cntl 5th sem

Sri Satya Sai Institute Of Science & Technology,Sehore

Department of Electronics and Communication Engineering

Lab Manual

of

CNTL

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Sri Satya Sai Institute Of Science & Technology,Sehore Department Of Electronics & Communication

List of Experiment

1. Study of prototype constant –K LOW PASS FILTER.

2. Study of prototype constant –K HIGH PASS FILTER.

3. To check frequency response of a ‘ low pass’ filter with the help of Spectrum Analyser.

4. To measure the image impedance of an asymmetrical L network using300Ω in series arm , 600Ω in shunt arm.

5. To check frequency response of a ‘ high pass’ filter with the help of Spectrum Analyzer.

6. To design an active LOW PASS FILTER at a cut off frequency of 1 kHz and pass band gain of 2 dB. Plot the frequency response curve.

7. To design an Active High Pass Filter of a cut off frequency of 1 kHz and pass band gain of 2 dB. Plot the frequency response curve

8. To measure the attenuation of Transmission line . 9.To Measure the input impedance of the line

10. Design of Symmetrical T-attenuator.

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EXPERIMENT NO.1

AIM: Study of prototype constant –K LOW PASS FILTER.

APPARATUS REQUIRED:Inductor (32 mH) 2 Nos, Capacitors(1 uf ) , functiongenerator, CRO, bread board Patch chords, connecting wires

THEORY:A LOW PASS FILTER is one which transmit all frequencies from zero up to some designated frequency called cut off frequency (fc) but attenuates frequency beyond this. The circuit diagram is as shown in the figure. If the constant K filter is a T or π network in which series and shunt impedances Z1and Z2 are connected by the relationshipZ1 Z2=Rk

2

Where Rk is a real constant that is resistance independent of frequency . Rk is often termed as design impedance of constant k filter.The constant k filter is a T or π filters as shown in the figure. Since the total series and shunt impedanceof both T or π filters are the same they will have same design impedance and cut off frequency.

Z1 Z2=Rk2=L/C

ZOT=L/C√(1-w2LC/4)

ZOT is real if w2LC/4<1 and imaginary if w2LC/4>1Cut off frequency fc at which the ZOT changes from being real to imaginaryωc

2LC/4=1fc=1/π(LC)1/2

L=Rk/π fc , C=1/π fc Rk




PROCEDURE :

1) Design the circuit and implement on breadboard.2) Set the output of function generator at 1 volt and connect at input ofthe filter.3) Connect the output on CRO.4) Changing the frequency of function generator from 100 hz to 1 mhz,get the reading of output taking the frequency in multiple of 10.5) Calculate the value of fc and Rk and match their theoretical andpractical values.

RESULT : Study of prototype constant –k low pass filter is complete.

PRECAUTIONS:1) Always make connection properly in breadboard2) All connections should be tight.

FREQUENTLY ASKED QUESTION’S:

1.Write disadvantage of prototype filter.

2. Define characteristics of filters?

3.What is the ratio between Z1 and Z2 during pass band?

4.How are m- derived superior to prototype filter?




EXPERIMENT NO.2

AIM: Study of prototype constant –K HIGH PASS FILTER.

APPARATUS REQUIRED:Inductor (2.4 mH),Capacitors(0.01 uf ) , function generator, CRO, bread boardPatch chords, connecting wires

THEORY:A HIGH PASS FILTER is a four terminal network which passes all signals of frequency

greater than its cut off frequency (fc) but attenuates frequency below this. The circuit diagram is as shown in the figure. If the constant K filter is a T or π network in which series and shunt impedances Z1and Z2 are connected by the relationship

Z1 Z2=Rk2

Where Rk is a real constant that is resistance independent of frequency . Rk is often termed as design impedance of constant k filter.The constant k filter is a T or π filters as shown in the figure. Since the total series and shunt impedance of both T or π filters are the same they will have same design impedance and cut off frequency.

Z1 Z2=Rk2=L/C

ZOT=L/C√(1-w2LC/4)

ZOT is real if w2LC/4<1 and imaginary if w2LC/4>1 Cut off frequency fc at which the ZOT changes from being real to imaginary

ωc2=1/4LC

fc=1/4π(LC)1/2

L=Rk/4π fc , C=1/4π fc Rk

PROCEDURE :

1) Design the circuit and implement on breadboard.2) Set the output of function generator at 1 volt and connect at input of the filter.




3) Connect the output on CRO.4) Changing the frequency of function generator from 1000 hz to 1 mhz, get the

reading of output taking the frequency in multiple of 10.5) Calculate the value of fc and Rk and match their theoretical and practical

values.

