ME full lab manual

1

OPEN:

SHORT:

S.No DISTANCE MOVED BY THE

MOVABLE PROBE ON SLOTTED

LINE(M)

VOLTAGE(V)

GAIN(dB)

MISMATCHED:



LINE(M)

VOLTAGE(V)

GAIN(dB)



LINE(M)

VOLTAGE(V)

GAIN(dB)

2

EX.NO:1 MEASUREMENT OF TRANSMISSION LINE PARAMETERS

AIM:

To measure the frequency/wavelength, VSWR, impedance and return loss by using

VRFT-03A-DSS and co-axial slotted line.

APPARATUS REQUIRED:

1. VRFT-03A-DSS (RF source) 2. BNC-BNC cable 3. Co-axial slotted line trainer (Vcom-03) 4. Load 50,100,short

PROCEDURE:

1. Switch ON the RF source. 2. RF source output is connected to the input of the co-axial slotted line. 3. Movable probe output is connected to input of the detector using BNC-BNC cable. 4. Detector output of the RF source is connected to CRO (or) multimeter to measure the

detector voltage.

5. Output of the co-axial slotted line trainer is kept short. 6. Difference between the voltage maximum or minimum or can be measured by

adjusting the movable probe on the co-axial trainer.

7. Repeat the same procedure for open matched and unmatched. 8. By using the formula.

THEORY:

Frequency:

Frequency is the number of occurrences of a repeating event per unit time. It is also

referred to as temporal frequency. The period is the duration of one cycle in a repeating

event, so the period is the reciprocal of the frequency. For example, if a newborn baby's heart

beats at a frequency of 120 times a minute, its period (the interval between beats) is half a

second

Wavelength:

The wavelength of a sinusoidal wave is the spatial period of the wavethe distance over which the wave's shape repeats. It is usually determined by considering the distance

4

between consecutive corresponding points of the same phase, such as crests, troughs, or zero

crossings, and is a characteristic of both traveling waves and standing waves, as well as other

spatial wave patterns. Wavelength is commonly designated by the letter lambda (). The concept can also be applied to periodic waves of non-sinusoidal shape. The term wavelength

is also sometimes applied to modulated waves, and to the sinusoidal envelopes of modulated

waves or waves formed by interference of several sinusoids. The SI unit of wavelength is the

meter.

Characteristic impedance:

The characteristic impedance or surge impedance of a uniform transmission line,

usually written Z0, is the ratio of the amplitudes of voltage and current of a single wave

propagating along the line; that is, a wave travelling in one direction in the absence of

reflections in the other direction. Characteristic impedance is determined by the geometry and

materials of the transmission line and, for a uniform line, is not dependent on its length. The

SI unit of characteristic impedance is the ohm.

The characteristic impedance of a lossless transmission line is purely resistive, with no

reactive component. Energy supplied by a source at one end of such a line is transmitted

through the line without being dissipated in the line itself. A transmission line of finite length

(lossless or lossy) that is terminated at one end with a resistor equal to the characteristic

impedance appears to the source like an infinitely long transmission line.

Return loss:

In telecommunications, return loss is the loss of signal power resulting from the reflection

caused at a discontinuity in a transmission line or optical fiber. This discontinuity can be a

mismatch with the terminating load or with a device inserted in the line. It is usually

expressed as a ratio in decibels (dB);

Where RL (dB) is the return loss in dB, Pi is the incident power and Pr is the reflected

power.

Return loss is related to both standing wave ratio (SWR) and reflection coefficient (). Increasing return loss corresponds to lower SWR. Return loss is a measure of how well

devices or lines are matched. A match is good if the return loss is high. A high return loss is

desirable and results in a lower insertion loss.

Return loss is used in modern practice in preference to SWR because it has better resolution for

small values of reflected wave.

6

VSWR:

In telecommunications, standing wave ratio (SWR) is the ratio of the amplitude of a partial

standing wave at antinodes (maximum) to the amplitude at an adjacent node (minimum), in

an electrical transmission line.

The SWR is usually defined as a voltage ratio called the VSWR, (sometimes pronounced

"viswar"), for voltage standing wave ratio. For example, the VSWR value 1.2:1 denotes

maximum standing wave amplitude that is 1.2 times greater than the minimum standing wave

value. It is also possible to define the SWR in terms of current, resulting in the ISWR, which

has the same numerical value. The power standing wave ratio (PSWR) is defined as the

square of the VSWR.

SWR is used as an efficiency measure for transmission lines, electrical cables that conduct

radio frequency signals, used for purposes such as connecting radio transmitters and receivers

with their antennas, and distributing cable television signals. A problem with transmission

lines is that impedance mismatches in the cable tend to reflect the radio waves back toward

the source end of the cable, preventing all the power from reaching the destination end. SWR

measures the relative size of these reflections. An ideal transmission line would have an SWR

of 1:1, with all the power reaching the destination and no reflected power. An infinite SWR

represents complete reflection, with all the power reflected back down the cable. The SWR of

a transmission line can be measured with an instrument called an SWR meter, and checking

the SWR is a standard part of installing and maintaining transmission lines.

8

RESULT:

Thus measurement of frequency, wavelength, VSWR, load impedance and return loss

was done.

