Nitk DC lab sim 2015

Amplitude Modulation

Aim:

Code:

%DSB-SC

Ac = input('carrier signal amplitude : ');

fc = input('carrier signal freq : ');

Am = input('Message signal amplitude : ');

fm = input('message signal freq : ');

t = [0:0.00001:0.05];

crr = Ac.*cos(2*pi*fc.*t);

msg = Am.*sin(2*pi*fm.*t);

subplot(3,1,1);

gridon;

plot(t,msg);

title('Message Signal');

xlabel('time ');

ylabel('Amplitude ');

subplot(3,1,2);

plot(t,crr);

title('Carrier Signal');

xlabel('time');

ylabel('Amplitude');

%DSB-AM

A = Ac.*(1+(Am/Ac).*sin(2*pi*fm.*t)).*cos(2*pi*fc.*t);

subplot(3,1,3);

plot(t,A);

title('Modulated DSB-AM Signal');

xlabel('time');


figure;

subplot(3,1,1);

gridon;

plot(t,msg);


xlabel('time');


subplot(3,1,2);

plot(t,crr);


xlabel('time ');


DSBSC = msg.*crr;

subplot(3,1,3);

plot(t,DSBSC);

title('Modulated DSB-SC Signal');

xlabel('time');


% SSB-AM

a1 = sin(2*pi.*fc.*t);

a1c = hilbert(m1);

b2 = msg;

b2c = hilbert(msg);

SSBAM = Ac.*0.5.*[b2.*a1 - b2c.*a1c];

figure;

subplot(3,1,1);

gridon;

plot(t,msg);


xlabel('time');


subplot(3,1,2);

plot(t,crr);


xlabel('time ');


subplot(3,1,3);

plot(t,abs(SSBAM));

title('Modulated SSB-SC Signal');

xlabel('time ');


Graphs:

Result:

Conclusion:

Sampling

Aim:

Code:

func1=0.1;

func2=0.2;

t=0:0.1:20;

x=sin(2*pi*func1*t);

plot(t,x);

title('orginal signal');

xlabel('time index');

ylabel('amplitude');

figure

x_samples=x(1:10:201);

stem(x_samples,'filled');

title('sampled signal');

xlabel('n');

ylabel('x[n]');

axis([0 20 -2 2]);

Result:

Conclusion:

Time Division Multiplexing

Aim:

Code:

x=0:.5:4*pi;

signala=sin(x);

l=length(signala);

signalb=triang(l);

figure(1)

stem(signalb);


xlabel('Time index');

title('triangular wave');

figure(2)

stem(signala);



title('sine wave');

figure(3)

fori=1:l

signal(1,i)=signala(i);

signal(2,i)=signalb(i);

end

tdmrg=reshape(signal,1,2*l);

stem(tdmrg);



title('time division multiplexing')

Result:

Conclusion:

Manchester Line Coding

Aim:

Code:

input=[1 1 0 1 1 0];

size2=size(input,2);

sign=1;

i=1;

whilei<size2+1

t = i:0.001:i+1-0.001;

if input(i)==1

sign=sign*-1;

mcode=-square(t*2*pi,50);

else

mcode=square(t*2*pi,50);

end

grid on

plot(t,mcode);

xlabel('time index');


title('Manchester line coding');

hold on

axis([1 10 -2 2]);

i=i+1;

end

Result:

Conclusion:

Bipolar NRZ

Aim:

Code:

input=round(randi([0 1],1,100));

k=0;

temp=0;

fori=1:length(x)

if(input(i)==0)

temp=i;

k=[k zeros(1,50)];

elseif(input(i)==1)

k=[k (-1)^temp*ones(1,50)];

end

end

figure(1)

stairs(1:length(y),y)

ylim([-1.2 1.2]);



title('Bipolar Non Return to Zero');

Result:

Conclusion:

Differential Encoding

Aim:

Code:

input=[1 0 1 0 1 1 0 1 1 0]; Z=size(x,2); ref_bit = 1; del_x = [ref_bitx(1:Z-1)];

fori= 1:Z if (x(i) == del_x(i)) y(i) =1; else y(i) = 0; end end diff_code = 1 - y;

figure(1) stairs(x); title('PN input sequence'); ylabel('Amplitude'); xlabel('Time index'); holdon; gridon; axis([1 10 -2 2]);

figure(2) stairs(diff_code); title('Differential Encoded sequence'); ylabel('Amplitude'); xlabel('Time index'); holdon; gridon; axis([1 10 -2 2]);

Result:

Conclusion:

PWM and PPM

Aim:

Code:

time=0:0.001:1;

signal=sawtooth(2*pi*10*t+pi);

y=length(signal);

x=0.75*sin(3*pi*1*time);

fori=1:y

if (x(i)>=signal(i))

pwm(i)=1;

elseif (x(i)<=signal(i))

pwm(i)=0;

end

end

plot(time,pwm,time,x,time,signal);

grid on;



title('PWM Wave');

axis([0 1 -1.5 1.5]);

%PPM

fori=2:n

if (pwm(i)==1 &&pwm(i-1)==0)

ppm(i)=1;

else

ppm(i)=0;

end

end

subplot(2,1,2)

plot(t,ppm);



title('PPM Wave');

axis([0 1 -1.5 1.5]);

Result:

Conclusion:

Delta Modulation

Aim:

Code:

amp=2;

t=0:2*pi/50:2*pi;

A=amp*sin(t);

l=length(x);

plot(x,'r');

delta=0.2;

hold on

An=0;

fori=1:l;

if A(i)>An(i)

d(i)=1;

An(i+1)=An(i)+delta;

else

d(i)=0; An(i+1)=An(i)-delta;

end

end

stairs(An)

title('Delta modulation')



legend('Analog signal','Delta modulation')

Result:

Conclusion:

Pulse Code Modulation

Aim:

Code:

n=input('Enter n value for n-bit PCM system : '); n1=input('Enter number of samples in a period : '); L=2^n; x=0:2*pi/n1:4*pi; s=8*sin(x); subplot(3,1,1); plot(s); title('Analog Signal'); ylabel('Amplitude'); xlabel('Time index'); subplot(3,1,2); stem(s);grid on; title('Sampled Signal'); ylabel('Amplitude'); xlabel('Time index');

%QUANTIZATION PROCESS vmax=8; vmin=-vmax; del=(vmax-vmin)/L; part=vmin:del:vmax;

code=vmin-(del/2):del:vmax+(del/2); [ind,q]=quantiz(s,part,code); l1=length(ind); l2=length(q);

fori=1:l1

if(ind(i)~=0)

ind(i)=ind(i)-1; end i=i+1; end fori=1:l2

if(q(i)==vmin-(del/2))

q(i)=vmin+(del/2); end end subplot(3,1,3); stem(q);grid on;

title('Quantized Signal'); ylabel('Amplitude'); xlabel('Time index');

% Encoding Process

figure code=de2bi(ind,'left-msb'); k=1; fori=1:l1 for j=1:n coded(k)=code(i,j);

j=j+1; k=k+1; end i=i+1; end subplot(2,1,1); grid on; stairs(coded);

axis([0 100 -2 3]);

title('Encoded Signal'); ylabel('Amplitude--->'); xlabel('Time--->');

% Demodulation Of PCM signal

qunt=reshape(coded,n,length(coded)/n); index=bi2de(qunt','left-msb');

q=del*index+vmin+(del/2); subplot(2,1,2); grid on; plot(q);

% Plot Demodulated signal

title('Demodulated Signal'); ylabel('Amplitude'); xlabel('Time index');

Result:

Conclusion:

Frequency Modulation

Aim:

Code:

fm = input('Message signal frequency : '); fc = input('carrier signal frequency : '); Am = input('Message signal amplitude : '); Ac = input(' carrier signal amplitude : '); t = [0:0.00001:0.05];

message = Am.*sin(2*pi*fm.*t); carrier = Ac.*cos(2*pi*fc.*t);

FM = Ac.*cos(2*pi.*fc.*t + Am.* sin(2*pi.*fm.*t)); figure; subplot(3,1,1); gridon; plot(t,message); title('Message Signal'); xlabel('time '); ylabel('Amplitude ');

subplot(3,1,2); plot(t,carrier); title('Carrier Signal'); xlabel('time '); ylabel('Amplitude');

subplot(3,1,3); plot(t,FM); title('Frequency Modulated Signal'); xlabel('time '); ylabel('Amplitude ');

Result:

Conclusion:

Documents

Nitk DC lab sim 2015