6th sem question bank even'11

P.E.S.I.T DEPT. OF TE VI SEM (AUTONOMOUS) 1

6th SEM QUESTION BANKINDEX

SL.NO. SUBJECTS CODE COURSE

INSTRUCTOR PAGE NO

1. INDEX -- -- 01

2. DIGITAL COMMUNICATION THEORY AND LABORATORY EC 351 Mr. MJR 2 – 3

3. INFORMATION THEORY AND CODING EC 352 Mr. HSP 4 - 7

4. VLSI DESIGN THEORY AND LABORATORY EC 353 Mr. RGB /

Ms. SSR 8 - 10

5. MICROCONTROLLER THEORY AND LABORATORY EC 354 Ms. SSM 11 - 12

6.NETWORK SECURITY (Elective 1) EC 379 Mr. MVA 13 – 16

7. OPTICAL FIBER COMMUNICATION (Elective 2) EC381 Prof. VM 17 – 23

8. SATELLITE COMMUNICATION(Elective 3) EC386 Ms. AGP 24 - 25

9. OPERATIONS RESEARCH ME 363 Mr. NLJ

To be announced

later10. PATTERN RECOGNITION EC 365 Dr. VK

11. MULTI MEDIA COMMUNICATION EC 375 Mr. AVK

Class Coordinator: Ms. Milana V N

DIGITAL COMMUNICATION THEORY AND LABORATORY QUESTION BANK

Subject Code: EC 351 Faculty: Mr. MJR

UNIT-11) State sampling theorem2) Write the equations for the spectrum of finite energy signal g(t),Sampled at 1/2W seconds and G(f), if

W is the highest frequency content of g(t).Draw the waveforms of G(f)and sampled version G(f).3) Obtain an expression for Fourier Transform of a sampled signal.4) State and prove sampling and reconstruction of low pass signals using Nyquist Criterion.5) Relate the flat top sampled signal with ideal sampling with relevant mathematical equations.6) Explain different channels in digital communication.7) With a block diagram explain a typical digital communication system.8) Explain the principle of Quadrature sampling of bandpass signals.9) Explain the principle of TDM. 10) What are the different aspects to be taken in to account in various types of

sampling and signal recovery? 11) With a suitable block diagram, explain the functioning of a PCM system. 12) Derive an expression for maximum signal to quantization noise ratio for PCM

system that employs linear quantization techniques. What will be the (S/N )dB if the destination power and signal amplitude are normalized?

13) Prove that the Shannon‟s channel capacity theorem can be easily achieved byincreasing the average power in PCM systems.

14) Related problems in chapter 4 of R1.UNIT-2

15) Explain the principles of Delta modulation. With relevant figures and mathematical expressions explain the functioning of DM transmitter and receiver.

16) Explain the principle of DPCM17) Explain with a suitable block diagram how ADPCM is used to code speech at low bit rate. 18) With a conceptual model, define and derive an expression for signal to distortion ratio. 19) What are discrete PAM signals? 20) Derive the expression for power spectral density of different types of discrete PAM signals. 21) What is ISI? Derive an expression for Nyquist pulse shaping criteria for distortion less baseband

binary transmission.22) What is correlative coding? 23) What is an Eye pattern? Explain how it is helpful in understanding the ISI problem.24) With a neat structure explain the concept of the adaptive equalization process. 25) What do you understand by Duobinary signaling?26) Related problems in chapter 5 and 6 of R1.


UNIT-3

27) How are digital modulation techniques classified? 28) With neat block diagrams explain Coherent BPSK receiver 29) Explain the working of a BPSK transmitter and receiver. What are the drawbacks of BPSK system? 30) Estimate the power spectral density of a BPSK signal.31) Explain the operation of Binary Frequency Shift Keying (BFSK) transmitter and receiver with

necessary block diagrams. 32) With neat block diagrams explain the DPSK transmitter and receiver. Illustrate the generation of

DPSK signal by assuming binary input sequence.33) Explain the frequency hopped spread M-ary FSK transmitter and receiver. 34) Discuss base band transmission of M-ary data. 35) Related problems in chapter 7 of R1.

UNIT-436) Explain the concept of maximum likely hood estimation. 37) Explain Gram – Schmidt Orthogonalization Procedure citing all steps. 38) Explain the response of bank of correlators to noisy input with expressions.39) How do you detect known signals in the presence of noise?40) What are the basic concepts involved in Estimation of signals? 41) State and prove properties of Matched filter. 42) Explain the principle of operation of correlation receiver with diagrams. 43) How matched filter helps in maximizing output signal to noise ratio? 44) How detection of signals with unknown phase in noise is carried out? 45) Related problems in chapter 9 of R1.

UNIT-5

46) What is spread spectrum technique? How are they classified? 47) Explain the working of direct sequence spread spectrum transmitter and receiver. 48) Discuss the pseudo-noise (PN) sequence with a neat diagram showing the

maximum length sequence generator. 49) With neat diagrams, explain the transmitter and receiver of slow frequency hop spread M-ary

frequency shift keying system. 50) Distinguish between slow frequency hopping and fast frequency hopping.51) Explain the application of spread spectrum technique to code-division multiple access. 52) With a neat block diagram explain OFDM?53) Mention the advantages of OFDM.

Reference Books:1) “Digital Communication”, Simon Haykin, John Whiley,20032) “OFDM for Wireless Communication Systems”, Ramjee Prasad, Universal Personal

communications3) “Digital Communications” ,Bernard Sklar, Pearson Education

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INFORMATION THEORY AND CODING QUESTION BANK

Subject Code: EC 352 Faculty: Mr. HSP

1. Explain the terms (i) Self information (ii) Average information (iii) Mutual Information.2. Discuss the reason for using logarithmic measure for measuring the amount of information.3. Explain the concept of amount of information associated with message. Also explain what is infinite

information and zero information.4. A binary source emitting an independent sequence of 0’s and 1’s with probabilities p and (1-p)

respectively. Plot the entropy of the source.5. Explain the concept of information, average information, information rate and redundancy as referred to

information transmission.6. Let X represents the outcome of a single roll of a fair dice. What is the entropy of X?7. A code is composed of dots and dashes. Assume that the dash is 3 times as long as the dot and has

one-third the probability of occurrence. (i) Calculate the information in dot and that in a dash; (ii) Calculate the average information in dot-dash code; and (iii) Assume that a dot lasts for 10 ms and this same time interval is allowed between symbols. Calculate the average rate of information transmission.