9

BLOCK DIAGRAM FOR S-PARAMETER ESTIMATION OF MICROWAVE

DEVICES:

KLYSTRON

POWER

SUPPLY

KLYSTRON

TUBE WITH

MOUNT

ISOLATOR

PIN

MODULATOR

VARIABLE

ATTENUATOR

FREQUENCY

METER

MICROWAVE

DEVICE

CRO

10

AIM:

To estimate the S-parameter of microwave devices like E-plane tee, H-plane tee and

magic tee.

APPARATUS REQUIRED:

1. Klystron power supply 2. Klystron tube with mount 3. Isolator 4. Pin modulator 5. Variable attenuator 6. Frequency meter 7. Cathode ray oscilloscope(CRO) 8. E-plane tee, H-plane tee, magic tee.

PROCEDURE:

1. Connections are given according to block diagram. 2. Microwave devices like E-plane tee, H-plane tee and magic tee is connected as

shown in the block diagram.

3. Input is given to one of the port, one port is terminated with matched load and other port is connected to load. Power output in two arms is noted for E-plane tee

and H-plane tee.

4. Input is given to one of the port, two ports are terminated with matched load and other port is connected to load. Power output in two arms is noted for magic tee.

5. VSWR is calculated for microwave devices.

THEORY:

E-PLANE TEE:

An E-plane Tee is a waveguide tee in which the axis of its side arm in parallel to the

E-field of the main guide. If the collinear arms are symmetric about the side arm, there are

two different transmissions characteristic. When the waves are fed into the side arm, the

waves appearing at port 1 and port 2 of the collinear arm will be in opposite phase and in the

same magnitude. Therefore

S13= - S23

EX.NO:2

S-PARAMETER ESTIMATION OF MICROWAVE DEVICES

11

TABULATION:-

NATURE OF

TEE

LOAD

PORT

Vmax( mV)

Vmin(mV)

VSWR=

Vmax/

Vmin

E-PLANE

TEE

H-PLANE

TEE

MAGIC TEE

1

2

3

1

2

3

1

2

3

4

12

H-PLANE TEE:

An H plane Tee is a wave guide tee in which the axis of the side arm is shunting the

E-field or parallel to the H field of the main guide as it can be seen that if two input waves

are fed into port1 and port 2 of the collinear arm, the output wave at port 3 will be phase and

additive.

MAGIC TEE:

A magic Tee is a combination of the E- plane Tee and H-plane Tee. The magic tee has

several characteristic. The magic Tee is commonly used for mixing, duplexing and

impedance measurement. Suppose the example there are two identical radar transmitters in

equivalent stock.

14

RESULT:

Thus the S-parameter of microwave devices like E-plane tee, H-plane tee and magic

tee was estimated.

15

BLOCK DIAGRAM FOR MICROSTRIP COUPLER:

KLYSTRON

POWER

SUPPLY

KLYSTRON

TUBE WITH

MOUNT

ISOLATOR

PIN

MODULATOR

VARIABLE

ATTENUATOR

FREQUENCY

METER

MICROSTRIP

COUPLER

CRO

16

EX.NO:3 DESIGN AND TESTING OF MICROSTRIP COUPLER

AIM:

To design and test the Microstrip coupler.

APPARATUS REQUIRED:

1. Klystron power supply 2. Klystron tube with mount 3. Isolator 4. Pin modulator 5. Variable attenuator 6. Frequency meter 7. Cathode ray oscilloscope(CRO) 8. Microstrip coupler.

THEORY:

A Microstrip coupler is a device in which measurement of incident wave and reflected

wave can be done separately. It consists of two transmission lines the main arm and auxiliary

arm both are electromagnetically coupled to each other.

Coupling factor, Directivity and Insertion loss can be found by using following

formulae,

1. Coupling factor (dB) = 10 log [V1/V3] 2. Directivity (D in dB) = 10 log [V2/V3] 3. Insertion loss (dB) = 10 log [V1/V2]

PROCEDURE:

1. Connections are given according to block diagram. 2. Input is given to port 1 and power output at port 2 is measured by terminating port

3 with matched load.

3. Input is given to port 1 and power output at port 3 is measured by terminating port 2 with matched load.



6. Coupling factor, Directivity and Insertion loss can be found by using above formulae.

17

TABULATION:

DIRECTION

PORT1

PORT2

PORT3

PORT4

FORWARD

REVERSE

18

RESULT:

Thus the Microstripcoupler was design and tested.

19

BLOCK DIAGRAM FOR MIOCROSTRIP COUPLER:

HORN

KLYSTRON

POWER SUPPLY

KLYSTRON TUBE

WITH MOUNT

ISOLATOR

VARIABLE

ATTENUATOR

FREQUENCY

METER

ROTARY

JOINT

DETECTOR

MOUNT

CRO

20

EX.NO:4 ANTENNA RADIATION PATTERN MEASUREMENT

AIM:

To measure the pattern of the Horn Antenna.

APPARATUS REQUIRED:

1. Klystron power supply. 2. Klystron Mount. 3. Isolator. 4. Variable attenuator. 5. Frequency meter. 6. Horn antenna. 7. Crystal detector. 8. VSWR meter.

THEORY:

The horn antenna represents a transition or matching section from the guided mode

inside the waveguide to the unguided mode outside the waveguides. The horn antenna

reduces reflections and also leads to a lower standing wave ratio. The horn antenna is used in

the transmission and reception of RF microwave signals and the antenna is normally used in

conjunction with waveguide feed. The horn antenna gains the name from it appearance. The

wavelength can be considered to open out or to be flared launching the signal towards the

receiving antenna.

