DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGG.

www.arivurp.tk

CO5104 COMMUNICATION SYSTEM LABORATORY I

Ex no. 1.a) RADIATION PATTERN OF HALF WAVE DIPOLE ANTENNA

AIM:

To find out the radiation pattern of the half wave dipole antenna.

APPRATUS REQUIRED:

1. Transmitting antenna(ST2262)

2. Receiving antenna

3. UHF transmitter

4. Field strength meter

5. Angle measurement panel

THEORY:

The three dimensional view of the radiation pattern of a horizontal wave dipole notice that

minimum radiation occurs at the end of the antenna. The wavelength of the dipole is λ/2 along at the

operating frequency , the antenna appropriate length of the horizontal dipole is calculated from

1ft = 468/f MHz

The input resistance at center of the half wave dipole antenna is iriade peraent of the gap size of

frequency alone 14 Mhz . But it is selected to the antenna length of antenna.

The difference is the current at various part of antenna is compensated for variable experiment.

The antenna is lying in the horizontal plane.

So that the electric field is in a horizontal plane. Therefore antenna is horizontally polarized.

The pattern is sine wave function & appear as a true carrier in horizontal direction.

PROCEDURE:

Connect the VHF transmitter to transmit radiation which in fixed frequency of 110 Mhz.

Place receiver and transmitter antenna in a parallel direction.

Rotate the angular measurement & note the reading in field strength meter.

Plot the readings in graph.

RESULT:

Thus the radiation pattern of half wave dipole antenna was studied.

TABULATION:

ANGLE (Deg) GAIN IN dB

RF

GENERATOR

Half wave

dipole

TRANSMIT

TER MAST

Half wave

dipole

RECEIVING

MAST

RF

DETECTOR

EX.No.1b RADIATION PATTERN OFYAGI- UDA ANTENNA

AIM:

To find out the radiation pattern of Yagi-uda antenna.

APPRATUS REQUIRED:

1.Transmitting antenna(ST2262)

2.Receiving antenna

3.UHF transmitter

4.Field strength meter

5.Angle measurement panel

THEORY:

The Figure shows the three dimensional of very particular radiator in the HF (3-30MHz)

,UHF(300-3000MHz) in Yagi- uda antenna contains reflectors driven element or feeder element &

directs in the yagi- uda antenna only one element is driven (fed by transmission)(line). The rest being

parasilite elements energized by mutual coupling the reflector having a lagging phase & the directors

leading phase.

The most common fold element for a Yagi-uda antenna is folded Dipole. Thus radiator is

exclusive designed to operate as an end fire array. This is accomplished by having the parastic

elements as the forward beam act as directors while there is the rear act as reflectors. The driven

element is reason with its length slightly less than N2 (usually is resonant with where as the length of

directors will be about 0.4 to 0.45λ). The separation between the directors will the driven element the

reflector is optimum at 0.25λ.

The major role of the reflector is played by its element next to the one energized and very little

in the performance of yagi-uda antenna is gained and more than one cut the most for elements are used

as reflectors. Consideration of improvements can be achievement it, more directors are added to the

array.

The length of a diameter of line detectors & reflectors as well as their respective determine the

optimum radiation characteristic usually Yagi-uda array here. Low input impedance & relatively

narrow band width the Yagi – uda array is widely used as a home T.V.

PROCEDURE:

Connect the UHF transmitter to transmitting antenna which in fixed to a frequency of 150 Mhz.

Place receiver and transmitter antenna in a parallel direction.

Rotate the angular measurement& note the reading in field strength meter.

Plot the readings in graph.

RESULT:

Thus the radiation pattern of Yagi-uda antenna was studied.

TABULATION:

ANGLE (Deg) GAIN IN dB

RF

GENERATOR

yagi

TRANSMIT

TER MAST

yagi

RECEIVING

MAST

RF

DETECTOR

EX.No.1c RADIATION PATTERN O F LOOP ANTENNA

AIM:

To find out the radiation pattern of loop antenna.