8. What do you understand by the term extension of a discrete memoryless source. Show that the entropy of the nth extension of a DMS is n times the entropy of the original source.

9. A card is drawn from a deck of playing cards. A) You are informed that the card you draw is spade. How much information did you receive in bits? B) How much information did you receive if you are told that the card you drew is an ace? C) How much information did you receive if you are told that the card you drew is an ace of spades? Is the information content of the message “ace of spades” the sum of the information contents of the messages ”spade” and “ace”?

10. a block and white TV picture consists of 525 lines of picture information. Assume that each consists of 525 picture elements and that each element can have 256 brightness levels. Pictures are repeated the rate of 30/sec. Calculate the average rate of information conveyed by a TV set to a viewer.

11. A zero memory source has a source alphabet S=S1, S2, S3 with P=1/2, 1/4, 1/4. Find the entropy of the source. Also determine the entropy of its second extension and verify that H(S2) = 2H(S).

12. Show that the entropy is maximum when source transmits symbols with equal probability. Plot the entropy of this source versus p (0<p<1).

13. The output of an information source consists OF 128 symbols, 16 of which occurs with probability of 1/32 and remaining 112 occur with a probability of 1/224. The source emits 1000 symbols/sec. Assuming that the symbols are chosen independently, find the rate of information of the source.

14. A CRT terminal is used to enter alphanumeric data into a computer, the CRT is connected through a voice grade telephone line having usable bandwidths of 3KHz and an output S/N of 10Db. Assume that the terminal has 128 chatracters and data is sent in an independent manner with equal probability.

1) Find average information per character.2) Find capacity of the channel.3) Find maximum rate at which data can be sent from terminal to the computer

without error.15. A message source produces two independent symbols A and B with probabilities P(A)=0.4 and

P(B)=0.6. Calculate the efficiency of the source and hence its redundancy. If the symbols are received in average with 4 in every 100 symbols in error, calculate the transmission rate of the system.

16. A message source produces two independent symbols U and V with probabilities P(v)=0.6 and P(U)=0.4. Calculate the efficiency of the source and hence the redundancy. If the symbols are received on average with 3 in every 100 symbols in error & calculate the transmission rate of the system.


17. The output of a DMS consists of the possible letters x1, x2…xn which occur with probabilities p1,p2,….pn

respectively. Prove that the entropy of H(x) of the source is at least log2n.18. What do you mean by source encoding? Name the functional requirements to be satisfied in the

development of an efficient source encoder.19. For a binary communication system, a ‘0’ or ‘1’ is transmitted. Because of noise on the channel, a ‘0’

can be received as ‘1’ and vice-versa. Let m0 and m1 represent the events of transmitting ‘0’ and ‘1’ respectively. Let r0 and r0 denote the events of receiving ‘0’ and ‘1’ respectively. Let p(m0) = 0.5, p(r1/m0) = p = 0.1, P(r0/m1) = q = 0.2i. Find p(r0) and p(r1)ii. If a ‘0’ was received what is the probability that ‘0’ was sentiii. If a ‘1’ was received what is the probability that ‘1’ was sent.iv. Calculate the probability of error.v. Calculate the probability that the transmitted symbol is read correctly at the receiver.

20. State Shannon-Hartley’s law. Derive an equation showing the efficiency of a system in terms of the information rate per Unit bandwidth. How is the efficiency of the system related to B/W?

21. For a discrete memory less source of entropy H(S), show that the average code-word length for any distortion less source encoding scheme is bounded as L≥H(S).

22. Calculate the capacity of a standard 4KHz telephone channel working in the range of 200 to 3300 KHz with a S/N ratio of 30 dB.

23. What is the meaning of the term communication channel. Briefly explain data communication channel, coding channel and modulation channel.

24. Obtain the communication capacity of a noiseless channel transmitting n discrete message system/sec.

25. Explain extremal property and additivity property.26. Suppose that S1, S2 are two memory sources with probabilities p1,p2,p3,……pn for source s1 and

q1,q2,…….qn for source s2 . Show that the entropy of the source s1 n

H(s1)≤ ∑ Pk log (1/qk) K=1

27. Explain the concept of B/W and S/N trade-off with reference to the communication channel.28. What are important properties of the codes?29. what are the disadvantages of variable length coding?30. Explain with examples:

Uniquely decodable codes, Instantaneous codes31. Explain the Shannon-Fano coding procedure for the construction of an optimum code32. Explain clearly the procedure for the construction of compact Huffman code.33. A discrete source transmits six messages symbols with probabilities of 0.3, 0.2, 0.2, 0.15, 0.1, 0.05.

Device suitable Fano and Huffmann codes for the messages and determine the average length and efficiency of each code.

34. Consider the messages given by the probabilities 1/16, 1/16, 1/8, ¼, ½. Calculate H. Use the Shannon-Fano algorithm to develop a efficient code and for that code, calculate the average number of bits/message compared with H.

35. Consider a source with 8 alphabets and respective probabilities as shown:A B C D E F G H0.20 0.18 0.15 0.10 0.08 0.05 0.02 0.01

Construct the binary Huffman code for this. Construct the quaternary Huffman and code and show that the efficiency of this code is worse than that of binary code36. Define Noiseless channel and deterministic channel.37. A source produces symbols X, Y,Z with equal probabilities at a rate of 100/sec. Owing to noise on the

channel, the probabilities of correct reception of the various symbols are as shown:P (j/i) X Y z


X

y

z

¾

¼

0

¼

½

¼

0

¼

¾

Determine the rate at which information is being received.38. Determine the rate of transmission l(x,y) through a channel whose noise characteristics is shown in fig.

