www.gusucode.com > signal 案例源码程序 matlab代码 > signal/SingleAndDoublePrecisionFiltersExample.m
%% Frequency Along _x_-Axis % Generate a quadratic chirp, |x|, sampled at 1 kHz for 2 seconds. The % frequency of the chirp is 100 Hz initially and crosses 200 Hz at |t| = 1 % s. % Copyright 2015 The MathWorks, Inc. t = 0:0.001:2; x = chirp(t,100,1,200,'quadratic'); %% % Compute and display the spectrogram of |x|. % % * Divide the signal into sections of length 128, windowed with a Hamming % window. % * Specify 120 samples of overlap between adjoining sections. % * Evaluate the spectrum at $\lfloor128/2+1\rfloor=65$ frequencies and % $\lfloor({\tt length(x)}-120)/(128-120)\rfloor=235$ time bins. spectrogram(x,128,120,128,1e3) %% % Replace the Hamming window with a Blackman window. Decrease the overlap % to 60 samples. Plot the time axis so that its values increase from top to % bottom. spectrogram(x,blackman(128),60,128,1e3) ax = gca; ax.YDir = 'reverse';