PROCEDURE: Antenna Radiation pattern:

1. Setup the equipment as keeping the axis of both antennas in same direction. 2. Energizes the Gunn oscillator for maximum output at desired frequency with square

wave modulation by tuning square wave amplitude and frequency of modulation

signal of Gunn power supply and by tuning the detector.

3. Also tune the SS tuner in the line for maximum output. 4. Obtain the full scale deflection on normal dB scale at any convenient range switch

position of VSWR, meter by gain control knob of VSWR meter or by variable

attenuator.

5. Tune the receiving horn to the left in 2 or 5 steps to 4 5 and note the corresponding VSWR dB reading in normal dB range. When necessary, change the

range switch to next higher range and add 10 dB to the observed reading.

6. Repeat the above steps but this time the receiving horn to right and note down the readings.S

7. Plot a relative power pattern (i.e.), output vs. angle. From diagram determine 3 dB width of the horn antenna.

21

PATTERN MEASUREMENT:

SIDE DEGREE VR(V) VT(V) GAIN IN dB

ANTICLOKWISE DIRECTION CLOCKWISE DIRECTION

23

GAIN MEASUREMENT:

S.NO

DISTANCE(CM)

VT(V)

VR(V)

GAIN IN dB

24

RESULT:

Thus the pattern of the wave of horn antenna was measured.

25

x(n) d^(n) d(n)

GENERAL BLOCK DIAGRAM OF ADAPTIVE FILTER

Filter i/p v(n) d^(n) d(n)

Filter o/p

Co-efficient vector

wn(z)

Adaptive

algorithm

ADAPTIVE

FILTER

ADAPTATION

PROCEDURE

26

EX.NO:5 DESIGN OF CHANNEL EQUALIZER USING LMS ALGORITHM

AIM:

To write the MATLAB program for LMS algorithm & simulate it.

REQUIREMENTS:

MATLAB Software, PC.

ALGORITHM:

The steepest descent adaptive filter, which has a weight vector equation given

by

Wn+1=Wn +E [e (n-L) X*(n)] --- (1)

So it must be replaced by an estimate such as sample mean.

r-1

E [e (n) x (n)] = 1/L e (n-1)*(n-1)

i=0

Now the equation (1) becomes

r-1

Wn+1= Wn +/L E [N-L] x (n-1) --- (2)

i=0

If we use one point sample of 2L=1 then we get

Wn+1 = Wn + e (n)x (n)

This is known as LMS algorithm.

27

OUTPUT:

28

THEORY:

Least mean squares (LMS) algorithms are a class of adaptive filter used to mimic a

desired filter by finding the filter coefficients that relate to producing the least mean squares

of the error signal (difference between the desired and the actual signal). It is a stochastic

gradient descent method in that the filter is only adapted based on the error at the current

time. It was invented in 1960 by Stanford University professor Bernard Widrow and his first

Ph.D. student, Ted Hoff.

PROGRAM :

clc;

clearall;

closeall;

order=2;

size=2;

fs=8192;

t=[0:1/fs:size];

n=fs*size;

f1=35;

f2=99;

voice=sin(2*pi*f1*t);

subplot(4,1,1);

plot(t,voice);

title('voice (dont have access to)');

noise=sin(2*pi*f2*t.^2);

primary=voice+noise;

subplot(4,1,2);

plot(t,primary);

title('primary=voice+noise(input1)');

ref=noise+.25*rand;

subplot(4,1,3);

plot(t,ref);

title('reference(noisy noise)(input2)');

w=zeros(order,1);

mu=.005;

fori=1:n-order

buffer=ref(i:i+order-1);

desired(i)=primary(i)-buffer*w;

w=w+(buffer.*mu*desired(i)/norm(buffer))';

end

subplot(4,1,4);

plot(t(order+1:n),desired);

title('adaptive output(hopefully its close to voice)');

30

RESULT:

Thus the MATLAB program for LMS algorithm was simulated.

32

EX.NO:6 CHARACTERSTICS OF /4 AND /2 TRANSMISSION LINES

AIM:

To stimulate the characteristics of a /4 and /2 transmission lines using MATLAB.

APPARATUS REQUIRED:

1. A personal computer 2. MATLAB 6.5 software.

THEORY:

HALF WAVELENGTH LINE (/2 LINES)

A half wave length transmission lines in one whose electrical length is one half

wavelengths. When a /2 line whose characteristics impedance is Zo is transmitted in a load

impedance ZL. Consider an RF sine wave of frequency f and wavelength transmitting from

input to the load. If Vo cos (2 (/x + ft) are the voltage and current on the transmission line,

then at the input x=0 and the input impedance is,

Zs=Vo cos (2ft) / Io cos (2ft)

At the load x=/2 and the load impedance of the lines is

ZL = Vo cos (+2ft) / Io cos ( + 2ft)

From the voltage trigonometry, we know that cos(+2ft)-cos(2ft).

ALGORITHM:

1. Initialization of parameter for /4 and /2 transmission lines ZL,Zs,Vs,Is. 2. Simulate the smith chart parameters and coordinates. 3. Find the location of stub and stub angle load and 4. Calculate the normalize value of impedance and admittance at the port on

transmission lines where stub is connected.

