microwav & opti communi lab manu

MADANAPALLE INSTITUTE OF TECHNOLOGY & SCIENCE

MADANAPALLI

ANGALLU, MADANAPALLE – 517 325

MICROWAVE AND OPTICAL COMMUNICATIONS

LABORATORY MANUAL

DEPARTMENT

OF

ELECTRONICS & COMMUNICATION ENGINEERING

JULY-2012

Prepared by: R.Ravindraiah & Sravan.P

MADANAPALLE INSTITUTE OF TECHNOLOGY & SCIENCE

MADANAPALLI

ANGALLU, MADANAPALLE – 517 325

MITS MITS/ECE

LAB WISE-LAB MANUALS DEPARTMENT : ECE

MICROWAVE AND OPTICAL COMMUNICATIONS

LABORATORY MANUAL

DEPARTMENT

OF

ELECTRONICS & COMMUNICATION ENGINEERING

JULY-2012

JAWARHARLAL NEHRU TECHNOLOGICAL UNIVERSITY

IV Year B.Tech ECE- I SEM

MICROWAVE AND OPTICAL COMMUNICATIONS LAB

PART-A

1. Gunn Diode Characteristics

2. Reflex Klystron Characteristics

3. Attenuation Measurement

4. VSWR Measurement

5. Waveguide Parameters Measurement

6. Impedance and Frequency Measurement

7. Scattering Parameters Of Magic Tee

PART-B

8. Directional Coupler Characteristics

9. Radiation Pattern Of Horn Antenna

10. Characterization Of LED

11. Characterization Of Laser Diode

12. Measurement Of NA for optical fiber cable

13. Measurement of losses for Analog Optical Link

Additional experiments

14. Analog & Digital Optical link setup

15. Frequency Modulation and Demodulation using Fiber Optic links

16. Pulse Width Modulation and Demodulation using Fiber Optic links

17. Pulse Position Modulation and Demodulation using Fiber Optic links

18. Data Communication through Fiber Optic link using RS 232.

../My%20Documents/Downloads/Gunn%20Diode.docx

../My%20Documents/Downloads/Reflex.docx

../My%20Documents/Downloads/Attenuation.docx

../My%20Documents/Downloads/swr.docx

../My%20Documents/Downloads/WG%20Parameters.docx

../My%20Documents/Downloads/Impedence.docx

../My%20Documents/Downloads/Magic%20Tee.docx

../My%20Documents/Downloads/Directional%20coupler.docx

../My%20Documents/Downloads/Horn%20Antenna.docx

../My%20Documents/Downloads/LED.docx

EXPERIMENT-1

STUDY OF I-V CHARACTERISTICS OF GUNN DIODE

Objective: To study the characteristics of the Reflex Klystron tube and to determine its

electronic tuning range.

Equipments Required:

Gunn Power Supply-GS-610,Gunn Oscillator XG-11, Isolator XI -621, Frequency Meter XF-

710, PIN Modulator XM-55, BNC Cable.

Procedure:

1. Set the components as shown in fig.1.

2. Keep the control knob of GUNN Power Supply as below:

Meter Switch - OFF

Gunn bias knob - Fully anticlockwise

PIN bias knob - Fully clockwise

PIN Mode frequency - Any position

3. Set the micrometer of Gunn Oscillator for required frequency of operation.

4. Switch „ON‟ the Gunn Power Supply.

5. Measure the Gunn diode current corresponding to the various Gunn bias voltage through

panel meter and meter switch. Do not exceed the bias voltage above 10 Volts.

6. Plot the voltage and current reading on the graph as shown in fig.2.

7. Measure the Threshold voltage which corresponds to maximum current.

NOTE:

DO NOT KEEP GUNN BIAS KNOB POSITION AT THRESHOLD POSITION FOR

MORE THAN 10 SECONDS READING SHOULD BE OBTAINED AS FAST AS

POSSIBLE OTHERWISE EXCESSIVE HEATING, GUNNDIODE MAY BURN.

Fig.1.1 Experimental setup to Study I-V characteristics of Gunn diode

Gunn Diode Current (mA)

Threshold Voltage

I max -------------------

Vth Gunn Bias Voltage(V)

Fig.1.2 I-V characteristics of Gunn diode

Gunn power

supply GS-

610

Isolator

XI-621

Variable

attenuato

r XA-520

Gun

Oscillator

XG-11

Frequenc

y meter

XF-455

PIN

Modulat

or XM-55

VSWR Meter

SW-115

Oscillo

scope

Detect

or

Mount

Observations:

S.no Gunn Bias Voltage(Volts) Gunn Diode Current(mA)

1

.2

3

4

5

6

7

8

9

10

--

--

--

--

--

--

Vth

--

--

--

--

--

--

--

--

--

I max

--

--

--

Threshold Voltage Vth =

EXPERIMENT-2

STUDY OF REFLEX KLYSTON CHARACTERISTICS

Objective: To study the characteristics of the Reflex Klystron tube and to determine its

electronic tuning range.


Klystron Power Supply(SKPS-610),Klystron Tube (2K-25) with Klystron Mount (XM 25),

Isolator (XI -621), Frequency Meter (XF- 710), Variable Attenuator (XA 520), Detector Mount

(XD-451), Wave Guide Stand (XU-535), VSWR Meter (SW-115), Oscilloscope , BNC Cable.

Procedure:

A. Carrier Wave Operation:

1. Connect the components and equipments as shown in fig.1.

2. Set the variable attenuator at the minimum position.

3. Set the Mod-Switch of Klystron Power Supply at CW position, Beam Voltage control knob to

Anti-clock wise and Reflector Voltage control knob to fully Clock wise and the Meter Switch to

position.

4. Rotate the knob of Frequency meter at one side fully.

5. Connect the DC Microampere meter with Detector.

6. Switch ON the Klystron Power Supply, VSWR meter and Cooling Fan for the Klystron Tube.

7. Put ON Beam voltage switch and rotate the Beam voltage knob clock wise slowly up to 300V

meter reading and observe Beam current position, “ The Beam current should not increase more

than 30mV.

8. Change the Reflector voltage slowly and watch Current Meter, set the voltage for maximum

deflection in the meter.

9. Tune the plunger of Klystron Mount for the maximum output.

10. Rotate the knob of Frequency meter slowly and stop at that position, where there is lowest

output current on multimeter. Read directly the frequency meter between to horizontal lines and

vertical mark. If micrometer type frequency meter is used read the micrometer reading and use

the frequency chart.

11. Change the reflector voltage and read the current and frequency for each reflector voltage.

B. Square Wave Operation:

1. Connect the components and equipments as shown in fig.1.

2. Set Micrometer of variable Attenuator around some position.

3. Set the range switch of VSWR Meter at 40db position , input selector switch to crystal

impedance position, meter switch to narrow position.

4. Set the MOD-Switch of Klystron Power Supply at AM position, beam voltage control

knob to fully anti- clock wise position.

