%-------------------------------------------------------- % This code can be used to generate Figure Figure 1.2 %-------------------------------------------------------- % This file requires the following files to be present in the same % directory: % %prince.wav clear all close all % Read the sound signal "prince.wav" [y,Fs] = audioread('prince.wav'); sound(y,Fs); %play the sound N=length(y); t=0:.8/(N-1):.8; %form time vector % FREQUENCY DOMAIN SIGNAL Y=fft(y)/N; % Calculate the spectrum of the signal df=1/(max(t)-min(t)); % Find the resolution in frequency f=0:df:df*(length(t)-1); % Form the frequency vector plot(f(1:2:N)*1e-3,abs(Y(1:(N+1)/2)),'k') %downsample for plotting axis([-1 20 0 .035]) grid minor set(gca,'FontName', 'Arial', 'FontSize',12, 'FontWeight','Bold'); xlabel('frequency, KHz'); ylabel('amplitude'); title('\itfrequency domain signal');
Matlab code 1.3 Matlab file “Figure1‐3.m”_________________________________
%-------------------------------------------------------- % This code can be used to generate Figure 1.3 %-------------------------------------------------------- % This file requires the following files to be present in the same % directory: % % prince.wav % matplot.m clear all close all % Read the sound signal "prince.wav" [y,Fs] = audioread('prince.wav'); sound(y,Fs); N = length(y); t = 0:.8/(N-1):.8; %form time vector df = 1/max(t); f = 0:df:df*(length(t)-1); % TIME FREQUENCY PLANE SIGNAL A=spectrogram(y,256,250,400,1e4); % Calculate the spectrogram matplot(t,f*1e-3, (abs(A)),30); % Display the signal in T-F domain colormap(1-gray); % Change the colormap to grayscale grid minor set(gca,'FontName', 'Arial', 'FontSize',12, 'FontWeight','Bold'); xlabel('time, s'); ylabel('Frequency, KHz'); title('\itsignal in time-frequency plane');
Matlab code 1.4 Matlab file “Figure1‐5.m”_________________________________
%-------------------------------------------------------- % This code can be used to generate Figure 1.5 %-------------------------------------------------------- % This file requires the following files to be present in the same % directory: % % tot30.mat % stft.m clear close all load tot30; % load the measured scattered field % DEFINITION OF PARAMETERS f = linspace(6,18,251)*1e9; %Form frequency vector BW = 6e9; % Select the frequency window size d = 2e-9; %Select the time delay % DISPLAY THE FIELD IN JFT PLANE [B,T,F] = stft(tot30,f,BW,50,d); xlabel('--->Time (nsec)'); ylabel('--> Freq. (GHz)'); cc = colorbar; tt = title(cc,'dBsm'); tt.Position = [ 8 -15 0 ]; colormap(1-gray) set(gca,'FontName', 'Arial', 'FontSize',12,'FontWeight','Bold'); axis tight; xlabel('time, ns'); ylabel('Frequency, GHz');
Matlab code 1.5 Matlab file “Figure1‐8.m”_________________________________
%-------------------------------------------------------- % This code can be used to generate Figure 1_8 %-------------------------------------------------------- clear all close all %% DEFINE PARAMETERS t = linspace(-50,50,1001); % Form time vector df = 1/(t(2)-t(1)); % Find frequency resolution f = df*linspace(-50,50,1001); % Form frequency vector %% FORM AND PLOT RECTANGULAR WINDOW b(350:650) = ones(1,301); b(1001) = 0; subplot(221); h=area(t,b); grid(gca,'minor') set(gca,'FontName', 'Arial', 'FontSize',12, 'FontWeight','Bold'); xlabel('time, s'); axis([-50 50 0 1.1]) set(h,'FaceColor',[.5 .5 .5]) subplot(222); h=area(f,fftshift(abs(ifft(b)))); grid(gca,'minor') set(gca,'FontName', 'Arial', 'FontSize',12, 'FontWeight','Bold'); xlabel('frequency, Hz') axis([-40 40 0 .35]) set(h,'FaceColor',[.5 .5 .5]) %% FORM AND PLOT HANNING WINDOW bb = b; bb(350:650) = hanning(301)'; subplot(223); h = area(t,bb); grid(gca,'minor') set(gca,'FontName', 'Arial', 'FontSize',12, 'FontWeight','Bold'); xlabel('time, s'); axis([-50 50 0 1.1]) set(h,'FaceColor',[.5 .5 .5]) subplot(224); h = area(f,2*fftshift(abs(ifft(bb)))); grid(gca,'minor') set(gca,'FontName', 'Arial', 'FontSize',12, 'FontWeight','Bold'); xlabel('frequency, Hz') axis([-40 40 0 .35]) set(h,'FaceColor',[.5 .5 .5])
Matlab code 1.6 Matlab file “Figure1‐11.m”________________________________
%-------------------------------------------------------- % This code can be used to generate Figure %-------------------------------------------------------- clear close all % TIME DOMAIN SIGNAL a = 0:.1:1; t = (0:10)*1e-3; stem(t*1e3,a,'k','Linewidth',2);% Figure 1-11 (a) set(gca,'FontName', 'Arial', 'FontSize',12, 'FontWeight','Bold'); xlabel('time, ms'); ylabel('s[n]'); axis([-0.2 10.2 0 1.2]); % FREQUENCY DOMAIN SIGNAL b = fft(a); df = 1./(t(11)-t(1)); f = (0:10)*df; ff = (-5:5)*df; figure; stem(f,abs(b),'k','Linewidth',2); % Figure 1-11 (b) set(gca,'FontName', 'Arial', 'FontSize',12, 'FontWeight','Bold'); xlabel('frequency, Hz') ylabel('S[k]'); axis([-20 1020 0 6.5]); figure; stem(ff,fftshift(abs(b)),'k','Linewidth',2);% Figure 1-11 (c) set(gca,'FontName', 'Arial', 'FontSize',12, 'FontWeight','Bold'); xlabel('frequency, Hz') ylabel('S[k]'); axis([-520 520 0 6.5]);
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