High Voltage Direct Current Transmission Question Bank

Anna University , Chennai

Electrical Engineering Department

High Voltage Direct Current Transmission 

UNIT-1
 2- MARKS
1. List out the applications of HVDC?
2. What are the types of transmission system?
3. State the comparison of AC & DC transmission system?
4. State the advantages in DC transmission?
5. State the disadvantage in dc transmission?
6. What are the types of DC link?
7. What is the need of smoothing reactor?
8. What are the factors to be considered for planning of Hvdc transmission?
9. Explain in two lines about choice of voltage level in DC transmission
10. What is DC breaker? How it will be useful?
11. Name the new modern trends in DC transmission.
12. What are the power semiconductor devices used in dc transmission?
13. Draw the converter station unit in hvdc transmission
14. How will overcome the disadvantages in dc transmission?

16- MARKS

1. For a fixed power transmission explain how the economic choice of voltage level selected in dc transmission system
2. Explain the technological development in control and protection , for better performance and reliability of dc transmission system
3. What are the different applications of dc transmission system? Explain them in detail?
4. With neat sketches explain the different kinds of dc link available?
5. Explain the comparison of AC and DC transmission in detail
6. Explain the application of dc transmission
7. Explain in detail about the planning of hvdc transmission?
8. Explain the technological development of modern trends in dc transmission
9. Explain the major components of a hvdc transmission in converter station unit?
10. State the advantages and disadvantages of dc transmission system with following economics, reliability, performance..
                           
UNIT-2
2- MARKS
1. Define pulse number?
2. Draw the diagram graetz bridge circuit
3. Write the equation of ac current and dc voltage harmonics
4. What is choice of converter configuration?
5. Define peak inverse voltage?
6. Draw the schematic diagram of three & two valve conduction mode
7. Define twelve pulse converter with schematic diagram
8. What is meant by neglecting overlap in graetz in bridge circuit

16-MARKS
1. For a 3 phase 6 pulse gratez’s circuit draw the timing diagram considering overlap angle is less than 60 degree and without overlap for the following
a) Voltage across load
b) Voltage across any two pair of conduction valves
2. Explain the individual characteristics of a rectifier and an inverter with sketches
3. Draw the schematic circuit diagram of a 6 pulse gratez’s circuit and explain its principle of operation
4. Discuss in detail the effect of source inductance on hvdc system
5. Show the rating of the valve used in gratez circuit is 2.094Pd where Pd is dc power transmitted
6. Explain the effect of overlap angle on the performance of converter circuit
7. Explain the choice of converter configuration for any pulse number
8. Explain the analysis of 12 pulse converter with bridge rectifier
9. Explain the technique involved in harmonic elimination of bridge rectifier
10. Explain the analysis of two and three valve conduction mode
11. With detailed analysis of converter with steady state analysis


UNIT- 3
2- MARKS
1. Define Synchronous Condenser
2. What will be the current regulation in inverter side?
3. Define transformer tap changing
4. State the transmission characteristics with rectifier and inverter
5. Define firing angle control
6. What is uncompounded inverter?
7. What is equidistant pulse control?
8. How will you protect against dc line faults?
9. Draw the characteristics curve for inverter compounding?
10. What are the types of transformer tap changer?
11. State the features of on load tap changer?
12. Draw the characteristics curve for inverter compounding?
13. For the operating point of two characteristics. state the constant current compounding?
14. Draw the voltage current characteristics of converters with compounding?

16-MARKS
1. Explain the individual characteristics of a rectifier and an inverter with sketches
2. Explain in detail about the transformer tap changer with its types
3. Explain in detail about the converter control characteristics of hvdc system
4. Draw and explain the inverter and rectifier compounding characteristics with constant voltage and current curve.
5. Explain the uncompounded inverter with neat sketches
6. Explain in detail the concept of reactive power requirement in hvdc converters
7. Explain in detail about current regulation from the inverter side
8. With the block diagram, discuss the principle of operation of a basic power controller


UNIT-IV
2- Marks
1. Define Harmonic.
2. How harmonics are generated?
3. Write the characteristics of Harmonics?
4. Write the fundamental components of harmonics with a order of ‘h’?
5. Define AC filter?
6. Define DC Filter?
7. What are the components present in AC & DC filter?
8. What are the interference produced in the communication lines.
9. Define total harmonics distortion?
10. How can we avoid the interference occur in communication line?
11. Define Telephone influence factor.
12. What are the types of AC filters & Dc?
13. Define single tuned filter?
14. How will protect the filter?