5. Switch ON the Klystron Power Supply, VSWR meter and Cooling Fan for the Klystron

Tube.

6. Put ON Beam voltage switch and rotate the Beam voltage knob clock wise slowly up to

300V deflection in meter.

7. Keep the AM – MOD amplitude knob and AM – FRE knob at the mid position.

8. Rotate the reflector voltage knob to get the deflection in VSWR meter.

9. Rotate the AM-MOD amplitude knob to get the maximum output in VSWR meter.

10. Maximize the deflection with frequency knob to get the maximum output in VSWR

meter.

11. If necessary, change the range switch of VSWR meter 30db to 50db if the deflection in

VSWR meter is out of scale or less than normal scale respectively. Further the output can

be also reduced by Variable Attenuator for setting the output for any particular position.

Find the oscillator frequency by Frequency Meter as described in the earlier setup.

C. Mode study on Oscilloscope

1. Set up the components and equipments as shown in fig.1.

2. Keep Position of variable attenuator at min. attenuation position.

3. Set mode selector switch to FM-MOD position, FM amplitude and FM frequency

knob at mid position, keep beam voltage knob fully anti-clock wise and reflector

voltage knob to fully clock wise and Beam switch to OFF position.

4. Keep the time/division scale of oscilloscope around 100Hz frequency measurement

and volt/div. to lower scale.

5. Switch “ON” the Klystron Power Supply and Oscilloscope.

6. Switch “ON” Beam voltage switch and set beam voltage to 300v by beam voltage

control knob.

7. Keep amplitude knob of FM modulator to maximum position and rotate the

reflector voltage anti-clock wise to get modes as shown in figure.4, on the

oscilloscope. The horizontal axis represents reflector voltage axis and vertical

represents output power.

8. By changing the reflector voltage and amplitude of FM modulation, any mode of

Klystron tube can be seen on oscilloscope.

Fig.2.1 Experimental Set up to study characteristics of Klystron tube

Output Waveforms:

output power(mW)

20

Repellar voltage

Frequency change (MHz)

50

0

-50

Repellar voltage

Fig.2.2 Characteristics of Klystron tube

Klystron

power supply

SKPS -610

2K 25

Isolator

XI-621 Variable

attenuato

r XA-520

Klystron

mount

XM-251

Frequenc

y meter

XF-455

Multimeter

VSWR Meter

SW-115

Oscilloscope

Observations: Beam Voltage = 230V

Repellar Voltage (V) Beam Current (mA) Frequency (GHz) Output

Current(mA)

MODE 1

--

--

--

--

--

--

0

(max)

0

MODE 2

--

--

--

--

--

--

0

(max)

0

MODE 3

--

--

--

--

--

--

0

(max)

0

Experiment-3

ATTENUATION MEASUREMENT

OBJECTIVE:

To measure the attenuation of the attenuator.

Equipment Required:

1. Microwave source

a. Gunn oscillator - XG-11

b. Klystron Tube - 2K25

2. Isolator - X1-21

3. Frequency meter - XF-10

4. Variable Attenuator - XA-520

5. Slotted line - XS-651

6. Tunable probe - XP-655

7. Detector mount - XD-451

8. Matched Termination - XL-400

9. Test attenuator

a. Fixed

b. Variable

10. Gunn Power Supply PIN Modulator/Klystron Power Supply + Klystron Mount.

11. Cooling Fan.

12. BNC- BNC cable and TNC-TNC cable.

Procedure:

A. Input VSWR Measurement

1. Connect the equipments as shown in the fig.

2. Energize the microwave source for maximum power at any frequency of

operation.

3. Measure the VSWR with the help of tunable probe, slotted line and VSWR meter

as described in experiment of measurement of low and medium VSWR.

4. Repeat the above step for other frequencies if required.

B. Insertion Loss/Attenuation Measurement

1. Remove the tunable probe, attenuator and matched termination from the slotted

section in the above setup.

2. Connect the detector mount to the slotted line, and tune the detector mount also

for maximum deflection on VAWR meter (Detector mount‟s output should be

connected to VSWR meter).

3. Set any reference level on the VSWR meter with the help of variable attenuator

(not test attenuator) and gain control knob of VSWR meter. Let it be P1.

4. Carefully disconnect the detector mount from the slotted line with out disturbing

any position on the setup. Place the test variable attenuator to the slotted line and

detector mount to other port of test variable attenuator. Keep the micrometer

reading of test variable attenuator to zero and record the reading of VSWR meter.

Let it be P2 then the insertion loss of test attenuator will be p1-p2db.

5. For measurement of attenuation of fixed and variable attenuator. Place the test

attenuator to the slotted line and detector mount at the other port of test attenuator.

Record the reading of VSWR meter. Let it be P3 then the attenuation value of

variable attenuator for particular position of micrometer reading of will be P1-

P3db.

6. In case the variable attenuator, change the micrometer reading and record the

VSWR meter reading. Find out attenuation value for different position of

micrometer reading and plot a graph.

7. Now change the operating frequency and all steps should be repeated for finding

frequency sensitivity of fixed and variable attenuator.

Note:

For measuring frequency sensitivity of variable attenuator the position of micrometer

reading of the variable attenuator should be same for all frequencies of operation.

Fig.3.1 Experimental setup to obtain Insertion loss and Attenuation measurement

Microwave

source

VSWR

meter

SW-115

Isolator

XI- 621

Frequency

meter

XA- 710

Variable

attenuator

XA-520

Attenua

tor XA-

520

Slotted

line

XS-651

Detector

mount

XD-451

Detecto

r mount

XD-451

OBSERVATIONS:

Beam voltage = __ V

Beam current = ___ mA

Repeller voltage =-___V

Power without attenuator P1 = ____ dB

Power with variable attenuator with attenuation at 7 mm P2= _____dB

Power with variable attenuator with attenuation at 5 mm P3=_______dB

Insertion loss or Attenuation with 7 mm = P1 – P2 dB

Insertion loss or Attenuation with 5 mm = P1 – P3 dB

Experiment-4

Determination of VSWR & Reflection Coefficient

OBJECTIVE: To determine the standing-wave ratio and reflection coefficient.

EQUIPMENTS:

Klystron Power Supply(SKPS-610), Klystron Tube( 2K-25) with Klystron Mount(XM-25),

Isolator (XI -621), Frequency Meter (XF- 710), Variable Attenuator (XA-520), Slotted line (X

565), Tunable probe (XP-655), Detector Mount(XD-451), Wave Guide Stand (XU-535), VSWR

Meter (SW-115), Movable short/ Termination (XL 400) or any unknown load, BNC Cable.

PROCEDURE:

1. Set up the equipment as shown in the figure.

2. Keep the variable attenuator in the minimum attenuation position.

3. Keep the control knobs of VSWR as below:

Range db - 40db/50 db

Input Switch - Low Impedance

Meter Switch - Normal

Gain (Coarse-Fine) - Mid position approx.

