Spread spectrum correlator - Patent Review 5022047

Claims

We 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.

2. The apparatus as set forth in claim 1 wherein said first reference-sequence-storage means and said receive-sequence-sto