P(A1)=0.6, P(A2)=0.3, P(A3)=0.1

39. For a discrete memory less source of entropy H(S), show that, the average code-word length for any distortionless source encoding scheme is bounded as L H(S).

40. Briefly discuss the classification of codes.41. Show that H(X,Y) = H(X/Y)+H(Y).42. State the properties of mutual information.43. Show that I(X,Y) = I(Y,X) for a discrete channel.44. For a binary erasure channels show in figure below and Find the following:

i. The average mutual information in bitsii. The channel capacityiii. The values of p(x1) and p(x2) for maximum mutual information

45. A DMS has an alphabet of seven symbols whose probabilities of occurrences are described here:Symbol: S0 S1 S2 S3 S4 S5 S6

Prob 0.25 0.125 0.125 0.125 0.125 0.0625 0.0625Compute the Huffman code for this source, moving a combined symbol as high as possible, Explain why the computed source code has an efficiency of 100%.

46. Consider a binary block code with 2n code words of same length n. Show that the Kraft inequality is satisfied for such a code.

47. Write short notes on the following:Binary Symmetric Channels (BSC), Binary Erasure Channels (BEC)Uniform Channel, Cascaded channels

48. Show that for a AWGN channel C where /2 = noise power spectral density in watts/Hz.


A1 0.5 B1

T R

0.5A2 0.5 B2

0.5

A3 0.5 B3

y1

e(y2)

y3

1-px1

p

px3

1-p

49. Consider an AWGN channel with 4 KHz bandwidth with noise power spectral density

watts/Hz. The signal power required at the receiver is 0.1mW. Calculate the capacity of the channel.50. If I(xi, yi) = I(xi)-I(xi/yj). Prove that I(xi,yj)=I(yj)-I(yj/xi)51. Consider a continuous random variable having a distribution as given below

Find the differential entropy H(x) 52. Design a single error correcting code with a message block size of 11 and show that by an example

that it can correct single error.53. If Ci and Cj an two code vectors in a (n,k) linear block code, show that their sum is also a code vector.54. Show CHT=0 for a linear block code.55. Prove that the minimum distance of a linear block code is the smallest weight of the non-zero code

vector in the code.56. What is error control coding? Which are the functional blocks of a communication system that

accomplish this? Indicate the function of each block. What is the error detection and correction on the performance of communication system?

57. Explain briefly the following:a. Golay codeb. BCH Code

58. Explain the methods of controlling errors59. List out the properties of linear codes.60. Explain the importance of hamming codes & how these can be used for error detection and correction.61. Write a standard array for (7.4) code62. Explain the properties of binary cyclic cods.63. With a neat diagrams explain the binary cyclic encoding and decoding64. Write short notes on the following

(i) BCH codes (ii) Majority Logic decodable codes (iii) Maximum length codes iv) R-S codes(v) Golay codes (vi) Burst errors & its correction

65. Draw the generalized encoder diagram for convolutional codes.66. Differentiate the systematic and nonsymmetric codes67. Explain the following terms.

Hamming distance code rate Free distance weight of code

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VLSI DESIGN THEORY AND LABORATORY

QUESTION BANK

Subject Code: EC353 Faculty: Mr.RGB / Ms. SSR

1. With the help of transfer characteristics bring out the differences in transistor structuresand actions of depletion and enhancement type of transistors.

2. Bring out a comparison between CMOS and Bipolar technologies. 3. Differentiate the three scaling models applying the scaling rule for the (i) Static power dissipation.

(ii)Gate 4. Delay (iii) Number of components. 5. What are switch logic and restoring logic circuits? Give an example for each. 6. Build and explain a 4 : 1 MUX using transmission gates. 7. Realize the following logic expressions using CMOS structures (i) Y=A.B•C(ii) Y=AB+AB

(iii) Y=AB+'D ( iv) Y=AB+CD8. What are uses of stick diagrams? Give a table of stick encodings for a simple single metal nMOS

process.9. Explain the working of CMOS inverter with the transfer characteristics.10. Using the concept of sheet resistance and standard gate capacitance - unit C Cg, show that the

delay unit `t' is not much different from transit time tsd, where tsd is the time taken for an electron to move from source to drain.

11. Explain the based design rules with suitable illustrations.12. Discuss the various parameters on which the threshold voltage of a MOS transistor depends.13. With the help of a flow chart explain the various design steps involved and the fabrication Steps

involved in successfully siliconising an VLS IC. 14. Give the structured design of n bit bus arbitration logic and show its one bit implementation. 15. Write relevant logic diagram / block diagram and explain the following:

a. Alternative forms of pull-ups.b. Super buffers.c. Design of an ALU subsystem.d. A 4:1 MUX using transmission gates.

16. With neat schematics, explain TWIN-TUB CMOS transistor manufacturing process.17. What are layout design rules? Describe any five design rules. 18. Differentiate between : i) Enhancement and depletion mode transistor.19. Prove that pull-up to pull-down ratio for an NMOS inverter is 4 : 1 for proper operation.20. Derive an expression for Ids in terms of physical parameter and voltages in NMOS transistor in non

- saturation region. 21. What is meant by CMOS perfect switch? Explain. 22. With a neat transfer characteristics and current curve, explain the different regions of

operation of a CMOS inverter. 23. What is latchup? Explain with neat diagram the latchup in CMOS circuits. 24. Explain with neat sketches, the design rules for wires, transistor design rules and

contacts. 26. Define the delay units. Show that the transit time and the time constant are inter

changeable in an NMOS inverter driven by another inverter. 27. Derive expressions for rise time and fall time of CMOS inverter with necessary sketches.