5. Calculate the normalized admittance of stub line and length of stub line. 6. Plot the characteristic of line on smith chart.

34

LAMDA PROGRAM:

Close all;

Clear all;

amp= rfckt.amplifer;

read(amp,sample 1t2.s2p);

analyse(amp,1.9e9);

data=calculate(amp, s11, s12, s21, s22, none);

[s11,s12,s21,s22]=deal(data{1},data{2},data{3},data{4});

delta= s11*s22-s12*s21;

k=(1-abs(s11)^2-abs(s22)^+abs(delta)^2,a2*abs(s12*s21);

abs_delta=abs(delta);

B=1+abs(s22)^2-abs(s11)^2-abs(delta)^2;

C=s22-delta*conj(s11);

37

CHARACTERSTICS OF /4 AND /2 TRANSMISSION LINES:

OUTPUT:

38

RESULT:

Thus the characteristics of /4 and /2 transmission lines is studied.

40

EX.NO:7 PERFORMANCE EVALUATION OF DIGITAL MODULATION

SCHEMES

AIM:

To write the MATLAB programs for PERFORMANCE EVALUATION OF DIGITAL

MODULATION SCHEMES (ASK, FSK, PSK, QPSK) & simulate it.

REQUIREMENTS:


ALGORITHM:

1. Start the program 2. Get the input binary sequence and determine its length 3. Append the analog input according to the digital input 4. Choose the sample value according for demodulation 5. Plot the waveform for input modulation and demodulation 6. Stop the program

THEORY:

Amplitude-shift keying (ASK):

ASK is a form of modulation that represents digital data as variations in the amplitude

of a carrier wave. Any digital modulation scheme uses a finite number of distinct signals to

represent digital data. ASK uses a finite number of amplitudes, each assigned a unique

pattern of binary digits. Usually, each amplitude encodes an equal number of bits. Each

pattern of bits forms the symbol that is represented by the particular amplitude. The

demodulator, which is designed specifically for the symbol-set used by the modulator,

determines the amplitude of the received signal and maps it back to the symbol it represents,

thus recovering the original data. Frequency and phase of the carrier are kept constant.

Frequency-shift keying (FSK):

FSK is a frequency modulation scheme in which digital information is transmitted

through discrete frequency changes of a carrier wave. The simplest FSK is binary FSK

(BFSK). BFSK uses a pair of discrete frequencies to transmit binary (0s and 1s) information.

With this scheme, the "1" is called the mark frequency and the "0" is called the space

frequency. The time domain of an FSK modulated carrier is illustrated in the figures to the

right.

42

Phase-shift keying (PSK)

PSK is a digital modulation scheme that conveys data by changing, or modulating, the

phase of a reference signal (the carrier wave).Any digital modulation scheme uses a finite

number of distinct signals to represent digital data. PSK uses a finite number of phases, each

assigned a unique pattern of binary digits. Usually, each phase encodes an equal number of

bits. Each pattern of bits forms the symbol that is represented by the particular phase. The

demodulator, which is designed specifically for the symbol-set used by the modulator,

determines the phase of the received signal and maps it back to the symbol it represents, thus

recovering the original data. This requires the receiver to be able to compare the phase of the

received signal to a reference signal such a system is termed coherent (and referred to as CPSK).

Alternatively, instead of operating with respect to a constant reference wave, the broadcast

can operate with respect to itself. Changes in phase of a single broadcast waveform can be

considered the significant items. In this system, the demodulator determines the changes in

the phase of the received signal rather than the phase (relative to a reference wave) itself.

Since this scheme depends on the difference between successive phases, it is termed

differential phase-shift keying (DPSK). DPSK can be significantly simpler to implement

than ordinary PSK since there is no need for the demodulator to have a copy of the reference

signal to determine the exact phase of the received signal (it is a non-coherent scheme). In

exchange, it produces more erroneous demodulations.

Quadrature Phase-shift keying (QPSK)

Sometimes this is known as quaternary PSK, quadriphase PSK, 4-PSK, or 4-QAM.

(Although the root concepts of QPSK and 4-QAM are different, the resulting modulated radio

waves are exactly the same.) QPSK uses four points on the constellation diagram, equispaced

around a circle. With four phases, QPSK can encode two bits per symbol, shown in the

diagram with gray coding to minimize the bit error rate (BER) sometimes misperceived as twice the BER of BPSK.

The mathematical analysis shows that QPSK can be used either to double the data rate

compared with a BPSK system while maintaining the same bandwidth of the signal, or to

maintain the data-rate of BPSK but halving the bandwidth needed. In this latter case, the

BER of QPSK is exactly the same as the BER of BPSK - and deciding differently is a

common confusion when considering or describing QPSK.

Given that radio communication channels are allocated by agencies such as the Federal

Communication Commission giving a prescribed (maximum) bandwidth, the advantage of QPSK over

BPSK becomes evident: QPSK transmits twice the data rate in a given bandwidth compared to BPSK -

at the same BER. The engineering penalty that is paid is that QPSK transmitters and receivers are

more complicated than the ones for BPSK. However, with modern electronics technology, the

penalty in cost is very moderate.

