JPS5684049A - 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 2piN/M rotation with an M-phase phase-modulated signal have one characteristic value. CONSTITUTION:The 1st and 2nd detection signals for polarized waves are applied to terminals 100 and 101 and the 2nd detection signal is inputted to prediscriminating circuit 1; and an estimated discrimination value, when detected, is applied to symbol substituting circuit 7 and the value of rotary parameter (n) is outputted to output terminal 7002 and applied to rotary converting circuit 6. In memory circuit 3', one of four four-phase phase-modulated signals is written as a representative discrimination value and its output enters rotary converting circuit 6 and rotated by xn/2 time according to the value of parameter (n) to obtain a characteristic value that corresponds to the estimated discrimination value, so that a corrected value can be obtained by memory-contents correcting circuit 5. The value is inputted to rotary converting circuit 6', which output a characteristic value decreased by parameter (n) to memory circuit 3''. Thus, high-speed corrections are made.