28. Draw the circuits and stick diagram of NMOS, CMOS inverters.


29. Design a parity generator using structural design approach and draw the stick diagram forNMOS parity generator.

30. Design a 4-bit adder using computational elements. Draw the relevant diagrams and truthtable.

31. Define noise margin. With necessary response, explain the inverter noise margin.32. What is Moore's law? Explain this law in the context of evolution of microelectronics.33. With the help of transfer and output characteristics, explain the working of MOS

enhancement mode transistor. 34. Describe with neat sketches the fabrication of N-well CMOS inserter. 35. Derive an expression for Ids of an nMOS transistor in non-saturation region. 36. Define the threshold voltage of a MOSFET. Explain the effect of different parameters on the

threshold voltage of a MOSFET. 37. With a circuit diagram and transfer characteristics discuss quantitatively the various regions of

operation of a CMOS inverter.38. Draw the circuit diagram and stick diagram of a 3 input NAND gate in both nMOS design style and

CMOS design style. 39. State the lambda based design rules for the following layers:

i. Poly silicon ii) Metal - I to polysilicon contact cutiii. nMOS depletion transistor iv) Diffusion

40. A particular layer of MOS circuit has a resistivity p = I Q - cm. A section of this layer is50μm long, 5μm wide and has a thickness of 1μm. Calculate the resistance along the length. What is the value of RS?

41. Define standard unit of capacitance and delay unit. Explain their significance. 42. Obtain an expression for overall time delay td when N number of CMOS inverters is driving a large

capacitive load CL. Show that the total delay is minimum, when f = e (base of normal logarithms), where f is the width factor.

43. Discuss the three scaling models and scaling factors used for scaling of MOS circuits.44. Substantiate with proper relations the limitations of substrate doping and depletion width

scaling. 45. Explain the structural design of bus arbitration logic for n-line bus with stick diagram.46. Realize the Boolean expression Y = ABC + D, using CMOS switches and verify the working with a

truth table. 47. Explain VLSI fabrication steps with neat schematics. 48. Draw and explain the construction of an n-mos transistor, explain the effect of channel

modulation.49. Explain setup and hold times with respect to memory element. 50. Discuss the advantages and disadvantages of sequential systems built from latches and

flipflops, using a suitable example. 51. Briefly explain the terms:

i) Moore's law ii) ASIC iii) Netlist iv) Stick diagram v) Layout.52. What are the challenges to be faced in the deep submicron VLSI?53. With illustrations, explain the important steps in a twin tub process.


54. Briefly explain:i) Latchupii) Body effect

55. A minimum size transistor is formed by a L = 2A, and w = 3X. Given its56. Vt = 0.7V, k' = 73pAJV2 and VGS = 5V, fnd the saturation current through a minimum sized n-type

transistor. Give expression for Vt. 57. How pipelining reduces the delay in sequential circuits?58. Draw the logic diagram and CMOS circuit diagram of a SR flipflop.

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MICROCONTROLLER THEORY AND LABORATORY

QUESTION BANK

Subject Code: EC 354 Faculty: Ms. SSM

1. Name four major Differences between a microprocessor and micro controller.2. List three essential items needed to makeup a development system for programming micro controller3. Explain Differences between RISC and CISC CPU architecture 4. Explain differences between Harvard & Von Neumann CPU architectures5. Explain 8051 architecture with neat block diagram6. List out all special function registers (SFR) in 8051 and explain each SFR primary function.7. Find maximum pulse rate that can be counted on T1 if oscillator frequency is 6 MHz8. In mode 0 find baud rate for serial port for a 6 MHz crystal.9. Find largest time delay possible for a timer in mode 1 if 6 MHz crystal used10. Explain interrupts in 8051.11. Define machine cycle and calculate time per machine cycle, assuming standard Operating frequency of 11.0592MHz.

11. Explain with diagram the feature and operation of port 3.12. Explain processor status word

11. Explain various addressing modes.12. Write a program to transfer a block of data from external ROM to Internal RAM.13. Explain (i) MOVX (ii) MOVC with examples14. Explain (i) XCH (ii) XCHD with examples15. Why is 8051 called Boolean Processor ?Justify.

15. Mention which SFRs are bit addressable and mention their bit addresses.16. Write a program to double the number in R2, and put the result in R3 (high byte) and R4 (low byte) 17. Explain (i) ACALL (ii) LCALL with examples18.Wrire a program to add BCD numbers found in internal RAM locations 25h, 26h and 27h. Put the result in RAM locations s 31h and 30h19. Write a program to find address of location where number A6h is stored in external RAM between locations 0100h and 0200h.20. Write a program to find number of zeros in an 8-bit data item.21. Write a program to find position of first high (logic 1) in an 8-bit data .That is scanned from D7-D0. 22. Write a program to convert a series of ASCII numbers to Packed BCD. Assume that the ASCII data is located in ROM locations starting at 0300h. Place the BCD data in RAM location starting from at 60h.23. Write a program to get an 8-bit binary number from port 1, convert it to ASCII and send the result to port 0.24.Write an ALP to use timer1 to read input from port 1,complement it and out put via Port2. This transfer is to be done once in 50msec25. Explain the function of SCON register.24. For XTAL = 11.0592 MHz find the TH1 value (in both decimal and hex) for each of following baud rates (a) 9600 (b) 4800 (c) 1200


25. Write a program to transfer serially the message “8051 is an eight bit micro controller” continuously at 57600 baud rate26. Explain interfacing of 8051 with RS232 connectors via the MAX232 27. Write a program to generate a square wave of time period 160 ms on P2.3 while at the same time the 8051 is sending out 55h and AAh to port 1 continuously.28. Write a program in which every 2 seconds ,the Led connected to P2.7 is turned on and off four times , while at same time the 8051 is getting data from Porte 1 and sending it to port 0 continuously. Make sure the on and off states are 50ms in duration.29. Explain the role of TCON.0 and TCON.2 in execution of external interrupt 0.30. Expain the differences between low-level and edge-triggered interrupt.31. Explain interfacing of 8051 with ADC804 32. Explain interfacing of 8051 with LCD 33. Explain interfacing a LM34/LM35 temperature sensor to 8051.34. Explain interfacing of 8051 with stepper motor.35. Interface DAC808 to 8051 and write ALP to generate positive going ramp waveform.

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NETWORK SECURITY (Elective 1)

QUESTION BANK

Subject Code: EC 379 Faculty: Mr.MVA

UNIT-1Introduction1) Define the three security goals2) Distinguish between passive and active security attacks. Name some passive attacks. Name some

active attacks.3) List and define five security services.4) Define eight security mechanisms.

