An automatic equalizer including a Viterbi decoder for trellis coded modulation system

The authors propose an automatic equalizer, applicable to trellis-coded modulation, that includes a Viterbi decoder and a carrier-phase controller and achieves reliable high-speed voiceband data transmission at 14.4 kb/s and above. The equalizer can perform the operations of equalization, demodulation, and decoding. Since the system reduces misadjustment of tap values and estimated carrier-phase shift due to decision errors, stable convergence can be achieved. Also presented is a method to utilize the reliability of decoded data in order to minimize misadjustment of the adaptive digital filters and the phase controller owing to undetected errors and miscorrected data in decoding