Spread spectrum correlator
First Claim
1. An apparatus for decoding a received spread spectrum signal having a data signal modulated with a PN code, comprising:
- threshold setting means for analyzing the pattern and application of the data signal, noise environment, and amount of error correction, and determining upper- and lower-threshold levels;
first reference-sequence-storage means for storing a first pseudo-noise signal;
second reference-sequence-storage means for storing a second pseudo-noise signal;
receive-sequence-storage means for storing the received spread spectrum signal;
first chip-comparison means coupled to said first reference-sequence-storage means and said receive-sequence-storage means, and responsive to the received spread spectrum signal for comparing each chip of the received spread spectrum signal with each respective chip of the first pseudo-noise signal to generate a first plurality of chip-comparison signals;
first summer means coupled to said first chip-comparison means and responsive to the first plurality of chip-comparison signals for adding the first plurality of chip-comparison signals to generate a first correlation signal;
second chip-comparison means coupled to said second reference-sequence-storage means and said receive-sequence-storage means, and responsive to the received spread spectrum signal for comparing each chip of the received spread spectrum signal with each respective chip of the second pseudo-noise signal to generate a second plurality of chip-comparison signals;
second summer means coupled to said second chip-comparison means and responsive to the second plurality of chip-comparison signals for adding the second plurality of chip-comparison signals to generate a second correlation signal; and
comparison means coupled to said first summer means and said second summer means, and responsive to the first correlation signal being greater than the upper-threshold level for generating a first data-symbol signal, responsive to the first correlation signal being less than the lower-threshold level for generating a second data-symbol signal, responsive to the second correlation signal being less than the lower-threshold level for generating a third data-symbol signal, and responsive to the second correlation signal being greater than the upper-threshold level for generating a fourth data-symbol signal.
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Abstract
An apparatus for decoding a received spread spectrum signal having a data signal modulated with a pseudo-noise code and transmitted as an RF spread spectrum signal. A first reference register holds a first pseudo-noise signal, a second reference register holds a second pseudo-noise signal, and a receive-register holds a received spread spectrum signal. A first modulo adder adds each chip of the received spread spectrum signal with each respective chip of the first pseudo-noise signal, thereby generating a first plurality of chip-comparison signals. A first summer adds the first plurality of chip-comparison signals, generating a first correlation signal. The comparator compares the correlation signal to an upper-threshold level and a lower-threshold level, and respectively generates a first data-symbol signal or a second data-symbol signal.
230 Citations
27 Claims
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1. An apparatus for decoding a received spread spectrum signal having a data signal modulated with a PN code, comprising:
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threshold setting means for analyzing the pattern and application of the data signal, noise environment, and amount of error correction, and determining upper- and lower-threshold levels; first reference-sequence-storage means for storing a first pseudo-noise signal; second reference-sequence-storage means for storing a second pseudo-noise signal; receive-sequence-storage means for storing the received spread spectrum signal; first chip-comparison means coupled to said first reference-sequence-storage means and said receive-sequence-storage means, and responsive to the received spread spectrum signal for comparing each chip of the received spread spectrum signal with each respective chip of the first pseudo-noise signal to generate a first plurality of chip-comparison signals; first summer means coupled to said first chip-comparison means and responsive to the first plurality of chip-comparison signals for adding the first plurality of chip-comparison signals to generate a first correlation signal; second chip-comparison means coupled to said second reference-sequence-storage means and said receive-sequence-storage means, and responsive to the received spread spectrum signal for comparing each chip of the received spread spectrum signal with each respective chip of the second pseudo-noise signal to generate a second plurality of chip-comparison signals; second summer means coupled to said second chip-comparison means and responsive to the second plurality of chip-comparison signals for adding the second plurality of chip-comparison signals to generate a second correlation signal; and comparison means coupled to said first summer means and said second summer means, and responsive to the first correlation signal being greater than the upper-threshold level for generating a first data-symbol signal, responsive to the first correlation signal being less than the lower-threshold level for generating a second data-symbol signal, responsive to the second correlation signal being less than the lower-threshold level for generating a third data-symbol signal, and responsive to the second correlation signal being greater than the upper-threshold level for generating a fourth data-symbol signal. - View Dependent Claims (2, 3, 4)
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5. An apparatus of decoding a received spread spectrum signal having a data signal modulated with a PN code, comprising:
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threshold setting means for analyzing the pattern and application of the data signal, noise environment, and mount of error correction, and determining upper- and lower-threshold levels; first reference-sequence-storage means for storing a first pseudo-noise signal; second reference-sequence-storage means for storing a second pseudo-noise signal; receive-sequence-storage means for storing the received spread spectrum signal; first chip-comparison means coupled to said first reference-sequence-storage means and said receive-sequence-storage means, and responsive to the received spread spectrum signal for comparing each chip of the received spread spectrum signal with each respective chip of the first pseudo-noise signal to generate a first plurality of chip-comparison signals; first summer means coupled to said first chip-comparison means and responsive to the first plurality of chip-comparison signals for adding the first plurality of chip-comparison signals to generate a first correlation signal; second chip-comparison means coupled to said second reference-sequence-storage means and said receive-sequence-storage means, and responsive to the received spread spectrum signal for comparing each chip of the received spread spectrum signal with each respective chip of the second pseudo-noise signal to generate a second plurality of chip-comparison signals; second summer means coupled to said second chip-comparison means and responsive to the second plurality of chip-comparison signals for adding the second plurality of chip-comparison signals to generate a second correlation signal; and comparison means coupled to said first summer means, and responsive to the first correlation signal being greater than the upper-threshold level for generating a first data-symbol signal, and responsive to the first correlation signal being less than the lower-threshold level for generating a second data-symbol signal. - View Dependent Claims (6, 7, 8)
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9. An apparatus for decoding a received spread spectrum signal having a data signal modulated with a PN code, comprising:
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first reference-sequence-storage means for storing a first pseudo-noise signal; second reference-sequence-storage means for storing a second pseudo-noise signal; receive-sequence-storage means for storing the received spread spectrum signal; first chip-comparison means coupled to said first reference-sequence-storage means and said receive-sequence-storage means, and responsive to the received spread spectrum signal for comparing each chip of the received spread spectrum signal with each respective chip of the first pseudo-noise signal to generate a first plurality of chip-comparison signals; first summer means couple to said first chip-comparison means and responsive to the first plurality of chip-comparison signals for adding the first plurality of chip-comparison signals to generate a first correlation signal; second chip-comparison means coupled to said second reference-sequence-storage means and said receive-sequence-storage means, and responsive to the received spread spectrum signal for comparing each chip of the received spread spectrum signal with each respective chip of the second pseudo-noise signal to generate a second plurality of chip-comparison signals; second summer means coupled to said second chip-comparison means and responsive to the second plurality of chip-comparison signals for adding the second plurality of chip-comparison signals to generate a second correlation signal; and comparison means having a upper-threshold level, coupled to said first summer means, and responsive to the first correlation signal being greater than an upper-threshold level for generating a first data-symbol signal. - View Dependent Claims (10, 11, 12)
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13. An apparatus for decoding a received spread spectrum signal having a data signal modulated with a PN code, comprising:
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a plurality of reference-sequence-storage means for storing a plurality of pseudo-noise signals; receive-sequence-storage means for storing the received spread spectrum signal; a plurality of chip-comparison means coupled to plurality of reference-sequence-storage means and said receive-sequence-storage means, and responsive to the received spread spectrum signal for comparing each chip of the received spread spectrum signal by each corresponding chip of the plurality of pseudo-noise signals to generate sets of a plurality of chip-comparison signals; a plurality of summer means respectively coupled to said plurality of chip-comparison means and responsive to the respective set of the plurality of chip-comparison signals for adding the plurality of chip-comparison signals within each set to generate a plurality correlation signals; and comparison means coupled to said plurality of summer means, and responsive to the plurality of correlation signals and one of a plurality of threshold levels for generating one of a plurality of data-symbol signals. - View Dependent Claims (14, 15)
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16. An apparatus for decoding a received spread spectrum signal having a data signal modulated with a PN code comprising:
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code-register means for storing a pseudo-noise signal; receive-sequence-storage means for storing the received spread spectrum signal; means for correlating the received spread spectrum signal with the pseudo-noise signal for generating a correlation signal; and comparison means responsive to the correlation signal for generating a first data-symbol signal when the correlation signal is greater than a upper-threshold level and for generating a second data-symbol signal when the correlation signal is less than a lower-threshold level. - View Dependent Claims (17, 18)
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19. An apparatus for decoding a received spread spectrum signal having a data signal modulated with a PN code comprising:
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code-register means for storing a plurality of pseudo-noise signals; receive-sequence-storage means for storing the received spread spectrum signal; means for correlating the received spread spectrum signal with the plurality of pseudo-noise signals for generating a plurality of correlation signals, respectively; and comparison means responsive to the plurality of correlation signals for generating one of a plurality of data-symbol signals in response to the correlation signals, respectively, crossing a particular set of a plurality of threshold levels. - View Dependent Claims (20, 21)
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22. A method using a correlator for decoding a received spread spectrum signal having a data signal modulated with a PN code comprising the steps, using said correlator, of:
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pseudo-noise signal in code register means; storing the received spread spectrum signal in receive-sequence-storage means; correlating the received spread spectrum signal with the pseudo noise signal for generating a correlation signal;
comparing the correlation signal to a upper-threshold level and a lower-threshold level;generating a 1-bit data signal in response to the correlation signal greater than the upper-threshold level; and generating a 0-bit data signal in response to the correlation signal less than the lower-threshold level.
