diff aim-mat/tools/filterbandamp.m @ 0:74dedb26614d

Initial checkin of AIM-MAT version 1.5 (6.4.2011).

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+++ b/aim-mat/tools/filterbandamp.m	Fri May 20 12:32:31 2011 +0100
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+% tool
+% 
+%   INPUT VALUES:
+%  
+%   RETURN VALUE:
+%
+% 
+% (c) 2003-2008, University of Cambridge, Medical Research Council 
+% Maintained by Tom Walters ([e-mail]), written by Stefan Bleeck ([e-mail])
+% http://www.pdn.cam.ac.uk/cnbh/aim2006
+% $Date: 2008-06-10 18:00:16 +0100 (Tue, 10 Jun 2008) $
+% $Revision: 585 $
+
+function ampscale=filterbandamp(fre,amp,fc,df1,bw,df2)
+% usage: ampscale=filterbandamp(fre,amp,fc,df1,bw,df2)
+% given a frequency and its associated amplitude, and the defining properties of
+% a bandpass filter (cf. Krumbholz et al (2000), JASA 108, 1170-1180, Fig.3)
+% this function returns the amplitude of the frequency component after it has
+% passed through the filter. The reurned amplitude should be used to SCALE the
+% amplitude of the given frequency component.
+% fre       frequency in Hz
+% amp       amplitude 
+% fc        lower cutoff frequency
+% df1       lower spectral ramp width
+% bw        bandwidth (of plateau)
+% df2       upper spectral ramp
+%
+% David Smith (16/05/02)
+
+if (fre<(fc-df1)) | (fre>(fc+bw+df2))
+    ampscale=0; %ignore everything outside passband
+elseif fre<=fc  %lower spectral ramp
+    ampscale=max(cos((fc-fre)*pi/(2*df1)),0);   %quarter-cycle of cosine function
+elseif fre<=fc+bw    %flat part of filter
+    ampscale=1; 
+else        %upper spectral ramp
+    ampscale=max(cos((fre-(fc+bw))*pi/(2*df2)),0);
+end
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