Abstract: There is disclosed a multi channel GPS digital signal processor on a single IC. Each channel contains circuitry to process L1 or L2 P(Y) and C/A-code signals. In addition a search processor is included to achieve fast signal acquisition. Low power adder/accumulators have been designed to provide for a high precision digital oscillator whose output is synchronous to a high speed clock. The IC contains a full low power null detector and eight correlators to aid in signal acquisition.

Abstract: There is disclosed a global positioning system receiver method and system which converts the analog signals to digital signals prior to performing signal acquisition and GPS unique processing functions. The A/D converter uses full null zone processing to increase anti-jamming capability and 4-level output to reduce signal processing. A single analog and digital channel is used for both the L1 and L2 channels as well as for all P(Y)-code and C/A-code thus allowing full multi channel tracking with several channels each tracking a separate signal while the remainder of the channels rove over all of the signals on the alternate L-band with programmable duty cycles. The system allows for Y-code substitution for P-code by multiplexing a portion of the Y-code generated between multiple channels.

Abstract: An enhanced P-code channel (60) for use in a GPS receiver (10) to simultaneously track L1 and L2 comprises a P-code clock generator (62) for generating two code clocks. The first code clock associates with L1 and the second associates with L2. The code clocks have the same frequency but different phases from one another. Circuitry (64) and (66) generate and store a plurality of P-code chips. A first circuit (68, 70) selects and updates P-code chips from the stored P-code chips that are in phase with the L1 code clock. A second circuit (72 and 74) selects and updates P-code chips from the P-code chips and phased with the L2 code clock.

Abstract: A GPS single-receiver pointing/attitude system derives pointing/attitude measurements by correlating a selected GPS code (either P or C/A), recovered from GPS navigation signals using a single GPS receiver with multiple GPS antennas (a reference antenna and at least two slave antennas for pointing or three for attitude). For a two antenna pointing application, the GPS receiver (FIG. 4) includes, for each receiver channel, the incoming GPS signals are applied to three code correlators (72-75) assigned to the reference antenna, and three code correlators (76-77) assigned to the slave antenna, which provide corresponding reference and slave I and Q correlation outputs.