SHANMUGHAARTS, SCIENCE, TECHNOLOGY AND RESEARCH ACADEMY

(SASTRA University)TIRUMALAISAMUDRAM THANJAVUR 613 402.

COURSE CODE COURSE NAME

: BECCEC 606 : COMMUNICATION LAB

BRANCH: ELECTRONICS AND COMMUNICATION ENGINEERING SEMESTER: VI

COURSE CODE : BECCEC606 COURSE NAME : COMMUNICATION LABORATORY

LIST OF EXPERIMENTS: 1. a) Measurement of modulation index of Amplitude Modulation. b) Envelope detector. 2. a)FM wave generation b)FM demodulation using PLL. 3. Generation of PAM, PWM, PPM. 4. 5. 6. 7. 8. 9. Implementation of a correlator. Implementation of a Matched Filter. Testing of TDM. Carrier Recovery from a QPSK Signal. Detection of a symbol in spite of ISI using Duobinary coding. Manchester Coding, Decoding and Clock Recovery.

10. Implementation of DPSK, QPSK, ASK, FSK,QAM communication link. 11. Implementation of CDMA. 12. Propagation loss and Bending loss measurements in optical fiber.

Measurement of modulation index of Amplitude Modulation EXP. No: Date : AIM 1. To generate and study amplitude modulated waveform using emitter modulator circuit with the given carrier frequency f0 = 2. To plot the graph between modulating signal amplitude and modulation index 3. To find the modulation index for various modulating signal amplitudes 4. To find the modulation index using trapezoidal method APPARATUS REQUIRED Apparatus Sl.No. 1 2 3 4 5 6 7 BJT Resistor Capacitor Power supply AFO CRO DIB Type/ Range / Value BF 195 100, 220, 1K, 5.6K 10F, 0.02F (0 30)v Quantity 1 1 Each 2,1 1

CIRCUIT DIAGRAM

Design Given Carrier frequency fc = 16KHz Modulating frequency fs = 1KHz f c = 1/ 2LC Let C = 0.02f, Then L = 5mH PROCEDURE 1. Give the circuit connection as per the diagram 2. Measure the DC voltage at collector, base, and emitter with respect to reference ground 3. Apply the carrier to the base of the transistor and modulating signal to the emitter 4. Get the modulated waveform at the output using CRO and find modulation index using the formula: m = Emax Emin / Emax+ Emin 5. Vary the amplitude of the modulating signal and find the modulation index 6. Tabulate the readings 7. Plot the graphs of modulating signal, carrier signal and modulated signal 8. Also plot the graph between the modulated wave and modulation index TRAPEZOIDAL METHOD 1. Apply the modulated wave to channel A of the CRO and the modulating signal to channel B and keep the CRO Time/division knob in XY position. 2. Get the trapezoidal display of modulation and find the modulation index using the formula m = (L1 L2) / (L1 + L2) 3. For particular amplitude of the modulating signal find m and check whether it tallies with the graph. TABULATION Waveform No. of div in X axis Modulating signal Carrier signal Sl.No. Time/div Time No. of div in Y axis Amp/ div Amplitude in volts

Modulating signal amplitude Em

Modulated wave amplitude Emax (v) Emin (v)

Modulation index m

Sl.No.

Modulating signal amplitude Em

Modulated wave amplitude L1 L2

Modulation index m (L1 - L2) / (L1 + L2 )

MODEL GRAPH

RESULT

Envelope Detector EXP.NO: DATE : AIM 1. To detect the given AM signal by using envelope detector. 2. To plot the output waveforms APPARATUS REQUIRED Sl.NO. Apparatus Type / Range / Quantity Value 1 Diode 1N4001 1 2 Resistor 10K 1 3 Capacitor .01F 1 CIRCUIT DIAGRAM

PROCEDURE 1. Rig up the circuit as shown in the figure 2. Apply the AM signal 3. Observe the output in CRO 4. Plot the input and output waveforms. TABULATION Waveform No. of Time/div Time div in X axis Modulating signal Carrier signal Modulated signal

No. of div in Y axis

Amp/ div

Amplitude in volts

MODEL GRAPH

RESULT

FM wave generation EXP.No: DATE : AIM To generate frequency modulated waveform using transistor circuit. APPARATUS REQUIRED SL.No. Description Type / Range/ Value Quantity 1 BJT BF 195 1 2 Resistors 10K, 470 2,1 3 Capacitors 330pF, 10pF, 2,3,1 1.5pF,100pF, 0.1F 4 Inductor 0.3H 1 5 AFO, RPS, CRO 1 CIRCUIT DIAGRAM

PROCEDURE 1. Give the circuit connection as per the diagram 2. Apply the modulating signal 3. Observe the frequency modulated output through TV 4. Vary the amplitude of the modulating signal and note the changes in the FM output.

