gusucode.com > DSISoft是由加拿大地质调查局发布的用于垂直地震剖面(VSP)数据处理的免费软件包 > dsisoftv3/dsisoftv3/dsisoftv3/main/harmon_new.m
function [dataout] = harmon_new(datain,freq1,freq2,inter,t1,t2)
% function [dataout] = harmon_new(datain,freq1,freq2,inter,t1,t2)
%
% Harmon is a time domain notch filter. Discrete Fourier
% Transforms are calculated to estimate noise phase and amplitude.
% The estimated noise is subtracted from the trace in the time domain.
% It has been rewritten to analyze a window of data from t1 to t2
% and then to apply it to the whole trace
%
% Usage:
%
% Input:
% datain : Input data
% freq1 : Start scanning at this frequency (Hz)
% freq2 : Upper frequency limit (Hz)
% inter : Frequency step (Hz) such that ((freq2-freq1)/inter) is
% a multiple of 10
% t1 : Start time of window (seconds)
% t2 : End time of window (seconds)
%
% Output:
% dataout : Output data
%
% Example :
% This is what I use to remove 60 Hz noise
% filtered = harmon_new(data,59.88,60.12,0.01,0,0.5);
%
% Reference:
% http://www.cg.NRCan.gc.ca/staff/adam/software/monofreq.html
%
% Warning: Program does not check for reasonable parameters
%
%written by: Erick ADAM
%Dec. 1995
%Rewritten by Marko Mah February 1999
%$Id: harmon_new.m,v 3.0 2000/06/13 19:20:30 gilles Exp $
%$Log: harmon_new.m,v $
%Revision 3.0 2000/06/13 19:20:30 gilles
%Release 3
%
%Revision 2.0 1999/05/21 18:45:46 mah
%Release 2
%
%Revision 1.10 1999/02/10 20:47:00 mah
%fixing up bugs previous programmer(s) put in
%
%Revision 1.9 1999/02/10 20:11:36 perron
%*** empty log message ***
%
%Revision 1.8 1999/02/10 20:07:19 perron
%modifying if statement at line 119
%
%Revision 1.7 1999/02/10 20:04:11 perron
%Modifying if statement at line 119
%
%Revision 1.6 1999/02/10 19:52:34 perron
%Modifying help text
%
%Revision 1.5 1999/02/10 16:15:19 eadam
%Optimisation by iterative windowing fro finding the maximum
%
%Revision 1.4 1999/02/10 13:50:49 mah
%fixed bug
%
%Revision 1.3 1999/02/02 15:55:12 mah
%corrected amplitude of correction
%
%Revision 1.2 1999/02/02 15:07:07 mah
%fixed a bug
%
%Revision 1.1 1999/02/02 14:20:47 mah
%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] = harmon_new(datain,freq1,freq2,inter,t1,t2)')
deltat=datain.fh{8}; %sampling interval in seconds
freq = freq1:inter:freq2; %Vector of frequencies for DFT
freqlen = length(freq); %Number of frequencies for DFT
samples = datain.fh{7}; %number of points per trace;
% the following converts t1 and t2 to points
t1pt=round(t1/deltat)+1;
t2pt=round(t2/deltat)+1;
%Initialize local variables for speedup
cos_wt = ones(samples,freqlen); % Cosine lookup table
sin_wt = ones(samples,freqlen); % Sine lookup table
dataout = datain; % Output variable
samp = (0.0 : deltat : (samples-1)*deltat)'; % Time vector
% Optimization : I create a lookup table for Sine and cosine.
for i = 1 : freqlen,
w = 6.283185307 * freq(i); % Convert frequency to radian (w = 2*PI*f)
cos_wt(:,i)=cos(samp*w); % Calculate cos(w*t) and store in lookup table
sin_wt(:,i)=sin(samp*w); % Calculate sin(w*t) and store in lookup table
end
%step = 10;
% Calculate amplitudes from DFT at each frequencies of vector freq
for COUNT=1:datain.fh{12} % Loop over over number of records
for tr=1:datain.th{COUNT}(12,1) % loop over traces
step = floor(freqlen/10); % Speedup to calculate DFT for every 10th frequencies
large= 0.0; % Maximum amplitude (reset to 0 before each scan)
trace = datain.dat{COUNT}(t1pt:t2pt,tr);
start_freq = 1; % start at the first frequency
end_freq = freqlen; % End at the last frequency
if step >= 1 % loop until every frequency is read
for j = start_freq:step:end_freq, % Loop over frequency range
suma = sum(trace.*cos_wt(t1pt:t2pt,j))* 2.0 /samples;
sumb = sum(trace.*sin_wt(t1pt:t2pt,j))* 2.0 /samples;
amp_max = (suma*suma)+(sumb*sumb); %Amplitude for freq(j)
if amp_max > large %if Amplitude freq(j) is larger than previous ones
freqi=j; %record the index of the maximum amplitude
large = amp_max; % reset large
a_max=suma; %record factor A of the DFT
b_max=sumb; %record factor B of the DFT
end % End if statement
end % loop over frequency
start_freq = (freqi-2)*step; % New frequency range as a function of the maximum amplitude
end_freq = (freqi-2)*step;
step = floor(step/10); % reduce the step by a factor of 10
end % End if statement
% the following corrects a_max and b_max because a smaller window was used to calculate them
a_max=a_max*samples/(t2pt-t1pt+1);
b_max=b_max*samples/(t2pt-t1pt+1);
% The filter is applied here
dataout.dat{COUNT}(:,tr) = datain.dat{COUNT}(:,tr)-((a_max*cos_wt(:,freqi))+(b_max * sin_wt(:,freqi)));
end % loop over traces
end % loop over records