4. Keep the control knobs of the Klystron power supply as below:

Beam voltage - OFF

Mod-switch - AM

Beam voltage knob - Fully anticlockwise direction

Reflector Voltage knob - Fully clockwise direction

AM-amplitude knob - Around fully clockwise

AM-frequency

& amplitude knob - Mid position

5. Switch „ON‟ the Klystron Power Supply, VSWR Meter and cooling fan.

6. Switch „ON‟ the Beam voltage switch position and set beam voltage at 300V.

7. Rotate the reflector voltage knob to get deflection in VSWR Meter.

8. Tune the output by tuning the reflector voltage, amplitude and frequency of AM

Modulation.

9. Tune the plunger of Klystron Mount and probe for maximum deflection in VSWR meter.

10. If required, change the range db-switch variable attenuator position and gain control knob

to get deflection in the scale of VSWR meter.

11. As you move probe along the slotted line, the deflection will change.

A. MEASUREMENT OF LOW AND MEDIUM VSWR:

1. Move the probe along the slotted line to get maximum deflection in VSWR Meter.

2. Adjust the VSWR meter gain control knob or variable attenuator until the meter

indicates „1.0‟ on normal VSWR scale.

3. Keep all the control knobs as it is, move the probe to next minimum position. Read

the VSWR on scale.

4. Repeat the above step for change of S.S. tuner probe depth and record the

corresponding SWR.

5. If the VSWR is between 3.2 and 10, change the range db switch to next higher

position and read the VSWR on second scale of 3 to 10.

B. MEASUREMENT OF HIGH VSWR:

1. Set the depth of S.S.Tuner slightly more for maximum VSWR.

2. Move the probe along with slotted line until a minimum is indicated.

3. Adjust the VSWR meter gain control knob and variable attenuator to obtain a reading og

3 db in the normal db scale (0 to 10 db) of VSWR Meter.

4. Move the probe to left on slotted line until full scale deflection is obtained on 0-10 db

scale. Note and record the probe position on slotted line let it be d1.

5. Repeat the step 3 and then move the probe right along the slotted line until full scale

deflection is obtained on 0-10 db normal db scale. Let it be d2.

6. Replace the S>S. tuner and termination by movable short.

7. Measure the distance between two successive minima positions of the probe. Twice this

distance is guide wavelength λg.

8. Compute SWR from the following equation:

λg

SWR = -------------------

π ( d1-d2)

Fig.4.1 Experimental set up for VSWR measurement

Microwave

source

Isolator

XI-621

Tunable

probe

XP-655

VSWR

meter

SW-115

Frequency

meter

XF-710

Variable

attenuator

XA-520

Slotted

line

XD-451

S STuner

XS-441

Matched

terminati

on XL-400

Output

E max 2V min --------------

E min ---- V max -----------

probe position

d1 d2

Fig.4.2(a)Standing wave Fig.4.2(b)Double minima method

Calculations:

d 1 =_____cm

d 2 =____cm

λ g= 2( d1 – d2)

Low and medium VSWR= S =______

Reflection coefficient ( for low VSWR) = S-1/S+1

High VSWR:

d 3 =_______cm

d 4 =_____cm

High VSWR= S =______

Reflection coefficient (for high VSWR) = S -1/S +1

Reflection coefficient (for low VSWR) =S-1/S+1

Experiment-5

Waveguide Parameters

Objective: To determine the frequency and wave length in a rectangular waveguide working in

TE10 mode.

Equipment Required:

Klystron Tube 2K25, Klystron Power Supply 5KPS-610,Klystron Mount XM-251,

Isolator XI-621, Frequency Meter X F710, Variable Attenuator XA-520, Slotted Section XS-

651, Tunable probe XP-655, VSWR Meter SW-115, Waveguide Stand XU-535, Movable Short

XT-481/Matched termination XL-400.

Procedure:

1. Set up the components and equipments as shown in fig.

2. Set up variable attenuator at minimum attenuation position.

3. Keep the control knobs of VSWR Meter as below:

Range - 50db

Input Switch - Crystal low impedance

Meter Switch - Normal position

Gain (Coarse & Fine) - Mid position.

4. Keep the Control Knobs of Klystron power supply as below

Beam voltage - OFF

Mod-switch - AM

Beam Voltage knob - Fully anticlockwise

Reflector Voltage - Fully clockwise

AM-Amplitude Knob - Around fully clockwise

AM-Frequency Knob - Around Mid position.

5. Switch „ON‟ the Klystron power supply, VSWR Meter and Cooling Fan Switch.

6. Switch „ON‟ the beam voltage switch and set beam voltage at 300v at with help of beam

voltage knob.

7. Adjust the reflector voltage to get some deflection in VSWR Meter.

8. Maximize the deflection with AM amplitude and frequency control knob of power

supply.

9. Tune the plunger of Klystron Mount for maximum deflection.

10. Tune the reflector voltage knob for maximum deflection.

11. Tune the probe for maximum deflection in VSWR Meter.

12. Tune the frequency meter knob to get a „dip‟ on the VSWR scale

and note down the frequency directly from frequency meter.

13. Replace the termination with movable short, and detune the frequency meter.

14. Move the probe along the slotted line. The deflection in VSWR meter will vary. Move

the probe to a minimum deflection position, to get accurate reading. If necessary increase to

VSWR meter range db switch to higher position. Note and record the probe position.

15. Move the probe to next minimum position and record the probe position again.

16. Calculate the guide wavelength as twice the distance between two successive minimum

position obtained as above.

17. Measure the waveguide inner broad dimension „a‟ which will be around 22.86

mm for X-band.

18. Calculate the frequency by following equation.

f = c/λ =

19. Verify with frequency obtained by frequency meter.

20. Above experiment can be verified at different frequencies.

Fig.5.1 Experimental set up for frequency & wave-length measurement

Calculations:

Microwave

source

VSWR

meter

SW-115

Isolator

XI- 621

Frequency

meter

XA- 710

Variable

attenuator

XA-520

Attenua

tor XA-

520

Slotted

line

XS-651

Tunable

probe

XP- 655

Detecto

r mount

XD-451

d 1 =_______ cm

d 2 =______ cm

λ g = 2( d 1- d 2) cm

λ c = 2.a ( where a = 2.286 cm i.e broader dimension of wave guide)

λ o = ______cm

Theoretical frequency f = C/ λ o (G Hz)

Practical frequency = ________ G Hz

EXPERIMENT-6

Impedance and Frequency Measurement

Objective: To measure an unknown Impedance using the smith chart.


Klystron Tube 2K25,Klystron Power supply SKPS-610,Klystron

Mount XM-251,Isolator XF62, Frequency Meter XF710, Variable Attenuator XA-

520, Slotted Line XS565,Tunable Probe XP655,VSWR Meter, Waveguide stand

SU535, SS Tuner (XT441), Movable Short/Termination, etc.