APPRATUS REQUIRED:

1.Transmitting antenna(ST2262)

2.Receiving antenna

3.UHF transmitter

4.Field strength meter

5.Angle measurement panel

THEORY:

Very versatile antenna type is the loop antenna. It is a small loop evaluation to an infinitesimal

Magnetic dipole where axis is perpendicular to the phase of the loop . Loop antenna takes many

different forms sum as rectangular, square, triangle, ellipse, circular & many other configurations.

Because of simplicity in analysis the construction. The circular loop is most popular and received the

widest attenuation.

The field pattern of electricity small antennas of any shape circular, elliptical, rectangular,

triangle, square etc., is similar to that of an infinitesimal dipole with a null to the plane of the loop

antenna as usually smaller than two resistances. Thus they are employed for transmission in radio

communication.

PROCEDURE:

1. Mount the loop antenna on the transmitting mast.

2. Mount detector antenna on the receiving mast. Keep it towards the transmitting mast to the

rotating it in counter clockwise direction.

3. Route the transmitting antenna behavior between 0-360 degree and observe the display at

RT detection.

4. Plot the readings on the graph.

RESULT:

Thus the radiation pattern of the loop antenna was studied.

TABULATION:

ANGLE (Deg) GAIN IN dB

RF

GENERATOR

loop

TRANSMIT

TER MAST

loop

RECEIVING

MAST

RF

DETECTOR

EX.No. 1d RADIATION PATTERN O F LOG PERODIC ANTENNA

AIM:

To draw the radiation pattern of log periodic antenna.

APPRATUS REQUIRED:

1. Transmitting antenna-(ST2262)

2. Receiving antenna

3. UHF transmitter

4. Field strength meter

5. Angle measurement panel

THEORY:

The main feature of this antenna is frequency impedance for both radiation & resistance pattern.

The radiation pattern may be unidirectional or bidirectional. Bandwidth of 10.1 is easily achievable.

The array consists of number of dipoles of different length and spacing, fed from a two wire

line which is transported between each adjustment pair of dipoles. The array is fed from the narrow end

and maximum. The radiation is in this direction.

PROCEDURE:

1. Mount the log periodic antenna on the transmitting mast.

2. Mount the detector antenna on the receiving mast keep its direction towards the

transmitting mast by rotating it in counter clockwise direction.

3. Rotate the transmitting antenna between 0-360 degree and observe the display at RF

detection .

4. Plot the reading on the graph.

RESULT:

Thus the rotation pattern of log periodic antenna was studied.

TABULATION:

ANGLE (Deg) GAIN IN dB

RF

GENERATOR

Log periodic

TRANSMIT

TER MAST

Log periodic

RECEIVING

MAST

RF

DETECTOR

BER SIMULATION OF BPSK IN AWGN CHANNEL AIM: To simulate the BER of BPSK modulation scheme (theoretical and practical)

value over AWGN channel using MATLAB.

SOFTWARE REQUIRED: Matlab 7.1

ALGORITHM:

TRANSMITTER SECTION: Define the number of information bits.

Generate the data using desired information

Initialize the SNR data

Raise the amplitude level of information bits and multiply with the generated

data.

CHANNEL SECTION: Take decision by comparing the received signal and the transmitted signal.

Count the errors between the transmitted and received signal.

Calculate the bit error rate.

Calculate the probability of error for the mean BER.

Calculate the BER theoretical calculation for the above modulation.

Plot the semi log graph between the BER and SNR in dB for practical and

theoretical modulation for BPSK modulation.

clc; clear all; close all; N=10^6; d=rand(1,N)>0.5; s=2*d-1; Eb_N0_dB=1:1:10; n=1/sqrt(2)*[randn(1,N)+j*randn(1,N)]; for ii=1:length(Eb_N0_dB) y=s+10^(-Eb_N0_dB(ii)/20)*n; ipHat=real(y)>0; nErr(ii)=size(find([d-ipHat]),2); end BER=nErr/N; figure(2) snrindb=1:10; semilogy (snrindb,BER,'g-v'); hold on; theoryBer=0.5*erfc(sqrt(10.^(snrindb/10)));

semilogy (snrindb,theoryBer,'r--'); grid on; title('BER OF BPSK MODULATION'); xlabel('SNR in dB'); ylabel('BER'); legend('BER-practical','BER-theoritical')

1 2 3 4 5 6 7 8 9 1010

-6

10-5

10-4

10-3

10-2

10-1

BER OF BPSK MODULATION

SNR in dB

BE

R

BER-practical

BER-theoritical

RESULT: Thus the simulations of BER of BPSK modulation were observed over

AWGN channel.

STUDY OF SPREAD SPECTRUM TECHNIQUES FOR

DSSS IN ASK MODULATION AIM: To simulate the direct spread spectrum techniques for amplitude shift keying

using MATLAB.

SOFTWARE REQUIRED: MATLAB 7.1

ALGORITHM:

Get the values for the input signal so in order to generate the carrier

signal.

Enter the length of input data.

Get the values of PN sequence N=T.

Generate the PN sequence and plot the graph.

Generate the value of data and enter the length of the data.

Get the spread spectrum sequence for the above generated sequence.

Multiply the data and PN sequence and get the direct spread spectrum

sequence.

End the program by plotting the spread spectrum response for DSSS.

FORMULA:

S0=sqrt (2*Eb/T0)*cos (2*pi*fc*t)

STUDY OF SPREAD SPECTRUM TECHNIQUES

DIRECT SPREAD SPECTRUM

clc; close all; clear all; Tb=0.01; n=10; fc=n/Tb; ebdb=5; N=input('Enter the length of data'); Eb=10^(ebdb/20); t=0.0011:0.0001:(N*Tb); tt=length(t) s0=sqrt(2*Eb/Tb)*cos(2*pi*fc*t);

subplot(5,1,1); plot(s0);

pn=[1 1 1 0 1 0 0] Nq=length(pn) Mq=[1:1:Nq]; t1q=0:0.00009:Tb/7; uq=length(t1q); iq=[1:1:Nq]; for iq=1:1:Nq ikq=Mq(iq); if pn(ikq)==1 kkq(:,ikq)=linspace(1,1,uq-2);

else kkq(:,ikq)=linspace(0,0,uq-2); end end dsq=reshape(kkq,1,[]); subplot(5,1,2); plot(dsq)

M=[1:1:N]; data=randn(1,N)>0.5; t1=0.0003:0.0001:Tb; u=length(t1); i=[1:1:N]; for i=1:1:N ik=M(i); if data(ik)==1 kk(:,ik)=linspace(1,1,u); ch(:,ik)=dsq; else

kk(:,ik)=linspace(0,0,u); ch(:,ik)=linspace(0,0,u); end end data ds=reshape(kk,1,[]); subplot(5,1,3); plot(ds) chs=reshape(ch,1,[]); subplot(5,1,4); plot(chs)

subplot(5,1,5); dsss=s0.*chs; plot(dsss)

OUTPUT

0 50 100 150 200 250 300 350 400 450 500-20

0

20

0 10 20 30 40 50 60 70 80 90 1000

0.5

1

0 50 100 150 200 250 300 350 400 450 5000

0.5

1

0 50 100 150 200 250 300 350 400 450 5000

0.5

1

0 50 100 150 200 250 300 350 400 450 500-20

0

20

RESULT: Hence the simulation of direct spread spectrum sequence for ASK modulation

were observed using MATLAB.

BER SIMULATION OF BPSK IN AWGN CHANNEL AIM: To simulate the BER of BPSK modulation scheme (theoretical and practical)

value over AWGN channel using MATLAB.

SOFTWARE REQUIRED: Matlab 7.1

ALGORITHM: TRANSMITTER SECTION:

Define the number of information bits.

Generate the data using desired information

Initialize the SNR data

Raise the amplitude level of information bits and multiply with the generated

data.

CHANNEL SECTION: Take decision by comparing the received signal and the transmitted signal.

Count the errors between the transmitted and received signal.

Calculate the bit error rate.

Calculate the probability of error for the mean BER.

Calculate the BER theoretical calculation for the above modulation.

Plot the semi log graph between the BER and SNR in dB for practical and

theoretical modulation for BPSK modulation.

PROGRAM:

clc; close all; clear all; Tb=0.01; n=10; fc=n/Tb; ebdb=5;

%GENERATION OF CARRIER SSIGNAL N=input('Enter the length of data'); Eb=10^(ebdb/20); t=0.0011:0.0001:(N*Tb); tt=length(t) s0=sqrt(2*Eb/Tb)*cos(2*pi*fc*t); subplot(5,1,1);

plot(s0); title('CARRIER SIGNAL');

%GENERATION OF PN SEQUENCE pn=[1 1 1 0 1 0 0] Nq=length(pn) Mq=[1:1:Nq]; t1q=0:0.00009:Tb/7; uq=length(t1q); iq=[1:1:Nq]; for iq=1:1:Nq ikq=Mq(iq); if pn(ikq)==1 kkq(:,ikq)=linspace(1,1,uq-2); kkq1(:,ikq)=linspace(1,1,uq-2); else kkq(:,ikq)=linspace(0,0,uq-2); kkq1(:,ikq)=linspace(-1,-1,uq-2);

end end dsq=reshape(kkq,1,[]); dsq1=reshape(kkq1,1,[]); subplot(5,1,2); plot(dsq) title('PN SEQUENCE');

%GENERATION OF DATA SEQUENCE M=[1:1:N]; data=randn(1,N)> 0.5; t1=0.0003:0.0001:Tb; u=length(t1); i=[1:1:N]; for i=1:1:N ik=M(i); if data(ik)==1 kk(:,ik)=linspace(1,1,u); ch(:,ik)=dsq; ch1(:,ik)=dsq1; else kk(:,ik)=linspace(0,0,u); ch(:,ik)=linspace(0,0,u); ch1(:,ik)=linspace(-1,-1,u); end end data ds=reshape(kk,1,[]); subplot(5,1,3); plot(ds) title('DATA SEQUENCE');

%GENERATION OF SPREAD SPECTRUM SEQUENCE chs=reshape(ch,1,[]); subplot(5,1,4); plot(chs) title('SPREAD SPECTRUM SEQUENCE');

%GENERATION OF BPSK SEQUENCE chs1=reshape(ch1,1,[]);

subplot(5,1,5); dsss=s0.*chs1; plot(dsss) xlabel('TIME PERIOD---->'); ylabel('AMPLITUDE------>'); title('DSSS IN BPSK');

OUTPUT

0 50 100 150 200 250 300 350 400 450 500-20

0

20CARRIER SIGNAL

0 10 20 30 40 50 60 70 80 90 1000

0.5

1PN SEQUENCE

0 50 100 150 200 250 300 350 400 450 5000

0.5

1DATA SEQUENCE

0 50 100 150 200 250 300 350 400 450 5000

0.5

1SPREAD SPECTRUM SEQUENCE

0 50 100 150 200 250 300 350 400 450 500-20

0

20

TIME PERIOD---->AM

PLIT

UD

E--

----

>

DSSS IN BPSK

RESULT: Thus the simulations of BER of BPSK modulation were observed over

AWGN channel.

LINEAR BLOCK CODE AIM:

To simulate the linear block code using MATLAB. SOFTWARE REQUIRED:

MATLAB 7.1

ALGORITHM: Clear the command window using clc

Enter the generator matrix

Perform the length of codeword (n) & number of message bits (k) from

input generator matrix.

Generate the 2k possible messages and display the command window.

Determine the codeword (x) using the formula x=mG & also calculate

weight of the each code words.

Display the minimum hamming distance (dmin) &cordword x.

Enter the received vector r

Obtain the parity check matrix (H)

Display the syndrome using S=YHT & corrected codeword.

.

PROGRAM:

clc; clear all; close all; % Input Generator Matrix g=input('Enter The Generator Matrix: ') disp ('G = ') disp ('The Order of Linear block Code for given Generator Matrix is:') [n,k] = size(transpose(g)) for i = 1:2^k

for j = k:-1:1 if rem(i-1,2^(-j+k+1))>=2^(-j+k)

u(i,j)=1; else

u(i,j)=0; end

end end u; disp('The Possible Codewords are :') c = rem(u*g,2) disp('The Minimum Hamming Distance dmin for given Block Code is= ') d_min = min(sum((c(2:2^k,:))'))

% Code Word r = input('Enter the Received Code Word:') p = [g(:,n-k+2:n)]; h = [transpose(p),eye(n-k)]; disp('Hammimg Code') ht = transpose(h) disp('Syndrome of a Given Codeword is :') s = rem(r*ht,2) for i = 1:1:size(ht)

if(ht(i,1:3)==s) r(i) = 1-r(i);

break; end

end disp('The Error is in bit:') i disp('The Corrected Codeword is :') r

OUTPUT:

Enter The Generator Matrix: [1 0 0 0 1 0 1;0 1 0 0 1 1 1;0 0 1 0 1 1 0;0 0 0 1 0 1 1]

g =

1 0 0 0 1 0 1

0 1 0 0 1 1 1

0 0 1 0 1 1 0

0 0 0 1 0 1 1

G = The Order of Linear block Code for given Generator Matrix is:

n =7

k =4

The Possible Codewords are :

c =

0 0 0 0 0 0 0

0 0 0 1 0 1 1

0 0 1 0 1 1 0

0 0 1 1 1 0 1

0 1 0 0 1 1 1

0 1 0 1 1 0 0

0 1 1 0 0 0 1

0 1 1 1 0 1 0

1 0 0 0 1 0 1

1 0 0 1 1 1 0

1 0 1 0 0 1 1

1 0 1 1 0 0 0

1 1 0 0 0 1 0

1 1 0 1 0 0 1

1 1 1 0 1 0 0

1 1 1 1 1 1 1

The Minimum Hamming Distance dmin for given Block Code is=

d_min =3

Enter the Received Code Word:[1 1 1 0 0 0 0]

r =1 1 1 0 0 0 0

RESULT: Hence the simulation of Linear block code were observed using MATLAB

COMMUNICATION LINK THROUGH FIBER

EX.NO- FIBER OPTIC ANALOG LINK

AIM:

To study & construct the analog link through fiber optic cable using 660nm, 850nm&1300nm

LED sources

APPARATUS REQUIRED:

Transmitter trainer kit

Receiver trainer kit

Step index multimode plastic fiber

Patch cards

THEORY:

TARNSMITTER:

Fiber optic transmitter consists of the following,

Buffer

Preamplifier

Driver circuit

Optical source

Function generator

Buffer provides both an electrical connection and isolation between the transmitter & the electrical

system supplying data. The driver provides the electrical power to the optical source to convert the

electrical current to the light energy.

RECEIVER:

Optical power transmitted by the transmitter is detected by photo diode or photo transmitter. And it is

also used to convert the light from the fiber cable into electrical current.

PROCEDURE: 1. Patch the circuit as per patching diagram. 2. Switch on the trainer kit & verify the function generator using CRO. 3. Connect the CRO CH1 at the input of driver circuit (Analog). 4. Now connect the CRO CH2 at the input of AC amplifier in receiver & verify the transmitted signal

received on the receiver side 5. Change the frequency & amplitude of the input signal which is going to be transmit through the fiber

optic cable & verify the corresponding changes in receiver using CRO in dual mode operation. 6. Set the amplitude of input signal to 5v &set the same receiver voltage. 7. Now change the LED source from 660nm to 850 nm & verify the changes in receiver output.

RESULT:

Thus the analog link through fiber optic cable was constructed and studied.

TABULATION:

MODEL GRAPH:

S.NO

AMPLITUDE TIME

EX.NO FIBER OPTIC DIGITAL LINK

AIM:

To study &construct the digital link through fiber optic cable using 660nm, 850nm&1300nm LED

sources

APPARATUS REQUIRED:

Transmitter trainer kit

Receiver trainer kit

Step index multimode plastic fiber

Patch cards

THEORY:

TARNSMITTER:

Fiber optic transmitter consists of the following,

Buffer

Preamplifier

Driver circuit

Optical source

Function generator

Buffer provides both an electrical connection and isolation between the transmitter & the electrical

system supplying data. The driver provides the electrical power to the optical source to convert the

electrical current to the light energy.Here the driver circuit is designed as ON &OFF according to the

input data that means when the data is high the LED goes to glow. When data is low it goes to OFF.

RECEIVER:

Optical power transmitted by the transmitter is detected by photo diode or photo transmitter. And it is

also used to convert the light from the fiber cable into electrical current. In digital signal transmission

the detected signal is not clear digital data .so that the detected output is given to the comparator& the

data is taken out on it’s output.

PROCEDURE: 1. Patch the circuit as per patching diagram. 2. Switch on the trainer &verify the function generator using CRO. 3. Connect the CRO CH1 at the input of driver circuit 4. Now connect the CRO CH2 at the output of comparator in receiver &verify the transmitted signal

received on the receiver side 5. Change the frequency &amplitude of the input signal which is going to be transmit through the fiber

optic cable &verify the corresponding changes in receiver using CRO in dual mode operation.

RESULT:

Thus the digital link through fiber optic cable was constructed and studied.

TABULATION:

MODEL GRAPH:

S.NO

AMPLITUDE TIME

IMPLEMENTATION OF ADAPTIVE FILTER USING DSP PROCESSOR

Ex.No.

Date:

OBJECTIVE:

To implement of Adaptive Filter using the instructions of TMS320c50.

AIM:

To write a assembly language program to calculate the Fast Fourier transform for the

given sequence

Apparatus Required:

MATLAB 7.1

PROGRAM

.mmregs

.text

B START

CTABLE:

.word 0FF82H

.word 083H

.word0167H

.word01CFH

.word0188H

.word09DH

.word0FF5BH

.word0FE38H

.word0FDACH

.word0FE01H

.word0FF31H

.word0DEH

.word0271H

.word0342H

.word02DDH

.word0132H

.word0FEADH

.word0FC20H

.word0FA92H

.word0FAEEH

.word0FDB6H

.word02CCH

.word096AH

.word0104CH

.word015F9H

.word0192EH

.word0192EH

.word015F9H

.word0104CH

.word096AH

.word02CCH

.word0FDB6H

.word0FAEEH

.word0FA92H

.word0FC20H

.word0FEADH

.word0132H

.word02DDH

.word0342H

.word0271H

.word0DEH

.word0FF31H

.word0FE01H

.word0FDACH

.word0FE38H

.word0FF5BH

.word09DH

.word0188H

.word01CFH

.word0167H

.word083H

.word0FF82H

*

Move the filter coefficients

from program memory to data memory

*

START

MAR *,AR0

LAR AR0,#0200H

RPT #33H

BLKP CTABLE,*+

SETC CNF

*Input data and perform convolution

LAR AR0,#4H

ISR:

LDP #0AH

LACC #0

SACL 0

OUT 0,05

MAR *,AR0

BANZ INC0,*-

IN 0,06H

LAR AR7,#0

MAR *,AR7

BACK:

BANZ BACK,*-

RPT #10H

IN 0,4

LAR AR0,#4H

B STORE

INC0: SPLK #0H,0H

RPT #15H

NOP

STORE:

