Pulse code modulation(PCM):

Pulse code modulation(PCM):

Pulse code modulation (PCM) data are transmitted as a serial bit stream of binary-coded time-division multiplexed words. When PCM is transmitted, premodulation filtering shall be used to confine the radiated RF spectrum in accordance with Appendix A. These standards define pulse train structure and system design characteristics for the implementation of PCM telemetry formats.

In Pulse code modulation a massage signal is converted to sample vertion discript time and discript amplitude.

MAT LAB CODE:

clear all;

close all;

clc;

F=10;

Fs=100*F;

t=0:1/Fs:1/F;

m=20*sin(2*pi*F*t);

N=10;

g=length(m)/N;

ms=m(1:g:end);

subplot(4,1,1)

plot(t,m);

subplot(4,1,2)

stem(ms);

Out put 

MAT LAB CODE:

Manual input

clear all;

close all;

clc;

F=10;

Fs=100*F;

t=0:1/Fs:1/F;

m=20*sin(2*pi*F*t);

N=input ('Enter Number of samp');

g=length((m)/N);

ms=m(1:g:end);

subplot(4,1,1)

plot(t,m);

subplot(4,1,2)

stem(ms);

Frequency Modulation

Frequency Modulation

Frequency modulation (FM) is the standard technique for high-fidelity communications as is evident in the received signals of the FM band (88-108 MHz) vs. the AM band (450-1650 KHz). The main reason for the improved fidelity is that FM detectors, when properly designed, are not sensitive to random amplitude variations which are the dominant part of electrical noise (heard as static on the AM radio). Frequency modulation is not only used in commercial radio broadcasts, but also in police and hospital communications, emergency channels, TV sound, wireless (cellular) telephone systems, and radio amateur bands above 30 MHz.

In case of FM intentinious frequency of carrer verid with WT massage signal.

Mat Lab Code

clear all;

close all;

clc;

F=10;

Fs=20*F;

t=0:1/Fs:1/F;

y=sin(2*pi*F*t);

plot(t,y);

Out Put:

Mat Lab Code Adding Noise

clear all;

close all;

clc;

F=10;

Fs=20*F;

t=0:1/Fs:1/F;

y1=sin(2*pi*F*t);

y2=cos(2*pi*F*t);

subplot(4,2,1);

plot(t,y1)

subplot(4,2,2);

plot(t,y2);

noise=rand(1,length(y1));

subplot(4,2,[3,4]);

plot(t,noise);

Output