Procedure:

1. Set up the equipments as shown in the fig.

2. Set the variable attenuator at minimum position.

3. Keep the control knobs of VSWR Meter as below:

Range - 50 db position

Input Switch - Crystal Low Impedance

Meter Switch - Normal position

Gain (Coarse-Fine) - Mid Position

4. Keep the control knobs of Klystron power supply as below:

Beam voltage switch - „OFF‟

Mod switch - AM

Beam voltage knob - Fully anticlockwise

Reflector voltage - Fully clockwise

AM- Amplitude - Around fully clockwise

AM-Frequency knob - Around Mid position

5. Switch „ON‟ the Klystron power supply, VSWR meter and cooling fan.

6. Switch „ON‟ the Beam Voltage Switch Position and set beam voltage at

300V with help of beam voltage knob.

7. Adjust the reflector voltage knob to get some deflection in VSWR meter.

8. Maximize the deflection with AM amplitude and frequency control knob of

power supply.

9. Tune the Plunger of Klystron Mount for maximum deflection.

10. Tune the reflector voltage knob for maximum deflection.

11. Tune the probe for maximum deflection in VSWR meter.

12. Tune the frequency meter knob to get a „dip‟ on the VSWR scale, and note

down the frequency directly from frequency meter.

13. Keep the depth of pin of S.S. Tuner to around 3-4 mm and lock it.

14. Move the probe along the slotted line to get maximum deflection.

15. Adjust VSWR meter gain control knob and variable attenuator until the

meter indicates 1.0 on the normal db SWR scale.

16. Move the probe to next minima position and note down the SWR So on

the scale. Also note down the probe position, let it be d.

17. Remove the S.S. Tuner and Matched termination and place movable short

at slotted line. The plunger of short should be at zero.

18. Note the position of two successive minima position. Let it be d1 and d2

Hence λg = 2(d1-d2).

19. Calculate

d / λg

20. Find out the normalized impedance as described in the theory section.

21. Repeat the same experiment for other frequency if required.

Fig.6.1 Experimental set up for impedance measurement

CALCULATIONS:

Microwave

source

VSWR

meter

SW-115

Isolator

XI- 621

Frequency

meter

XA- 710

Variable

attenuator

XA-520

Movable

short

XT-481

Slotted

line

XD-451

S STuner

XS-441

Matched

terminatio

n XL-400

Tunable

probe

XP-655

d 1=_________ cm

d 2 = ________ cm

λg = 2 ( d 2- d 1) cm

d 3 = _____ cm

d 4 = ________ cm

Low and medium SWR

d = (d 3 – d 4) cm

d / λg =

Experiment- 7

Study of Magic Tee

Objective: Study of Magic Tee


Micro wave source, Isolator, Variable attenuator, frequency meter, slotted line, tunable probe,

magic tee, matched terminations, waveguide stand, detector mount, VSWR meter and

accessories.

Procedure:

1. Remove the tunable probe and magic tee from slotted line and connect the

detector mount to the slotted line.

2. Connect all the components as shown in experimental set up.

3. Energize the microwave source for particular frequency of operation.

4. With the help of variable attenuator and gain control knob of VSWR meter set

any power level in the VSWR meter let it be P1.

5. Without changing the attenuation level measure the power at port 3 of the magic

tee let it be P3. Now the insertion loss = P1-P3 (db).

6. Now measure the power at port2. E-arm by shorting port3 & port4. Let it be P2.

Then coupling factor of E-arm = p1-P2 (db).

7. Similarly measure power at port4 (H-arm) by shorting port2 & port3. Then

coupling factor of H-arm = P1-P4 (db).

8. Now connect H-arm to the slotted line and measure power at port2. Isolation =

P4-P2 (db).

Fig.7.1 Experimental setup of study of magic tee

Observations:

Beam voltage = _____ V

Beam current=______mA

Repeller voltage= _______ V

Power at port1 P1=______ dB (P2 & P4 are matched termination)

Power at port2 (E-arm) P2=________ dB (P1 & P4 are matched termination)

Power at port3 P3= _______ dB

Power at port4 (H-arm) P4= ________ dB (P1 & P2 are matched termination)

Microwave

source

VSWR

meter

SW-115

Isolator

XI- 621

Frequenc

y meter

XA- 710

Variable

attenuator

XA-520 Matched

terminati

on XL-400

Slotted

line

XS-651

TEE

4 XE- 3

345/350

Matched

terminati

on XL-400

Probe

SP- 655

Matched

terminati

on XL-400

2

1

Matched

terminati

on XL-400

TEE

4 XE- 3

345/350

Matched

terminati

on XL-400

Matched

terminati

on XL-400

2

1

Slotted

line

XS-651

Detecto

r mount

XD-451

Insertion loss = P1-P3 (db) = P2-P3 = ________dB

Coupling Factor of E-arm = P2-P4 (db) = __________ dB

Or

Coupling Factor of H-arm = P1-P4 (db) = __________ dB

Isolation =P3-P4 (dB) = _________ dB

Max Power = (Only matched termination without magic tee).

EXPERIMENT-8

Directional Coupler

OBJECTIVE: To study the function of multihole directional coupler by

measuring the following parameters

1. Mainline and auxiliary-line VSWR.

2. The coupling factor and directivity of the coupler.

EQUIPMENTS:

Microwave Source (Klystron or Gunn diode), Isolator, Frequency

Meter, variable attenuator, slotted line, tunable probe, Detector mount matched

termination, MHD Coupler, Waveguide stand, Cables and Accessories, VSWR

meter.

PROCEDURE:

1. Main Line SWR Measurement

1. Set up the equipments as shown in fig.

2. Energize the microwave source for particular frequency of operation

as described in the procedures given in the operation of Klystron

tube/Gunn Oscillator.

3. Follow the procedure as described for VSWR measurement (low and

medium SWR measurement).

4. Repeat the same for other frequencies.

2. Auxiliary Line SWR Measurement

1. Set up the components and equipments as shown in fig.

2. Energize the microwave source for particular frequency of operation

as described in the operation of Klystron tube/Gunn Oscillator.

3. Measure SWR as described in the experiment of SWR measurement

(low and medium SWR measurement).


3. Measurement of Coupling Factor, Insertion loss, Isolation & Directivity

1. Set up the components and equipments as shown in the fig.

2. Energize the microwave source for particular frequency of operation.

3. Remove the multi-hole directional coupler and contact the detector

mount to the frequency meter. Tune the detector for maximum

output.

4. Set any reference level of power on VSWR meter, and note down the

reading (reference level let X).

5. Insert the directional coupler as shown in second fig. with detector to

the auxiliary port3 and matched termination to port2, without

changing the position of variable attenuator and gain control knob of

VSWR meter.

6. Note down the reading on VSWR meter on the scale with the help of

range-db switch if required. Let it be Y.

7. Calculate coupling factor which will be X-Y= C(dB).

8. Now carefully disconnect the detector from the auxiliary port3and

match termination from port2 without disturbing the set-up.

