PURPOSE: To compensate each interference between signals by composing a corresponding cross polarized signal after passing through a common distortion generating circuit with a main polarized signal to be interferred comprising plural digital modulation signals and outputting the result at a common composite circuit.

CONSTITUTION: In Block diagram applied to the signal transmission of the 4- multi-carrier system, the circuit is provided with a control circuit 40 and a compensating circuit 39. The delay time in a delay circuit in the circuit 39 is set to a time four times that of a conventional circuit. Through the constutution above, each polarized wave interference is compensated among four corresponding digital modulation signals belonging to the cross polarized wave of the four digital modulation signal belonging to the main polarized wave by having only to use one transversal filter to the 4 digital modulation signals having different frequency region.