Rate 2/3 mask trellis coded modulation using rate 1/2 convolutional encoder

摘要

A method for performing rate 2/3 Multiple Amplitude Shift Keying (MASK) encoding utilizing a rate 1/2 convolutional encoder (10) is described. In accordance with one embodiment of the invention, a rate 1/2 encoder is used to generate two coded symbols and a second bit is used as an uncoded symbol. A mapper (20) generates amplitude modulation data in response to the uncoded symbol and the pair of coded symbols whereby the uncoded symbol is the most significant. In a decoder, a variable threshold decoder (88) is used to determine the uncoded symbol where the threshold is varied on the set of coded symbols received.