ENCODING/DECODING ADDITIONAL SYMBOLS IN A COMMUNICATIONS SYSTEM

摘要

A digital communication system with combined block encoding and differential and/or amplitude modulation is described. For every codeword period, one or more additional bits can be transmitted by applying differential modulation and/or amplitude modulation to the codewords. In differential modulation, additional information may be sent by changing or not changing the sign of a codeword. In amplitude modulation, additional information may be sent by changing the amplitude of successive codewords. A combination of differential and amplitude encoding may also be used. Thus, the data rate can be increased without increasing the symbol transmission rate.