Pulse or digital communications – Repeaters – Testing
Patent
1991-07-26
1993-08-03
Kontz, Curtis
Pulse or digital communications
Repeaters
Testing
371 378, 371 43, 332103, 329304, H03M 1312
Patent
active
052336298
ABSTRACT:
Coded modulation schemes based on codes for QPSK modulation are directly incorporated into QAM based modulation systems, forming trellis coded QAM for communicating information. Concatenated coding with QPSK based trellis coding and symbol error correcting coding is used. In an encoder, an N-bit QAM constellation pattern is divided into four subsets, each including N/4 symbol points of the constellation pattern. A two-bit QPSK codeword is assigned to each of the four subsets. A symbol to be transmitted is first encoded using an outer error correcting encoding algorithm. Part of the symbol is then encoded with an inner code that comprises a rate 1/2 trellis encoding algorithm to provide a QPSK codeword, which is mapped with the remaining bits of the symbol to provide a modulation function. The remaining bits correlate the symbol with one of the symbol points included in the subset defined by the QPSK codeword. A receiver is provided to recover information from the modulation function.
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Heegard Chris
Lery Scott A.
Paik Woo H.
General Instrument Corporation
Kontz Curtis
Lipsitz Barry R.
Tse Young
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