wavevib.m

基于matlab的反演程序,用于地球物理勘探中射线追踪及偏移成像程序.

function [w,tw]=wavevib(fmin,fmax,dt,slength,wlength)
% WAVEVIB: creates a vibroseis (Klauder) wavelet
%
% [w,tw]=wavevib(fmin,fmax,dt,slength,wlength)
%
% WAVEVIB generates a vibroseis waveform (Clauder wavelet) by
% first calling SWEEP to generate a linear sweep and then calling
% AUTO to autocorrelate that sweep. Theoretically, the autocorrelation
% length is ~ 2*slength but only only the central 'wlength' long
% part is generated. This is like windowing the auto with a boxcar.
%
%
% fmin= minimum swept frequency in Hz
% fmax= maximum swept frequency in Hz
% dt= time sample rate in seconds
% slength= sweep length in seconds
% wlength= desired wavelet length
%
% w= output wavelet
% tw= time coordinate vector for w
% 
% by G.F. Margrave, June 1991
%
% NOTE: It is illegal for you to use this software for a purpose other
% than non-profit education or research UNLESS you are employed by a CREWES
% Project sponsor. By using this software, you are agreeing to the terms
% detailed in this software's Matlab source file.
 
% BEGIN TERMS OF USE LICENSE
%
% This SOFTWARE is maintained by the CREWES Project at the Department
% of Geology and Geophysics of the University of Calgary, Calgary,
% Alberta, Canada.  The copyright and ownership is jointly held by 
% its author (identified above) and the CREWES Project.  The CREWES 
% project may be contacted via email at:  [e-mail]
% 
% The term 'SOFTWARE' refers to the Matlab source code, translations to
% any other computer language, or object code
%
% Terms of use of this SOFTWARE
%
% 1) Use of this SOFTWARE by any for-profit commercial organization is
%    expressly forbidden unless said organization is a CREWES Project
%    Sponsor.
%
% 2) A CREWES Project sponsor may use this SOFTWARE under the terms of the 
%    CREWES Project Sponsorship agreement.
%
% 3) A student or employee of a non-profit educational institution may 
%    use this SOFTWARE subject to the following terms and conditions:
%    - this SOFTWARE is for teaching or research purposes only.
%    - this SOFTWARE may be distributed to other students or researchers 
%      provided that these license terms are included.
%    - reselling the SOFTWARE, or including it or any portion of it, in any
%      software that will be resold is expressly forbidden.
%    - transfering the SOFTWARE in any form to a commercial firm or any 
%      other for-profit organization is expressly forbidden.
%
% END TERMS OF USE LICENSE

 wlength=.5*wlength;
 [s,t]=sweep(fmin,fmax,dt,slength);
 halfw=auto(s,fix(wlength/dt)+1);
 w=[halfw(length(halfw):-1:2) halfw];
 tw=xcoord(-(length(halfw)-1)*dt,dt,w)';

 % normalize
 % generate a refenence sinusoid at the dominant frequency
 refwave=sin(2*pi*(fmin+fmax)*.5*t);
 reftest=convm(refwave,w);
 fact=max(refwave)/max(reftest);
 w=(w*fact)';