updated pwin.m

sigproc/pwin.m

@@ -1,50 +1,76 @@
-function [g, info] = pwin(name,tshift,fshift,varargin)
+function [g, info] = pwin(name,varargin)
 %PWIN periodically sampled window
 %
 %   Input parameters:
-%     name : window name
+%     name   : window name
 %     tshift : time shift
 %     fshift : frequency shift
 %
 %   Output parameters:
-%     g : window
+%     g    : window
+%     info : struct with additional parameters
 %
+%   `pwin` generates a periodically sampled cosine-type windows that can be
+%   fractionally modulated and shifted. Per default, the window is designed 
+%   such that one period of the underlying cosine fits into its nominal
+%   length `L`. `fshift` decreases that period additively. The `tshift`
+%   indicates the factor times pi by which the underlying cosine is shifted.
+%   Currently supported windows: 'hanning', 'hamming'
+%
+%   Optional parameters:
+%     'tshift',tshift   shift in time ([0,1]...half a period)
+%     'fshift',fshift   shift in frequency (max depends on L)
+%     'fs',fs           sampling frequency, controls shift resolution
+%
+%   See also:  freqwin, pgauss, firwin, firkaiser
 
 
 definput.import={'setnorm'};
-definput.keyvals.fs = 10000;
-definput.keyvals.fc = 10;
+definput.importdefaults={'null'};
+definput.flags.centering={'wp','hp','shift'};
+definput.keyvals.fs = 1000;
+definput.keyvals.fc = 1;
 definput.keyvals.phi = 0;
 definput.keyvals.L = 1;
+definput.keyvals.tshift = 0;
+definput.keyvals.fshift = 0;
 
 
 [flags,kv]=ltfatarghelper({},definput,varargin);
 
-kv.phi = 2*pi*kv.fc*tshift;
-kv.fc = kv.fc + fshift;
-
-%make the cosine...
-dt = 1/kv.fs;
-t = (0:dt:kv.L-dt)';
-x = cos(2*pi*kv.fc*t + kv.phi) + 1; % '+1' is just the offset, quasi-arbitrary
-
-%...make the rectangular window...
-T = 1/kv.fc;
-rect = zeros(size(x));
-rect(1:floor(T*kv.fs)) = ones(floor(T*kv.fs),1) * 0.5;%this '0.5' is the counterpart to the offset above
-rect = circshift(rect, floor(kv.phi/(2*pi*kv.fc)*kv.fs));
 
-%...and the periodically sampled signal
-persamp = x.*rect;
+if ischar(name)
+    kv.phi = -2*pi*kv.fc*kv.tshift;
+    kv.fc = kv.fc + kv.fshift;
 
-switch name  
- %the windows are then more or less their superpositions
- case {'hanning'}
-     g=(0.5+0.5*persamp);
- otherwise
-  error('Unknown window: %s.',name);
-end;
+    %make the cosine...
+    dt = 1/kv.fs; %the cosine should always have length T*kv.fs
+    t = (0:dt:kv.L-dt)';
+    x = cos(2*pi*kv.fc*t + kv.phi) + 1; % '+1' is just the offset, quasi-arbitrary
 
-g=setnorm(g,flags.norm);
+    %...make the rectangular window...
+    T = 1/kv.fc;
+    rect = zeros(size(x));
+    rect(1:floor(T*kv.fs)) = ones(floor(T*kv.fs),1) * 0.5;%this '0.5' is the counterpart to the offset above
+    rect = circshift(rect, round(kv.tshift*T*kv.fs));
+    %...and the periodically sampled signal
+    persamp = x.*rect;
+    persamp = middlepad(persamp(persamp~=0), numel(persamp));
+    persamp = circshift(persamp, round(kv.tshift*T*kv.fs));
 
+    switch name  
+     %the windows are then more or less their superpositions
+     case {'hanning'}
+         g=(0.5+0.5*persamp);
+     case 'hamming'
+         g=0.54+0.46*persamp;
+     otherwise
+      error('Unknown window: %s.',name);
+    end
+else
+    g = [];
+    disp('not yet implemented.');
+end
+    g = setnorm(g, flags.norm);
+
 info = [];