%信道幅頻響應

%Design filter by specifying delay in units and
%looking at mag and phase response
%Good deafult values for fft_size = 128 and num_carriers = 32
delay_1 = 6;   %   6
attenuation_1 = 0.35;   %   0.35
delay_2 = 10;   %   10
attenuation_2 = 0.30;   %   0.30
num=[1,zeros(1,delay_1-1),attenuation_1,zeros(1,delay_2-delay_1-1),attenuation_2];
[H,W]=freqz(num,1,512);   %   compute frequency response
mag=20*log10(abs(H));   %   magnitude in dB
phase=angle(H)*180/pi;   %   phase angle in degrees
figure(9),clf
subplot(211),plot(W/(2*pi),mag)
title('多徑信道幅度響應')
xlabel('數字頻率'),ylabel('幅度 dB')
subplot(212),plot(W/(2*pi),phase)
title('多徑信道相位響應')
xlabel('數字頻率'),ylabel('相位度數')

break