MATLAB: How to multiply with carrier

Question

I am writing a code to transmit and receive three audio signals . After Reading them . I passed them through LPF then resampled them at same sampling rate then upsampled the signals by factor of 2 . Now To transmit them i am multiplying them with carrier . but the upsampled and transmitted signals are same

There is no effect of multikplying with carrier .

shouldnt after multiplying with carrier , i get spectrums at fc+fm and fc-fm.

Kindly if someone can help

Thank you,

Upsampled_1=upsample(Signal_1,2);

Upsampled_2=upsample(Signal_2,2);

Upsampled_3=upsample(Signal_3,2);

% Multiplying With Carrier Frequency;

%

T1=size(Upsampled_1)./8192;

T2=size(Upsampled_2)./8192;

T3=size(Upsampled_3)./8192;

t1=0:(1000/Fs_1):(T1-(1/Fs_1))

t2=0:(1000/Fs_1):(T2-(1/Fs_1))

t3=0:(1000/Fs_1):(T3-(1/Fs_1))

Carrier_1= cos(2*pi*10000*t1);

Carrier_2= cos(2*pi*20000*t1);

Carrier_3= cos(2*pi*30000*t1);

Transm_1= Upsampled_1 * Carrier_1;

Transm_2= Upsampled_2 * Carrier_2;

Transm_3= Upsampled_3 * Carrier_3;

Answer 1

I do not have ‘Signal’ so I cannot run your code.

You need to do element-wise multiplication with the (.*) operator, not the (*) operator:

Transm_1= Upsampled_1 .* Carrier_1;
                      ↑ ← HERE

and so for the others.