16-Marks
1. Write short notes on the following:
 (a) Telephone influence factor
 (b) Harmonic distortion
2. What are the filter configuration that are employed for HVDC Converter station ? Give design aspect of one such filter.
3. Derive an equation for harmonic voltage and current for single tuned filter and discuss the influence of network admittance.
4. Give a detailed account of design aspects of following filters
   (a) Single tuned filter
   (b)Double tuned filter
5. It is required to eliminate harmonics of order 10 and below 10 other than fundamental in a 12 pulse converter suggest and derive an equation?
6. Explain in detail about different types of transformer tap changing.

UNIT-V
2-Marks
1. Define Dc Cables?
2. State the basic physical phenomenon arising in DC insulation?
3. What is meant by dielectric constant in DC cable?
4. Define dielectric stress?
5. Compare the economics of Dc cables with AC cables.
6. Define system simulation.
7. What is meant by HVDC system simulation?
8. Draw the block diagram of system simulation.
9. Distinguish AC cable vs DC cable transmission?
10. State the number of tools used for simulation of dynamic system.
11. What are the requirements for good simulation tool?
12. What are the two approaches are available in transient analysis of simulation?

16-Marks
1. Describe the comparison of economics of AC and DC.
2. Explain in detail about the modeling of HVDC system for digital dynamic simulation.
3. Explain in detail about HVDC system simulation
4. Describe the philosophy and tools used in HVDC simulation.
5. Explain the Dielectric stress in cables.
6. Describe the Physical phenomenon arising in DC insulation.

CS2251 Design and Analysis of Algorithms Most Important Questions - 2014 Edition

Anna University, Chennai

Department of Computer Science Engineering

4th Semester

CS2251 Design and Analysis of Algorithms 

Most Important Questions - 2014 Edition

(Regulation 2008) 

 
UNIT I  
1. Explain Towers of Hanoi problem and solve it using recursion.
2. Find the time complexity and space complexity of the following problems.
3. Factorial using Recursion.
4. Compute nth Fibonacci Number.
5. Compute xn or exponentiate (x,n).
6. mxn matrix multiplication , mxn matrix addition.
7 Sequential/linear search.
8. Describe best, worst and average case analysis with an example.  

UNIT II  
1. Explain the binary search algorithm with an example.
2. Explain mimmax problem using Divide and conquer technique. Compute its time complexity.
3. Explain merge sort with an example. Compute its time complexity.
4. Explain Quick sort with an example. Give its time complexity.
5. Solve the knapsack problem using greedy technique.
6. Explain Prim’s algorithm to construct Minimum cost spanning tree.
7. Explain Kruskal’s algorithm to construct Minimum cost spanning tree.
8. Explain Optimal Randomized algorithm to construct Minimum cost spanning tree.
9. Explain single source shortest path algorithm (Dijkstra’s algorithm).

UNIT III 
1. Explain all pairs shortest path algorithm with an eg. Give its time complexity
2. What is multistage graph? Explain with an eg. Write the pseudo code for the finding the minimum cost path using forward approach.
3. What is multistage graph? Explain with an eg. Write the pseudo code for the finding the minimum cost path using backward approach.
4. Write an algorithm for 0/1 knapsack problem.
5. Write and explain an algorithm for BFS and DFS. Give an eg.
6. Give an algorithm to identify articulation points and to construct biconnected components.Explain with an eg.

UNIT IV  
1. Explain N-Queens problem using Backtracking.
2. Explain Graph Coloring.
3. Explain sum of subsets.
4. Explain Hamiltonian cycles.
5. Solve Knapsack problem using backtracking.
6. Explain Traveling Salesperson problem using branch and bound techniques.

UNIT V  
1. Explain the basic concepts of P, NP, NP-Complete and NP-Hard.
2. Prove a graph problem is NP-Hard.
3. Explain a NP-Hard Scheduling problem.
4. Explain a NP-Hard code generation problem.
5. Explain the concepts of Approximation algorithm. 

CS2253 Computer Organization and Architecture - Most Important Questions 2014 Edition

Anna University , Chennai

computer Science Engineering Department 

II Year CSE – IV sem

CS2253 Computer Organization and Architecture

Most Important Questions – 2014 Edition

Unit 1

1. Explain the Differences between CISC & RISC
2. Explain the various Instruction types?
3. Write in detail about various addressing modes.
4. Explain the various generations of Computer
5. Explain the Booth’s algorithm for multiplication of signed two’s Complement numbers.                               6. Explain the multiple bus organization in detail.
7. Explain the floating point addition and subtraction
8. State the Non – restoring division technique
9. Draw and explain the flowchart of floating point addition process
10. Explain with a diagram the designs of a fast multiplier using carry save Adder circuit .Give the block diagram for a floating point adder / sub tractor unit and discuss its operation

