I have matlab codes bust i did not able to explain i Viva please examples all 4 code to me any one. CODE for Transmitter And Receiver.

    code 1
clc;
close all;
clear all;
h=0.5; fs=1000;
T=1/fs; t=0:T:1;
%Message Signal:
Am = 10;
fm = 10;
x = Am*sin(2*pi*fm*t);
figure;
figure(1);
plot(t, x);
lfftm=length(x);
ffm=fftshift(fft(x));
mfft=(-lfftm/2:lfftm/2-1)/(lfftm*T);
title('Message Signal');
xlabel('time(t)');
ylabel('Amplitude');
%X=fft(x);
figure(2);
plot(mfft,abs(ffm));
title('frequency domain msg');

code 2
%Carrier Signal:
Ac = Am/h; fc = 10*fm;
y = Ac*cos(2*pi*fc*t);
figure(3);
plot(t(1:1000), y(1:1000));
title('Carrier Signal');
xlabel('time(t)');
ylabel('Amplitude');
lfftmy=length(y);
ffmy=fftshift(fft(y));
mffty=(-lfftmy/2:lfftmy/2-1)/(lfftmy*T);
%Y=fft(y); figure(4);
plot(mffty,abs(ffmy));
title('frequency domain carrier');

code 3
%Modulated Signal:
z = ammod(x, fc, fs, 0, Ac);
figure(5);
plot(t(1:1000), z(1:1000));
title('Modulated Signal');
xlabel('time(t)');
ylabel('Amplitude');
%Z=(fft(z));
lfftmz=length(z);
ffmz=fftshift(fft(z));
mfftz=(-lfftmz/2:lfftmz/2-1)/(lfftmz*T);
figure(6);
plot(mfftz,abs(ffmz));
title('frequency domain AM');

code4
%Demodulated Signal:
d = amdemod(z, fc, fs, 0, Ac);
figure(7);
plot(t(1:1000), d(1:1000));
title('Demodulated Signal');
xlabel('time(t)');
ylabel('Amplitude');
ylim([-10, 10]);
%D=fft(d);
lfftmd=length(x);
ffmd=fftshift(fft(x));
mfftd=(-lfftmd/2:lfftmd/2-1)/(lfftmd*T);
figure(8);
plot(mfftd,abs(ffmd));
title('frequency domain demodulation');