9. Connect the matched termination to the auxiliary port3 and the

detector to port 2 and measure the reading on VSWR meter. Suppose

it is Z.

10. Compute insertion loss X-Z in db.

11. Repeat the steps from 1 to 4.

12. Connect the directional coupler in the reverse direction, i.e. port2 to

frequency meter side. Matched termination to port1 and detector

mount port3 without disturbing the position of the variable attenuator

and gain control knob of VSWR meter.

13. Measure and note down the reading on VSWR meter. Let it be Yd.

X-Yd gives Isolation 1(dB).

14. Compute the directivity as Y-Yd=I-C


Fig. Experimental set up for multi-hole directional coupler

Observations:

Beam voltage = ______ V

Beam current = ________mA

Repeller voltage =_________ V

Power without Directional coupler P1 = _______ dB

Power at Port 2 of D.C( Port 1 is connected and Port 3 is terminated), P2= _______

dB

Microwave

source

VSWR

meter

SW-115

Isolator

XI- 621

Frequency

meter

XA- 710

Variable

attenuator

XA-520

Matched

terminati

on XL-400

Slotted

line

XS-651

3

1 MHD 2

coupler

XK-620

Matched

terminati

on XL-400

Probe

SP- 655

Matched

terminati

on XL-400

Matched

terminati

on XL-400

3

2 MHD 1

coupler

XK-620

Power at Port 3 of D.C( Port 1 is connected and Port 2 is terminated), P3=

_____dB

Power at Port 3 of D.C( Port 2 is connected and Port 1 is terminated),P4=_____dB

Coupling factor C= P1- P3(dB)=______ dB

Insertion loss Il = P1 – P2 (dB)=_________ dB

Isolation I = P1 – P4 (dB)=_________ dB

Directivity (theoretical) D = I - C (dB)=________ dB

Directivity (practical) D = P3 – P4 (dB) =__________ dB

Experiment-9

Radiation Pattern of Horn Antenna

Objective: To measure the radiation pattern of pyramidal horn antenna.


S No Components & Equipments Model No

1. Gunn Power supply GS-610

2. Gunn Oscillator XG-11

3. PIN modulator XM-55

4. Isolator XI-621

5. Variable attenuator XA-520

6. Detector mount XD-451

7. VSWR Meter SW-115

8. Radiation Pattern or Microprocessor Controlled Twin

Table

XTB-105

9. Pyramidal Horn Antenna XH-541

10. E-plane bend XB-771

11. Wave guide stand XU-535

12. Frequency Meter XF-710

Accessories

1. Cooling fan CF-205

2. BNC cable

3. TNC cable

(Gunn source, Isolator, Transmitting Antenna, Receiving Antenna, DC Ammeter.)

Procedure:

A. Antenna Radiation Pattern:

1. Set up the equipment as shown in fig.1.Keeping the axis of both the antennas in same line.

2. Make sure no objects are closed. The propagation path and the distance between the

Transmitting antenna & the antenna at receiving end is much greater than 2d2/λ where d is

the size of broad wall of the transmitting antenna „λ‟ is wavelength.

3. Energize the Gunn Oscillator for maximum output at desired frequency with square wave

modulation by tuning square wave amplitude and frequency of modulating signal of Gunn

power supply and by tuning the detector.

4. Also tune the S.S. Tuner, in the line for maximum output (if S.S. Tuner is in the set up).

5. Obtain full scale deflection (0 db) on normal db scale (0-10 db) at any convenient range

switch position of the VSWR Meter by gain control knob of VSWR meter or by variable

attenuator.

6. Tune the receiving horn to the left in 20- 5

0 steps up to 4

0-5

0 and note the corresponding

VSWR db reading in normal db range. When necessary, change switch to next higher

range and add 10 db to the observed value.

7. Plot a relative power pattern i.e. output Vs. Angle.

8. From diagram determine 3 db-width (beak width) of the horn Antenna.

B. GAIN MEASUREMENT:

1. Set up the equipment as shown in the figure.1

2. Keep the range db switch meter at 50 db position with gain control full.

3. Energize the Gunn Oscillator for maximum output at desired frequency with square

wave modulation by tuning square wave amplitude and frequency of modulating

signal of Gunn power supply and by tuning the detector.

4. Obtain full scale deflection in VSWR meter with variable attenuator

5. Replace the transmitting horn antenna by detector mount and change the appropriate

range db position to get the deflection. On Scale (do not touch the gain control knob).

Note and record the range db position and deflection of VSWR Meter.

6. Calculate the difference in db between the power in step 4 and 5.

Horn antennas

Tx Rx

Fig.9.1 Experimental set up to obtain the antenna gain & radiation pattern

Gunn

Oscillator

XG-11

VSWR

meter

SW-115

Isolator

XI- 621

PIN

Modulator

XM-55

Variable

attenuator

XA-520

Frequen

cy meter

XA- 710

Detector

mount

XD-451

Gunn power

supply GS-610

I mA

-550 90

0 55

0

-100 10

0

00

Fig.9.2 Radiation pattern of horn antenna

Observations:

Angle of rotation (90 + or 90-) Degrees Output power dB

0 0

+100

+200

+300

+400

+500

+600

-100

-200

-300

-400

-500

-600

--

--

--

--

--

--

--

--

--

--

--

--

--

Radial Distance between horns S = 2 D2

/ λ

Where D= 10.2 cm

And λ = C / f where C=3*108 m/s & f= 9.3 G Hz

Gain ,

G =

Where Pr and Pt are receiving and transmitting powers.

Experiment-10

Characteristics of LED

Objective:

a) To plot the volt-ampere characteristics of a LED.

b) To determine the cut-in voltage, dynamic & static forward bias resistance.

Equipment required:

Semiconductor trainer module containing bread board, LED CQ124, 1KΩ - resistor – 1no.

Procedure:

1. Connect the equipment as shown in fig.

2. Use CQ124 LED and make it forward bias connection.

3. Increases the voltage applied to diode gradually in steps and note the ammeter and

voltmeter readings and plot is drawn.

Precautions:

1. Do not connect the ammeter across the supply (or) to diode.

2. Do not connect the voltmeter in series with the diode.

3. Select the meters of proper range which are somewhat greater than required ratings.

Circuit Diagram:

1 K Ω + (0-200)mA - CQ124

(0-15) V + -

(0-30) V

Fig.10.1 Circuit diagram to obtain V-I characteristics of LED

A

V

Graph:

I (mA)

I

------------------------------------

∆I -----------------------------------

∆V V V(volts)

Fig.10.2 V-I characteristics of LED

Dynamic resistance = ∆ V/ ∆I Ohms

Static resistance = V/ I Ohms

Tabular column:

Voltage (volts) Current (mA)

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

Cut-in voltage of LED= __ volts

EXPERIMENT-11

STUDY OF CHARACTERISTICS LASER DIODES

Objective:

To study VI Characteristic of Laser Diode.