UNIT 2

1. Explain the concept of hardwired control unit (16)
2. Explain the concept of micro programmed control unit (16)
3. a. Sketch and explain the multiple bus organization (8)
b. Explain the execution of complete instruction (8)
4. Explain in detail about nano-programming (16)

UNIT 3

1. Describe in detail about pipeline processing. (16)
2. a. Explain in detail about data hazards (10)
b. Briefly explain about different types of exception. (6)
3. Explain in detail about instruction hazards (16)
4. Explain in detail about the following
a) Influence on instruction set (8)
b) Data path considerations (8)

UNIT 4

1. Illustrate the characteristics of some common memory technologies. (16)
2. (a)Describe in detail about associative memory. (8)
(b) Comparing paging and segmentation mechanisms for implementing the virtual memory. (8)
3. What is Memory Interleaving? Explain the addressing of multiple modules Memory system. (16)
4. Discuss the different mapping techniques used in cache memories and their relative merits and demerits. (16)
5. What do you mean by virtual memory? Discuss how paging helps in implementing virtual memory. (16)
6. (a) Discuss any six ways of improving the cache performance. (8)
(b) Illustrate memory read and write operation. (8)

UNIT 5 

1. Explain with the block diagram the DMA transfer in a computer System. (16)
2. (a) Describe in detail about IOP organization. (8)
(b) Describe the data transfer method using DMA. (8)
3. Write short notes on the following
(a) Magnetic disk drive (8)
(b) Optical drives (8)
4. Discuss the design of a typical input or output interface. (16)
5. What are interrupts? How are they handled? (16)

Anna University - Nov / Dec 2013 Exam Results Announced

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EC2255 Control Systems – Most Important Questions – 2014

Anna University

Department of ECE

4 Semester

EC2255 Control Systems

Most Important Questions – 2014 Edition

(Regulation 2008)

 

Unit-1

1. Write the differential equations governing the Mechanical system shown in fig .and determine the transfer function. (16)

2. Determine the transfer function Y2(S)/F(S) of the system shown in fig. (16)

3. Write the differential equations governing the Mechanical rotational system shown in fig. Draw the Torque-voltage and Torque-current electrical analogous circuits. (16)

4. Determine the overall transfer function C(S)/R(S) for the system shown in fig. (16)

5. Obtain the closed loop transfer function C(S)/R(S) of the system whose block diagram is shown in fig. (16)

6. For the system represented by the block diagram shown in fig. Determine C1/R1and C2/R1. (16)

7. Obtain the closed loop transfer function C(S)/R(S) of the system whose block diagram is shown in fig. (16)

8. Find the overall gain of the system whose signal flow graph is shown in fig. (16)

9. Draw a signal flow graph and evaluate the closed loop transfer function of a system whose block is shown in fig. (16)

10. Derive the transfer function for Armature controlled DC servo motor. (16)

11. Derive the transfer function for Field controlled DC servo motor. (16)

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Unit-2

1. (a) Derive the expressions and draw the response of first order system for unit step input. (8)

(b) Draw the response of second order system for critically damped case and when input is unit step. (8)

2. Derive the expressions for Rise time, Peak time, and Peak overshoot. (16)

3. A potential control system with velocity feedback is shown in fig. What is the

Response of the system for unit step input? (16)

4. Measurements conducted on a Servomechanism show the system response to be

c(t)=1+0.2 ê 60t-1.2 ê –10 t. when subjected to a unit step. Obtain an expression for closed loop transfer function. (16)

5. A positional control system with velocity feedback is shown in fig. What is the

response c(t) to the unit step input. Given that ς =0.5.and also calculate rise time, peak time, Maximum overshoot and settling time. (16)

6. A unity feedback control system has an open loop transfer function G(S) = 10/S(S+2). Find the rise time, percentage over shoot, peak time and settling time. ( 16)

7. A closed loop servo is represented by the differential equation, where c is the

displacement of the output shaft, r is the displacement of the input shaft and ( e= r-c) Determine undammed natural frequency, damping ratio and percentage maximum overshoot for unit step input. (16)

8. For a unity feedback control system the open loop transfer function

G(S) = 10(S+2)/ {S2 (S+1)}. Find (a) position, velocity and acceleration error constants.

