%% WINDOWSINE_DEMO5
%%
%% This Matlab m-file prompts the user to define a signal consisting
%%  of a sum of sinewaves.  The user is then prompted for window 
%%  parameters and DFT length parameters for the analysis.  
%%  The windowed signal and its corresponding DFT are plotted.
%%
%%  Difference between windowsine_demo4.m and windowsine_demo5.m
%%   is that #4 takes DT frequencies in rad/sec and assumes fs=1.
%%
%%   #5 takes CT frequencies in Hz, and allows user to set sample
%%    frequency.

%-------------------------------------------------------------------
%%% Get the signal parameters and compute the signal
disp(' ')
disp('Signal parameters')
disp('-----------------')
f=input('Enter frequencies of sinewaves (Hz):  ');
amp=input('Enter amplitudes of sinewaves [DEFAULT=1]:  ');
if isempty(amp)
  amp=ones(size(f));
end
phi=input('Enter phases of sinewaves [DEFAULT=0]:  ');
Tinterv=input('Enter length of time interval:  ');
fs=input('Enter sampling frequency (Hz):  ');

%%% Get the signal x(t) which is a sum of sinewaves
[x,t]=sum_sine(f,Tinterv,fs,phi,amp);

%%% Display the number of samples in signal
disp(' ')
str=sprintf('     X(t):  contains %i samples',length(x));
disp(str);

%-------------------------------------------------------------------
%%% Get the window parameters and window the signal

disp(' ')
disp('Window parameters')
disp('-----------------')
win_length=input('Enter window length (number of samples):  ');
win_type=input('Enter window type [DEFAULT=''boxcar'']:  ');
if isempty(win_type)
  win_type='boxcar';
end

%%% Window that signal
ind=1:win_length;
window=feval(win_type,win_length)';
v=x(ind).*window;
t=t(ind);

%%% Display the length of the window in seconds
win_secs=(win_length-1)/fs;
disp(' ')
str=sprintf('     WINDOW:  %s window is %0.2f seconds long',win_type,win_secs);
disp(str);

%-------------------------------------------------------------------
%%% Get the DFT parameters and compute the sampled spectrum

disp(' ')
disp('DFT parameters')
disp('--------------')
dft_length=input('Enter DFT length [DEFAULT=8192]:  ');
if isempty(dft_length)
  dft_length=8192;
end

%%% Find the DFT
[Vk,fk]=fr_resp(v,dft_length,fs);

disp(' ')
str=sprintf('     DFT size:  %i points',dft_length);
disp(str);
%-------------------------------------------------------------------
%%% Plots

subplot(311)
plot(t,v)
axis([min(t) max(t) min(v) max(v)])
xlabel('Time (seconds)')
ylabel('v(t)');
title('Windowed sinusoid')
fixfont(14,14,14)

subplot(212)
maxdbVk=max(10*log10(abs(Vk)));
plot(fk,10*log10(abs(Vk)))
xlabel('Frequency (Hz)')
ylabel('10*log10|V[k]|');
title('Results of DFT analysis')
fixfont(14,14,14)
axis([min(fk) max(fk) maxdbVk-60 maxdbVk])