Traditional Symmetric-Key Ciphers5) Define a symmetric-key cipher.6) Distinguish between a substitution cipher and a transposition cipher.7) Distinguish between a monoalphabetic and a polyalphabetic cipher.8) Distinguish between a stream cipher and a block cipher.9) Are all stream ciphers monoalphabetic? Explain.10) Are all block ciphers polyalphabetic? Explain.11) List three monoalphabetic and polyalphabetic ciphers each.12) List two transposition ciphers.13) List four kinds of cryptanalysis attacks.14) By using play fair cipher technique find the plaintext of key = COMPUTER and cipher text =

OFTIBLDHXM. 15) Encrypt the message "meet me at the usual place at then rather than eight O clock'' using hill cipher

with the key . Show your calculations and the result.

16) Encrypt the following message using hill cipher technique.

Key =

Plaintext = FRIDAY. 17) In a transposition cipher the two parts have the key 213 i.e the message is written in 3 columns with the

last row stopped with X for completion. Find the ciphered text for the message. "MEET ME AT VTU IN BELGAUM".

UNIT-2Introduction to Modern Symmetric-Key Ciphers 18) Explain why modern block ciphers are designed as substitution ciphers instead of transposition ciphers.19) Explain why both substitution and transposition ciphers can be thought of as permutations.20) List some components of a modern block cipher.21) Define a P-box and list its three variations. Which variation is invertible?22) Define an S-box and mention the necessary condition for an S-box to be invertible.23) Define a product cipher and list the two classes of product ciphers.24) Distinguish between diffusion and confusion.25) Distinguish between a Feistel and a non-Feistel block cipher.


26) Distinguish between differential and linear cryptanalysis. Which one is a chosen-plaintext attack? Which one is a known-plaintext attack?

Data Encryption Standard (DES)27) What is the block size in DES? What is the cipher key size in DES? What is the round-key size in

DES? What is the number of rounds in DES?28) How many permutations are used in a DES cipher algorithm? How many permutations are used in the

round-key generator?29) How many exclusive-or operations are used in the DES cipher?30) Why does the DES function need an expansion permutation?31) What is the difference between a weak key, a semi-weak key, and a possible weak key?32) What is double DES? What kind of attack on double DES makes it useless?33) What is triple DES? What is triple DES with two keys? What is triple DES with three keys?

Advanced Encryption Standard (AES)34) List the criteria defined by NIST for AES35) List the parameters (block size, key size, and the number of rounds) for the three AES versions.36) How many transformations are there in each version of AES? How many round keys are needed for

each version?37) Compare DES and AES. Which one is bit-oriented? Which one is byte-oriented?38) Compare the substitution/permutation in DES and AES

Asymmetric-Key Cryptography39) Distinguish between symmetric-key and asymmetric-key cryptosystems.40) Distinguish between public and private keys in an asymmetric-key cryptosystem. Compare and

contrast the keys in symmetric-key and asymmetric-key cryptography.41) Define a trapdoor one-way function and explain its use in asymmetric-key cryptography.42) Briefly explain the idea behind the knapsack/RSA cryptosystem.

What is the one-way function in this system? What is the trapdoor in this system? Define the public and private keys in this system Describe the security of this system.

43) Define elliptic curves and explain their applications in cryptography.44) In an RSA system, the public key of a given user is e = 31, n = 3599, what is the private key of this

user? 45) Perform Encryption and Decryption using the RSA algorithm, given:

p = 7, q = 11, e = 17, M = 8.

UNIT-3Message Integrity and Message Authentication46) Distinguish between message integrity and message authentication.47) Define the first/second/third criterion for a cryptographic hash function.48) Distinguish between an MDC and a MAC.49) Distinguish between HMAC and CMAC


Cryptographic Hash Functions50) Define a cryptographic hash function.51) Define an iterated cryptographic hash function.52) Describe the idea of the Merkle-Damgard scheme and why this idea is so important for the design of a

cryptographic hash function.53) List the main features of the SHA-512 cryptographic hash function. What kind of compression function

is used in SHA-512?

Digital Signature54) Compare and contrast a conventional signature and a digital signature.55) List the security services provided by a digital signature.56) Compare and contrast attacks on digital signatures with attacks on cryptosystems.57) Compare and contrast existential and selective forgery.58) Define the RSA digital signature scheme and compare it to the RSA cryptosystem.59) Describe the RSA digital signature scheme.60) Explain digital signature standard.

UNIT-5Web Security61) What protocols comprise SSL?62) What is the difference between an SSL connection and an SSL session?63) List and briefly define the parameters that define an SSL session state/connection.64) Explain about the services provided by SSL record protocol?65) Discuss about the steps involved in SSL record protocol transmission.66) Compare TLS record format with SSL record format.67) List and briefly define the principal categories of Secured electronic transaction (SET) participants.68) Write short notes on Secured electronic transaction (SET). 69) Write short notes on Web security requirements.70) Enlist key features of SET.

Intruders71) List and briefly define three classes of intruders.72) What are two common techniques used to protect a password file?73) What are three benefits that can be provided by an intrusion detection system?74) What is the difference between statistical anomaly detection and rule-based intrusion detection?75) What metrics are useful for profile-based intrusion detection? 76) What is the difference between rule-based anomaly detection and rule-based penetration

identification?77) What is a honeypot?78) What is a salt in the context of UNIX password management?79) List and briefly define four techniques used to avoid guessable passwords.


UNIT-5Malicious Software 80) What is the role of compression in the operation of a virus?81) What is the role of encryption in the operation of a virus?82) What are typical phases of operation of a virus or worm?83) In general terms, how does a worm propagate?84) What is a digital immune system?85) How does the behavior-blocking software work?86) What is a DDoS?87) Write short notes on Viruses. 88) Write a brief description about The Nature of viruses.

Firewalls89) List three design goals for a firewall.90) List four techniques used by firewalls to control access and enforce a security policy.91) What information is used by a typical packet-filtering router?92) What are some weaknesses of a packet-filtering router?93) What is the difference between a packet-filtering router and a stateful inspection firewall?94) What is an application-level gateway?95) What is a circuit-level gateway?96) In the context of access control, what is the difference between a subject and an object?97) What is the difference between an access control list and a capability ticker?98) What are the two rules that a reference monitor enforces?99) What properties are required of a reference monitor?