43

OUTPUT FOR AMPLITUDE SHIFT KEYING:

44

PROGRAM FOR AMPLITUDE SHIFT KEYING:

clc;

clearall;

x=[1 0 1 1 0 1];

n=length(x);

t=0:1:25;

y=sin(t);

ask=0;

fori=1:n

if (x(i)==1)

ask=[ask 4*y];

else (x(i)==0)

ask=[ask 0*y];

end

end

demod=0;

ptr=10;

fori=1:n

if ask(ptr)>0

demod(i)=1;

else

demod(i)=0;

end

ptr=ptr+length(t);

end

subplot(4,1,1);

stem(x);

title('message signal');

xlabel('time');

ylabel('amplitude');

subplot(4,1,2);

plot(y);

title('carrier signal');

xlabel('time');


subplot(4,1,3);

plot(ask);

title('modulated signal');

xlabel('time');


subplot(4,1,4);

stem(demod);

title('demodulated signal');

xlabel('time');


45

OUTPUT FOR FREQUENCY SHIFT KEYING:

46

PROGRAM FOR FREQUENCY SHIFT KEYING:

clc;

clearall;

closeall;

x=[1 0 1 1 0 1];

n=length(x);

t=0:1:25;

y=sin(t);

z=sin(2*t);

fsk=0;

fori=1:n

if (x(i)==1)

fsk=[fsk y];

else (x(i)==0)

fsk=[fsk z];

end

end

demod=0;

ptr=10;

fori=1:n

iffsk(ptr)>0

demod(i)=1;

else

demod(i)=0;

end

ptr=ptr+length(t);

end

subplot(5,1,1);

stem(x);


xlabel('time');


subplot(5,1,2);

plot(y);

title('carrier signal 1');

xlabel('time');


subplot(5,1,3);

plot(z);


xlabel('time');


subplot(5,1,4);

plot(fsk);


xlabel('time');


subplot(5,1,5);

stem(demod);


xlabel('time');


47

OUTPUT FOR PHASE SHIFT KEYING:

48

PROGRAM FOR PHASE SHIFT KEYING:

clc;

clearall;

closeall;

x=[1 0 1 1 0 1];

n=length(x);

t=0:1:25;

y=sin(t);

z=-y;

psk=0;

fori=1:n

if (x(i)==1)

psk=[psk y];

else (x(i)==0)

psk=[psk z];

end

end

demod=0;

ptr=10;

fori=1:n

ifpsk(ptr)>0

demod(i)=1;

else

demod(i)=0;

end

ptr=ptr+length(t);

end

subplot(5,1,1);

stem(x);


xlabel('time');


subplot(5,1,2);

plot(y);


xlabel('time');


subplot(5,1,3);

plot(z);


xlabel('time');


subplot(5,1,4);

plot(psk);


xlabel('time');


subplot(5,1,5);

stem(demod);


xlabel('time');


49

OUTPUT FOR QUADRATURE PHASE SHIFT KEYING:

OUTPUT FOR QUADRATURE PHASE SHIFT KEYING:

50

PROGRAM FOR QUADRATURE PHASE SHIFT KEYING:

clc;

clearall;

closeall;

input=randsrc(1,10,[1,0]);

k=1;

fori=1:10

for j=1:50

m(k)=input(i);

k=k+1;

end

end

figure(1);

subplot(3,1,1);

plot(m);

title('INPUT BITS');

xlabel('Time(s)');

ylabel('Amplitude(v)');

grid;

axis([1,500,0,2]);

k=1;

l=50;

fori=1:10

if rem(i,2)~=0

if(input(i)==1)

for j=1:100

msgodd(k)=1;

k=k+1;

end

else

for j=1:100

msgodd(k)=-1;

k=k+1;

end

end

end

if(input(i)==1)

for j=50:150

msgeven(l)=1;

l=l+1;

end

else

for j=50:150

msgeven(l)=-1;

l=l+1;

end

end

end

subplot(3,1,2);

plot(msgodd);

title('MESSAGE ODD');

xlabel('Time(s)');


grid;

52

axis([1,500,-1.5,1.5]);

subplot(3,1,3);

plot(msgeven);

title('MESSAGE EVEN');

xlabel('Time(s)');


grid;

axis([1,500,-1.5,1.5]);

n=1:100;

s=sin(2*pi*2*n/50);

c=cos(2*pi*2*n/50);

k=1;

fori=1:5

for j=1:100

c1(k)=s(j);

c2(k)=c(j);

k=k+1;

end

end

fori=1:500

qo(i)=msgodd(i)*c1(i);

qe(i)=msgeven(i)*c2(i);

qpsk(i)=qo(i)+qe(i);

end

figure(2);

subplot(3,1,1);

plot(qo);

title('INPHASE BITS');

xlabel('Time(s)');


grid;

axis([1,500,-1.5,1.5]);

subplot(3,1,2);

plot(qe);

title('OFFSET QUADRATURE PHASE BITS');

xlabel('Time(s)');


grid;

axis([1,500,-1.5,1.5]);

subplot(3,1,3);

plot(qpsk);

title('OFFSET QPSK WAVEFORM');

xlabel('Time(s)');


grid;

axis([1,500,-1.5,1.5]);

54

RESULT:

Thus theMATLAB programs for PERFORMANCE EVALUATION OF DIGITAL

MODULATION SCHEMES (ASK, FSK, PSK, QPSK) was simulated.

