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VELAMMAL COLLEGE OF ENGINEERING AND TECHNOLOGY,MADURAIDEPARTMENT OF EEE

Course Name : B.E Branch/Sem/Sec : EEE/VI/A&B Sub Code/Name : EC6651 COMMUNICATION ENGINEERING

QUESTION BANKUNIT I - ANALOG COMMUNICATION

AM – Frequency spectrum – vector representation – power relations – generation of AM – DSB, DSB/SC, SSB, VSB AM Transmitter & Receiver; FM and PM – frequency spectrum – power relations: NBFM & WBFM, Generation of FM and DM, Armstrong method & Reactance modulations : FM & PM frequency.

PART-A

S.No Questions Knowledge Level Books

1. Define modulation? Remember T22. What are the types of analog modulation? Remember T23. Define depth of modulation or Modulation index of AM. Remember R14. Find the significance of modulation index . Remember T25. What is the need for modulation? Remember T26. What are the types of AM modulators? Remember T17. List out the classification of modulation. Remember T28. What is single tone and multi tone modulation? Remember T29. What are the advantages of VSB-AM? Remember R110. Define demodulation. Remember T211. Define multiplexing. Remember T212. What is meant by frequency translation? Remember T213. What are advantages and disadvantages of SSB? Remember T214. What are the applications of SSB-SC-AM? Remember T2

15. What is the difference between high level modulation and lowlevel modulation? Remember T2

16. What is diagonal clipping and how can we eliminate it and peak negative clipping? Remember T1

17. Define Amplitude modulation. Remember R118. What is over modulation and Envelope distortion? Remember R119. Define frequency modulation. Remember T220. Define modulation index of frequency modulation. Remember T221. Define phase modulation. Remember T2

22. What is meant by detection? Name the methods for detecting FM? Remember T1

23. What are the advantages of Ratio detector? Remember T2

24. Draw the block diagram of a method for generating a narrow band FM. Remember T2

25. What are the types of Frequency Modulation? Remember T2

26. What is the basic difference between an AM signal and a narrowband FM signal? Remember T1

27. What are the two methods of producing an FM wave? Remember T2

28. List the properties of the Bessel function. (MAY/JUNE 2015) Give the average power of an FM signal. Remember T1



QUESTION BANK

29. Define Carson’s rule.

Remember T2

30. Define the deviation ratio D for non-sinusoidal modulation. Remember R131. What are the disadvantages of FM system? Remember R132. What are the types of FMdetectors? Remember T233. What are the types of phase discriminator? (Nov/DEC 2015) Remember R134. What are the disadvantages of balanced slope detector? Remember T235. Define frequency Deviation. Remember T136. Define Phase deviation. Remember T137. Give the merits of ratio detector. Remember T138. Draw the frequency spectrum of FM. Remember T1

39. Define super heterodyne principle. Remember T1

40. Compare AM DSBFC with DSB-SC and SSB-SC. Understand R141. Compare linear and non-linear modulators. Understand T242. How will you generating DSBSC-AM? Remember R143. Why VSB is preferred for TV transmission? Remember T244. Show the frequency spectrum of AM wave. Remember T145. Show the basic envelope detector. Remember T146. Compute the BW of AM signal given by Understand T1

47. Illustrate the relationship between FM and PM with block diagrams. 0r How PM wave can be converted to FM wave? Understand T1

48. How is the narrow band FM converted to Wide band FM? Remember T149. Difference between Narrow band FM and Wide Band FM. Understand R1

50. How will you generate message from frequency-modulated signals? Remember T2

51. Compare the noise performance of an AM and FM system? Understand R152. How is threshold reduction is achieved in FM system? Remember T2

53. Compare the noise performance of AM receiver with that of DSB-SC receiver. Understand T1

PART – B


1. Explain in detail about the FM generation using Armstrong method Understand T2

2.

i)Explain the demodulation of an AM wave using envelope detector.ii)Explain the envelop detector circuit used for AM demodulation

Understand T2

3. Explain the working of FM stereo transmitter with Understand T1



QUESTION BANKnecessary circuitry.

