Pulse or digital communications – Receivers – Particular pulse demodulator or detector
Reexamination Certificate
2005-04-19
2005-04-19
Tse, Young T. (Department: 2637)
Pulse or digital communications
Receivers
Particular pulse demodulator or detector
C375S142000, C375S150000, C708S422000
Reexamination Certificate
active
06882692
ABSTRACT:
In a direct sequence spread spectrum receiver an “as received” signal is decoded by correlation. Phase shift key, complementary code key modulated signals are correlated by transforming samples of the signal in a series of butterfly transform processors producing a number of correlations equal to the number of possible transmitted codewords. The largest correlation is selected as the transmitted signal. To reduce the number of processors required to transform a multi-level phase shift key signal, a correlation method and apparatus are disclosed wherein the butterfly transforms are modified with additional twiddle factors selected from a set of twiddle factors. In the alternative, the inputs to the butterfly processors of a correlator can be weighted as a function the additional twiddle factors. A set of signal samples is correlated for each combination of the set of additional twiddle factors and the largest correlation selected as the signal.
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Chernoff Vilhauer McClung & Stenzel LLP
Sharp Laboratories of America Inc.
Tse Young T.
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