| 摘要 |
<p>An 8-ary PSK demodulation apparatus for receiving an input signal Rk(Xk, Yk) comprised of a k<th> quadrature-phase component Yk and a k<th> in-phase component Xk, and for generating soft decision values LAMBDA (sk,0), LAMBDA (sk,1), and LAMBDA (sk,2) for the input signal Rk(Xk, Yk) by a soft decision means. A calculator calculates Zk by subtracting a level Yk of the quadrature-phase signal component Yk from a level Xk of the in-phase signal component Xk, and outputs the Zk as a first soft decision value. A first selector selects the Zk or reverse -Zk, according to an MSB of the quadrature-phase signal component Yk. A second selector selects the Zk or 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. A first adder adds 2ROOT 2 Yk to an output of the third selector, and outputs the result value as a third soft decision value. A fourth selector selects an output of the second selector or a value "0" according to the MSB of the Zk. A second adder adds 2ROOT 2Xk to an output of the fourth selector, and outputs the result value as a second soft decision value. <IMAGE></p> |