RESULT :Study of prototype constant –k high pass filter is complete

PRECAUTIONS:1. Always make connection when kit is in off position.2. All connections should be tight.


1.Write disadvantage of prototype filter.


3.What is the ratio between Z1 and Z2 during pass band?

4.How are m- derived superior to prototype filter?




EXPERIMENT NO.3

AIM: To check frequency response of a ‘ low pass’ filter with the help of Spectrum Analyser.

APPARATUS REQUIRED: 1. Spectrum Analyzer HM 5006 2. BNC-BNC cable 2 Nos 3. Low pass filter

THEORY: Low pass filter is the filter which allows only the low frequency signal to pass through it.

PROCEDURE :A) Switch on the spectrum analyzer and check if the instrument is meeting the calibration

requirements else refer to the manual supplied along with the instrument.B) Set the spectrum analyzer as given below:

CENTER FREQUENCY 000.0ATTENUATION (10 dBx2)SCAN WIDTH 2 MHz/Div

C) Set the Tracking Generator as given below :ATTENUATION ALL PRESSEDON/OFF SWITCH ONLEVEL +1 dB (clockwise)

D) Connect the given filter between the Spectrum Analyzer and Tracking generator as shown in the fig1.

E)You will observe the curve as follows (Fig 2.)F ) Now switch on the marker push button. MK is lit and the display shows the marker frequency. The marker is shown on the screen as a vertical needle. Now adjust the Marker knob so as to align the needle with the spectral line under observation. The reading as obtained on the display is the required frequency




G) In order to find the Bandwidth of the given filter start moving the marker Knob and note its reading at –3 dB (marked X in the fig.) . In order to find the pass band of filter scan using the center frequency knob up to 300 MHz.

OBSERVATIONS :

S.No. 3 dB gain Frequency

RESULT :frequency response of a ‘ low pass’ filter with the help of Spectrum

Analyser is checked.

PRECAUTION :1) Never exceed the input to the Spectrum Analyzer beyond 10 mV rms with no

attenuation and 1 V rms with all attenuation switches pressed .2) While using Tracking Generator never apply signal from external source to any of its

BNC terminals .

FREQUENTLY ASKED QUESTION’S:1) What is Spectrum Analyzer? 2) Difference between CRO and Spectrum Analyzer?3) What is the reference level in SA ?4) What do you understand by Sensitivity of SA ?




EXPERIMENT NO.4

AIM: To measure the image impedance of an asymmetrical L network using300Ω in series arm , 600Ω in shunt arm.

APPARATUS REQUIRED: Resistors(600 Ω,350Ω,300Ω),RPS ,CRO , multimeter

THEORY :Since the asymmetrical networks have unequal input and output impedance therefore their

behavior is described in terms of iterative impedance , image impedance , image transfer constant and iterative transfer constant.

Image impedance :

Every asymmetrical four terminal network as two image impedances such that when one of them is connected at the appropriate terminals the impedance measured at the other pair of terminal equals the second image impedance. Image impedances are usually denoted by Z01 and Z02

Z01=√(Z12/2+Z 1Z2 ) Z01=√Zoc1Zsc1

Z02= Z 1Z2/√Z12+Z 1Z2 Z02= √Zoc2Zsc2

PROCEDURE :1) Design the circuit and implement on breadboard.2) Open the circuit at terminal 2-2..3) Connect the multimeter and vary DC voltage connected between terminal 1-14) Vary the DC voltage from (5-20V) and note the value of current and apply the same procedure for Zsc.5) For Z21 repeat the above procedure to calculate Zoc2 andZsc2.




6) Finally compare those values with theoretical values.

OBSERVATION TABLE :

SNO. Practical value1. Applying Z01 as

input load=520ΩZ02=

2. Applying Z02 as input load=350Ω

Z01=

RESULT : The image impedance of asymmetrical network is----------

PRECAUTIONS:1) Always make connection when kit is in off position.2) All connections should be tight.


1. Define Image Impedance, Iterative Impedance. 2. What is Half Section ,where they are used. 3. What are attenuators?

4. What is difference between attenuators and equalizers ?




EXPERIMENT NO.5

AIM: To check frequency response of a ‘ high pass’ filter with the help of Spectrum Analyzer.

APPARATUS REQUIRED: 1. Spectrum Analyzer HM 5006 2. BNC-BNC cable 2 Nos 3. High pass filter

THEORY:High pass filter is the filter which allows only the high frequency signals to

pass through it.

PROCEDURE :

A) Switch on the spectrum analyzer and check if the instrument is meeting the calibration requirements else refer to the manual supplied along with the instrument.