4.i)Explain the working of a SSB transmitter and receiver. ii)Explain the direct and indirect method generation of Fm signal.

Understand T1

5.i)Illustrate the operation of VSB transmissionii)Explain the operation or Armstrong Frequency modulation system

Understand T1

6.

i) Compare AM with FM with special reference to spectrum, power requirements, sidebands and bandwidth required ii) Explain any two methods used for generating SSB/SC.With neat block diagram, explain the Tuned Radio Frequency (TRF) receivers.

Understand T2

7.With the help of neat block diagram, explain the functioning of a heterodyne radio receiver. List out the significance of it over the TRF receivers

Understand R1

8. With the help of a neat block diagram, explain FM receiver Understand T1

9. Show the block diagram of single sideband AM transmitter and explain function of each block. Understand T1

10.i. Compare wide band and narrow band Fm systemii. How does the phase-shift method efficiently suppress the unwanted side band?Explain with diagram

Understand T1

11.i. With a neat block diagram, explain the operation of Armstrong frequency modulation system.ii. Illustrate the operation of VSB transmission

Understand T1

12.Name the methods used for the suppression of unwanted side band in AM transmission?Discuss the working of any ome of them?

Understand T1

13.Explain the principle of indirect method of frequency modulation with diagram

Understand T1

14.i)Compare the relationship between PM and FMii)Explain the generation of FM signal using reactance modulation scheme.

Understand T1

15. Explain the working of SSB transmitter and receiver. Understand T1

16.Name the method used for the suppression of unwanted bands in Am transmission?Discuss the working of any one of them.

Understand T1

17.Explain the working of direct and indirect method of transmitting FM signals

Understand T1

18.Solve the expression for Am wave and its power relation and give the time and frequency domain representation of AM wave

Understand T1

19.Derive an expression for the amplitude modulated wave and its power relations. Also give its time

Understand T1



QUESTION BANK

20.Derive an expression for the amplitude modulated wave and its power relations

Understand T1

21.Illustrate an analytical expression for the frequency modulated wave.

Understand T1

22.Expalin any one method of generating the frequency modulated signals with the relevant sketch.

Understand T1

PART-C

1.

A carrier wave of 10MHZ is amplitude modulated to 50% level with tone of 5000Hz.Sketch the waveform and amplitude modul tion in time and frequency domain.Assume carrier amplitude as 10V. (15)

Apply T2

2.

(i) For a modulation coefficient m=0.2 and an unmodulated carrier power Pc=1000W, calculate the total sideband power, upper and lower sideband power, modulated carrier power and totaltransmitted power.(8)(ii) With a neat block diagram explain the frequency division multiplexing applied in AM broadcast.(7)

Apply T2

3.

List out the relative merits of high level modulation and low level modulation in AM transmission. The anode dissipation of a class Cpower amplifier is 944 watts when modulation depth is 60%, the 25%. Find.

Carrier power and modulator tube dissipation when modulation depth is 100%

AF output and rating of the modulation value to affect 100% modulation.

Overall efficiency at 60% modulation depth.

Apply T2

Multiple choice questions

1. What we use for impedance matching in RF amplifiers?a) RC coupling b) Transformer coupling c) Direct coupling d) RF coupling

2. Neutralization cancels unwanted feedback by bypassing the feedback to the neutral or ground plane.a) True b) False3. In a receiver, distortion can occur in ________a) Mixer b) Detector c) IF amplifiers d) Either mixer or detector or IF amplifiers4. How we limit the response of a receiver to a weak signal?a) by the AGC b) by the noise that is generated in the receiver c) by the dynamic range of the receiver d) by the type of detector circuit being used5. When aliasing will takes place?a) Sampling signals less than Nyquist Rate b) Sampling signals more than Nyquist Ratec) Sampling signals equal to Nyquist Rate d) Sampling signals at a rate which is twice of Nyquist Rate6. A resonant circuit is a simple form of bandpass filter.



