JPS5684050A - Axial ratio compensating circuit - Google Patents

Abstract

PURPOSE:To compensate cross-wave interference when transmitting two data by using two orthogonal polarized waves, by applying the advantage that all symbol groups bearing the relation of 2-N/M rotation with an M-phase phase-modulated signal have one characteristic value. CONSTITUTION:To terminals 100 and 101, the 1st and 2nd detection signals for polarization are inputted and to terminal 100, the 2nd data is supplied as an interference component. The signal from terminal 101 is converted by prediscriminating circuit 1 into the estimated discrimination value of the 2nd data, which is applied to the next symbol substituting circuit 7. According to the count value of modulo 4 in circuit 7, outputs appear at terminals 7001 and 7002 and one output characteristic to the estimated value is selected from the next memory circuit 3, supplied to output terminal 104 and subtracted as the interference component from the 1st polarized wave signal by subtracting circuit 22. On the basis of the input and output signals of final discriminator 21, memory-contents correcting circuit 5 calculates and inputs a corrected value to rotary converting circuit 6, which outputs a discrimination value, rotated according to the count value from circuit 7, to memory circuit 3, thereby correcting the characteristic value.