资源简介
s变换的MATLAB程序,s变换广泛用于地震监测和参数估计,具有重要的研究价值
代码片段和文件信息
function [sttf] = st(timeseriesminfreqmaxfreqsamplingratefreqsamplingrate)
% Returns the Stockwell Transform of the timeseries.
% Code by Robert Glenn Stockwell.
% DO NOT DISTRIBUTE
% BETA TEST ONLY
% Reference is “Localization of the Complex Spectrum: The S Transform“
% from IEEE Transactions on Signal Processing vol. 44. number 4 April 1996 pages 998-1001.
%
%-------Inputs Needed------------------------------------------------
%
% *****All frequencies in (cycles/(time unit))!******
% “timeseries“ - vector of data to be transformed
%-------Optional Inputs ------------------------------------------------
%
%“minfreq“ is the minimum frequency in the ST result(Default=0)
%“maxfreq“ is the maximum frequency in the ST result (Default=Nyquist)
%“samplingrate“ is the time interval between samples (Default=1)
%“freqsamplingrate“ is the frequency-sampling interval you desire in the ST result (Default=1)
%Passing a negative number will give the default ex. [stf] = st(data-1-122)
%-------Outputs Returned------------------------------------------------
%
% st -a complex matrix containing the Stockwell transform.
% The rows of STOutput are the frequencies and the
% columns are the time values ie each column is
% the “local spectrum“ for that point in time
% t - a vector containing the sampled times
% f - a vector containing the sampled frequencies
%--------Additional details-----------------------
% % There are several parameters immediately below that
% the user may change. They are:
%[verbose] if true prints out informational messages throughout the function.
%[removeedge] if true removes a least squares fit parabola
% and puts a 5% hanning taper on the edges of the time series.
% This is usually a good idea.
%[analytic_signal] if the timeseries is real-valued
% this takes the analytic signal and STs it.
% This is almost always a good idea.
%[factor] the width factor of the localizing gaussian
% ie a sinusoid of period 10 seconds has a
% gaussian window of width factor*10 seconds.
% I usually use factor=1 but sometimes factor = 3
% to get better frequency resolution.
% Copyright (c) by Bob Stockwell
% $Revision: 1.2 $ $Date: 1997/07/08 $
% This is the S transform wrapper that holds default values for the function.
TRUE = 1;
FALSE = 0;
%%% DEFAULT PARAMETERS [change these for your particular application]
verbose = TRUE;
removeedge= FALSE;
analytic_signal = FALSE;
factor = 1;
%%% END of DEFAULT PARAMETERS
%%%START OF INPUT VARIABLE CHECK
% First: make sure it is a valid time_series
% If not return the help message
% if verbose disp(‘ ‘)end % i like a line left blank
if nargin == 0
if verbose disp(‘No parameters inputted.‘)end
st_help
t=0;s
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