an error in modulation

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ahmad ramadan 2019-2-25

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链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/446908-an-error-in-modulation

i want to translate(modulate) the recorded signal by 5kHz , but i get an error shown below last line

%we define the time interval
fs=100*1000;
ts=1/fs;
t=0:ts:5-ts;
No=length(t) %how many points in t
nbit = 16 ;   %Bits per sample
m = audiorecorder(fs,nbit,2)
disp('Start speaking.')
recordblocking(m, 5);  %limit the recording by 5 sec
disp('End of Recording.')
play(m);  % Play the speech
r = getaudiodata(m);%Store recorded audio signal in numeric array
figure(1) ; 
plot (t,r)
xlabel ('time')
ylabel('amplitude') ;
title('speech over time')
%finding the FT for the signals
M=abs(fftshift(fft(r)/No));
%creating the vector for the frequency axis
f=[-No/2:No/2-1]/(No*ts);
figure(2);
plot (f,M) ; % plot the  magnitude spectrum 
xlabel ('frequency')
ylabel('amplitude') ;
title('Magnitude Spectrum of speech')
fc = 5000;  %carrier frequency
c=cos(2*pi*fc*t);  % carrier to translate frequency by 5kHz
y = r;
g=r.*c;
%finding the FT for the signals
G=abs(fftshift(fft(g)/No));
figure 2;
plot (f,G) ; % plot the  magnitude spectrum of translated signal
xlabel ('frequency')
ylabel('amplitude') ;
title('translated spectrum by 5Khz')
the error is 
Error using  .* 
Matrix dimensions must agree.
Error in ex4 (line 30)
g=r.*c;