Apparatus for reducing auto-correlation or cross-correlation in weak CDMA signals
First Claim
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1. A CDMA receiver, comprising:
- a first data path for correlating an incoming CDMA signal, located within a scanned signal window, with a locally generated signal;
a second data path for verifying the incoming CDMA signal, located within the scanned signal window, against a lock signal, the second data path determining whether the incoming CDMA signal has at least one characteristic which differentiates the incoming CDMA signal from an auto-correlated signal or a cross-correlated signal; and
means for inputting a second incoming CDMA signal to the first data path if the incoming CDMA 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
20 Claims
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1. A CDMA receiver, comprising:
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a first data path for correlating an incoming CDMA signal, located within a scanned signal window, with a locally generated signal; a second data path for verifying the incoming CDMA signal, located within the scanned signal window, against a lock signal, the second data path determining whether the incoming CDMA signal has at least one characteristic which differentiates the incoming CDMA signal from an auto-correlated signal or a cross-correlated signal; and means for inputting a second incoming CDMA signal to the first data path if the incoming CDMA signal lacks the at least one characteristic. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A cellular telephone including a GPS receiver, comprising:
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a cellular telephone transceiver for transmitting and receiving cellular telephone signals; a Global Positioning System (GPS) receiver, coupled to the cellular telephone transceiver, comprising; a first data path for correlating an incoming GPS signal, located within a scanned signal window, with a locally generated signal; a second data path for 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 which differentiates the incoming GPS signal from an auto-correlated signal and a cross-correlated signal; and a data path executive for monitoring the first data path and, when the incoming GPS signal does not contain the at least one characteristic, for continuing to search the scanned signal window for a second incoming GPS signal. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification