1. Apparatus comprising: a receiver for receiving a GTCQ-encoded signal, and a trellis-code-quantization decoder, responsive to said receiver, for developing a frame of signal samples that form a) a first approximation of input signal samples represented by said GTCQ-encoded signal when said received GTCQ-encoded signal has a first plurality of bits, or b) a second approximation of said input signal samples represented by said GTCQ-encoded signal when said received GTCQ-encoded signal has a second plurality of bits, where said second approximation more faithfully approximates said input signal samples than said first approximation when the number of bits in said second plurality is greater than the number of bits in said first plurality.