Importance

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Abstract

A data receiver comprises a demodulator for recovering a received data signal comprising a stream of interleaved regularly spaced one-dimensional symbols of a phase invariant symbol constellation, each of the received symbols representing 3 bits, Z.sub.0, Z.sub.1, Z.sub.2 produced by convolutionally coding a first data bit X.sub.1 to derive bits Z.sub.0, Z.sub.1 and precoding a second data bit X.sub.2 to derive bit Z.sub.2. The received symbols are applied to a first decoder for estimating data bit X.sub.1 and a bit Y.sub.2, Y.sub.2 being applied to a postcoder for conversion to an estimate of data bit X.sub.2. The first decoder may comprise a Viterbi decoder or a 4-level slicer. In a preferred embodiment of the invention the received signal includes a plurality of regularly spaced synchronization intervals, each comprising a number of received symbols, and the second decoder is prevented from changing state during the synchronization intervals.

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First Claim