METHODS AND SYSTEMS FOR ACQUIRING SIGNALS USING COHERENT MATCH FILTERING
First Claim
1. A method for verifying a detection of a correlation peak representing an acquisition of a received acquisition code symbol sequence, the method comprising:
- receiving the acquisition code symbol sequence, wherein the acquisition code symbol sequence includes a plurality of acquisition code symbols, and wherein an acquisition code symbol includes a subcode sequence having a plurality of subcodes;
performing a correlation of the plurality of subcodes to produce a plurality of correlation peaks;
correcting each peak of the plurality of correlation peaks in frequency, phase, and time to produce a plurality of coherently-aligned peaks;
performing a coherent match filter process on the plurality of coherently-aligned peaks to produce a match filter result; and
verifying the detection of the correlation peak when the match filter result exceeds a first threshold.
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Abstract
Embodiments include methods and apparatus for verifying the detection of a correlation peak, which may represent an acquisition of a received acquisition code symbol sequence. The method includes determining a series of coherently-aligned peaks from a series of correlation peaks. Determining the plurality of coherently-aligned peaks includes correcting a frequency offset and a phase offset for each of the plurality of correlation peaks. A coherent match filter process is performed on the plurality of coherently-aligned peaks. A detection of the correlation peak may be verified when the match filter result exceeds a threshold.
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Citations
20 Claims
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1. A method for verifying a detection of a correlation peak representing an acquisition of a received acquisition code symbol sequence, the method comprising:
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receiving the acquisition code symbol sequence, wherein the acquisition code symbol sequence includes a plurality of acquisition code symbols, and wherein an acquisition code symbol includes a subcode sequence having a plurality of subcodes; performing a correlation of the plurality of subcodes to produce a plurality of correlation peaks; correcting each peak of the plurality of correlation peaks in frequency, phase, and time to produce a plurality of coherently-aligned peaks; performing a coherent match filter process on the plurality of coherently-aligned peaks to produce a match filter result; and verifying the detection of the correlation peak when the match filter result exceeds a first threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A receiver configured to receive and detect an acquisition code symbol sequence from a received acquisition code symbol sequence having a plurality of subcodes, the receiver comprising:
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a correlation calculator configured to produce a plurality of correlation peaks from a correlation of the received acquisition code symbol sequence and a stored version of the acquisition code symbol sequence; a frequency offset calculator coupled to the correlation calculator and configured to determine a frequency offset from the plurality of correlation peaks; a phase offset calculator coupled to the correlation calculator and configured to determine a phase offset from the plurality of correlation peaks; a peak corrector coupled to the frequency offset calculator and the phase offset calculator, the peak corrector configured to produce a plurality of coherently-aligned peaks by adjusting the plurality of correlation peaks for frequency offset and phase offset; and a coherent peak detector coupled to the peak corrector and configured to verify a detection of a correlation peak when the plurality of coherently-aligned peaks represents an acquisition of the acquisition code symbol sequence. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for acquiring an acquisition code symbol sequence comprising:
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non-coherently detecting a correlation peak from a plurality of correlation peaks generated from an acquisition code symbol sequence; correcting the plurality of correlation peaks for phase, frequency, and timing offsets to produce a plurality of corrected correlation peaks; and coherently verifying a detection of the correlation peak from the plurality of corrected correlation peaks.
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Specification