Communications system that reduces auto-correlation or cross-correlation in weak signals
First Claim
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1. A communications system, comprising:
- a first data path to a CPU for correlating an incoming GPS signal, located within a scanned signal window, with a locally generated signal; and
a second data path to a CPU verifying the incoming GPS signal, located within the scanned signal window, against a lock signal, the second data path determining whether the incoming GPS signal has at least one characteristic that differentiates the incoming GPS signal from an auto-correlated signal or a cross-corrrelated signal, wherein the locally generated signal can change in order to continue to search the scanned signal window for a second incoming GPS signal if the incoming GPS signal lacks the at least one characteristic.
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Abstract
The present invention discloses methods, apparatuses, and systems for eliminating auto- and cross-correlation in weak signal CDMA systems, such as GPS systems. The invention uses parallel data paths that allow standard correlation of signals in parallel with verification of the lock signal to determine whether the system has locked onto the proper signal within the scanned signal window. The invention can be made with multiple CPUs, a single CPU with dual input modes, on multiple IC chips, or as a single IC chip solution for small, low cost reception, downconversion, correlation, and verification systems.
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Citations
19 Claims
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1. A communications system, comprising:
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a first data path to a CPU for correlating an incoming GPS signal, located within a scanned signal window, with a locally generated signal; and a second data path to a CPU verifying the incoming GPS signal, located within the scanned signal window, against a lock signal, the second data path determining whether the incoming GPS signal has at least one characteristic that differentiates the incoming GPS signal from an auto-correlated signal or a cross-corrrelated signal, wherein the locally generated signal can change in order to continue to search the scanned signal window for a second incoming GPS signal if the incoming GPS signal lacks the at least one characteristic. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification