DEMODULATION APPARATUS AND METHOD IN A COMMUNICATION SYSTEM EMPLOYING 8-ARY PSK MODULATION

摘要

An 8-Ary PSK demodulation apparatus for receiving an input signal Rk(Xk, YK) comprised of a kth quadrature-phase component Yk and a kth in-phase componen t Xk, and for generating soft decision values .LAMBDA.(SK,0), .LAMBDA.(SK,1), and .LAMBDA.(SK,2). A calculator calculates Zk by subtracting a level Y of the quadrature-phase signal component YK from a level XK of the in-phase signal component Xk. A first selector selects the Zk, according to an MSB of the quadrature-phase signal component Yk. A second selector selects the Zk o r the reverse ZK according to an MSB of the in-phase signal component Xk. A third selector selects an output of the second selector or a value "0" according to an MSB of the ZK.