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Micro-controller based Mobile Jammer Project

Sun, 03 Jun 2012 15:57:00 +0000

What is the project?

Cell phone jamming is the use of an electronic device to prevent the transferring of data through a wireless phone

Is Jamming useful?

Jammers can be used practically anywhere
Jammers are used primarily where silence is necessary or data transfer might be destructive
Jammers are simple to build and use

Why might cell phone use be destructive?

As wireless phones rapidly overtook society in the 21st century, many problems arose with the quick, easy option to transfer data either by voice or files through them such as : Espionage, Exposure of images, recording conversation or video remotely, Cheating (Academically), etc.

How do they work?

Jammers simply overflow the frequency used by wireless phones with radio waves
Enough interference caused by these waves will prevent communication between a wireless phone and a base tower
Some Jammers are small, hand-held sized devices while others can be very large
Smaller Jammers interfere mostly with the wireless phones themselves while devices with larger radii may interfere with the towers directly
Some Quick Numbers…
Wireless phone network ranges generally from 800-1900Mhz
Small Jammers block all communication in this range for a 30 ft radius
Commercial size Jammers can block all communication for 5 miles
Originally much of the technology associated with jamming was developed for military purposes
A huge part of security in The military is data security; Jamming communications signals locally can prevent the loss of data
Some Law Enforcement agencies use Jammers to prevent criminals from communicating
Law Enforcement and Military both use Jammers for preventing signals from certain kinds of remote explosive detonation devices
Development Over Time
Jammers originally worked on analog signals
Eventually Jamming was necessary on digital networks
Newer Jammers will block AMPS, iDEN, and GSM networks

Can I have one?

Of course not (legally)! Jammers are highly illegal to civilians in the US
Worldwide they are used in Libraries, Banks, Prisons, Hospitals, Churches, Movie theaters, and other places where locals or govt. have deemed wireless phone use more of a problem than a plus

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UNIT-I

1. Explain the different theories of charge formation in clouds.

2. What are the mechanisms by which lightning strokes develop and induce over

voltages on over head power lines?

3. Give the mathematical models for lightning discharges and explain them.

4. What are the causes for switching and power frequency over voltages? How are

they controlled in power system?

5. Explain the different methods employed for lightning protection of over head lines.

6. Explain with suitable figures the principles and functioning of (a) Expulsion gaps (b)

Protector tubes.

7. What is a surge arrester? Explain its function as a shunt protective device?

8. What is meant by insulation co-ordination? How are the protective devices chosen

for optimal insulation level in a power system?

9. Write short notes on: (a) Rod gaps used as protective devices (b) Ground wires for

protection of over head lines.

10. Derive the expression for the voltage and current waves on the long transmission

lines and obtain the surge impedance of the line.

11. Explain the different aspects of insulation design and insulation co-ordination

adopted for EHV systems.

12. A three phase single circuit transmission line is 400 km long . If the line is rated for

220 kV and has the parameter, R=0.1 ohms/km, L= 1.26 mH/km, C=0.009µF/km

and G=0 . Find (a) Surge impedance and (b) the velocity of propagation neglecting

the resistance of the line. If the surge of 150 kV and infinitely long tail strikes at one

end of the line, what is the time taken for the surge to travel to the other end of the

line?

13. An infinite rectangular wave on a line having a surge impedance of 500Ω strikes a

transmission line terminated with a capacitance of 0.004µF, Calculate the extent to

which the wave front is retarded?

14. An under ground cable of inductance 0.189 mH/km and of capacitance 0.3µF/km is

connected to an over head line having an inductance of 1.26mH/km and capacitance

of 0.009µF/km. Calculate the transmitted and reflected voltage and current waves at

the junction, if the surge of 200kV travels to the junction (i) along the cable (ii) along

the over head line.

15. A transmission line has the following line constants R=0.1 Ω/km, L= 1.26 mH/km and

C= .009µF/km and G=0. If the line is a 3 phase line and is charged from one end at

a line voltage of 230kV, find the rise in voltage at the other end , if the line length is

400km.

UNIT-II

1. Describe the current growth phenomenon in a gas subjected to uniform electric

fields.

2. Define Townsend’s first and second ionization coefficients. How is the condition for

breakdown obtained in a Townsend discharge?