NOP

NOP

NOP

NOP

MAR *,AR1

LAR AR1,#0300H

LACC 0

AND #0FFFH

SUB #800H

SACL *

LAR AR1,#333H

MPY #0

ZAC

RPT #33H

MACD 0FF00H,*-

APAC

LAR AR1,#0300H

SACH *

LACC *

ADD #800H

SFR

SACL *

OUT *,4

LACC #0FFFH

SACL 0

OUT 0,05

NOP

B ISR

.end

RESULT:

Thus assembly language program to perform Adaptive filter was written and executed

successfully

IMPLEMENTATION OF MULTIRATE SIGNAL PROCESSING USING DSP PROCESSOR

Ex.No.

Date:

OBJECTIVE:

To implement of Multirate Signal Processing using the instructions of TMS320c50.

AIM:

To write a assembly language program to calculate Multirate Signal Processing for the

given sequence

Apparatus Required:

MATLAB 7.1

PROGRAM

.mmregs

.text

B START

CTABLE:

.word 0FF82H

.word 083H

.word0167H

.word01CFH

.word0188H

.word09DH

.word0FF5BH

.word0FE38H

.word0FDACH

.word0FE01H

.word0FF31H

.word0DEH

.word0271H

.word0342H

.word02DDH

.word0132H

.word0FEADH

.word0FC20H

.word0FA92H

.word0FAEEH

.word0FDB6H

.word02CCH

.word096AH

.word0104CH

.word015F9H

.word0192EH

.word0192EH

.word015F9H

.word0104CH

.word096AH

.word02CCH

.word0FDB6H

.word0FAEEH

.word0FA92H

.word0FC20H

.word0FEADH

.word0132H

.word02DDH

.word0342H

.word0271H

.word0DEH

.word0FF31H

.word0FE01H

.word0FDACH

.word0FE38H

.word0FF5BH

.word09DH

.word0188H

.word01CFH

.word0167H

.word083H

.word0FF82H

*

Move the filter coefficients

from program memory to data memory

*

START

MAR *,AR0

LAR AR0,#0200H

RPT #33H

BLKP CTABLE,*+

SETC CNF

*Input data and perform convolution

LAR AR0,#4H

ISR:

LDP #0AH

LACC #0

SACL 0

OUT 0,05

IN 0,06H

LAR AR7,#0

MAR *,AR7

BACK:

BANZ BACK,*-

IN 0,4

NOP

NOP

NOP

NOP

MAR *,AR1

LAR AR1,#0300H

LACC 0

AND #0FFFH

SUB #800H

SACL *

LAR AR1,#0300H

LACC 0

AND #0FFFH

SUB #800H

SACL *

LAR AR1,#333H

MPY #0

ZAC

RPT #33H

MACD 0FF00H,*-

APAC

LAR AR1,#0300H

SACH *

LACC *

ADD #800H

SFR

SACL *

MAR *,AR0

BANZ NO_OUT,*-

MAR *,AR0

BANZ NO_OUT,*-

MAR *,AR1

OUT *,4

LAR AR0,#4H

NO_OUT:

LACC #0FFH

SACL 0

OUT 0,05

NOP

B ISR

.end

RESULT:

Thus assembly language program to perform Multirate Signal Processing

was written and executed successfully.

EX.NO:08

CALCULATION OF FFT USING TMS320C50

OBJECTIVE:

To implement the processing technique for calculation of FFT using the instructions of

TMS320c50.

AIM:

To write a assembly language program to calculate the Fast Fourier transform for the

given sequence.

THEORY:

The fast fourier transform (FFT) is an algorithm used to compute the DFT with minimum number of

calculations. It makes use of the symmetry and periodicity properties of twiddle factor Wk

N to

effectively reduce the DFT computation time. It is based on the fundamental principal of decomposing

the computation of DFT of a sequence of length ‘N’ into successively smaller discrete Fourier

transforms.