55

OFDM Transmitter

OFDM Receiver

56

EX.NO:8 ORTHOGONAL FREQUENCY DIVISION

MULITIPLEXING(OFDM)TRANSCEIVER

AIM:

To write the program for Orthogonal Frequency Division

Multiplexing(OFDM)transceiver and simulate it using MATLAB.

APPARATUS REQUIRED:

MATLAB software

Personal Computer

ALGORITHM:

1. Start the program. 2. Get the values of G, Kmax, Kmin and Fs. 3. Run the program. 4. Encode by format. 5. Plot the graph. 6. Stop the program.

THEORY:

OFDM TRANSMITTER

In an OFDM schemes , a large number of orthogonal ,overlapping, narrow band sub

channel or sub carriers,transmitted in parallel, divide the available transmission bandwidth.

The separation of the sub carriers is theoretically minimal such that there is a very compact

spectral utilization. The attraction of OFDM is mainly due to how the system handles the

multipath interference at the receiver. Multipath generated two effects :frequency selective

fading and intersymbol interference.

OFDM RECEIVER

The design of OFDM receivers is open , there are only transmission standards. With

an open receiver design, most of the research and innovations are done in the receiver. For

example the frequency sensitivity drawback is mainly a transmission channel predicting

issues, something that is done in the receiver.

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OUTPUT:

TRANSMITTER

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PROGRAM:

OFDM TRANSMITTER:

%DVB-T 2K Transmission

%The available bandwidth is 8 MHz

%2K is intended for mobile services

clearall;

closeall;

%DVB-T Parameters

Tu=224e-6; %useful OFDM symbol period

T=Tu/2048; %baseband elementary period

G=0; %choice of 1/4, 1/8, 1/16, and 1/32

delta=G*Tu; %guard band duration

Ts=delta+Tu; %total OFDM symbol period

Kmax=1705; %number of subcarriers

Kmin=0;

FS=4096; %IFFT/FFT length

q=10; %carrier period to elementary period ratio

fc=q*1/T; %carrier frequency

Rs=4*fc; %simulation period

t=0:1/Rs:Tu;

%Data generator (A)

M=Kmax+1;

rand('state',0);

a=-1+2*round(rand(M,1)).'+i*(-1+2*round(rand(M,1))).'; A=length(a);

info=zeros(FS,1);

info(1:(A/2)) = [ a(1:(A/2)).']; %Zero padding

info((FS-((A/2)-1)):FS) = [ a(((A/2)+1):A).'];

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%Subcarriers generation (B)

carriers=FS.*ifft(info,FS); tt=0:T/2:Tu;

figure(1);

subplot(2,1,1);

stem(tt(1:20),real(carriers(1:20)));

subplot(2,1,2);

stem(tt(1:20),imag(carriers(1:20))); figure(2);

f=(2/T)*(1:(FS))/(FS); subplot(2,1,1);

plot(f,abs(fft(carriers,FS))/FS); subplot(2,1,2);

pwelch(carriers,[],[],[],2/T);

% D/A simulation

L = length(carriers);

chips = [ carriers.';zeros((2*q)-1,L)]; p=1/Rs:1/Rs:T/2;

g=ones(length(p),1); %pulse shape figure(3);

stem(p,g);

dummy=conv(g,chips(:));

u=[dummy(1:length(t))]; % (C) figure(4);

subplot(2,1,1);

plot(t(1:400),real(u(1:400))); subplot(2,1,2);

plot(t(1:400),imag(u(1:400))); figure(5);

ff=(Rs)*(1:(q*FS))/(q*FS); subplot(2,1,1);

plot(ff,abs(fft(u,q*FS))/FS); subplot(2,1,2);

pwelch(u,[],[],[],Rs);

[b,a] = butter(13,1/20); %reconstruction filter

[H,F] = FREQZ(b,a,FS,Rs);

figure(6);

plot(F,20*log10(abs(H)));

uoft = filter(b,a,u); %baseband signal (D)

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figure(7);

subplot(2,1,1);

plot(t(80:480),real(uoft(80:480))); subplot(2,1,2);

plot(t(80:480),imag(uoft(80:480))); figure(8);

subplot(2,1,1);

plot(ff,abs(fft(uoft,q*FS))/FS); subplot(2,1,2);

pwelch(uoft,[],[],[],Rs);

%Upconverter

s_tilde=(uoft.').*exp(1i*2*pi*fc*t);

s=real(s_tilde); %passband signal (E)

figure(9);

plot(t(80:480),s(80:480)); figure(10);

subplot(2,1,1);

%plot(ff,abs(fft(((real(uoft).').*cos(2*pi*fc*t)),q*FS))/FS);

%plot(ff,abs(fft(((imag(uoft).').*sin(2*pi*fc*t)),q*FS))/FS);

plot(ff,abs(fft(s,q*FS))/FS);

subplot(212);

%pwelch(((real(uoft).').*cos(2*pi*fc*t)),[],[],[],Rs);

%pwelch(((imag(uoft).').*sin(2*pi*fc*t)),[],[],[],Rs);

pwelch(s,[],[],[],Rs);

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OFDM RECEIVER:

%DVB-T 2K Reception

clearall;

closeall;

Tu=224e-6; %useful OFDM symbol period

T=Tu/2048; %baseband elementary period

G=0; %choice of 1/4, 1/8, 1/16, and 1/32

delta=G*Tu; %guard band duration

Ts=delta+Tu; %total OFDM symbol period

Kmax=1705; %number of subcarriers

Kmin=0;