3. Derive the criterion for breakdown in electronegative gases.

4. What are the anode and the cathode streamers? Explain the mechanism of their

formation and development leading to breakdown.

5. What is Paschen’s law? How do you account for the minimum voltage for breakdown

under a given ’p x d’ condition?

6. Explain the various theories that explain breakdown in commercial liquid dielectrics.

7. What is stressed oil volume theory, how does it explain breakdown in large volumes

of commercial liquid dielectrics?

8. What do you understand by “intrinsic strength” of a solid dielectric? How does

breakdown occur due to electrons in a solid dielectric?

9. Explain the different mechanisms by which breakdown occurs in solid dielectrics in

practice.

10. Describe the mechanism of short term breakdown of composite insulation.

UNIT-III

1. Explain with diagram, different types of rectifier circuits for producing high d.c

voltages.

2. Why is Cockcroft Walton circuit preferred for voltage multiplier circuits? Explain its

working with a schematic diagram.

3. Give the expression for ripple and regulation in voltage multiplier circuits. How are

the ripple and regulation minimized?

4. Describe with a neat sketch the working of a Van de Graaff generator. What are the

factors that limit the maximum voltage obtained?

5. Explain the different schemes for cascade connection of transformers for producing

very high a.c. voltages.

6. What is the principle of operation of a resonant transformer? How is it advantageous

over the cascade connected transformer?

7. What is Tesla coil? How is damped high frequency oscillations obtained from a

Tesla coil?

8. Give the Marx circuit arrangement for multistage impulse generators. How is the

basin arrangement modified to accommodate the wave time control resistance?

9. Describe the circuit arrangement for producing lightning current waveforms in lab.

10. What is trigatron gap? Explain its functions and operations

UNIT-IV

1. Discuss the different methods of measuring high dc voltages. What are the

limitations in each method?

2. Describe the generating voltmeter used for measuring high dc voltages.

3. What is capacitance voltage transformer? Explain with phasor diagram how a tuned

capacitance voltage transformer can be used for voltage measurements in power

systems.

4. Explain the principle and construction of an electrostatic voltmeter for high voltages.

What are its merits and demerits for high voltage a.c measurement?

5. Give the basic circuit for measuring the peak voltage of (i) a.c voltage and (ii)

impulse voltage. What is the difference in measurement technique in the above two

cases?

6. Explain how a sphere gap can be used to measure the peak value of voltages.

What are the parameters and factors that influence such voltage measurement?

7. Give the schematic arrangement of an impulse potential divider with an oscilloscope

connected for measuring impulse voltages. Explain the arrangement used to

minimize errors.

8. Explain the different method of high current measurement with their relative merits

and demerits.

9. What are the different types of resistive shunts used for impulse current

measurement? Discuss their characteristics and limitations.

10. What are the requirements of an oscillograph for impulse and high frequency

measurement in high voltage test circuits?

11. Explain the necessity of earthing and shielding arrangements in impulse

measurements and in high voltage laboratories. Give a sketch of the multiple shielding

arrangements used for impulse voltage and current measurement.

12. What is mixed potential divider? How is it used for impulse voltage measurements?

13. The H.V arm of an RC divider has 15 numbers of 120 ohms resistors with a 20pF

capacitor to ground from each of the junction points. The L.V arm resistance is 5

ohms. Determine the capacitance needed in the L.V arm for correct compensation.

14. A coaxial shunt is to be designed to measure an impulse current of 50 kA. If the

bandwidth of the shunt is to be at least 10MHz and if the voltage drop across the shunt

should not exceed 50 V, find the ohmic value of the shunt and its dimensions.

15. A Rogowski coil is to be designed to measure impulse current of 10kA having a rate

of change of current of 1011A/s. the current is read by a TVM as potential drop across

the integrating circuit connected to the secondary. Estimate the values of mutual

inductance, resistance and capacitance to be connected, if the meter reading is to be

10V for full scale deflection.

UNIT-V

1. What are the different power frequency tests done on insulators? Mention the

procedure for testing.

2. What is the significance of impulse tests? Briefly explain the impulse testing of

insulators.

3. What are the significance of power factor tests and partial discharge tests on

bushing? How are they conducted in the laboratory?

