todb.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 Sdb= todb(S,refamp)
% TODB: converts from (real,imaginary) to (decibels, phase)
%
% Sdb = todb(S,refamp);
% Sdb = todb(S);
%
% converts a complex spectrum from (real,imaginary) to 
% (decibels,phase angle). Thus if S is a complex spectrum,
% then plot(real(todb(S))) will plot the decibel amplitude
% and plot(imag(todb(S))) will plot the phase spectrum (radians)
%
% S= input complex spectrum
% refamp = input reference amplitude
%           decibels are dbdown from this value. If defaulted,
%           refamp=max(abs(S))
% Sdb= output complex spectrum in the special format:
%       (dbdown, phase angle)
% 
% the INVERSE of this process is the function FROMDB found in
% the seismic toolbox
%
% by G.F. Margrave, May 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
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%
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% END TERMS OF USE LICENSE

 amp=abs(S); 
 phs=angle(S); 
if(nargin==1)
   refamp=max(max(amp));
end

amp=20*log10(amp/refamp);
Sdb=amp + i*phs;