(b) The steady state error when the input is R(S) where R(S) =3/S –2/S2 +1/3S3 (16)

9. The open loop transfer function of a servo system with unity feedback system is G(S) = 10/ S (0.1S+1).Evaluate the static error constants of the system. Obtain the steady state error of the system when subjected to an input given by the polynomial r(t) = a0 +a1t +a2 /2 t2 . (16)

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Unit-3

1. Plot the Bode diagram for the following transfer function and obtain the gain and phase cross over frequencies. G(S) = 10/ S(1+0.4S) (1+0.1S) (16)

2. The open loop transfer function of a unity feedback system is

G(S) = 1/ S(1+S)(1+2S) Sketch the Polar plot and determine the Gain margin and Phase margin. (16)

3. Sketch the Bode plot and hence find Gain cross over frequency, Phase cross over frequency, Gain margin and Phase margin(S) = 0.75(1+0.2S)/ S (1+0.5S) (1+0.1S) (16)

4. Sketch the Bode plot and hence find Gain cross over frequency, Phase cross over frequency, Gain margin and Phase margin. G(S) = 10(S+3)/ S(S+2) (S2+4S+100) (16)

5. Sketch the polar plot for the following transfer function .and find Gain cross over frequency, Phase cross over frequency, Gain margin and Phase margin.

G(S) = 10(S+2)(S+4)/ S (S2 -3S+10) (16)

6. Construct the polar plot for the function GH(S) =2(S+1)/ S2. Find Gain cross over frequency, Phase cross over frequency, Gain margin and Phase margin. (16)

7. Plot the Bode diagram for the following transfer function and obtain the gain and phase cross over frequencies. G(S) =KS2 / (1+0.2S) (1+0.02S). Determine the value of K for a gain cross over frequency of 20 rad/sec. (16)

8. Sketch the polar plot for the following transfer function and find Gain cross over frequency, Phase cross over frequency, Gain margin and Phase margin.

G(S) = 400/ S (S+2)(S+10) (16)

9. A unity feed back system has open loop transfer function G(S) = 20/ S(S+2)(S+5). Using Nichol’s chart, determine the closed loop frequency response and estimate all the frequency domain specifications. (16)

10. Sketch the Bode plot and hence find Gain cross over frequency, Phase cross over frequency, Gain margin and Phase margin. G(S) = 10(1+0.1S)/ S(1+0.01S) (1+S). (16)

11. Write the short notes on correlation between the time and frequency response? (16)

12. What is compensation? Why it is needed for control system? Explain the types of compensation? (16)

13. Realize the basic compensators using electrical network and obtain the transfer function. (16)

14. Design a suitable lead compensators for a system with unity feedback and having open loop transfer function G(S)= K/ {S(S+1) (S+4)} to meet the specifications. (i)Damping ratio=0.5

(ii) Undamped natural frequency. Wn =2 rad/sec. (16)

15. A unity feed back system has an open loop transfer function G(S)= K/ {S(S+1)(0.2S+1). Design a suitable phase lag compensators to achieve following specifications Kv= 8 and Phase margin 40 deg with usual notation. (16)

16. Explain the procedure for lead compensation and lag compensation? (16)

17. Explain the design procedure for lag- lead compensation. (16)

18. Consider a type 1 unity feed back system with an OLTF Gf(S) =K/{S (S+1) (S+4)}. The system is to be compensated to meet the following specifications Kv > 5sec and PM>43 deg. Design suitable lag compensators (16)

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Unit-4

1. Using Routh criterion, determine the stability of the system whose Characteristics equation is S4+8S3+18S2+16S+5 =0. (16)

2. F(S)=S6 +S5-2S4-3S3-7S2-4S1-4 =0.Find the number of roots falling in the RHS plane and LHS plane. (16)

3. Draw the Nyquist plot for the system whose open loop transfer function is

G(S) H(S) =K/{S (S+2) (S+10)}.Determine the range of K for which closed loop

System is stable. (16)

4. Construct Nyquist plot for a feedback control system whose open loop transfer function is given by G(S)H(S) =5/ S(1-S).comment on the stability of open loop and closed loop transfer function. (16)

5. Sketch the Nyquist plot for a system with the open loop transfer function G(S)H(S) =K({1+0.5S) (1+S)} /{ (1+10S) (S-1)). Determine the range of values of K for which the system is stable. (16)

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Unit-5

1. Write notes on controllability and absorbability. (16)

2. Explain sampling theorem briefly and sample & hold operation. (16)

3. Explain stability analysis of sampled control system and Jury’s stability. (16)

4. Explain state space representation for descries time system. (8)

5. Explain state space representation for continues time system. (8)

6. Explain the solution for state equation for discrete time system. (8)

7. Explain the solution for state equation for continues time system (8)

8. Explain jury’s stability test. (16)

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EC2254 Linear Integrated Circuits Most Important Questions – 2014 Edition

Anna University

Department of ECE

4 Semester

EC2254 Linear Integrated Circuits

(Regulation 2008)

 