Write short notes on Design principles of firewalls.

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OPTICAL FIBER COMMUNICATION (Elective 2)LESSON PLAN

Subject Code: EC381 Faculty: Prof. VM

Chapter 1 Overview of Optical Fiber Communications 1. With a neat block diagram, briefly explain the features of the elements of an optical fiber transmission link. 2. What are the advantages of optical fiber over two wire copper cable? 3. Draw a visible light spectrum in terms of wavelength and demarcate the portion of the spectrum used for optical communication. 4. What are monomode and multimode fibers? 5. Explain the term numerical aperture. 6. Derive an expression for numerical aperture and maximum acceptance angle In case of a step index optical fiber in terms of refractive indices of core and cladding material. 7. A silica tube with the inside and outside diameter of 6mm and 8mm respectively, is to have a certain thickness of glass deposited on the inner surface. What should the thickness of this glass deposition be if a fiber having a core diameter of 50μm and an outer cladding diameter of 125μm is to be drawn from this perform? 8. Describe the merits and limitations of optical fibers. 9. Discuss the terms ‗step index‘, ‗graded index‘, ‗numerical aperture‘ and ‗single mode fibers‘. 10. Define ―normalized frequency‖ and ―normalized propagation constant‖ with their expressions for step index fiber. 11. Define v number and normalized propagation constant for optical fibers. 12. Determine the cutoff wavelength for single mode operation of guide having radius α = 5μm,no = 1.450, Δ = 0.002.(Ans = 1.218μm). 13. Design a multimode step index fiber with V number V =100 and a numerical aperture NA = 0.30.This would be used in data link with 0.82μm light emitting diode source. (Ans: α = 43.5μm, no = 1.458, ncl = 1.427) 14. Find the numerical aperture, v number and the number of propagating modes for a step index fiber with indices 1.5 and 1.48 with core radius 25 m, if the wavelength of the optical signal propagating in the fiber is 1300. 15. A gif with parabolic refractive index profile core has a refractive index at the core axis of 1.5 and a relative index of difference of 1%.estimate the maximum possible core diameter which allows single mode operation at a wavelength of 1.3 m. Justify the use of normalized frequency parameter. 16. List the mechanical properties of fibers and explain any one. 17. Derive s=S(D/d)2 where d and D are fiber and perform diameters and S and s are perform feed and fiber draw speeds 18. List out the methods of fabricating optical fibers. 19. Describe in detail fiber drawing process. 20. List the advantages of optical fiber communication 21. Explain basic optical laws 22. Write a note on fiber types and modes of operation 23. Explain the structure of step index fiber 24. With the help of wave equations explain step index fibers and modes in step index fibers 25. Explain single mode fibers 26. Write a note on fiber materials 27. Explain various methods fiber fabrication, explain with neat sketches 28. Write note mechanical properties of fibers.


Chapter 2 Signal Degradation in Optical Fibers

1. Derive equation for the number of modes in a S.I. fiber starting from fundamental principles. 2. What is mode coupling? Explain with necessary equations. 3. Describe the principle of opto-mechanical switching. 4. Explain with necessary diagrams the different fiber structures with their applications. 5. Explain skew rays and meridional rays. 6. Derive the expression for phase shift changes that undergoes in optical fiber when light rays propagate. Show that what condition must be required for ray angle for wave guiding. 7. Define the term attenuation coefficient. 8. Consider a 30 km long optical fiber cable that has an attenuation of 0.8 db /km at 1300 nm. Find the optical power output in db if power input to the cable is 200 w. 9. Explain briefly the mechanisms that cause absorption of light in an optical fiber. 10. Explain the scattering loss phenomenon using relevant equations. 11. Derive an expression for material dispersion starting from group velocity concept. 12. Calculate the pulse spread in 1 km fiber at 800nm if spectral width relative to wavelength is 5%. Assume dmat |()| at 800nm as 108.24 ps/(nm.km) 13. Briefly explain the phenomenon for optical power loss due to bending of an optical fiber. 14. Explain the phenomenon of material and waveguide dispersion in an optical fiber. 15. Find the pulse broadening due to intermodal dispersion in 10 km fiber with indices 1.5 and 1.48 16. Find the pulse broadening per km due to material dispersion for the following sources operating at 850nm. 17. A led with spectral width of 45nm. 18. A laser with spectral width of 2nm. Assume a fiber dispersion parameter of 0.025. 19. Discuss the design optimization of single mode fibers. 20. What is integrated optics? 21. Describe the working of an acousto-optic modulator. 22. Differentiate between intrinsic and extrinsic absorption. 23. Derive an expression for the pulse spread due to material dispersion using group delay concept. 24. The input power to an optical fiber is 2mw while power measured at the output end is 2μw.If the fiber attenuation is 0.5db/km, calculate the length of the fiber.

Chapter 3 Optical Sources & Detectors

1. What is a heterojunction structure? Discuss the basic operating characteristics of hetero junction structure semiconductor light emitting diodes (LEDs) and laser diodes. 2. What is a semi conducting material used in light source working in (a) 800 to 900nm, (b) 1100 to 1600nm region. 3. What is internal quantum efficiency? Name the 2 principal factors that can adversely reduce this efficiency. 4. Explain energy band diagrams of intrinsic and extrinsic materials 5. What are direct and indirect band gap materials? 6. Write a note semiconductor device fabrication 7. Explain basic structure of an LED 8. Write a note on light source materials 9. Explain modes and threshold conditions of laser diode 10. Explain rate equations of a laser diode. 11. Write a note on the following – a) Resonant frequencies, b)Laser diode structures and radiation patterns 12. What are single mode lasers explain 13. Explain modulation of laser diodes 14. Temperature effects in laser diode P.E.S.I.T DEPT. OF TE VI SEM (AUTONOMOUS) 18

15. Explain principles photo diodes 16. Explain the working principle of avalanche photodiodes 17. Write a note on photo detector noise 18. What is detectors response time, explain? 19. What is external quantum efficiency?


