Matlab rogram for TDM

Time Division Multiplexing (TDM)

A multiplexing technique which processes information of different transmitters successively in defined time segments for transmission over one channel.

It can be of two types:

1.Asynchronous Time Division Multiplexing

2.Synchronous Time Division Multiplexing

A simple MATLAB program for TDM 

clc;

 

clearll;

 

closeall;

 

x=0:.5:4*pi;

 

sig1=8*sin(x);

 

l=length(sig1);

 

sig2=8*triang(l);

 

subplot(221)

 

plot(sig1);

 

title('Sinosoidal Signal');

 

ylabel('Amp---------->');

 

xlabel('time----------->');

 

subplot(222);

 

plot(sig2)

 

title('trangular Signal');

 

ylabel('Amp---------->');

 

xlabel('time----------->');

 

subplot(223)

 

stem(sig1);

 

title('Sinosoidal Signal');

 

ylabel('Amp---------->');

 

xlabel('time----------->');

 

subplot(224);

 

stem(sig2)

 

title('trangular Signal');

 

ylabel('Amp---------->');

 

xlabel('time----------->');

 

l1=length(sig1);

 

l2=length(sig2);

 

for i=1:l2

 

sig(1,i)=sig1(i);

 

sig(2,i)=sig2(i);

 

end

 

tdmsig=reshape(sig,1,2*l1);

 

figure

 

stem(tdmsig);

 

title('Tdm Signal')

 

ylabel('Amp---------->');

 

xlabel('time----------->');

 

demux=reshape(tdmsig,2,l2);

 

for i=1:l1

 

sig3(i)=demux(1,i);

 

sig4(i)=demux(2,i);

 

end

 

figure

 

subplot(2,1,1)

 

plot(sig3)

 

title('Recovered Sinosoidal Signal');

 

ylabel('Amp---------->');

 

xlabel('time----------->');

 

subplot(2,1,2);

 

plot(sig4);

 

title('Recovered Triangular Signal');

 

ylabel('Amp---------->');

 

Delta Modulation using Simulink

Delta Modulation:

1. Next form of pulse modulation.
2. Transmits information only to indicate whether the analog signal that is being encoded goes up or goes down.
3. The Encoder Outputs are highs or lows that “instruct” whether to go up or down, respectively.
4. DM takes advantage of the fact that voice signals do not change abruptly.
5. The analog signal is quantized by a one-bit ADC (a comparator implemented as a comparator). 
6. The comparator output is converted back to an analog signal with a 1-bit DAC, and subtracted from the input after passing through an integrator.
7. The shape of the analog signal is transmitted as follows: a "1" indicates that a positive excursion has occurred since the last sample, and a "0" indicates that a negative excursion has occurred since the last sample.

Generation of Delta modulated signal using Simulink in MATLAB

MATLAB PROGRAM FOR Delta Modulation Sine Wave

 Delta Modulation Sine Wave

 The operation of a delta modulator is to periodically sample the input message, to make a comparison of the current sample with that preceding it, and to output a single bit which indicates the sign of the difference between the two samples.

Matlab program for Delta Modulation

subplot(212)

hold on

m1=sin(2*pi*t)

plot(m1,'black')

title('sin wave')

xlabel('time')

ylabel('amplitude')

d=2*pi/100

for n=1:1:100

    if n==1

        e1(n)=m1(n)

        eq1(n)=d*sign(e1(n))

        mq1(n)=eq1(n)

    else

        e1(n)=m1(n)-mq1(n-1)

        eq1(n)=d*sign(e1(n))

        mq1(n)=mq1(n-1)+eq1(n)

    end

end

stairs(mq1,'black')

hleg=legend('original signal','stair case approximated signal')

hold off