Unit-1

1. Draw and explain about the equivalent circuit of OP-AMP.

2. Explain about DC characteristics of OP-AMP.

3. Explain in detail about slew rate of an OP-AMP

4. Explain in detail about Widlar current source.

5. Explain briefly about manufacturing process of monolithic ICs.

6. Explain briefly about construction of monolithic bipolar transistor.

7. What is current mirror? Explain

8. Discuss in detail about AC performance characteristics of an op-amp.

9. Explain in briefly about open loop and closed loop configurations.

10. Explain in detail about BJT differential amplifier with active loads.

11. Explain in detail about voltage sources and voltage references.

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Unit-2

1. How op-amp can be used as an antilog amplifier?

2. Explain briefly about op-amp integrator.

3. Draw and explain about voltage to current converter.

4. With neat circuit diagram explain about instrumentation amplifier.

5. Explain briefly abut Schmitt trigger with neat diagram.

6. Explain the following in briefly (i). Precision diode (ii). Peak detector

7. Describe briefly about clippers and clampers.

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Unit-3

1.Describe the application of PLL.

2.Explain about the gilbert multiplier cell.

3.Derive the expression for voltage to frequency conversion factor.

4.With neat diagram explain the operating principles of PLL.

5.Explain briefly about application of analog multiplier ICs.

6.Explain briefly about Monolithic PLL IC 565.

7.Explain about the variable transconductance technique.

8.Explain about the analog multiplier using emitter coupled transistor technique.

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Unit-4

1. Explain the operation of successive approximation type A/D converter,

2. What output voltage would be produced by a D/A converter whose output range is 0 to

10v and whose input binary number is (i).10(for a 2-bit D/A converter) (ii). 0110(for a 4- bit DAC)?

3. Briefly explain about dual slope A/D converter.(

4. What is delta sigma modulation? Explain the A/D conversion using delta modulator.

5. Explain briefly about the specifications of D/A And A/D converters. 6. Explain briefly about the weighted resister Type D/A converter.

7. Describe briefly about R-2R ladder and its types.

8. Discuss about switches for D/A converters briefly.

9. Explain briefly about flash type A/D converter.

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Unit-5

1. Explain the operation of op amp as multivibrator.

2. Write short notes on operation of function generator.

3. Write short notes on

(i). Tuned amplifiers

(ii). Power amplifiers

4. Explain in detail about the function of 555 timer in monostable and derive the

expression for frequency of oscillation.

5. Explain the operation of switching regulator.

6. Explain the functional diagram of LM 380 power amplifier.

7. Explain the following in briefly

(i) Triangular wave generator

(ii) Sawtooth generator

8. Explain in detail about the functional diagram of ICL8038.

9. Explain in detail about the function of IC 723 general purpose regulators.

10. Explain the following in detail

(i) isolation amplifier

(ii) opto coupler

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EC2253 Electromagnetic Fields Most Important Questions – 2014 Edition

Anna University

Department of ECE

4 Semester

EC2253 Electromagnetic Fields

(Regulation 2008)

Most Important Questions

 

Unit-1

1. State gauss law for the electric and magnetic fields. Derive its integral and differential forms. Make at least two conclusions

2. A positive charge Qv c/m³ occupies the volume of a sphere. At a point in the interior at a distance of r from the centre, a small probe of charge of +q is inserted. What is the force acting on the probe charge?

3. State ampere’s force law. How it is different from coulombs law?

4. Explain the tracing of a charged particle motion in x-y plane, in the region of crossed electric field B=B₀ a_z.Assume that the charge q having mass m start at t=0 at that point with initial velocity v= v_x a_x + v_yoa_y.What is the result for B₀ = 0?

5. Prove that divergence of a curl of avector is zero,using stokes theorem

6. A magnetic field H= 3 cosx a_x+z cosx a_y,A/m for z0

= 0 for z<0

is applied to a perfectly conducting surface in xy plane. Find the current density on the conductor surface

7. Let A=5 ax and B= 4 a_x+ B_y. Find by such that, angle between A and B is 45. If B also has a term B_z a_z, what relationship must exist between by B_y and B_z

8. A uniform line charge =25 nc/m lies on the line, x=-3m and y=4m, in free space. Find the electric field intensity at a point(2,3,15)m

9. Two small identical conducting sphere have charges of 2nc and -1nc respectively. When they are separated by 4cm apart, find the magnitude of the force between them. If they are brought into contacts and then again separated by 4cm, find the force between them

10. Obtain the expressions for D and E using gauss’s law

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Unit-2

1. Derive the expression for coefficient of coupling in terms of mutual and self inductances

2. An iron ring with a cross sectioned of 3 cm2 and a mean circumference of 15 cm is wound with 250 turns wire carrying a current of 0.3A. The relative permeability of the ring is 1500. Calculate the flux established in the ring

3. Obtain the expressions for D and E using Gauss’s law

4. Write short notes on faradays laws of electromagnetic induction

5. Derive the electrostatic boundary conditions at the interface of two dielectric media. If one of the medium is conductor, discuss the field pattern

6. Discuss electric field in free space, dielectric and in conductors

7. Derive the expression for curl H=J

8. Explain the concepts of scalar magnetic potential and vector magnetic potential

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Unit-3

1. Using the concept of magnetic vector potential, derive Biot Savart’s law and amperes law

2. Find the magnetic flux density at the centre of a square of sides equal to 5 cm and carrying 10A of current

3. List the properties of dielectric materials

4. Derive the expression for coefficient of coupling in terms of mutual and self inductances

5. Derive the expression for the capacitance of a parallel plate capacitor with two dielectric media

6. Derive an expression for inductance of a solenoid with N turns and l meter length carrying a current of I amperes

7. Explain in detail the principle of operation of a motor

8. Derive H due to a circular current loop and extend the same to compute H due to a long solenoid?

9. Derive the boundary relation at the boundary between a conductor and dielectric

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Unit-4

1. Derive general field relations for time varying electric and magnetic fields using Maxwell’s equation

2. On the basis of the analysis of the transmission line compare circuit theory and field theory

3. With necessary explanation, derive the Maxwell’s equation in differential and integral forms

4. What do you mean by displacement current? Write down the expression for the total current density

5. Derive the expression for total power flow in coaxial cable

6. Derive Maxwell’s equations derived from amperes law in integral and point forms

7. Explain briefly about the motional emf and derive an expression for it

8. Discuss the pointing sector and pointing theorem

9. Define faradays laws. What are the different ways of emf generation? Explain with governing equation and suitable example for each

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Unit-5

1. Derive wave equations in phasor form and also derive for

2. Explain about the propagation of EM waves in good conductor

3. Derive the transmission and reflection coefficients for the electromagnetic waves. Discuss the above for an open line and a short circuited line

4. Derive the electromagnetic wave equations

5. State pointing vector and establish its usage in EM wave analysis

6. Discuss the wave motion in good conductors

7. Explain the reflection of plane waves by a perfect dielectric

8. Derive the expression for input impedance and standing wave ratio of transmission lines

9. Define Brewster angle and derive its expression

10. Derive the relationship between electric and magnetic fields

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EC2252 Communication Theory – Most Important Questions 2014 Editions

Anna University

Department of ECE

4 Semester

EC2252 Communication Theory

(Regulation 2008)

Most Important Questions – 2014 Edition

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UNIT-1 AMPLITUDE MODULATION

1. Explain the principles of operation of balanced modulator used for generating DSBSC

2. How SSB is generated? Explain

3. Explain in detail the methods of generating AM signal and derive the frequency spectrum of AM signal

4. Describe how AM generation is done using nonlinear circuits. Derive the output voltage expression for the circuit

5. Write short notes on VSB generation

6. Explain the working principles of linear modulators for generating AM.

7. Explain the principle of synchronous detection

8. Discuss the different distortions that occur in diode detectors

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UNIT-2 ANGLE MODULATION

1. Derive an expression for a single tone FM signal and draw its frequency spectrum With a help of neat circuit explain Armstron method of generating FM signal
2. Explain the indirect method of generation of FM wave &any one method of demodulation of FM wave
3. Explain in detail the tansmission bandwidth of FM signal with diagrams
4. Explain how FM to PM and PM to FM is obtained
5. Explain the operation of direct FM tewrasmitter
6. Obtain the expession for narrow band and wide band FM
7. Explain how amplitude limiting is obtained in an FM ratio detectors
8. Explain the Wide Band Frequency Modulation
9. Explain the detection of FM using Foster Seely Discriminator

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UNIT-3 NOISE PERFORMANCE OF DSB- SSB RECEIVERS

1. Explain the following terms 1) shot noise 2)noise temperature 3)noise figure
2. Derive the quadrature and in phase components of a narrow band process Explain how various noise are generated and method of representing them
3. Write short notes on noise temperature & noise figure
4. Derive the effective noise temperature of cascaded amplifier.
5. Explain the narrow band representation of noise in terms of envelope and phase components

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UNIT-4 NOISE PERFORMANCE OF AM AND FM RECEIVERS

1. Derive the noise power spectral density of the FM demodulator and explain its performance with diagram
2. Explain the noise performance of AM system using envelope detection
3. Compare the performance of noise in AM & FM
4. Obtain the expresion for SNR in PM system
5. Obtain the expresion for SNR in AM system using envelope detector in the receiver

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UNIT -5 INFORMATION THEORY

1. Derive the channel capacity of binary symmetric channel
2. Write a notes on binary symmetric channel ,discrete channel capacity , continous channel capacity &channel capacity theorem
3. Find the mutual information &channel capacity of the channel shown.
4. Give the algorithm for Shanon -Fano coding
5. Give the algorithm for Huffman coding