The FFT algorithm provides speed-increase factors, when compared with direct computation of

the DFT.

The direct evaluation of DFT using the formula

requires N

2 complex multiplications and N (N-1) complex additions. Thus for reasonably large values

of N (in the order of 1000) direct evaluation of the DFT requires an inordinate amount of computation.

By using FFT algorithms the number of computations can be reduced. For example, for an N-point

DFT, the number of complex multiplications required using FFT is N 2 log2 N. If N=16, the number

of complex multiplications required for direct evaluation of DFT is 256, whereas using FFT only 32

multiplications are required.

Two Types of FFT :

1. Decimation in time ( DIT ) Algorithm :

Decimation in-time algorithm is used to calculate the DFT of a N-point sequence. The idea is to

break the N-point sequence into two sequences, the DFTs of which can be combined to give the DFT

of the original N-point sequence. Initially the N-point sequence is divided into two N 2 –point

sequences xe(n) and xo(n), which have the even and odd members of x(n) respectively. The N 2 –point

DFTs of these two sequences are evaluated and combined to give the N-point DFT. Similarly the N 2 –

point DFTs can be expressed as a combination of N 4 –point DFTs. This process is continued until we

left with 2-point DFT. This algorithm is called decimation-in-time because the sequence x(n) is often

splited into smaller subsequences.

2. Decimation-in-frequency algorithm :

It is a popular form of the FFT algorithm. In this the output sequence x(k) is divided into

smaller and smaller subsequences, that is why the name decimation in frequency. Initially the input

sequence x(n) is divided into two sequences x1(n) and x2(n) consisting of the first N 2 – samples of

x(n) and the last N 2 – samples of x(n) respectively. Then we find the N 2 – point sequences f(n) and

g(n) as

f(n) = x1(n) + x2(n) and g(n) = [x1(n) - x2(n)]WnN

The N 2 – point DFTs of the above two sequences give even numbered and odd numbered output

samples respectively.

The above procedure can now be iterated to express each N 2 – point DFT as a combination of two N

4 – point DFTs. This process is continued until we left with 2-point DFT.

PROGRAM:

IN .set 8010H

BITREV .set 8020H

REAL .set 8040H

IMG .set 8050H

.MMREGS

.TEXT

LDP #100H

LAR AR1,#IN

LAR AR2,#BITREV

SPLK #2H,05H

LMMR INDX,#8005H

MAR *,AR2

RPT #3H

BLDD #IN,*BR0+

LAR AR2,#BITREV

LAR AR3,#8030H

LAR AR0,#1H

FFT1: MAR *,AR2

LACC *+

SACB

LT *+

MPY #1H

APAC

MAR *,AR3

SACL *+

LACB

SPAC

SACL *+,AR0

BANZ FFT1,*-

LAR AR3,#8030H

LAR AR4,#REAL

LAR AR5,#IMG

MAR *,AR3

LACC *

SACB

ADRK #2H

LT *-

MPY #1H

APAC

MAR *,AR4

SACL *

ADRK #2H

LACC #0H

MAR *,AR5

SACL *

ADRK #2H

LACB

SPAC

MAR *,AR4

SACL *-

LACC #0H

MAR *,AR5

SACL *-,AR3

LACC *,AR4

SACL *

ADRK #2H

SACL *,AR3

ADRK #2H

LT *

MPY #0FFFFH

MAR *,AR5

SPL *,AR3

LT *

MPY #1H

MAR *,AR5

ADRK #2H

SPL *

H: B H

RESULT:

Thus assembly language program to perform FFT was written and executed successfully

www.arivurp.tk

INPUT:

8010-0001

8011-0001

8012-0000

8013-0000

BIT_REV:

8020-0001

8021-0000

8022-0001

8023-0000

FFT1:

8030-0001

8031-0001

8032-0001

8033-0001

REAL:

8040-0002

8041-0001

8042-0000

8043-0001

IMG:

8050-0000

8051-FFFF

8052-0000

8053-0001