镜像滤波器

原型滤波器  h[k]

镜像滤波器  (-1)^k * h[k]。 镜面对称

补码滤波器  与原型滤波器构成全通。   hcomp(k) = -h[k],    hcomp(L+1) = 1 - h(k), k=2*L+1

Num = [ 1/5, 1/5, 1/5, 1/5, 1/5];

N = 2
part_N = 2*N +1;
Num_temp = Num(1:part_N);
figure(3)
temp1 = abs(freqz(Num_temp, 1, 512, fs));

mir_num = Num_temp;
mir_num(2:2:end) = mir_num(2:2:end) *(-1);
temp2 = abs(freqz(mir_num, 1, 512, fs));

bu_num = -Num_temp;%127 63*2 +1 L = 63
bu_num(N+1) = 1 + bu_num(N+1);
temp3 = abs(freqz(bu_num, 1, 512, fs));
x = 1:512;
plot(x, temp1, x, temp2, x, temp3);
legend('原型滤波器','镜像FIR滤波器','补码FIR滤波器');

figure(2)
plot(x, temp1 + temp3);