www.gusucode.com > SIMULINK Sigma-Delta Toolbox 工具箱matlab源码程序 > SIMULINK Sigma-Delta Toolbox/Sigma-Delta_Toolbox/calculateSNR.m
%Copyright (c) 2009, Richard Schreier %All rights reserved. % %Redistribution and use in source and binary forms, with or without %modification, are permitted provided that the following conditions are %met: % % * Redistributions of source code must retain the above copyright % notice, this list of conditions and the following disclaimer. % * Redistributions in binary form must reproduce the above copyright % notice, this list of conditions and the following disclaimer in % the documentation and/or other materials provided with the distribution % % THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" % AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE % IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE % ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE % LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR % CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF % SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS % INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN % CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) % ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE % POSSIBILITY OF SUCH DAMAGE % function snr = calculateSNR(hwfft,f,nsig) % snr = calculateSNR(hwfft,f,nsig=1) Estimate the signal-to-noise ratio, % given the in-band bins of a (Hann-windowed) fft and % the location of the input signal (f>0). % For nsig=1, the input tone is contained in hwfft(f:f+2); % this range is appropriate for a Hann-windowed fft. % Each increment in nsig adds a bin to either side. % The SNR is expressed in dB. if nargin<3 nsig = 1; end signalBins = [f-nsig+1:f+nsig+1]; signalBins = signalBins(signalBins>0); signalBins = signalBins(signalBins<=length(hwfft)); s = norm(hwfft(signalBins)); % *4/(N*sqrt(3)) for true rms value; noiseBins = 1:length(hwfft); noiseBins(signalBins) = []; n = norm(hwfft(noiseBins)); if n==0 snr = Inf; else snr = dbv(s/n); end