Same as part 02, simulate a sound source moving on a straight line, allowing the user to specify a minimum distance that the observer is from the sound trajectory, but make the sound source a 3-tone signal.
function [signal] = project_01_part03(f0, fs, secs, velocity, dist_from_track) %comment out f0, fs, secs, velocity, and dist_from_track to specify values %from command line c = 340; %speed of sound velocity = 10; %velocity of sound source f1 = 466.16; %basis of 3-tone signal f2 = 523.25; %basis of 3-tone signal f3 = 783.99; %basis of 3-tone signal fs = 8000; %sampling frequency secs = 10; %duration of sound dist_from_track = 5; %shortest distance from observer to track time = -secs/2:1/fs:secs/2; x = velocity*time; %x-position of sound source on track hypo = zeros(1,length(time)); %change in hypotenuse equals relative distance from sound source to observer for i = 1:length(hypo) hypo(i) = sqrt((x(i))^2 + dist_from_track^2); end env = 1./hypo; %velocity relative to observer is orig velocity vector * adj/hypo (cosine) vel_rel_observer = velocity*x./hypo; f1v = zeros(1,length(time)); f2v = zeros(1,length(time)); f3v = zeros(1,length(time)); for i = 1:length(time) f1v(i) = f1*(c/(c+vel_rel_observer(i))); f2v(i) = f2*(c/(c+vel_rel_observer(i))); f3v(i) = f3*(c/(c+vel_rel_observer(i))); end signal_1f = env.*sin(2*pi*f1v.*time); signal_2f = env.*sin(2*pi*f2v.*time); signal_3f = env.*sin(2*pi*f3v.*time); signal = signal_1f+signal_2f+signal_3f; subplot(321), plot(time,vel_rel_observer,'Color',[1,0.12,0.12]), axis([min(time),max(time),-1.5*velocity,1.5*velocity]), grid on; title('Velocity of sound source'), xlabel('time (s)'), ylabel('velocity (m/s)'); subplot(323), plot(time,env,'g'), grid on; title('Amplitude envelope'), xlabel('time (s)'), ylabel('amplitude'); subplot(325), plot(time,signal,'b'), grid on; title('Doppler effect on signal'), xlabel('time (s)'), ylabel('amplitude'); subplot(322), plot(time,f1v,'Color',[0.98,0.68,0]), grid on; title('Frequency shift (f1)'), xlabel('time (s)'), ylabel('frequency (Hz)'); subplot(324), plot(time,f2v,'Color',[0.10,0.48,0.01]), grid on; title('Frequency shift (f2)'), xlabel('time (s)'), ylabel('frequency (Hz)'); subplot(326), plot(time,f3v,'Color',[0.53,0.81,0.98]), grid on; title('Frequency shift (f3)'), xlabel('time (s)'), ylabel('frequency (Hz)'); signal = signal/max(abs(signal)); %normalizes input %print project_01_part03 -dpng -r100; %wavwrite(signal,fs,'project_01_part03'); soundsc(signal,fs); |