
From:  Rick T 
Subject:  How can I increase/decrease (frequency/pitch) and phase using fft/ifft tia sal22 
Date:  Mon, 4 Apr 2011 11:11:04 1000 
Example I have a signal that repeats 1 time every second and I want to
have it repeat 3 times a second instead.
%Voiceprint raise lower freq phase conjugate signal
tic
clear all, clc,clf,tic
%% Sound /beep calculation complete
filerawbeepStr='calculations_complete.wav';
filerawbeeppathStr='/home/rat/Documents/octave/raw/';
filevoiceprepathStr='/home/rat/Documents/octave/eq_research/main/
transform/voice/';
filewavpathStr='/home/rat/Documents/octave/eq_research/main/transform/
wav/';
[ybeep, Fsbeep, nbitsbeep] =
wavread(strcat(filerawbeeppathStr,filerawbeepStr));
%addpath(”/home/rat/Documents/octave/eq_research/main/transform/”);
%add path to location of functions
%1a voice print import
[vp_sig_orig, fs_rate, nbitsraw] =
wavread(strcat(filevoiceprepathStr,'voice8000fs.wav'));
%vp_sig_orig=vp_sig_orig’;
vp_sig_len=length(vp_sig_orig);
%2a create frequency domain
ya_fft = fft(vp_sig_orig);
vp_sig_phase_orig = unwrap(angle(ya_fft));
%get Magnitude
ya_fft_mag = abs(ya_fft);
%3a frequency back to time domain
ya_ifft=real(ifft(ya_fft));
%adjust frequency/phase here? How?
vp_sig_new=real(ifft(ya_fft_mag.*exp(i*vp_sig_phase_orig)));
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