite signals to track the phase of the L1 and L2 P-code and the carrier phase of the L2 signal. The in-phase channel of the L1 signal, after L1 carrier demodulation with the aid of the publicly known C/A code, is first correlated with the P-co

A GPS receiver uses the energy of the L1 and L2 GPS satellite signals to track the phase of the L1 and L2 P-code and the carrier phase of the L2 signal. The in-phase channel of the L1 signal, after L1 carrier demodulation with the aid of the publicly known C/A code, is first correlated with the P-code from a P-code generator in the L1 channel of the receiver. The correlation output is filtered over two W-bit periods, using an integrate-and-dump (I&D) filter, to determine whether a polarity change has occurred. Similarly the in-phase and quadrature channels of the received L2 Y-code signal are correlated with the P-code from the P-code generator in the receiver L2 channel and I&D filtered over the corresponding period of two W-bits. Polarity transitions between the two W-bits over the I&D integration period are detected by a threshold comparison with the I&D output of the L1 punctual P-code correlation signal. If a polarity change has occurred, the L1 and L2 I&D outputs are not used for L2 carrier demodulation. When there is no polarity change, the I&D output of the L1 in-phase Punctual P-code correlation is combined with the L2 in-phase Punctual P-code correlation in accordance with the L1 and L2 signal power ratio. This summed signal is multiplied with the I&D output of the L2 quadrature channel early-late P-code correlation to obtain a product signal that provides an estimate of the L2 carrier phase.

대표청구항 ▼

[ What is claimed is:] [1.] A global positioning satellite (GPS) demodulator configured to receive a GPS signal which includes modulated C/A code, L1 P-code, L2 P-code and encrypting W-code signals, the demodulator comprising:an L1 P-code generator configured to generate first and second L1 P-code s

[ What is claimed is:] [1.] A global positioning satellite (GPS) demodulator configured to receive a GPS signal which includes modulated C/A code, L1 P-code, L2 P-code and encrypting W-code signals, the demodulator comprising:an L1 P-code generator configured to generate first and second L1 P-code signals that are local replica signals of the L1 P-code of the GPS signal;a first demodulator configured to demodulate the GPS signal based on, in part, the first and second L1 P-code signals, to thereby generate first and second demodulated L1 P-code signals;a first pair of integrate-and-dump (I&D) filters configured to generate a first integrated L1 P-code signal by integrating the first demodulated L1 P-code signal and configured to generate a second integrated L1 P-code signal by integrating the second demodulated L1 P-code signal during a predetermined integration period;a first thresholding module configured to generate a first switch control signal by comparing the first integrated L1 P-code signal to a first predetermined threshold value to determine whether the encrypting W-code changed polarity during the predetermined integration period; anda first switch configured to output a first adjusting signal based on a signal derived from the first and second integrated L1 P-code signals and based on the first switch control signal, wherein the L1 P-code generator is further configured to be adjusted based on a signal derived from the first adjusting signal, to thereby accurately generate the first L1 P-code signal which tracks the L1 P-code of the GPS signal.