RECEIVER AND METHOD FOR DIRECT SEQUENCE SPREAD SPECTRUM SIGNALS
First Claim
1. A method of processing a Direct Sequence Spread Spectrum DSSS signal, the method comprising:
- performing DSSS acquisition to obtain estimates of a frequency offset and a spreading code phase;
sequentially obtaining, for each one of a plurality of segments of a received DSSS signal, a correlation function between the DSSS signal segment and a replica of a spreading code by using a time and frequency transform based correlation method with coarse Doppler compensation, the estimated frequency offset and the spreading code phase; and
performing DSSS carrier tracking by tracking the phase of a correlation peak in the obtained correlation functions, and applying phase corrections to the obtained correlation functions to provide fine Doppler compensation,wherein the time and frequency transform based correlation method involves, for each segment of the received DSSS signal, obtaining a plurality of samples, performing a time to frequency transformation, multiplying the transformed samples by a complex conjugate of the time to frequency-transformed replica of the spreading code, and performing an inverse time to frequency transformation.
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Abstract
A received Direct Sequence Spread Spectrum DSSS signal is processed by performing DSSS acquisition to obtain estimates of a frequency offset and a spreading code phase, sequentially obtaining, for each one of a plurality of segments of a received DSSS signal, a correlation function between the DSSS signal segment and a replica of a spreading code by using a Time and Frequency Transform based correlation method, the estimated frequency and the spreading code phase, and performing DSSS carrier tracking by tracking the phase of a correlation peak in the obtained correlation functions, and applying phase corrections to the obtained correlation functions to provide fine Doppler compensation. The time and frequency transform based correlation method involves, for each segment of the received DSSS signal, obtaining a plurality of samples and transforming the samples from the time domain to the frequency domain.
14 Citations
15 Claims
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1. A method of processing a Direct Sequence Spread Spectrum DSSS signal, the method comprising:
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performing DSSS acquisition to obtain estimates of a frequency offset and a spreading code phase; sequentially obtaining, for each one of a plurality of segments of a received DSSS signal, a correlation function between the DSSS signal segment and a replica of a spreading code by using a time and frequency transform based correlation method with coarse Doppler compensation, the estimated frequency offset and the spreading code phase; and performing DSSS carrier tracking by tracking the phase of a correlation peak in the obtained correlation functions, and applying phase corrections to the obtained correlation functions to provide fine Doppler compensation, wherein the time and frequency transform based correlation method involves, for each segment of the received DSSS signal, obtaining a plurality of samples, performing a time to frequency transformation, multiplying the transformed samples by a complex conjugate of the time to frequency-transformed replica of the spreading code, and performing an inverse time to frequency transformation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. Apparatus for receiving a Direct Sequence Spread Spectrum DSSS signal, the apparatus comprising:
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means for performing DSSS acquisition to obtain estimates of a frequency offset and a spreading code phase; means for sequentially obtaining, for each one of a plurality of segments of a received DSSS signal, a correlation function between the DSSS signal segment and a replica of a spreading code by using a time and frequency transform based correlation method with coarse Doppler compensation, the estimated frequency and the spreading code phase; and means for performing DSSS carrier tracking by tracking the phase of a correlation peak in the obtained correlation functions, and applying phase corrections to the obtained correlation functions to provide fine Doppler compensation, wherein the time and frequency transform based correlation method involves, for each segment of the received DSSS signal, obtaining a plurality of samples, performing a frequency transformation to transform the samples from the time domain to the frequency domain, multiplying the transformed samples by a complex conjugate of the frequency-transformed replica of the spreading code, and performing an inverse frequency transformation.
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Specification