Measurement of Lasing Threshold using Current versus Optical Power Characteristics

(Power Meter Optional).

Equipment:

Fiber Link – E Kit.

Glass Fiber Cable with ST connector: 1 No.

Patch cords.

Voltmeter.

Ammeter.

Power Supply.

Fig 11.1 Link-K set up to study VI characteristics of LASER

Table 11.1 Tabular column to note Forward Voltage and Foeward currents:

Forward Voltage (volts) [JP3] Forward Current (mA) [JP2]

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

Threshold voltage==_____ V

PROCEDURE:

Confirm that the power switch is in OFF position and then connect it to the kit.

Make the jumper settings and connection as shown in the block diagram

Insert the jumper connecting wires (provided along with the kit) in jumper JP1, JP2 and

JP3 at positions shown in the diagram.

Connect the ammeter and volt-meter with the jumper wires connected to JP1, JP2 and

JP3 as shown in the block diagram.

Keep the potentiometer P5 in anti-clockwise rotation; it is used to control intensity of

laser diode.

Connect external signal generator to ANALOG IN post of Analog buffer and apply sine

wave frequency of 1MHz, 1V p-p signal precisely.

Then connect ANALOG OUT post to ANALOG IN post of transmitter.

Then Switch on the power supply.

To get the IV characteristics of Laser diode, rotate P5 slowly and measure forward

current and corresponding forward voltage at JP1, JP2 and JP3 respectively.

Take number of such readings for various current values and plot IV characteristics

graph.

Fig 11.2 LASER characteristics

EXPERIMENT-12

STUDY OF NUMERICAL APERTURE OF OPTICAL FIBER

OBJECTIVE:

The objective of this experiment is to measure the numerical aperture of the plastic fiber

provided with the kit using 660 nm wavelength LED.

EQUIPMENTS:

Link-A kit.

1 Meter Fiber cable.

NA JIG.

Steel Ruler.

Power supply.

Fig 12.1: Block Diagrams for Numerical Aperture Measurement

PROCEDURE:

Connect the power supply cables with proper polarity to kit. While connecting this, ensure

that the power supply is OFF. Do not apply any TTL signal from Function Generator. Make

the connections as shown in block diag.

Keep all the switch faults in OFF position.

Keep Pot P3 fully Clockwise Position and P4 fully anticlockwise position.

Slightly unscrew the cap of LED SFH756V (660 nm). Do not remove the cap from the

connector. Once the cap is loosened, insert the fiber into the cap. Now tight the cap by

screwing it back. Keep Jumpers JP2 towards +5V position, JP3 towards sine position, JP5 &

JP6 towards TX1 position.

Keep switch S3 towards VI position.

Insert the other end of the fiber into the numerical aperture measurement jig. Hold the white

sheet facing the fiber. Adjust the fiber such that its cut face is perpendicular to the axis of the

fiber.

Keep the distance of about 10 mm between the fiber tip and the screen. Gently tighten the

screw and thus fix the fiber in the place.

Now adjust Pot P4 fully Clockwise Position and observe the illuminated circular patch of

light on the screen.

Measure exactly the distance d and also the vertical and horizontal diameters MR and PN

indicated in the block diagram.

Mean radius is calculated using the following formula. r = (MR + PN) / 4

Find the numerical aperture of the fiber using the formula. NA = sin max = r / [d2 + r2]1/2

Where max is the maximum angle at which the light incident is properly transmitted through

the fiber.

EXPERIMENT-13

STUDY OF LOSSES IN OPTICAL FIBER

OBJECTIVE:

The objective of this experiment is to measure propagation loss in plastic fiber provided with

the Lab for three different wavelengths of radiation as 950 nm, 660 nm and also to measure

the bending loss.

EQUIPMENTS:

Link-A kit.

20 MHz Dual Trace Oscilloscope.

1 & 3 Meter Fiber cable.

Power supply.

Fig 13.1: Block Diagrams for Fiber loss measurement

PROCEDURE:

Make the connections and Jumper settings as shown in block diagram Connect the power

supply cables with proper polarity to kit. While connecting this, ensure that the power supply

is OFF.


Switch on the power supply.

Select the frequency range of Function Generator with the help of Range Selection Switch

SW1, frequency can be varied with Pot P2. Adjust the voltage LEVEL of the Sine Wave with

Pot P1 as per following setting. FREQUENCY: 1KHz, LEVEL: 2Vp-p.

Connect SINE post of the Function Generator section to IN post of Analog Buffer Section.

Keep Jumpers JP2 & JP4 towards +12V position, JP3 towards sine position, JP5 towards

TX1 position, JP6 towards TX1 position & JP7 shorted.

Keep switch S3 towards TX IN position.

Connect OUT post of the Analog Buffer Section to TX IN post of TRANSMITTER.

Slightly unscrew the cap of LED SFH 756V TX1 (660 nm) from kit. Do not remove the cap

from the connector. Once the cap is loosened, insert the fiber into the cap and assure that the

fiber is properly fixed. Now tight the cap by screwing it back. Keep INTENSITY pot P3 at

minimum position i.e. fully anticlockwise.

Connect the other end of the fiber to detector SFH 250V (RX 1) in kit very carefully.

Check the output signal of the Analog Buffer at its OUT post in Kit. It should be same as that

of the applied input signal.

Now replace 1 meter fiber by 3 meter fiber without disturbing any of the previous settings.

Measure the amplitude level at the receiver side again. You will notice that it is less than the

previous one. Mark this as V2.

If alpha is the attenuation of the fiber then we have, P1/P2=V1/V2=exp[-alpha (L1-L2)]

where alpha = nepers / meter L1 = fiber length for V1 L2 = fiber length for V2 This alpha is

for the wavelength of 950 nm. To get the alpha for 660 nm wavelength proceed as follows.

Remove fiber from TX2 & connect it to TX1.

Keep Jumpers JP5 & JP6 towards TX1 position.

Observe the output signal from the detector at ANALOG OUT post on CRO by adjusting

INTENSITY (Optical Power Control) Pot P3 in kit and you should get the reproduction of

the original transmitted signal. Mark this amplitude level as V1.

Now replace 1 meter fiber by 3 meter fiber without disturbing any of the previous settings.

Measure the amplitude level at the receiver side again. You will notice that it is less than the

previous one. Mark this as V2. If alpha is the attenuation of the fiber then we have,

P1/P2=V1/V2=e [-alpha (L1-L2)]

where alpha = nepers / meter

L1 = fiber length for V1

L2 = fiber length for V2

Compare the values of alpha and find out the wavelength which has less attenuation in the

fiber.

MEASUREMENT OF BENDING LOSSES:

Bend the fiber in a loop as shown in block diagram Measure the amplitude of the received

signal.

Keep reducing the diameter to about 2 cm & take corresponding output voltage readings. (Do

not reduce loop diameter less than 2 cm.)

