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view m-toolbox/classes/+utils/@math/blwhitenoise.m @ 36:5eb86f6881ef database-connection-manager
Remove commented-out code
author | Daniele Nicolodi <nicolodi@science.unitn.it> |
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date | Mon, 05 Dec 2011 16:20:06 +0100 |
parents | f0afece42f48 |
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% BLWHITENOISE return a band limited gaussian distributed white noise % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % DESCRIPTION: BLWHITENOISE return a band limited Gaussian distributed % white noise % % CALL: wn = blwhitenoise() % % INPUTS: npts - number of data points in the series. Note, number of % seconds is npts*fs % fs - sampling frequency % fl - lower bandwidth frequency % fh - higher bandwidth frequency % % OUTPUTS: wn - band limited gaussian white noise % % REFERENCES: % % [1] Kafadar, K., Gaussian white-noise generation for digital signal % synthesis. IEEE Transactions on Instrumentation and Measurement IM-35(4), % 492-495, 1986. % % VERSION: $Id: rand.m,v 1.2 2008/10/24 06:19:23 hewitson Exp $ % % HISTORY: 04-01-2010 Luigi Ferraioli % Creation % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% function Xt = blwhitenoise(npts,fs,fl,fh) % generate linear spaced frequency vactor for fft f = (0:floor(npts/2)).*fs./npts; f = f'; nf = length(f); % amplitude vector amp = zeros(nf,1); % phase vactor phs = zeros(nf,1); % select frequency range if fh>fs/2 fh = fs/2; end if fl<0 fl = 0; end idxl = f>=fl; idxh = f<=fh; idx = idxl&idxh; n1s = sum(idx); phs(idx,1) = -pi + (2*pi).*rand(n1s,1); phs(1,1) = 0; phs(end,1) = 0; amp(idx,1) = sqrt(npts); amp(1,1) = 0; amp(end,1) = 0; % get final random phase and constant amplitude phs = [phs;-1.*flipud(phs(2:end-1))]; amp = [amp;flipud(amp(2:end-1))]; % fft signal Xf = amp.*(cos(phs)+1i.*sin(phs)); % time domain signal Xt = ifft(Xf); end % END