c8_6.m

经典书籍《通信系统仿真原理与无线应用》chap8部分课后题仿真源代码

clear
x = randn(1,5000);
order = 3;
fn = 1;
bw = 0.2*fn;
[b,a] = butter(order,bw);
xf = filter(b,a,x);

kk = 0; % set exit counter
while kk == 0 % test exit counter
k = menu('后处理',...
'直方图',...
'PSD',...
'自相关',...
'退出');
if k == 1
   % B = input('直方个数 > ');
hist(xf,20)
ylabel('Ni'); xlabel('(a)')
pause

elseif k ==2
settle = 100;                  % ignore transient
fs = 1000;                    % sampling frequency
N=5000;
f = (0:(N-1))*fs/N;           % frequency scale
%[b,a] = butter(3,0.2);        % filter
NN = N+settle;                % allow transient to die
%out = filter(b,a,xf);             % filter output
%out = out((settle+1):NN);       % strip off initial samples
window = hanning(N)';         % set window function
%winout = out.*window;         % windowed filter output
winout = xf.*window;  
fout = abs(fft(winout,N)).^2;     % transform and square mag
U = sum(window.*window);      % window energy
flout = fout/U;               % scale spectrum
psdl = 10*log10(abs(flout));  % log scale
plot(f(1:500),psdl(1:500))
grid; axis([0 100 -70 10]);
xlabel('Frequency, Hz')
ylabel('PSD')
pause

elseif k == 3
s1=corrcoef(xf)
pause

elseif k == 4
kk = 1; % set exit counter to exit value
end
end