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EC2251 Electronic Circuits II – Most Important Questions – 2014 Editions

Anna University

Department of ECE

4 Semester

EC2251 Electronic Circuits II

(Regulation 2008)

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UNIT I

1. Explain about various feedback networks with diagrams

2. Determine the input and output resistance of current shunt feedback network

3. Discuss the Nyquist criterian for stability of feedback amplifiers.

4. What is the effect of negative feedback on distortion , noise, input and output impedance of feedback amplifiers?

5. Explain current series feedback amplifier with diagram

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UNIT II

1. Explain about RC phase shift oscillator

2. Derive the frequency response of wien bridge oscillator

3. How clap oscillator differ from colpitts oscillator

4. Explain any one type of LC oscillator

5. Explain Armstrong oscillator and derive frequency of oscillation

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UNIT III

1. Discuss about double tuned amplifier with diagram

2. Explain class C tuned amplifier with diagram

3. Explain Hazeltine Neutralization model

4. Explain in detail single tuned amplifier with diagrams

5. Derive the efficiency of class B tuned amplifier

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UNIT IV

1. What is the response of low pass RC circuit for step , pulse and square inputs

2. Explain the working principle of Bistable multivibrator

3. Explain transistor switching times

4. Explain in detail about Astable multivibratior

5. Explain any one type of clippers

6. Explain about clampers

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UNIT V

1. Explain about Miller integrator with diagrams

2. Discuss about current timebase circuit with suiable diagrams

3. Explain blocking LC oscillator with base timing

4. Explain about free running blocking oscillator

5. Explain the principle of Astable multivibrator with emitter base timing

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CS2204 Analog and Digital Communication – Most Important Questions – 2014 Edition

Anna University

Department of Computer Science Engineering

Third Semester

CS2204 - Analog and Digital Communication

Question Bank [2014-15] [MOST IMPORTANT]

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UNIT 1 FUNDAMENTALS OF ANALOG COMMUNICATION

TEXT BOOK: Wayne Tomasi, “Electronic Communication Systems – Fundamental through advanced”, 5/e, Pearson Education. (for UNIT I to IV).

PART – B

1. Define modulation index for FM and PM and obtain the relation between modulation index

and modulating signal for FM and PM. (8)

2. Compare the advantages and disadvantages of angle modulation with amplitude modulation.(8)

3. Explain the principle of Amplitude Modulation and derive an expression for AM-DSBFC signal. Draw the AM waveform and frequency spectrum and explain the voltage distribution and power distribution in AM. (16)

4. Discuss about the sets of side frequencies produced when a carrier is Frequency Modulated by a single frequency sinusoid and Derive an expression for the average power of angle modulated wave. (16)

5. Explain any one method each for generating and receiving Amplitude Modulated and Angle

Modulated Signal. (16)

PROBLEMS:

1. To a conventional AM modulator, one input is a 500 KHz carrier with amplitude of 20 V

(peak). The other input is a 10KHz modulating signal that is of sufficient amplitude to cause a change in the output wave of ±7.5V (peak). Determine

(i) Upper and lower side frequencies.

(ii) Modulation coefficient and percent modulation.

(iii) Peak amplitude of the modulated carrier and the upper and lower side frequency voltages. (iv) Maximum and minimum amplitudes of the envelope.

(v) The expression for the modulated wave. (vi) Draw the output spectrum.

(vii) Sketch the output envelope. (16)

2. For an FM modulator with deviation sensitivity K1= 4 KHz/V and a modulating signal vm(t) = 10Sin(2π2000 t) , détermine,

(i) The peak frequency deviation

(ii) The carrier swing

(iii) and the modulation index.

(iv) What is the peak frequency deviation produced if the modulating signal were to double in amplitude. (8)

3. For an FM modulator with a modulation index m=1, a modulating signal

vm(t) = VmSin(2π1000 t) and an unmodulated carrier vc(t) = 10Sin(2π500Kt), determine,

(i)	The number of sets of significant side frequencies,
(ii)	Their amplitudes.
(iii)	Draw the frequency spectrum showing their relative amplitudes.	(6)

6. The output of an AM transmitter is given by Vm(t) = 500(1 + 0.4 sin3140t)sin(6.28x107t).

Calculate the (1) Carrier frequency

(2) Modulating frequency

(3) Modulation index

(4) Carrier power if load is 600 Ω.

(5) Total power.