FS=4096; %IFFT/FFT length

q=10; %carrier period to elementary period ratio

fc=q*1/T; %carrier frequency

Rs=4*fc; %simulation period

t=0:1/Rs:Tu;

tt=0:T/2:Tu;

%Data generator

sM = 2;

[x,y] = meshgrid((-sM+1):2:(sM-1),(-sM+1):2:(sM-1)); alphabet = x(:) + 1i*y(:);

N=Kmax+1;

rand('state',0);

a=-1+2*round(rand(N,1)).'+i*(-1+2*round(rand(N,1))).'; A=length(a);

info=zeros(FS,1);

info(1:(A/2)) = [ a(1:(A/2)).'];

info((FS-((A/2)-1)):FS) = [ a(((A/2)+1):A).']; carriers=FS.*ifft(info,FS);

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OUTPUT:

RECEIVER

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%Upconverter

L = length(carriers);

chips = [ carriers.';zeros((2*q)-1,L)]; p=1/Rs:1/Rs:T/2;

g=ones(length(p),1);

dummy=conv(g,chips(:));

u=[dummy; zeros(46,1)];

[b,aa] = butter(13,1/20);

uoft = filter(b,aa,u);

delay=64; %Reconstruction filter delay

s_tilde=(uoft(delay+(1:length(t))).').*exp(1i*2*pi*fc*t);

s=real(s_tilde);

%OFDM RECEPTION

%Downconversion

r_tilde=exp(-1i*2*pi*fc*t).*s; %(F) figure(1);

subplot(2,1,1);

plot(t,real(r_tilde));

axis([0e-7 12e-7 -60 60]); grid on;

figure(1);

subplot(2,1,2);

plot(t,imag(r_tilde));

axis([0e-7 12e-7 -100 150]); grid on;

figure(2);

ff=(Rs)*(1:(q*FS))/(q*FS); subplot(2,1,1);

plot(ff,abs(fft(r_tilde,q*FS))/FS); grid on;

figure(2);

subplot(2,1,2);

pwelch(r_tilde,[],[],[],Rs);

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%Carrier suppression

[B,AA] = butter(3,1/2);

r_info=2*filter(B,AA,r_tilde); %Baseband signal continuous-time (G)

figure(3);

subplot(2,1,1);

plot(t,real(r_info));

axis([0 12e-7 -60 60]); grid on;

figure(3);

subplot(2,1,2);

plot(t,imag(r_info));

axis([0 12e-7 -100 150]); grid on;

figure(4);

f=(2/T)*(1:(FS))/(FS); subplot(2,1,1);

plot(ff,abs(fft(r_info,q*FS))/FS); grid on;

subplot(2,1,2);

pwelch(r_info,[],[],[],Rs);

%Sampling

r_data=real(r_info(1:(2*q):length(t)))... %Baseband signal, discrete-time

+1i*imag(r_info(1:(2*q):length(t))); % (H)

figure(5);

subplot(2,1,1);

stem(tt(1:20),(real(r_data(1:20)))); axis([0 12e-7 -60 60]);

gridon;

figure(5);

subplot(2,1,2);

stem(tt(1:20),(imag(r_data(1:20)))); axis([0 12e-7 -100 150]);

gridon;

figure(6); f=(2/T)*(1:(FS))/(FS); subplot(2,1,1);

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plot(f,abs(fft(r_data,FS))/FS); grid on;

subplot(2,1,2);

pwelch(r_data,[],[],[],2/T);

%FFT

info_2N=(1/FS).*fft(r_data,FS); % (I)

info_h=[info_2N(1:A/2) info_2N((FS-((A/2)-1)):FS)];

%Slicing

for k=1:N,

a_hat(k)=alphabet((info_h(k)-alphabet)==min(info_h(k)-alphabet));

end;

figure(7)

plot(info_h((1:A)),'.k');

title('info-h Received Constellation')

axissquare;

axisequal;

figure(8)

plot(a_hat((1:A)),'or');

title('a_hat 4-QAM')

axissquare;

axisequal;

gridon;

axis([-1.5 1.5 -1.5 1.5]);

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RESULT:

Thus the Orthogonal Frequency Division Multiplexing (OFDM) Transceiver was simulated in

MATLAB.

74

EX.NO:9 SIMULATION OF MICROSTRIP ANTENNA

AIM:

To design and test the Microstrip antenna using MATLAB.

REQUIREMENTS:


ALGORITHM:

1. Enter the dielectric constant value, the resonant frequency value in GHz, height of the micro-strip antenna in mm and width of the micro-strip antenna in cm.

2. Effective dielectric constant of micro-strip is Calculated and displayed. 3. Increase in length of micro-strip in cm is Calculated and displayed. 4. Length of micro-strip in cm is Calculated and displayed. 5. Effective length of micro-strip in cm is Calculated and displayed. 6. The program is run and output is visualized in the command window.

THEORY:

Micro strip radiation can be transmitted through space or through the atmosphere in a

microwave beam from a microwave antenna and the microwave energy can be collected with

a microwave antenna.