Plot a graph of the received signal amplitude versus the loop diameter.

Fig 13.2 Expected Waveforms

Observations:

Output amplitude when L1=1meter optical cable is used,V1=____ mV

Output amplitude when L2=3meter optical cable is used,V2=______ mV

Loss in dB=10/[L1-L2]log(V2/V1)=_____dB

Table 13.1: Bending Losses

Diameter of the bent cable cm Output voltage mV

10

8

6

4

3

EXPERIMENT-14

14.1 SETTING UP A FIBER OPTIC ANALOG LINK

OBJECTIVE:

The objective of this experiment is to study an 660 nm/ 950 nm Fiber Optic Analog Link.

In this experiment you will study the relationship between the input signal & received

signal.

EQUIPMENTS:

Link-A kit.

20 MHz Dual Channel Oscilloscope.


Power supply.

Fig 14.1 Block Diagram to set up Analog Link

PROCEDURE:

Make the connections and Jumper settings as shown in block diagram Connect the power

supply cables with proper polarity to kit. While connecting this, ensure that the power

supply is OFF.



Select the frequency range of Function Generator with the help of Range Selection

Switch SW1, frequency can be varied with Pot P2. Adjust the voltage LEVEL of the Sine

Wave with Pot P1 as per following setting. FREQUENCY: 1KHz, LEVEL: 2Vp-p.

Connect SINE post of the Function Generator section to IN post of Analog Buffer Section.

Keep Jumpers JP2 & JP4 towards +12V position, JP3 towards sine position, JP5 towards

TX1 position, JP6 towards TX1 position & JP7 shorted.





fiber is properly fixed. Now tight the cap by screwing it back. Keep INTENSITY pot P3 at

minimum position i.e. fully anticlockwise.


Check the output signal of the Analog Buffer at its OUT post in Kit. It should be same as that

of the applied input signal.


INTENSITY (Optical Power Control) Pot P3 in kit and you should get the reproduction of

the original transmitted signal.

To measure the analog bandwidth of the link, connect the external Signal Generator with

2Vp-p sine wave to IN post of Analog Buffer Section and vary the frequency of the input

signal from 100 Hz onwards. Measure the amplitude of the received signal for each

frequency reading.

Plot a graph of gain / Frequency. Measure the frequency range for which the response is

flat.


Remove Fiber from TX1. Slightly unscrew the cap of LED SFH 450V TX2 (950 nm)

from kit. Do not remove the cap from the connector. Once the cap is loosened, insert the

fiber into the cap and assure that the fiber is properly fixed. Now tight the cap by

screwing it backs. Keep INTENSITY pot P3 at minimum position i.e. fully anti

clockwise.

Check the output signal of the Analog Buffer at its OUT post in Kit. It should be same as

that of the applied input signal.


INTENSITY (Optical Power Control) Pot P3 in kit and you should get the reproduction

of the original transmitted signal.

To measure the analog bandwidth of the link, connect the external Signal Generator with

2Vp-p sine wave to IN post of Analog Buffer Section and vary the frequency of the input

signal from 100Hz onwards. Measure the amplitude of the received signal for each frequency

reading.

Plot a graph of gain / Frequency. Measure the frequency range for which the response is flat.

Fig 14.2 Expected Analog input and Output waveforms

14.2 SETTING UP A FIBER OPTIC DIGITAL LINK.

OBJECTIVE:

The objective of this experiment is to study 950 and 660 nm fiber optic digital link. Here you

will study how digital signal can be transmitted over fiber cable and reproduced at the

receiver end.

EQUIPMENTS:

Link-A kit.



Power supply.

Fig 14.3 Block Diagram to set up Digital link

PROCEDURE:


that the power supply is OFF. Now switch on the power supply.


Keep Jumpers JP2 & JP4 towards +5V position, JP3 towards pulse position, JP5 & JP6

towards TX1 position.

Keep Switch SW1 at 100 Hz - 1 kHz.

Feed the Onboard Square (TTL) signal of about 1 KHz to IN post of Digital Buffer Section

and observe the signal at its OUT post . It should be same as that of the input signal.

Connect OUT post of the Digital Buffer Section to TX IN post of TRANSMITTER.

Slightly unscrew the cap of LED SFH 756V (660 nm). Do not remove the cap from the


screwing it back.

Connect the other end of the fiber to detector SFH 551V RX2 (Digital Detector) very

carefully.

Keep Switch S3 in TXIN position.

Observe the received signal on CRO at TTL OUT post. The transmitted signal & received

signal are same. Vary the frequency of the input signal and observe the output response.


Remove fibre from TX 1 and connect to TX 2 (SFH 450V (950 nm).

Observe the received signal on CRO at TTL OUT post.

Fig 14.4 Expected Digital input and Output waveforms

EXPERIMENT-15

STUDY OF FREQUENCY MODULATION & DEMODULATION USING FIBER OPTIC

LINK

OBJECTIVE:

The objective of this experiment is to study Frequency Modulation & Demodulation over

Fiber Optic Link using 660 nm and 950 nm LED.

EQUIPMENTS:

Link-A kit.



Power supply.

Fig 15.1 Block diagram Frequency Modulation and Demodulation Using fiber Optic Link

PROCEDURE:


that the power supply is OFF.


Select the frequency range of about 1 KHz from Function Generator with the help of Range

Selection Switch SW 1, frequency can be varied with Pot P2. Adjust the voltage LEVEL of

the Sine Wave to 2Vp-p with Level Pot P1.

Keep Jumpers JP2 towards +12V position, JP3 towards sine position, JP5 & JP6 towards

TX1 position & JP7 shorted.


Connect SINE post of the Function Generator section to FM IN post of FM Modulator

Section.

Connect FM OUT post section of FM Modulator section to IN post of Analog Buffer Section.




fiber is properly fixed. Now tight the ap by screwing it back. Keep INTENSITY pot P3 at

minimum position i.e fully anti clockwise.



INTENSITY pot P3 & you should get the reproduction of the original transmitted signal.

Connect ANALOG OUT in Receiver Transimpedance Amplifier Section to FM DEMOD IN

post of FM Demodulator Section.

Connect FM DEMOD OUT post to IN post of Filter Section.

Observe demodulated signal at FM DEMOD OUT post and then observe output at Filter

OUT post which is same as Input signal.

Fig 15.2 Expected waveforms

EXPERIMENT-16

STUDY OF PULSE WIDTH MODULATION AND DEMODULATION

OBJECTIVE:

The objective of this experiment is to study Pulse Width Modulation and Demodulation

over Fiber Optic Digital Link.

EQUIPMENTS:

Link-A kit.



Power supply.

Fig 16.1 Block diagram Pulse Width Modulation and Demodulation Using fiber Optic Link

PROCEDURE:

Connect the power supply cables with proper polarity to kit. While connecting this,

ensure that the power supply is OFF. Now switch on the power supply.





Connect SINE post of the Function Generator section to PWM IN post of PWM/ PPM

Modulator Section.

Keep sine frequency at 1 KHz & amplitude of 2Vp-p.

Keep Jumpers JP1 at 32 KHz position.

Observe PWM signal at PWM OUT Post.

Connect PWM OUT post of PWM/PPM Modulator Section to IN post of Digital Buffer

Section.


Slightly unscrew the cap of SFH756V (660 nm). Do not remove the cap from the


screwing it back.


Connect the other end of fiber to detector SFH551V (Digital Detector) very carefully.

Observe the received signal over fiber at TTL OUT post. It should be exactly similar to

the signal available at PWM OUT post.

Slide the switch SW 2 to PWM position.

Connect this TTL OUT post to PWM DEMOD IN Post in PWM / PPM Demodulator

Section.

Vary input freq. POT P2 and observe demodulated signal at DEMOD OUT post.

Connect PWM / PPM DEMOD OUT post to IN post of Filter Section and observe output

at its OUT post which is same as Input signal.

For Different Sampling frequencies change the jumper cap of JP1 from 32 KHz to the desired

value of frequency. You can observe the PWM output clearly at lower sampling frequency,

demodulated PWM OUT is more Distorted at lower sampling frequency.

EXPERIMENT-17

STUDY OF PULSE POSITION MODULATION & DEMODULATION

OBJECTIVE:

The objective of this experiment is to study Pulse Position Modulation & Demodulation over

Fiber Optic Digital Link.

EQUIPMENT:

Link -A Kit.


1 meter fiber cable.

Power Supply.

Fig 17.1 Block diagram for Pulse Position Modulation and Demodulation Using fiber Optic Link

PROCEDURE:


that the power supply is OFF.





Connect SINE post of the Function Generator section to PPM IN post of PWM/ PPM

Modulator Section.


Keep sine frequency at 1 KHz & amplitude of 2Vp-p.

Keep Jumpers JP1 at 32 KHz position.

Observe PPM signal at PPM OUT Post.

Connect PPM OUT post of PWM/PPM Modulator section to IN post of Digital Buffer

Section.


Slightly unscrew the cap of SFH756V (660 nm). Do not remove the cap from the connector.

Once the cap is loosened, insert the fiber into the cap. Now tight the cap by screwing it back.


Connect the other end of fiber to detector SFH551V (Digital Detector) very carefully.

Observe the received signal over fiber at TTL OUT post. It should be exactly similar to the

signal available at PPM OUT post.

Connect this TTL OUT post to PPM DEMOD IN Post in PWM / PPM Demodulator Section.

Slide the switch SW 2 to PPM position.

Vary input freq. (not more than 3 KHz) & observe demodulated signal at DEMOD OUT

post.

Connect DEMOD OUT post to FILTER IN post & observe output at FILTER OUT post

which is same as Input signal.

For Different Sampling frequencies change the jumper cap of JP1 from 32 KHz to the desired

value of frequency.

EXPERIMENT-18

SETTING UP PC TO PC COMMUNICATION LINK USING OPTICAL GLASS

FIBER AND RS-232 INTERFACE

OBJECTIVE:

To study fiber optic digital link with help of 1310nm laser diode.

EQUIPMENT:

Fiber Link – E Kit.

Glass Fiber Cable with ST connector: 1 No.

Patch cords.

RS-232 Cable.

Computers – PC, PC/XT, 386 or 486 –two Nos.

Power Supply

Fig 18.1 Schematic connection for Data transmission via optical link

PROCEDURE:

Confirm that the power switch is in OFF position and then connect it to the

kit.

Make the jumper settings and connections.

Connect COM1 post in RS-232 section to BUFFER IN post of TTL buffer

Section.

Connect BUFFER OUT post to TTL IN post of transmitter.

Connect TTL OUT post of receiver to COM2 post in RS232 section.

Then connect one end of RS-232 cable from PC1 to COM1 connector on

LINK-E kit & connect second RS-232 cable from PC2 to COM2 connector

on LINK-E kit

Connect the fiber between Laser diode and detector as per the

instructions.

Keep jumper JP1 towards right position.

Keep switch SW1 towards TTL position.

After putting ON one of the PC, go to START MENU, PROGRAMS,

ACCESSORIES, COMMUNICATION and then click on HYPER

TERMINAL.

A new Window will open, where you Double Click on HYPERTERMINAL.

Two Widows will open one at the background and another (small window)

with title Connection Description which will be Active.

Enter the name in the box by which you would like to store your

connection, for e.g. (PC2PC), and Click OK. Also you could select the Icon

provided below. The background window title will change to the name

provided by you.

Then specify connect using: by selecting Direct to COM1 or port where

your cable is connected and then click on OK.

Now Window with Title COM1 Properties will appear where Port Setting

should be done as shown below and click on OK.

(Bits per sec. -2400)

Data bits -8,Parity - None,Stop bits -1,

Flow control - Xon/Xoff

After the above settings you click OK. The Background window will

become Active Click on File, Save As, and save it in the Directory, which

you want. Perform the same procedure on PC2, the computer with whom

you want to communicate.

To start communication between the PC1 to PC2, click on the TRANSFER

Menu and again click on Send File of PC1. A window will be prompted

having title Send File with File Name and Protocol.

Select Browse for the file, which you would like to send to the PC

connected, select the file and Click on Open, the file name and address

will be displayed in the small window. Then select the Kermit Protocol,

(optional use protocols are X modem, Y modem and 1K Xmodem ).

To receive the file on the PC2, click on the TRANSFER Menu and again

click on Receive File. A window will be prompted having title Receive File with

Location at which you want to store the Received file and Receiving Protocol.

Select Browse for the location where you would like to store the received file, select the

folder and click OK, the folder name and address will be displayed in the small window.

Protocol to be selected should be Kermit and same as file transmitting PC.

On the PC1 from which the selected file to be transmitted, click on SEND. A window

will open showing file transfer status. Immediately at the Receiving PC2, click Receive

(otherwise Time Out Error will be displayed and communication will fail) .You will see a

window showing that file is being received in the form of packets.

After file is transferred, both the windows in the (transmitting & receiving PCs) will

close. Check for the received file in the folder where the file is stored.

You can do this procedure vice-versa to transfer the file.

NOTE:

To change the bits per second rate (bauds Rate) go to properties in the

Hyper Terminal window, Click on File Menu, Properties and configure, in

the bits per second select other rates. From 2400 to 9600 bps. You will

observe that the rate at which the file is transferred will vary with the

selected baud rate. Also you can observe and check that by removing

fiber from detector, packets increment and file transfer stops. Also ensure

that at the left corner of the hyper terminal window connected time must

be ON, if disconnected label is there go to call option and press call.

If HyperTerminal is not installed in your computer then, on PC Go to My

Computer, Control Panel, Add Remove Programs, Windows Setup,

Communication, Check Hyper Terminal and click OK.