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UNIT 2 – DIGITAL COMMUNICATION

1. With neat block diagrams, explain Binary FSK modulator and demodulator system and discuss the bandwidth requirements. (16)

2. Explain the generation and detection of BPSK system with the help of block diagrams. Also obtain the minimum double sided Nyquist bandwidth. (16)

3. Discuss in detail the operation of QPSK modulator and demodulator with its truth table, phase diagram and constellation diagram.(16)

4. Define QAM. Illustrate the concept of 8-QAM transmitter with the truth table and explain the 8- QAM receiver. (8)

5. What is carrier recovery? Discuss how carrier recovery is achieved by Squaring loop and Costas loop circuits in detail.(16)

PROBLEMS:

1. For a BPSK modulator with a carrier frequency of 70 MHz and an input bit rate of 10 Mbps,

determine

(i) Maximum and minimum upper and lower side frequencies

(ii) Sketch the output spectrum

(iii)Minimum Nyquist bandwidth and baud rate. (16)

2. For a QPSK modulator with an input data rate equal to 12 Mbps and a carrier frequency of 100

MHz, determine the following

(i) Minimum double sided Nyquist bandwidth

(ii) Baud rate

(iii)Sketch the output spectrum (8)

3. For the DPSK modulator determine the output phase sequence for the following input bit sequence: 11001100101010. Assume that the reference bit is equal to 1. (8)

4. Determine the bandwidth and baud for an FSK signal with a mark frequency of 32KHz, a space frequency of 24KHz and a bit rate of 4Kbps. (4)

5. Define bandwidth efficiency. For an 8-PSK system, operating with information bit rate of 24 kbps, determine (i) Baud (ii) Minimum bandwidth (iii) Bandwidth efficiency. (4)

6. For a QPSK modulator with an input data rate equal to 10 Mbps and a carrier frequency of 75

MHz, determine the minimum double sided Nyquist bandwidth.(4)

7. Determine the (1) peak frequency deviation and (2) minimum bandwidth, for a binary FSK

signal with mark frequency of 45 KHz and an input bit rate of 3 Kbps. (4)

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UNIT 3 – DIGITAL TRANSMISSION

1. With neat block diagram explain Pulse Code Modulation (PCM) system and explain the

advantages and disadvantages of digital transmission. (16)

2. Draw and explain the Sample and Hold circuit and Compare natural sampling and flat top sampling. (16).

3. Explain Delta modulation PCM Transmitter and Receiver. Describe slope overload distortion and granular noise. What are the ways to reduce this noise? (16)

4. Explain Differential Pulse Code Modulation (DPCM) system with block diagram. (16)

5. What is ISI? What are the causes of ISI? (8)

PROBLEMS:

1. A 12 bit linear PCM code is digitally compressed into 8 bits. The resolution is 0.03V.

Determine the following for an analog input voltage of 1.465V. (8) (i) 12 bit linear PCM code.

(ii) Eight bit compressed code. (iii) Decoded 12 bit code.

(iv) Decoded voltage

(v) Percentage error.

2. For minimum line speed with an 8 bit PCM for speech signal ranging upto 1 volt, (i) Calculate the resolution and quantization error.

(ii) Calculate the coding efficiency for a resolution of 0.01 volt with the 8 bit PCM. (4)

3. For a compressor with µ = 255, determine

(i) The voltage gain for the following relative values of Vin, Vmax, 0.75Vmax, 0.5Vmax,

0.25Vmax.

(ii) The compressed output voltage for a maximum input voltage of 4 V.

(iii) Input and output dynamic ranges.

(iv) Compression. (10)

ALL THE SOLVED PROBLEMS IN THE TEXT BOOK – Wayne Tomasi. CHAPTER-10

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UNIT 4 – DATA COMMUNICATIONS

[Wayne Tomasi. CHAPTER- 21, 22]

1. Write about the various Error Detection techniques and Error Correction techniques. (16)

2. Describe the physical, electrical and functional characteristics of RS 232 interface (16)

3. Explain data communication modem with a block diagram and write short notes on

Asynchronous modems and Synchronous modems. (16)

4. Write short notes about the history of data communications and about the standards and organizations for data communication. (16)

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UNIT 5 – SPREAD SPECTRUM AND MULTIPLE ACCESS TECHNIQUES

TEXT BOOK: Simon Haykin, “Communication Systems”, 4th Edition, John Wiley & Sons., 2001.

1. Define Pseudo noise sequence? How PN sequence is generated using LFSR? Explain with an example. Write about the properties of the PN sequence. (16)

2. Describe direct sequence spread spectrum (DS-SS) with coherent BPSK. (16)

3. Describe Slow and Fast Frequency Hopping spread spectrum (FH-SS). (16)

4. With typical examples for each explain TDMA and CDMA. [(ie) Explain GSM and IS -95 wireless communication systems] and Compare the merits and demerits of TDMA and FDMA multiple access schemes. (16)

5. Explain the working of Multi pulse excited Predictive Coding and Code excited Predictive coding with suitable diagrams. (16)

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