QUESTION BANKa) True b) False7. Which statement is true for high level amplitude modulation?a) all RF amplifiers are of class A b) all RF amplifiers can be nonlinear c) minimum RF power is required d) maximum RF power is required8. Which statement is true for low level amplitude modulation?a) all RF amplifiers are of class A b) all RF amplifiers can be linear c) minimum RF power is required d) maximum RF power is required9. Which two networks can be used for impedance matching?a) pi network and T network b) pi network and bridge network c) bridge network and T networkd) pi network and omega network10. Which statement is true about frequency multipliers?a) they are essentially balanced modulators b) they are essentially class C amplifiersc) they are essentially class AB amplifiers d) they are essentially mixers11. The carrier signal is given bya)Vc sinwct b)Vc sinwmt c)Vm sinwmt d) Vm sinwct12. The image channel rejection in a super heterodyne receiver is determined by ___________

(a)IF stages only (b) RF stages only (c)Detector & RF stages only (d) The RF and IF amplifier13.The fidelity of receiver relates o variation of output with modulating frequency when the output load is _________a)Resistive(b)Inductive (c)Capacitive (d)None of the above14.The Envelope detector is an

(a) Synchronous Detector (b) Asynchronous Detector (c) Product demodulator (d) Coherent detector 15.A balanced modulator is used in the generation of which of the following ______________.a)DSB-SC signal (b) FM signal (c) PM signal (d) PAM signal16.All types of linear modulation can be detected by ____________.a)Product demodulator (b) Envelope detector (c) Filtering (d) Linear detector17.Which one of the following is an indirect way of generating FM?a)Reactance FET Modulator (b) Varactor diode Modulator (c)Armstrong Modulator 18.In Phase modulation, Phase deviation is proportional to___________.a)Carrier amplitude (b) Carrier phase (c)Message signal (d)Message signal frequencies19.The type of noise reduced by limiters in FM receivers is a)Avalanche noiseb)Burst noise c)Narrow band pass noise d)Impulse noise20.A constant amplitude If signal is generated bya)detector b) limiter c)mixer d)oscillator

Course incharge Module Co-ordinator HoD/EEE

UNIT II - DIGITAL COMMUNICATION



QUESTION BANKPulse modulations – concepts of sampling and sampling theorem, PAM, PWM, PPM, PTM, quantization and coding: DCM, DM, slope overload error. ADM, DPCM, OOK systems – ASK, FSK, PSK, BSK, QPSK, QAM, MSK, GMSK, applications of Data communication.

PART-A


1. What are the advantages of digital transmission? Remember T12. What are the disadvantages of digital transmission? Remember T13. Define pulse code modulation. Remember R14. What is the purpose of the sample and hold circuit? Remember T15. What is the Nyquist sampling rate? Remember T16. Define and state the causes of fold over distortion. Remember T17. Define overload distortion. Remember T18. Define quantization Remember T19. Define dynamic range. Remember T110. Define coding efficiency. Remember T111. Define Companding. Remember T112. Define slope overload. How it is reduced. Remember T113. Define adaptive delta modulation. Remember T114. Define peak frequency deviation for FSK. Remember T115. Define modulation index for FSK. Remember T116. Define bit rate. Remember T117. Define Baud rate. Remember T118. Define QAM. Remember T1

19. Show the relationship between the minimum bandwidth required for an FSK system and the bit rate.

Remember T1

20. What is meant by Digital Amplitude Modulation (DAM)? Remember T121. Define FSK bite rate & baud. Remember R122. What is meant by Frequency Shift Keying (FSK)? Remember R123. What do you meant by M-ary encoding? Remember R124. What does QPSK mean? Remember T125. What is meant by offset QPSK? Remember T126. What does QAM stands for? Remember T127. Define Bandwidth efficiency. Remember T228. Define carrier recovery & what are all the methods used for this? Remember T129. What is meant by DPSK? Remember T230. What is meant by Probability of error & Bit Error Rate? Remember T2