Microwave antennas are used for transmitting and receiving the microwave are used

for transmitting and receiving the microwave radiation. Microwave antenna are usually

essential parts of microwave telecommunication systems. Microwave antennas are as

antennas typically comprise an open ended wave guide and a parabolic reflector or horn and

they typically transmit a predetermined frequency in a predetermined direction. Microwave

antennas are usually equipped with a reflector having a structure of predetermined shape on

which is placed a micro of reflecting microwaves. The structure and the mirror are supported

by a frame mainly formed of tubes welded together or of welded or viveted compartments.

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OUTPUT:

Enter the dielectric constant value=25

Enter the resonant frequency value in ghz:15

Enter the height of the Microstrip antenna in mm:20

Width of the Microstrip in cm=

w = 0.2774

ereff = 13.4077

The effective dielectric constant of the Microstrip=

ereff =

13.4077

increase in length of the Microstrip in cm=

inclen =

2.8865

Length of the Microstrip in cm=

len =

-5.5000

Effective length of the Microstrip in cm=

leff =

0.2731

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PROGRAM:

clc;

clearall;

er=input('Enter the dielectric constant value=');

fr=input('Enter the resonant frequency value in ghz:');

h=input('Enter the height of the microstrip antenna in mm:');

c=30;%10^9cm/sec

%--------------width calculation-------------

w=((sqrt(2/(er+1))*c)/(2*fr));

display('Width of the microstrip in cm=');

display(w);

%----------dielectric constant calculation----------

wbyh=w/h;

ereff=((er+1)/2)+((er-1)/2)*(1+12*1/wbyh)^-0.5

display('The effective dielectric constant of the microstrip=');

display(ereff);

%---------increase in length calculation--------------

a=((ereff+0.3)/(ereff-0.258));

b=((wbyh+0.264)/(wbyh+0.813));

inclen=0.412*h*a*b;

display('increase in length of the microstrip in cm=');

display(inclen);

%----------length------------

len=(c/(2*fr*sqrt(ereff)))-(2*inclen);

display('Length of the microstrip in cm=');

display(len);

%------------effective length of microstrip----

leff=len+(2*inclen);

display('Effective length of the microstrip in cm=');

display(leff);

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RESULT:

Thus the Microstrip antenna was designed and tested by using MATLAB.

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EX.NO:10 PERFORMANCE EVALUATION OF SIMULATED CDMA

SYSTEM

AIM:

To evaluate the performance of CDMA using MATLAB.

REQUIREMENTS:


ALGORITHM:

1. Pseudo noise sequence is generated by using the maximum length sequence shift register of length = 3 and length of PN sequence is 7.

2. Random digital is generated by using maximum length sequence. 3. The spread message is modulated by using primary phase shift keying technique

and it is transmitted over AWGN channel.

4. The received message is demodulated and despread using correlation of the same PN sequence.

5. Bit Error Rate (BER) is calculated.

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PROGRAM:

clc;

clearall;

N=128;

M=32;

snr_db=0:15;

K=[0 10];

r1=(pi/4)*(exp(-K(1))/(K(1)+1))*((1+K(1))*besseli(0,K(1)/2)+K(1)*besseli(1,K(1)/2))^2;

r2=(pi/4)*(exp(-K(2))/(K(2)+1))*((1+K(2))*besseli(0,K(2)/2)+K(2)*besseli(1,K(2)/2))^2;

fori=1:length(snr_db)

snr=10^(snr_db(i)/10);

p_awgn(i)=(sqrt(snr));

p_ray(i)=(sqrt((pi/2)*(snr/(((2-pi/2)*snr/N)+(M-1)*snr/N)+1)));

p_rician1(i)=(sqrt((r1*snr)/((M*(1-r1)*snr)/N+1)));

p_rician2(i)=(sqrt((r2*snr)/((M*(1-r2)*snr)/N+1)));

end

figure(1);

semilogy(snr_db,p_awgn,'-*',snr_db,p_ray,'-^',snr_db,p_rician1,'-+',snr_db,p_rician2,'-+');

title('signal to noise ratio of AWGN,RAYLEIGH,RICIAN CHANNEL');

xlabel('10*log10SNR');

ylabel('Average error probability');

legend('AWGN','RAYLEIGH','K=0 RICIAN','K=10 RICIAN');

clearall;

snr_db=0:15;

p_ray1=ray(128,8);

p_ray2-ray(128,64);

p_ray3=ray(128,128);

figure(2);

semilogy(snr_db,p_ray1,'-+',snr_db,p_ray2,'-*',snr_db,p_ray3,'-^');

title('BER in rayleigh fading(number of users=8)');



legand('M=8 rayleigh','M=64 rayleigh','M=128 rayleigh');

clearall;

snr_db=0:15;

p_rician1=rician(128,8);



figure(3);

semilogy(snr_db,p_rician1,'-^',snr_db,p_rician2,'-*',snr_db,p_rician3,'-+');

title('BER in rician fading channel K=0(number of users=8)');



legand('M=8 rician','M=64 rician','M=128 rician');

clearall;

snr_db=0:15;




figure(4);

semilogy(snr_db,p_rician1,'-^',snr_db,p_rician2,'-*',snr_db,p_rician3,'-+');

title('BER in rician fading channel K=0(number of users=64)');



legand('M=64 rician','M=128 rician','M=256 rician');

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OUTPUT:

84

RESULT:

Thus the performance evaluation of CDMA system was done by using MATLAB.

Documents

ME full lab manual