Pulse or digital communications – Receivers – Particular pulse demodulator or detector
Patent
1997-08-04
1999-10-05
Chin, Stephen
Pulse or digital communications
Receivers
Particular pulse demodulator or detector
375262, 375231, 375233, 371 436, H03D 100, H04L 2706, H04L 2302, H04L 512
Patent
active
059635991
ABSTRACT:
A truncated maximum likelihood sequence estimator that provides a best estimate of a transmitted symbol sequence includes a lookup table and a comparator. The lookup table may be responsive to at least a next sample of a received RF signal, a first decision made on a first previous sample of the RF received signal and a second decision made on the second previous sample of the RF received signal. The lookup table provides at an output at least one threshold value stored in the lookup table that is addressed by the next sample of the received signal, the first decision made on the first previous sample and the second decision made on the second previous sample. The comparator is coupled to the output of a lookup table and is responsive to the at least one threshold value and a current sample of the received RF signal. The comparator compares the current sample of the received RF signal with at least one threshold value and provides a best estimate of the transmitted symbol sequence. The truncated maximum likelihood sequence estimator can be used for example to determine a best estimate of a transmitted symbol sequence of a current sample of 4-ary frequency shift keyed signal or a 2-ary frequency shift keyed received signal. In addition, the truncated maximum likelihood estimator can be used within a wireless radio that transmits and receives an RF waveform including a modulated symbol stream to provide the best estimate of the received modulated symbol stream. Further, the truncated maximum likelihood estimator can be used within a wireless local area network that includes at least one computer interfaced to a wireless radio containing the truncated maximum likelihood sequence estimator to provide wireless communications between either computers or between a computer and a computer network.
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Brodsky Wesley G.
Curtis Robert G.
Chin Stephen
Maddox Michael W.
Raytheon Company
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