# problem in 8psk demodulation-decision region

Started by March 10, 2003
 Hi everyone, I am trying to simulate 8PSK modulation-demodulation scheme in matlab. The problem arises in the decision making after matched filtering and re-sampling. I am comparing the angles of received signal and taking decision accordingly as shown in the code below. But seems that it misses out few symbols or is not working properly. Any idea???? what would be the optimum decision????????? Thanks, kunal. ( Here, ym is the Received signal after Matched filtering and Re-sampling. and s1=[1 1 1]; s2=[0 1 1]; s3=[0 1 0]; s4=[0 0 0]; s5=[0 0 1]; s6=[1 0 1]; s7=[1 0 0]; s8=[1 1 0]; ) k2=1; for i=1:length(ym) ang1=angle(ym(i)); if(ang1>15*pi/8 & ang1<=pi/8) Rx(1,k2:k2+2)=s1; elseif(ang1>pi/8 & ang1<=3*pi/8) Rx(1,k2:k2+2)=s2; elseif(ang1>3*pi/8 & ang1<=5*pi/8) Rx(1,k2:k2+2)=s3; elseif(ang1>5*pi/8 & ang1<=7*pi/8) Rx(1,k2:k2+2)=s4; elseif(ang1>7*pi/8 & ang1<=9*pi/8) Rx(1,k2:k2+2)=s5; elseif(ang1>9*pi/8 & ang1<*pi/8) Rx(1,k2:k2+2)=s6; elseif(ang1>11*pi/8 & ang1<*pi/8) Rx(1,k2:k2+2)=s7; elseif(ang1>13*pi/8 & ang1<*pi/8) Rx(1,k2:k2+2)=s8; else end; k2=k2+3; end; after this I am comparing Rx with the original data using biterr.