Patent ID: 7289577

Claim:
A modulation method for modulating an input digital signal into a multi-value symbol stream, the modulation method comprising: generating a first multi-value modulation signal having first multi-value symbols from the input digital signal with a first modulator; generating a second modulation signal containing second multi-value symbols from a part of information of said input digital signal by using a second modulator, a channel distortion of said first multi-value modulation signal being estimated by using only said second modulation signal to demodulate said first multi-value modulation signal in a receiver; and inserting said second multi-value symbols into said first multi-value symbols to produce said multi-value symbol stream such that an arrangement of signal points corresponding to the first multi-value symbols of the first quadrature baseband signal is determined based on an arrangement of signal points corresponding to the second multi-value symbols of the second modulation signal in said multi-value symbol stream, and the resultant multi-value symbols constitute said multi-value symbol stream.