Chapter 4 Power launching and Coupling

1. Find the power coupled from a led with material refractive index 3.6, which limits 1.3 m optical beam from an emitting

area of 35 m radius and 150(w/cm2sr) or axial radiance into a step index fiber with indices 1.5 and 1.48 with core radius 35m. Also find the coupling loss at the interface. Compare the optical powers coupled into two step index fibers one of which has a core radius of 25 m with NA=0.20 and another with core radius of 50 m with 50, NA=0.20.The LED is having a circular emitting area of radius 35 m and Lambartian emission pattern with 150 w/cm2Sr axial radiance. 2. Explain how the power coupled depends on the wavelength of light. 3. Derive an expression for coupling loss in fiber joints. 4. Discuss the misalignment problems in fiber-to-fiber joints. 5. Describe how splicing equipment works. 6. Mathematically analyze the power loss due to mechanical axial misalignment in the fiber joints. 7. What are the different coupling components used in fiber to sources and detectors? 8. Derive an expression for power coupled into a led step index fiber for both cases a) rs<a and b) rs>=a, where rs is radius of curvature of the emitting surface and ‗a‘ radius of the core. 9. Discuss different lensing systems used in coupling of optical fibers. 10. Derive an expression for coupling efficiency of non-imaging micro sphere lensing system. 11. What are the problems involved in connecting the output of a led to a fiber. 12. Using rate equations for photons and carriers (electrons), show that laser is a threshold device. 13. With a neat diagram, explain the working of an edge emitting LED. Also mention its special features and usage. 14. The radiative and non-radiative recombination life times of minority carriers in the active region of a double hetero junction LED are 60 nsec and 90 nsec respectively. Determine the total carrier recombination lifetime and optical power generated internally if the peak emission wavelength is 870nm and drive current is 40mA. Show that the optical power coupled into a step index fiber due to an LED with Lambartian distribution is given by: P = PS (NA)2 for rs <= a with usual notations. 15. Obtain expression for connector return loss. 16. Explain the following: Fused bi-conical taper coupler, Lensed optical fiber connector. 17. An LED has a circular area of emission radius 35μm and Lambartian emission pattern with axial radiance of 150w/cm2 .sr. Compute the optical power coupled into an optical fiber having a core radius of 50μm and NA = 0.20. 18. Explain fusion splicing method with a neat sketch.

Chapter 5 Optical Receiver Operation

1. Describe the optical signal path through an optical data link indicating all relevant components, electrical, optical signals/ wave shapes. 2. Define the following with respect to photo detector –―quantum efficiency‖ and ―Responsivity‖. 3. When 3*1011 photons each with a wavelength of 0.85 m are incident on a photo diode, on average 1.2*1011 electrons are collected at the terminals of the device. Determine quantum efficiency and Responsivity of the photo diode at 0.8 m. 4. Give detailed account of thermal, shot noise and I.S.I. 5. How is the performance of digital receiver measured? 6. Give two different interpretations for bit error rate and its typical value for a good digital receiver. 7. What are the different sources of errors in optical receiver system? 8. In the context of optical receivers, describe the three types of pre-amplifiers. 9. Discuss the conditions that limit receiver performance. 10. Derive an expression for the SNR at the output of an optical receiver. 11. Draw the block diagram of a typical optical receiver and derive the expression for the mean output current from photodiode. 12. What is BER of optical receiver and obtain an expression for BER in an optical receiver. 13. Write a note on digital signal transmission 14. Explain various error sources in signal detection systems 15. Explain atypical optical receiver

16. How is digital receiver performance, explain? 17. Write a note on the following – a. Receiver noise, b)Receiver sensitivity, c)Preamplifier types, d) Analog receivers

Chapter 6 Analog Systems

1. What are the basic elements of an analog link and what is CNR. 2. Derive an expression for carrier to noise ratio of an analog optic communication system under limiting conditions of noise sources involved. 3. What is sub-carrier multiplexing? 4. Explain the multi-channel transmission techniques. 5. Determine the minimum incoming optical power level required to detect a 400 mbps FSK signal at BER of 10-9, using an ideal heterodyne synchronous receiver operating at a wavelength of 1.55 m. (Assume average number of photons/bit=18 for ideal receiver). 6. What is relative intensity noise?

Chapter 7 Digital Transmission Systems

1. Describe the different line codes adopted for fiber optic transmission. 2. Explain what rise time budget is. 3. Establish the relationship between fiber rise time and the 3-dB bandwidth. 4. Derive an expression for the total system time budget in terms of transmitter fiber and receiver rise time. 5. Draw the optical path through a digital link with relevant components and electrical/optical waveforms at every stage. 6. Compute the total system rise time for the following optical communication system.Rise time of led together with drive circuitry 15ns, Material dispersion related rise time degradation over 6 km fiber length =21ns, Receiver BW=25 MHz,BW distance product =400 MHz.km,Q=0.7,Length of fiber=6 km.

Chapter 8 Advanced Systems and Techniques 1. What is wavelength division multiplexing? 2. What are optical amplifiers? How are they classified? 3. Draw the basic structure of an STS-1 SONET frame. Bring out relations among STS-OC and STM frames. 4. Explain the features of WDM and give an example of WDM component. 5. Discuss the application of optical amplifiers? 6. Explain how an angular dispersive device is used as a demultiplexer. 7. What are fiber amplifiers? 8. Compare fiber amplifiers with optical amplifiers. 9. Explain the working of an erbium doped fiber amplifier. 10. Describe the operation of traveling wave amplifier and define optical gain, amplifier noise figure and optical bandwidth with their expressions. 11. Consider the following parameter values for a 1300nm. In GaAsP laser amplifier: 12. Material gain coefficient (g)=100cm-1 13. Amplifier cavity length (l)=200 m 14. Refractive index (n)=3.5