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23. A method using a correlator for decoding a received spread spectrum signal having a data signal modulated with a PN code comprising the steps, using said correlator, of:
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storing a pseudo-noise signal in code register means; storing the received spread spectrum signal in receive-sequence-storage means; correlating the received spread spectrum signal with the pseudo-noise signal for generating a correlation signal; comparing the correlation signal to a upper-threshold level; and generating a 1-bit data signal in response to the correlation signal greater than the upper-threshold level.
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24. A method using a correlator for decoding a received spread spectrum signal having a data signal modulated with a PN code comprising the steps, using said correlator, of:
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storing a plurality of pseudo-noise signals in code register means; storing the received spread spectrum signal in receive-sequence-storage means; correlating the received spread spectrum signal with the plurality of pseudo-noise signals for generating a plurality of correlation signals; comparing the plurality of the correlation signals to a plurality of threshold levels; and generating one of a plurality of data-symbol signals in response to the comparing step.
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25. An apparatus for transmitting a transmitted signal having a data signal modulated with spread spectrum, comprising:
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means for generating the data signal having data symbols; and means for generating a pseudo-noise signal having L chips, and for modulating each data symbol of the data signal by the L chips of the pseudo noise signal.
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26. An apparatus for decoding a received spread spectrum signal having a data signal modulated with a PN code, comprising:
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threshold setting means for analyzing the pattern and application of the data signal, noise environment, and amount of error correction, and determining upper- and lower-threshold levels; first reference-sequence-storage means for storing a first pseudo-noise signal; receive-sequence-storage means for storing the received spread spectrum signal; first chip-comparison means coupled to said first reference-sequence-storage means and said receive-sequence-storage means, and responsive to the received spread spectrum signal for comparing each chip of the received spread spectrum signal with each respective chip of the first pseudo-noise signal to generate a first plurality of chip-comparison signals; first summer means coupled to said first chip-comparison means and responsive to the first plurality of chip-comparison signals for adding the first plurality of chip-comparison signals to generate a first correlation signal; and comparison means coupled to said first summer means, and responsive to the first correlation signal being greater than the upper-threshold level for generating a first data-symbol signal, and responsive to the first correlation signal being less than the lower-threshold level for generating a second data-symbol signal.
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27. An apparatus for decoding a received spread spectrum signal having a data signal modulated with a PN code, comprising:
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first reference-sequence-storage means for storing a first pseudo-noise signal; receive-sequence-storage means for storing the received spread spectrum signal; first chip-comparison means coupled to said first reference-sequence-storage means and said receive-sequence-storage means, and responsive to the received spread spectrum signal for comparing each chip of the received spread spectrum signal with each respective chip of the first pseudo-noise signal to generate a first plurality of chip-comparison signals; first summer means coupled to said first chip-comparison means and responsive to the first plurality of chip-comparison signals for adding the first plurality of chip-comparison signals to generate a first correlation signal; and comparison means having a upper-threshold level, coupled to said first summer means, and responsive to the first correlation signal being greater than an upper-threshold level for generating a first data-symbol signal.
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Specification