B) Set the spectrum analyzer as given below:CENTER FREQUENCY 000.0ATTENUATION (10 dBx2)SCAN WIDTH 2 MHz/Div

C) Set the Tracking Generator as given below :ATTENUATION ALL PRESSEDON/OFF SWITCH ONLEVEL +1 dB (clockwise)

D) Connect the given filter between the Spectrum Analyzer and Tracking generator as shown in the fig1.

E)You will observe the curve as follows (Fig 2.)

F ) Now switch on the marker push button. MK is lit and the display shows the marker frequency. The marker is shown on the screen as a vertical needle. Now adjust the Marker knob so as to align




the needle with the spectral line under observation. The reading as obtained on the display is the required frequency

G) In order to find the Bandwidth of the given filter start moving the marker Knob and note its reading at –3 dB (marked X in the fig.) . In order to find the pass band of filter scan using the center frequency knob up to 300 MHz.

OBSERVATIONS :

S.No. 3 dB gain Frequency

RESULT : frequency response of a ‘ high pass’ filter with the help of Spectrum

Analyzer. is checked.

PRECAUTION :1) Never exceed the input to the Spectrum Analyzer beyond 10 mV rms with no

attenuation and 1 V rms with all attenuation switches pressed .2) While using Tracking Generator never apply signal from external source to any of its

BNC terminals .

FREQUENTLY ASKED QUESTION’S: 1) What is Spectrum Analyzer? 2) Difference between CRO and Spectrum Analyzer? 3)What is the reference level in SA ? 4)What do you understand by Sensitivity of SA ?




EXPERIMENT NO.6

AIM: To design an active LOW PASS FILTER at a cut off frequency of 1 kHz and pass band gain of 2 dB. Plot the frequency response curve.

APPARATUS REQUIRED:OP- AMP(IC-741),RESISTORS 10k,10k,20kCapacitors(ceramic type) - 0.01μf,Function Generator, CRO, Bread BoardPatch chords, connecting wires

THEORY:A Low Pass Filter is a four terminal network which stops all signals of frequency greater

than its cut off frequency (fc). The circuit diagram is as shown in the figure. The input is given at non-inverting terminals of OP-AMP via a resistor and capacitor as shown in the figure. Gain A is given by

A=1+Rf/R1

Cut off frequency is given byFc=1/2πRC

PROCEDURE :1)Assume and take C=0.01 uf.2)design the circuit and implement on breadboard.3)Set the output of function generator at 1 volt and connect the input to the filter.4)Connect the output on CRO.5)Changing the frequency of function generator from 100 hz to 1 Mhz, get the

reading of output taking the frequency in multiple of 10.




6)Plot frequency response curve between Gain and Frequency.

OBSERVATION TABLE:

S.NO. Vin (volts) Input frequency (Hz)

V0(volts) Gain=20logV0/Vin

CALCULATION:Let C=0.01 μfFc=1/2πRCGain=20logV0/Vin

If Vin=1 VGain=20logV0

RESULT :Frequency response curve is plotted on the graph paper.


FREQUENTLY ASKED QUESTION’S:1. what are filters?2. What is the difference between Active and Passive filters?3. What do you understand by frequency transformation ?





EXPERIMENT NO.7

AIM: . To design an Active High Pass Filter of a cut off frequency of 1 kHz and pass band gain of 2 dB. Plot the frequency response curve

APPARATUS REQUIRED:OP- AMP(IC-741),RESISTORS 10k,10k,20kCapacitors(ceramic type) - 0.01μf, Function Generator, CRO, Bread Board

Patch chords, connecting wires

THEORY:A HIGH PASS FILTER is a four terminal network which passes all signals of frequency greater than its cut off frequency (fc) but attenuates frequency below this. The circuit diagram is as shown in the figure. The input is given at non-inverting terminals of OP-AMP via a resistor and capacitor as shown in the figure. Gain A is given by

A=1+Rf/R1

Cut off frequency is given byFc=1/2πRC

PROCEDURE :

1)Assume and take C=0.01 uf.2)design the circuit and implement on breadboard.3)Set the output of function generator at 1 volt and connect at input of the filter.4)Connect the output on CRO.5)Changing the frequency of function generator from 100 hz to 1 mhz, get the

reading of output taking the frequency in multiple of 10.6)Plot frequency response curve between Gain and Frequency

OBSERVATION TABLE:




SNO. Vin (volts) Input frequency (Hz) V0(volts) Gain=20logV0/Vin

CALCULATION:Let C=0.01 ufFc=1/2πRCGain=20logV0/Vin

If Vin=1 VGain=20logV0

RESULT :Frequency response curve is plotted on the graph paper.


FREQUENTLY ASKED QUESTION’S:1.What are filters?2. What is the difference between Active and Passive filters?3. What do you understand by frequency transformation ?4.Define characteristics of filters?




