noch.m,v

具有特色的地震数据处理源码

head	3.0;
access;
symbols;
locks; strict;
comment	@// @;


3.0
date	2000.06.13.19.20.57;	author gilles;	state Exp;
branches;
next	2.0;

2.0
date	99.05.21.18.46.08;	author mah;	state Exp;
branches;
next	1.2;

1.2
date	99.05.17.17.16.06;	author mah;	state Exp;
branches;
next	1.1;

1.1
date	99.01.06.19.09.06;	author kay;	state Exp;
branches;
next	;


desc
@@


3.0
log
@Release 3
@
text
@function [dataout]=noch(datain,F1,F2,F3,F4)

%[dataout]=noch(datain,F1,F2,F3,F4)
%
%noch filter
%
%Frequencies <=F1 and >=F4 are untouched
%Frequencies between F2 and F3 are zeroed
%Frequencies between F2 and F1 as well as between F3 and F4 are linearily
%reduced
%
% All frequencies are in Hertz (Hz)
%
%DSI customized VSP processing software
%
%written by Kristen Beaty January, 1998

%$Id: noch.m,v 2.0 1999/05/21 18:46:08 mah Exp gilles $
%$Log: noch.m,v $
%Revision 2.0  1999/05/21 18:46:08  mah
%Release 2
%
%Revision 1.2  1999/05/17 17:16:06  mah
%fixed help message
%
%Revision 1.1  1999/01/06 19:09:06  kay
%Initial revision
%
%
%Copyright (C) 1998 Seismology and Electromagnetic Section/
%Continental Geosciences Division/Geological Survey of Canada
%
%This library is free software; you can redistribute it and/or
%modify it under the terms of the GNU Library General Public
%License as published by the Free Software Foundation; either
%version 2 of the License, or (at your option) any later version.
%
%This library is distributed in the hope that it will be useful,
%but WITHOUT ANY WARRANTY; without even the implied warranty of
%MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
%Library General Public License for more details.
%
%You should have received a copy of the GNU Library General Public
%License along with this library; if not, write to the
%Free Software Foundation, Inc., 59 Temple Place - Suite 330,
%Boston, MA  02111-1307, USA.
%
%DSI Consortium
%Continental Geosciences Division
%Geological Survey of Canada
%615 Booth St.
%Ottawa, Ontario
%K1A 0E9
%
%email: dsi@@cg.nrcan.gc.ca

disp('[dataout]=noch(datain,F1,F2,F3,F4)');

dataout=datain;
nrec=datain.fh{12};
int=datain.fh{8}; %sampling interval
Ny=1./(int.*2); %Nyquist frequency
npts=datain.fh{7}; %number of points in each trace
N=2^(nextpow2(npts)+1); %number of points to be used in fft

f=2*Ny*(0:N/2-1)/N; %frequency vector

%create filter function in frequency domain
x=[1 1 0 0 1 1];
xf=[0 F1 F2 F3 F4 f(N/2)];
m=interp1(xf,x,f);

filt=zeros(N,1);
filt(1:N/2)=m;
m2=fliplr(m);
filt(N/2+1)=1;
filt(N/2+2:N)=m2(1:length(m2)-1);
%'filt' is filter function in frequency domain

for COUNT=1:nrec %loop over records
 ntr=datain.th{COUNT}(12,1); %number of traces in this record
 filtmat=ndgrid(filt,1:ntr);%create filter matrix
 in_freq=fft(datain.dat{COUNT},N); %performs N points fft on columns
 out_freq=zeros(N,ntr); %initialize
 out_freq=in_freq.*filtmat; %multiply in freq. domain
 out=ifft(out_freq,N); %N points inverse fft
 dataout.dat{COUNT}=real(out(1:npts,:));

 %error check
 re=real(out(1:npts,1));
 im=imag(out(1:npts,1));
 for i=npts:-1:1
  rat(i)=im(i)./re(i);
 end;
 x=find(rat>10^-6);
 if ~ isempty(x)
  error('imaginary part of inverse fft is too large');
 end %if
end %loop over records
@


2.0
log
@Release 2
@
text
@d18 1
a18 1
%$Id: noch.m,v 1.2 1999/05/17 17:16:06 mah Exp mah $
d20 3
@


1.2
log
@fixed help message
@
text
@d18 1
a18 1
%$Id: noch.m,v 1.1 1999/01/06 19:09:06 kay Exp mah $
d20 3
@


1.1
log
@Initial revision
@
text
@d12 2
d18 5
a22 2
%$Id: $
%$Log:$
@