Model graph:

RESULT

FM demodulation using PLL EXP.No: DATE : AIM To detect the given FM wave using Phase Locked Loop (PLL) APPARATUS SL.No. Description Typ/ Range/ Value Quantity 1. IC 565 1 2. Resistors 12K 1 3. Capacitors 0.01F, 0.001F, 1 Each 10F 4. DRB 1 5. RPS, AFO, CRO 1 CIRCUIT DIAGRAM

PROCEDURE 1. Make the connection of PLL as shown in the figure 2. Measure the free running frequency of VCO at pin 4, with the input signal Vin equal to zero. Compare it with calculated value = 1. 2 / 4RTCT 3. Give the FM signal at pin.2 4. Compute the lock range and capture range frequencies using formula given in step 5 Compare it with the practical values

5. The lock range fL and capture range fC of the PLL are fL = 8fout / (+V) (-V) fC = [ fL /2(3.6)(103)C]1/2 where fout is the free running frequency of VCO 6. Take the demodulated output from pin.7 MODEL GRAPH

RESULT

Generation of Pulse Amplitude Modulation (PAM) EXP.No: DATE : AIM To generate the pulse amplitude modulated signal and to plot its waveform. APPARATUS REQUIRED Sl.NO. Description Type / Range / Quantity Value 1 Transistor BC 147 1 2 Resistors 1K 3 3 CRO 1 4 AFO 1 CIRCUIT DIAGRAM

PROCEDURE 1. Give the circuit connections as per the diagram 2. Give a sinusoidal waveform as the input modulating signal 3. Apply a pulse carrier signal 4. Observe the received pulse amplitude modulated wave TABULATION Waveform No. of div in X axis Time/div Time No. of div in Y axis Amp/ div Amplitude in volts

Modulating signal Carrier signal MODEL GRAPH

RESULT

Generation of Pulse Position Modulation (PPM) EXP.No: DATE : AIM To obtain pulse position modulation using IC 555 To plot the obtained waveform APPARATUS REQUIRED SL.No. Description Type / Range /Value 1. IC 555 2. Resistors 21K, 3.3K 3. Capacitor 0.01F 4 AFO, RPS, CRO CIRCUIT DIAGRAM

Quantity 1 1 Each 1 1 Each

PROCEDURE 1. Give the circuit connection as per diagram 2. Apply a sine wave as modulating signal at pin.5 of the IC 3. Obtain the pulse position modulated wave at the pin.3 of the IC 4. Draw the graph between modulated output and time period TABULATION Waveform No. of div Time/div Time No. of div Amp/ div in X axis in Y axis Input Output

Amplitude in volts

MODEL GRAPH

RESULT

Generation of Pulse Width Modulation (PWM) EXP.No: DATE : AIM To generate pulse width modulated waveform using timer IC555. APPARATUS REQUIRED Sl.No. Description Type / Range/ Quantity Value 1 IC 555 1 2 Resistor 10K 1 3 Capacitor 0.01F 1 4 DRB 1 5 RPS, AFO, CRO 1 CIRCUIT DIAGRAM

PROCEDURE 1. Give the circuit connections as per the diagram 2. Apply the modulating signal at the pin.5 of the IC 3. Apply the carrier signal at the pin.2 of the IC 4. Obtain the pulse width modulated wave at the pin.3 of the IC 5. Draw the graph between modulated output and time period TABULATION Waveform No. of div in X axis Time/div Time No. of div in Y axis Amp/ div Amplitude in volts

Modulating signal Carrier signal PWM output

MODEL GRAPH

RESULT

Ex.No: Date:

Propagation Loss and Bending Loss Measurement in Optical Fiber.

Aim: The aim of this experiment is to measure propagation and bending loss in optical fiber. Apparatus Required: Fiber optic kit, Connecting cords, two optical fibers (1m and 0.5m length), CRO, mandrel. Procedure: Propagation Loss: 1. Connect power supply to board. 2. Make the following connections(as shown in the figure). a. Connect function generator 1Khz sine wave output to input 1 socket of emitter circuit. b. Connect 0.5m optic fiber between emitter 1 output and detector 1 input. c. Connect detector 1 output to amplifier 1 input. d. Connect the output from amplifier to CRO. 3. Switch on the power supply. 4. Set the oscilloscope channel 1 to 0.5V/div and 4-6div amplitude by using X1 probe with the help of variable pot in function generator block at input. 5. Observe the output signal from detector tr10 on CRO. 6. Adjust the amplitude of the received signal same as that of transmitted one with the help of gain adjust pot. In AC amplifier block. Note this amplitude as V1. 7. Now replace the previous FO cable with 1m cable without disturbing any previous setting. 8. Measure the amplitude at the receiver side again at output of amplifier 1 socket tp28.Note this as V2. Calculate the propagation constant or attenuation constant with the help of following formula. V1 V2 Where is loss in nepers/meter. 1 neper=8.686 dB. L1=length of shorter cable(0.5m) L2=length of longer cable(1m)

= - (L1-L2)

Trainer Setup:

Observation: Input Amplitude: Length of cable Output Voltage

Bending Loss: 1. Repeat all the steps from 1 to 6 of the previous experiment(propagation loss experiment)using 1m cable. 2. Wind the FO cable on the mandrel and observe the corresponding AC amplifier output on CRO. It will be gradually reducing showing loss due to bends. 3. Note the output voltage in CRO for 0,1,2,and 3 bends Trainer Setup:

Observation: Input Amplitude: No: of Bends Output Amplitude

Result:

Ex.No: Date:

Manchester Coding, Decoding and Clock Recovery.