EXPERIMENT NO.8

AIM :To measure the attenuation of Transmission line .

APPARATUS REQUIRED : Trainer kit, CRO, Patch chords

THEORY:

The Ohmic resistance R & the conductance G are responsible for energy disputation in

the form of heat. These losses, which determine the attenuation characteristics ,are

expressed in terms of attenuation “A” and can be calculated by

A=20log(V2/V1)Where V1= amplitude of signal at I/PV2 = amplitude of signal at O/PA = attenuation for given lengthIn this experiment we will measure the attenuation for the different trunks of

transmission line available on the trainer. See fig.

PROCEDURE:

1. Adjust Ri and Rl for 18Ω and 68Ω respectively with the help of DMM.2. Make connections as shown in diagram.3. Set the sine wave frequency to approx 100Khz and level to 0.4 v.4. Oscilloscope Ch1 shows applied input Ch2 shows outputs.5. Measure signal level at input, and at 20,50,75 and 100m length.6. Now calculate the attenuation in dB at various lengths by the formula given below:

A=20log(V2/V1)http://rkdf.blogspot.in visit for study materials 17



7. The attenuation is approx –2 dB at 100m.8. Try the same with open ended line and short ended line.

OBSERVATION :

Length(m) V1 (input) V2 (output)255075100

RESULT : It is verified that when length increases, attenuation also increases

PRECAUTIONS:1. All connections should be made correctly.2. Supply given should be of right polarity.3. The readings should be taken accurately.




EXPERIMENT NO.9

AIM : To Measure the input impedance of the line

THEORY:The input impedance of the line depends on feature like the ohmic resistance, the

conductance, the inductance and the capacitance. It is also related to the resistance that loads the line at the opposite end and to both the frequency and voltage to the signal. The purpose of first part to measure the I/P impedance of the line under different load conditions:

1. Line terminated with match load .2. Open line3. Short circuited lineIn the second part of the test we will measure the phase displacement between the I/P voltage

and current, under the 3 conditions of line termination. When the modulus and the phase displacements are known the impedance vector is fully identified.

PROCEDURE:1. Adjust Ri and RL for 18Ω and 68Ω respectively with the help of DMM.2 Make the connections as shown in the Diagram.3. A 1Ω resistance in series between the generator and the transmission line as shown in the

Diagram allows to measure the value of input current.4. Set the I/P at 0.4V p-p and freq 100 Khz of sine wave(both measurement on CRO)5. Take readings of Vin and Vm across 1Ω on CRO.6. Calculate the I/P impedance according to the following formula:

Zin=Vin/I=Vin/Vmx1 Ω7. Change the freq to 1 Mhz and note the values of Vin and Vm at this freq.

Note down these results. The I/P impedance at 100 Khz is around 80 Ω and at 1 Mhz is 50Ω.




Repeat the experiment with shorted and open line.

RESULT : The Input Impedance of the Transmission line is measured as-……….

PRECAUTIONS:1. All connections should be made correctly.2. Supply given should be of right polarity.3. The readings should be taken accurately.

FREQUENTLY ASKED QUESTION’S:1. What is the input impedance of an infinite line 2. What is the expression for input impedance of a line terminating in a load resistance Zr and

having a characteristic impedance Zo




EXPERIMENT NO.10

AIM : Design of Symmetrical T-attenuator.

APPARATUS REQUIRED :Resistors R1(180 Ω) , R2(202 Ω),function generator, CRO .

THEORY : An attenuator is a four terminal device which attenuates the given input signal. Attenuators does

not distort the signal as it is made up of resistors. Resistors are frequency independent components. So there is no effect of frequency variation of input. A voltage divider is simplest attenuator. In a Symmetrical T-attenuator terminated at characteristic impedance of R0 values of R1 and R2 can be defined as

R1=R0(N-1)/(N+1)R2=2R0(N/N2-1)N=antilog α/20

Where α= attenuation in decibels

PROCEDURE : 1. Make connections as shown in figure on bread board.2. set the output of function generator to 1V.3. Connect the output of circuit to CRO.




OBSEERVATION TABLE :

SN Input voltage Output voltage(volts)

Attenuation(dB)=20 log(Vo/Vin)

RESULT :The designed network gives a 20 dB attenuation to all input voltages.

PRECAUTIONS:1.Make all the connections properly.2.Insure appropriate value of resistances and capacitances.3.Switch off power supply and function generator when not in use

FAQ’S: 1.What are attenuators?

2.What is difference between attenuators and equalizers?



cntl 5th sem

Documents

frequency fc

active low pass filter

active high pass filter

pass band

designated frequency

study of prototype constant

frequency response curve

input ofthe filter