raise_cosine_filter.m

用MATLAB编写的升余弦滤波

% Parameters. 
Delay = 3; 
DataL = 20;
R = .5; 
Fs = 8; 
Fd = 1; 
PropD = 0; 
% Generate random data. 
x = randsrc(DataL, 1, [],1245); %建立20行1列的由1，-1随机组成的矩阵
% at time 0, 1/Fd, 2/Fd, ... 
tx = [PropD: PropD + DataL - 1] / Fd; %从0到0+20-1（就是19）的1行20列的矩阵
% Plot data. 
figure(1),stem(tx, x, 'kx'); %画图
% Set axes and labels. 
axis([0 30 -1.6 1.6]); %axis([xmin xmax ymin ymax])
xlabel('Time'); 
ylabel('Amplitude'); 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Design filter.
[yf, tf] = rcosine(Fd, Fs, 'fir', R, Delay);
% Upsample and filter. 
[yo, to] = rcosflt(x, Fd, Fs, 'filter', yf); %用升余弦滤波器进行滤波
% Plot data. 
figure(2),stem(tx, x, 'kx'); hold on; 
% Plot filtered data. 
plot(to, yo, 'b-'); hold off; 
% Set axes and labels. 
axis([0 30 -1.6 1.6]);  xlabel('Time');  ylabel('Amplitude'); 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Correct for propagation delay 
PropD = Delay * Fd; 
% at time 0, 1/Fd, 2/Fd, ... 
tx = [PropD: PropD + DataL - 1]/ Fd; 
% Plot data. 
figure(3),stem(tx, x, 'kx'); hold on; 
% Plot filtered data. 
plot(to, yo, 'b-'); hold off; 
% Set axes and labels. 
axis([0 30 -1.6 1.6]); xlabel('Time'); ylabel('Amplitude'); %主要在说延时的问题
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Design filter. 
[yg, tg] = rcosine(Fd, Fs, 'fir', .2, Delay); 
% Filter data. 
[yo1, to1] = rcosflt(x, Fd, Fs, 'normal/fir/filter',yg); 
% Plot data. 
figure(4),stem(tx, x, 'kx'); hold on; 
% Plot filtered data. 
plot(to, yo, 'b-',to1, yo1, 'r-'); hold off; 
% Set axes and labels. 
axis([0 30 -1.6 1.6]); xlabel('Time'); ylabel('Amplitude'); %修改滚降系数所产生的不同效果的比较。
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Design square root filter. 
[ys, ts] = rcosine(Fd, Fs, 'fir/sqrt', R, Delay); 
% Filter at the transmitter. 
[yc, tc] = rcosflt(x, Fd, Fs, 'filter', ys); 
% Plot data
figure(5),stem(tx, x, 'kx'); hold on; 
% Plot filtered data. 
plot(tc, yc, 'm-'); hold off; 
% Set axes and labels. 
axis([0 30 -1.6 1.6]); xlabel('Time'); ylabel('Amplitude'); %方根升余弦滤波的结果
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Filter at the receiver. 
[yr, tr] = rcosflt(yc, Fd, Fs, 'filter/Fs', ys); 
% Adjust for propagation delay. 
tcc = tc + Delay .* Fd; txx = tx + Delay .* Fd; 
% Plot data. 
figure(6),stem(txx, x, 'kx'); hold on; 
% Plot filtered data. 
plot(tcc, yc, 'm-',tr, yr, 'b-'); hold off; 
% Set axes and labels. 
axis([0 30 -1.6 1.6]); xlabel('Time'); ylabel('Amplitude');%接受端滤波
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Design and filter. 
[yo2, to2] = rcosflt(x, Fd, Fs, 'normal/fir', R, Delay); 
% Plot data. 
figure(7),stem(tx, x, 'kx'); hold on; 
% Plot filtered data. 
plot(to2, yo2, 'b-'); hold off; 
% Set axes and labels. 
axis([0 30 -1.6 1.6]); xlabel('Time'); ylabel('Amplitude'); %快速滤波