31. What is meant by antipod l signaling? Remember T232. Show the formula for the error distance of the PSK. Remember R133. What does 8-QAM & 16-QAM means? Remember T134. What are all the types of FSK systems & explain them? Remember T1

http://easyengineering.net/








QUESTION BANK35. What is meant by peak frequency deviation? Remember T136. What is meant by pulse modulation & name the methods of it? Remember T137. Define Pulse Width Modulation (PWM). Remember R138. Define Pulse Position Modulation (PPM) & Pulse Amplitude

Modulation (PAM).Remember R1

39. What is meant by Codec? Remember T140. What are all the two basic techniques used to perform the sample

and hold Function?Remember T1

41. Define the term synchronous transmission. Remember T142. What is meant by Adaptive Delta Modulation in PCM? Remember T143. Show the formula for percentage error of PCM. Remember T144. What is meant by Inter Symbol Interference (ISI)? Remember T145. Compare Amplitude Shift Keying (ASK) & Frequency Shift

Keying (FSK)? Understand T1

46. Compare the bandwidth efficiency of BPSK and QPSK modulated signals.

Understand T1

47. Explain how eye pattern is used to measure ISI in pulse transmission.

Understand T1

48. What are the methods of pulse modulation Remember T149. Differentiate Bit rate and Band rate of digital modulation Understand T150. What are the advantages of digital transmission? Remember R151. What are the disadvantages of digital transmission? Remember R152. Define pulse code modulation. Remember R153. What is the purpose of the sample and hold circuit? Remember T154. What is the Nyquist sampling rate? Remember T155. Define and state the causes of fold over distortion. Remember T156. Define overload distortion. Remember T157. Define quantization Remember T1

PART-BS.No Questions Knowledge Level Books

1. For the binary data transmission obtain the expressions and waveforms for ASK,FSK and PSK schemes.

Understand T1

2. Show the block diagram of a TDM system and explain where is TDM applied?

Understand T1

3. Explain the pulse code modulation scheme and draw the waveforms.

Understand T2

4. Explain the generation and noise performance of delta modulation. Understand

5. Explain quantization noise in PCM system. How can it be reduced?

Understand T1

6. Using block diagram, explain the functioning of each block present in a PCM transmitter a d receiver

Understand T1

7. Explain the functioning of FSK digital transmitter cum receiver operation in detail with the relevant diagrams.

Understand T1

8. Explain the working of a FSK modulator and demodulator with Understand T2








QUESTION BANKthe signal constellation diagram

9. With a neat block diagram explain the principle of DPCM.How does it differ from DM?

Understand T2

10. Explain the operation of QPSK receiver and derive the expression for its bit error probability

Understand R1

11. Explain in detail about the operation of ASK and BSK with neat diagram

Understand R1

12. List the advantages of digital communication and Explain GMSK and QAM techniques with neat diagram

UnderstandR1

13. Explain about different types of delta modulation schemes. Understand T1

14. i) Compare performances of PSK and FSK.ii) Draw the block diagram of a PCM communication system. Explain the function of each block with neat sketch of input and output at each stage.

Understand T1

15. Show the block diagram of BPSK transmitter and receiver. Explain the same digital modulation scheme with appropriate constellation diagram.

Understand T1

16. How does ADM differ from DM? Support your answer with block diagram and waveforms.

Understand T1

17. Show the block diagram of QPSK transmitter and receiver. Explain the same digital modulation scheme with appropriate constellation diagram.