15. Faced reflectivity (r1=r2)=0.2% 16. Internal absorption =23cm-1 17. Confinement factor ( )=0.3 18. Find minimum and maximum optical amplifications for single pass phase shift have 900 and 00 respectively. 19. What is Kerr effect? 20. List out the applications and limitations of fiber optic system. 21. Explain operational principles of WDM P.E.S.I.T DEPT. OF TE VI SEM (AUTONOMOUS) 21

22. Explain passive devices used with WDM 23. What is the role star couplers, explain? 24. Explain Mach-Zehnder interferometer multiplexer 25. Explain reflection grating. 26. Explain general applications of optical amplifiers 27. Explain classification of optical amplifiers 28. What is erbium doped optical amplifiers? 29. Write a note amplifier noise 30. Explain the following – a)In-line amplifiers, b) Pre amplifiers, c) Multichannel operation 31. What are wavelength converters, explain? 32. Explain the common topologies used for fiber optic networks 33. Explain transmission formats and speeds with respect SONET frame 34. Write a note optical interfaces 35. Explain the following – a. SONET / SDH ring, b) SONET / SDH network 36. What are wavelength networks, explain? 37. Explain the principle of photonic switching, what are its advantages? 38. Write a note on non linear effects on network performance

1. a) Show with neat diagrams the ray optics representation of skew rays and meridional rays in a step index fiber. Derive an expression for maximum ray entrance angle in terms of core and cladding refractive index for a meridional ray.

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b) Give expressions for refractive index profiles from n1 to n2 as a function of radial distance for r ≤ a for graded index fibers. Plot the profiles for α values of 1, 2, ∞. Assume fibers have a 25 µm core radius, n1 = 1.48 and ∆ = 0.01. Estimate the number of modes at 820 nm for parabolic profile.

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c) Define Group velocity and Group Delay. Explain material dispersion and derive an expression for pulse spread ∆T

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d) For a 8 km multimode step index fiber with n1 = 1.485 and n2 = 1.462, calculate pulse spread due to intermodal dispersion. Also calculate Fiber Capacity

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2. a) Draw and explain cross section diagram of a typical GaAlAs double hetero-structure LED and energy band diagram

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b) Briefly explain factors responsible for response time of photodiode. 4c) An InGaAs p-i-n photodiode receiver has the following parameters at 1550 nm. ID = 1nA, η = 0.95,

RL = 500 Ω and surface leakage current is negligible. The incident optical power is 500nW and the receiver bandwidth is 150 MHz. Determine the noise currents in the receiver.

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3. a) Describe signal path through an optical data link showing relevant optical/ electrical blocks and input/output electrical/optical signal wave shapes.

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b) Define receiver sensitivity and the Quantum limit 4c) Make the rise time budget for a 1.3 µm, light wave system designed to operate at 1Gb/s over a

single mode fiber with a repeater spacing of 50 km. The LED transmitter and the Si p-i-n receiver have rise times of 0.25ns and 0.35 ns, respectively. The source spectral width is 3nm and D = 2ps/( km-nm) at the operating wavelength. Calculate system rise time. Can the optical system be operated in RZ or NRZ format?

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4. a) Explain operating principles of WDM and mention few WDM standards 6b) A 2x2 directional coupler has an input power level of Po = 200 µW. The output powers at the three

ports are P1 = 90 µW, P2 = 80 µW and P3= 5nW. Define and determine coupling ratio, excess loss, insertion losses at port 0 and 1 and cross talk.

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c) Draw the block diagram of typical Raman amplification system. Explain the terms – stokes shift, Raman gain spectrum and Raman gain length for a Raman Amplifier

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5. a) Discuss self phase modulation and cross phase modulation non linear effects in optical communication system

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b) What is four wave mixing? Show how three equally spaced ( spacing ∆f) optical frequencies f i , fj, and fk can mix to produce inter modulation frequencies due to FWM

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c) Explain largest distance Power Budget for N stations. Obtain power budget for 25 stations in a tabular form if stations are 100m apart, attenuation of fiber is 0.22dB/km at 1550 nm, connector loss is 1dB, Tap loss is 10dB, Coupler throughput loss is 0.9 dB, coupler intrinsic loss =0.5dB

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SATELLITE COMMUNICATION (Elective 3)

QUESTION BANK

Subject Code: EC386 Faculty: Ms. AGPUNIT 1

1. Briefly explain the history of satellite communication.2. Explain centripetal and centrifugal force.3. What are 3 Kepler’s laws of planetary motion?4. What are the differences between geosynchronous and geostationary satellite orbit?5. What is the period and velocity of geostationary satellite?6. What are orbital elements?7. Explain the location of satellite in the orbit.8. Explain elevation angle and azimuth angle determination.9. Explain orbital perturbation.10. Explain the different techniques to launch the satellite onto GEO.11. What are the different types of satellite subsystems?12. Explain different types of antennas.13. What is reliability and redundancy?

UNIT 21. Derive the equation for power received by antenna.2. What is noise temperature and noise figure?3. Explain the design of uplink and down link4. What is C/N ratio and derive the equation for C/N ratio?5. Explain the design of Ku and and its link performance.

UNIT 31. What is multiple access and what are the different types of multiple access?2. Explain FDMA.3. What is intermodulation and get the equation for inter modulation.4. What is TDMA?5. What is DAMA?6. Explain random access.7. Explain CDMA?8. What is channel capacity?9. Explain the different techniques in error control coding.10. Explain the different techniques in ARQ.

UNIT 41. What is VSAT?2. Explain 3 basic implementation of telecommunication system.3. What are the basic techniques involved in satellite link design of VSAT?4. Explain the antennas, transmitter and receivers used in VSAT earth station.5. Explain the orbital consideration for LEO?6. Explain NGSO.

UNIT 51. What is DBS TV?


2. Explain DBS TV receiver with block diagram.3. Explain the design consideration of DBS TV.4. Explain the techniques involved in error controlling in DBS TV.5. Explain DBS TV uplink earth station with diagram.6. What is GPS? What are the principles involved in GPS position location?7. Explain GPS receivers and codes.8. Explain GPS receiver operation with relevant diagram.9. Explain GPS C/A code accuracy.10. What is differential GPS?

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6th sem question bank even'11

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