Aim: To investigate Manchester coded and decoded output of a given signal. Apparatus Required: Trainer Kits ST2503 and ST2501/2502, fiber optic kit, Connecting cords, CRO. Procedure: Encoding: 1. Make the connection as shown below. 2. Turn on power to the ST2503 board. 3. Connect CLK and DATA OUT terminal to CLK IN and DATA IN terminal of Manchester encoder 4. Observe encoded output on oscilloscope.

Decoding: 1. Connect output of Manchester encoder to input of Manchester decoder. 2. Observe Manchester decoder output on oscilloscope. 3. This experiment can be performed by passing encoded signal through optic fiber using ST2501/2502. 4. Make connections as shown below and observe the output on CRO.

Result:

Ex.No: Date:

Time Division Multiplexing Sixteen Channels

Aim: To investigate 16 channel TDM using digital signals. Apparatus: Trainer kits ST2503 and ST2501/2502, optic fiber, connecting cords, CRO. Procedure: 1. Make connections as below. 2. Turn on power to the ST2503. 3. Observe multiplexed data on oscilloscope.

4. Connect OUT terminal of multiplexer to IN terminal of demultiplexer. 5. Observe demultiplexed 16 channel output on oscilloscope. Take output signal as external trigger signal to oscilloscope to trigger demultiplexed output. 6. Connect output of emitter circuit to detector circuit of ST2501 through fiber optic cable as shown below

7. Connect OUT terminal of multiplexer to IN terminal of emitter circuit. 8. Connect OUT terminal of detector circuit to IN terminal of comparator circuit. 9. Adjust comparator bias to get suitable output. 10. Connect OUT terminal of comparator circuit to IN terminal of 16 channel demultiplexer of ST2503. 11. Repeat step 5. Result:

Ex.No: Date:

Carrier recovery from QPSK demodulation.

Aim: To recover the carrier from QPSK modulated signal. Apparatus required: QPSK kit CRO Power supply Procedure: QPSK transmitter Select appropriate power supply and clock 600 bps. Toggle the DIP switch DS1 and DS2 to generate 00011011 such that SW1 5,4,2,1 - ON - 8,7,6,3 OFF. This should generate an NRZ o/p as 0 0 0 1 1 0 1 1 which becomes the selected data for QPSK modulation. Separately monitor WP with CRO. QPSK Receiver Interconnect the transmitter and receiver module through the inter connecting cable provided. Check the WP and other waves on transmitter. Check the QPSK output, PSK output and other

Result:

Ex.No: Date:

AMPLTUDE SHIFT KEYING.

Aim: To generate ASK for the given input signal using 555 timer Apparatus required: SL.No. 1 2 3 4 5 Description IC555 Resistors Transistor Capactor AFO, RPS, CRO Type / Range/ Value Quantity 1 220, 47K, 1each 120K, 4.7K BC107 1 0.01 F 2 1

Procedure: 1. Rig up the circuit as shown in figure. 2. Connect carrier signal 3. Verify the output through CRO. Circuit diagram:

Model output:

Tabulation Signal Modulating sine wave ASK input Modulated wave Result:

Y axis

X axis

Volts/ div

Time / div

Time period

Amplitude

Ex.No: Date:

FREQUENCY SHIFT KEYING.

Aim: To generate FSK for the given input signal using 555 timer Apparatus required: SL.No. 1 2 3 4 5 Description IC555 Resistors Transistor Capactor AFO, RPS, CRO Type / Range/ Value Quantity 1 330,1K, 22K, 1each 5.6K SL 100 1 0.01 F 2 1

Procedure: 1. Rig up the circuit as shown in figure. 2. Connect carrier signal 3. Verify the output through CRO. Circuit diagram:

5VInput digital signal

330 SL100 1K 22K 4 8 3CRO

5555.6K 5 1

2

0.01 F

0.01 F

Model output:

Tabulation Signal Modulating sine wave FSK input Result:

Y axis

X axis

Volts/ div

Time / div

Time period

Amplitude

Ex.No: Date:

Detection of a symbol in spite of ISI using Duobinary coding.

Aim: To detect ISI using Duobinary coding. Apparatus required:

Block diagram:

Procedure: 1. Rig up the circuit as shown in figure. 2. Connect the input 3. Observe the output

Result:

Ex.No: Date:

Implementation of a Matched Filter.

Aim: To implement a matched filter. Apparatus required:

Block diagram:

Procedure: 1. Rig up the circuit as shown in figure. 2. Connect the input 3. Observe the output

Result:

Ex.No: Date:

Implementation of Correlator

Aim: To implement of correlator. Apparatus required:

Block diagram:

Procedure: 1. Rig up the circuit as shown in figure. 2. Connect the input 3. Observe the output Result:

Ex.No: Date:

Implementation of CDMA.

Aim: To implement a CDMA. Apparatus required:

Block diagram:

Procedure: 1. Rig up the circuit as shown in figure. 2. Connect the input 3. Observe the output Result: