Coded modulation apparatus

摘要

A transmitting section performs error-correcting coding of signal streams, converts the signal streams into a 2m-value quadrature amplitude-modulated radio signal, and transmits the radio signal to a channel. A receiving section receives the radio signal and generates signal streams having the same signal format as that of the above signal streams. An encoder codes a signal stream according to even and odd parity rules respectively set for the first and second half portions of a frame pulse. A decoder decodes a signal stream on the assumption that different parity rules are applied for the first and second half periods of the signal stream, and at the same time reproduces a frame pulse. This coded modulation scheme can eliminate uncertainty in the arrangement of signal streams in a rate converter.