4. Mention the different electrical tests done on isolators and circuit breakers.

5. Why is synthetic testing advantageous over the other testing methods for short

circuit tests? Give the layout for synthetic testing.

6. Explain the partial discharge tests on high voltage cables. How is a fault in the

insulation located in this test?

7. Explain the method of impulse testing of high voltage transformers. What is the

procedure adopted for locating the failure?

8. What is an operating duty cycle test on a surge arrester? Why is it more significant

than other tests?

9. Explain the importance of RIV measurement for EHV power apparatus.

10. Explain with a schematic diagram one method of measuring RIV of transmission

line hardware.

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UNIT I - OVER VOLTAGES IN ELECTRICAL POWER SYSTEMS

PART A

1. Why protection of transmission line important?

2. What are the causes of over voltages in electric system?

3. How does switching over voltage originate?

4. What is Isokeraunic level?

5. What are the factors that influence the lightning induced voltage on transmission

lines?

6. How is transmission lines classified?

7. Define attenuation and distortion.

8. How is attenuation and distortion caused?

9. What are the causes for the change of induction on transmission line?

10. What are the causes for the change of capacitance on transmission line?

11. What is the effect of corona on transmission lines?

12. What are the principles observed in the lattice diagram?

13. Define corona.

14. What are the components of switching surges?

15. How does switching surges cause damage to circuit breaker?

16. What are the factors of origin of switching surges?

17. Give the factor for over voltages generation in EHV system.

18. Give the situation that give rise to switching over voltages of short duration and

lower magnitude.

19. What are the different method by which switching over voltages of short duration

and long magnitude be calculated?

20. What are the different measures to control or reduce over voltages?

UNIT II - ELECTRICAL BREAKDOWN IN GASES, SOLIDS AND LIQUIDS

PART A

1. What are the different gases that are used as insulating medium?

2. What are the various phenomena that occur inn gaseous dielectric?

3. What is break down voltage?

4. Give the types of electrical discharge in gases.

5. Define spark breakdown and ionization.

6. Give the theories that explain the mechanism for breakdown.

7. What are the conditions in the gases that govern the ionization process?

8. Define the elastic collision & inelastic collision.

9. Define electron drift velocity.

10. What is Maxwellian distribution?

11. What is Druyesteynian distribution?

12. Define collision cross section.

13. What is mean free path?

14. What are the different processes by which radiation can be absorbed by atom?

15. Define the secondary ionization process.

UNIT III - GENERATION OF HIGH VOLTAGES AND HIGH CURRENTS

PART A

1. Give the different forms of high voltages.

2. Give the circuits that produce high dc voltages.

3. On what factors does ripple δV depend?

4. Give the circuits that produce high dc voltages.

5. How is ripple voltage kept low?

6. What is the use of regulator circuit?

7. What are the types of regulator?

8. What are the chief advantages of resonant transformers?

9. Give the advantages of high frequency transformers.

10. What are the components of multistage impulse generator?

11. What are the different circuits that are used for producing switching impulse

voltage?

12. Define standard switching impulse voltage.

13. Define duration of wave.

14. What are the essential parts of impulse current generator?

15. Define peak to peak ripple.

1. Why is measurement of high voltages and high current necessary?

2. What are the methods available for measuring dc voltages?

3. What are the methods available for measuring ac voltages of high frequency?

4. What are the methods available for measuring ac voltages of power frequency?

5. What are the methods available for measuring dc current?

6. What are the methods available for measuring ac current of high frequency?

7. What are the methods available for measuring ac current of power frequency?

8. What are limitations in the series resistance design?

9. What is generating voltmeter?

10. What are the advantages and limitations of generating voltmeter?

11. Give the different methods of measuring dc electric field strength.

12. How series capacitance is formed in voltmeter for measurement?

13. What are the advantages of capacitance voltage transformers (CVT)?

14. What are the sources that contribute to the error?

15. What are the different ways by which sphere gap can be arranged?

UNIT V - HIGH VOLTAGE TESTING AND INSULATION COORDINATION

PART A

1. What is the necessity of high voltage testing?

2. What are the classifications of over voltage test?

3. Define disruptive discharge voltage.

4. Define withstand voltage

5. Define fifty percent flashover voltage.

6. What is hundred percent flashover voltages.

7. Define creepage distance.

8. Give the absolute parameters for testing.

9. What is type test and routine test?

10. Give the different power frequency test.

11. What is dry& wet flashover test?

12. Give the different impulse test.

13. Define the impulse withstand voltage test.

14. What is the various type of pollution?

15. What are the different types of power frequency test for bushing?

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UNIT I - OVER VOLTAGES IN ELECTRICAL POWER SYSTEMS

PART A

1. Why protection of transmission line important?

2. What are the causes of over voltages in electric system?

3. How does switching over voltage originate?

4. What is Isokeraunic level?

5. What are the factors that influence the lightning induced voltage on transmission

lines?

