AUTOMATIC EQUALIZER SYSTEM FOR QAM MODEM

摘要

PURPOSE: To select an automatic equalizer with less data transmission delay in the transmission through a line with small distortion and to select an automatic equalizer with a large equalization capability in the transmission through a line with large distortion. ;CONSTITUTION: A reception signal is demodulated by a demodulator 1 and distortion of a telephone line or the like is equalized by a 1st automatic equalizer 2 and a 2nd automatic equalizer 5. A reception signal equalized by the 1st automatic equalizer 2 is given to a 1st coordinate discrimination means 3 to discriminate a coordinate on a complex plane and a 1st reference coordinate is outputted. A reception signal equalized by the 2nd automatic equalizer 5 is given to a 2nd coordinate discrimination means 6 to discriminate a coordinate on a complex plane and a 2nd reference coordinate is outputted. A 1st error extract means 4 calculates an error between an output of the 1st automatic equalizer 2 with the 1st reference coordinate on the complex plane and a 2nd error extract means 7 calculates an error between an output of the 2nd automatic equalizer 5 with the 2nd reference coordinate on the complex plane. The 1st automatic equalizer 2 and the 2nd automatic equalizer 5 are sequentially corrected based on the error.;COPYRIGHT: (C)1993,JPO&Japio