6. How is transmission lines classified?

7. Define attenuation and distortion.

8. How is attenuation and distortion caused?

9. What are the causes for the change of induction on transmission line?

10. What are the causes for the change of capacitance on transmission line?

11. What is the effect of corona on transmission lines?

12. What are the principles observed in the lattice diagram?

13. Define corona.

14. What are the components of switching surges?

15. How does switching surges cause damage to circuit breaker?

16. What are the factors of origin of switching surges?

17. Give the factor for over voltages generation in EHV system.

18. Give the situation that give rise to switching over voltages of short duration and

lower magnitude.

19. What are the different method by which switching over voltages of short duration

and long magnitude be calculated?

20. What are the different measures to control or reduce over voltages?

UNIT II - ELECTRICAL BREAKDOWN IN GASES, SOLIDS AND LIQUIDS

PART A

1. What are the different gases that are used as insulating medium?

2. What are the various phenomena that occur inn gaseous dielectric?

3. What is break down voltage?

4. Give the types of electrical discharge in gases.

5. Define spark breakdown and ionization.

6. Give the theories that explain the mechanism for breakdown.

7. What are the conditions in the gases that govern the ionization process?

8. Define the elastic collision & inelastic collision.

9. Define electron drift velocity.

10. What is Maxwellian distribution?

11. What is Druyesteynian distribution?

12. Define collision cross section.

13. What is mean free path?

14. What are the different processes by which radiation can be absorbed by atom?

15. Define the secondary ionization process.

UNIT III - GENERATION OF HIGH VOLTAGES AND HIGH CURRENTS

PART A

1. Give the different forms of high voltages.

2. Give the circuits that produce high dc voltages.

3. On what factors does ripple δV depend?

4. Give the circuits that produce high dc voltages.

5. How is ripple voltage kept low?

6. What is the use of regulator circuit?

7. What are the types of regulator?

8. What are the chief advantages of resonant transformers?

9. Give the advantages of high frequency transformers.

10. What are the components of multistage impulse generator?

11. What are the different circuits that are used for producing switching impulse

voltage?

12. Define standard switching impulse voltage.

13. Define duration of wave.

14. What are the essential parts of impulse current generator?

15. Define peak to peak ripple.

1. Why is measurement of high voltages and high current necessary?

2. What are the methods available for measuring dc voltages?

3. What are the methods available for measuring ac voltages of high frequency?

4. What are the methods available for measuring ac voltages of power frequency?

5. What are the methods available for measuring dc current?

6. What are the methods available for measuring ac current of high frequency?

7. What are the methods available for measuring ac current of power frequency?

8. What are limitations in the series resistance design?

9. What is generating voltmeter?

10. What are the advantages and limitations of generating voltmeter?

11. Give the different methods of measuring dc electric field strength.

12. How series capacitance is formed in voltmeter for measurement?

13. What are the advantages of capacitance voltage transformers (CVT)?

14. What are the sources that contribute to the error?

15. What are the different ways by which sphere gap can be arranged?

UNIT V - HIGH VOLTAGE TESTING AND INSULATION COORDINATION

PART A

1. What is the necessity of high voltage testing?

2. What are the classifications of over voltage test?

3. Define disruptive discharge voltage.

4. Define withstand voltage

5. Define fifty percent flashover voltage.

6. What is hundred percent flashover voltages.

7. Define creepage distance.

8. Give the absolute parameters for testing.

9. What is type test and routine test?

10. Give the different power frequency test.

11. What is dry& wet flashover test?

12. Give the different impulse test.

13. Define the impulse withstand voltage test.

14. What is the various type of pollution?

15. What are the different types of power frequency test for bushing?

PART-B