Understand T1

18. Explain QPSK with a block diagram an spectrum. Also discuss the phasor diagram for sinusoidals.

Understand R1

19. How does ADM differ from DM? Support your answers with block diagram and waveforms

Understand R1

20. With neat block diagram explain PAM modulation demodulation process and derive an expression for PAM ave and depth of modulation

UnderstandR1

PART - C21. Solve a problem for an AM DSBSC modulator with fc=100KHZ and

fm(max)=10KHZ .Determine i) Frequency limits for upper side bands ii)Bandwidth iii) upper and lower side band frequencies produced modulating signal is a single frequency 3KHz tone iv) Draw the output frequency spectrum (15)

Apply T2

22. Construct a PCM system has the following parameters: a maximum analog input frequency of 4 KHz a maximum decoded voltage at the receiver of ±2.55 V, and a minimum dynamic range of 46dB.Calculate the following:(i)Minimum sample rate.(ii)Minimum number of bits used in the PCM code.(iii) Resolution.(iv)Quantization error. (15)

Apply T2

23. i) Explain in detail DPCM communication system with block diagram.ii) Solve a problem for minimum line speed with an 8 bit PCM for speech signal ranging upto 1 volt. Calculate the resolution and quantization error. Also analyze about the coding efficiency for a

Apply T2



QUESTION BANKresolution of 0.01 volt with the 8 bit PCM. (15)

24. Solve a problem for a QPSK system and the given parameters C = 10-12 W, fb = 60 kbps, N = 1.2 x 10-14 W, B = 120 kHz, determine the carrier power, noise power, noise power density, energy per bit, carrier-to-noise power ratio and Eb/N0 ratio.

Apply T2

25. Develop an FM modulator with fc=50KHZ and fm(max)=1KHZ .Determine i) Frequency limits for upper side bands ii)Bandwidth iii) upper and lower side band frequencies produced modulating signal is a single frequency 4 KHz tone iv) Draw the output frequency spectrum

Apply T2

Multiple Choice Questions

1) Graphical representation of linear block code is known as a. Pi graphb. Matrixc. Tanner graphd.None of the above2) A linear code a. Sum of code words is also a code word b. All-zero code word is a code wordc. Minimum hamming distance between two code words is equal to weight of any non zero code wordd. All of the above3) For decoding in convolution coding, in a code tree, a. Diverge upward when a bit is 0 and diverge downward when the bit is 1b. Diverge downward when a bit is 0 and diverge upward when the bit is 1c. Diverge left when a bit is 0 and diverge right when the bit is 1d. Diverge right when a bit is 0 and diverge left when the bit is 14) The code in convolution coding is generated using a. EX-OR logicb. AND logicc. OR logicd. None of the above5) Interleaving process permits a burst of B bits, with l as consecutive code bits and t errors when a. B ≤ 2tl b. B ≥ tl c. B ≤ tl/2 d. B ≤ tl6) For a (7, 4) block code, 7 is the total number of bits and 4 is the number of a. Information bits b. Redundant bits c. Total bits- information bits d. None of the above7) Parity bit coding may not be used for a. Error in more than single bit b. Which bit is in error c. Both a & b d. None of the above8) Parity check bit coding is used for a. Error correction b. Error detection c. Error correction and detection d. None of the above9) For hamming distance dmin and t errors in the received word, the condition to be able to correct the errors is a. 2t + 1 ≤ dminb. 2t + 2 ≤ dminc. 2t + 1 ≤ 2dmind. Both a and b10) For hamming distance dmin and number of errors D, the condition for receiving invalid codeword is a. D ≤ dmin + 1b. D ≤ dmin

- 1c. D ≤ 1 - dmind. D ≤ dmin

11. Which circuit is called as regenerative repeaters?a) Analog circuits b) Digital circuits c) Amplifiers d) A/D converters12. What are the advantages of digital circuits?a) Less noise b) Less interference c) More flexible d) All of the mentioned13. How many different combinations can be made from a n bit value?a) 2^(n+1) b) 2^(n) c) 2^(n)+1 d) None of the mentioned



QUESTION BANK

14. How many bytes does a gigabyte have?a) 1 million bytes b) 10 million bytes c) 1 billion bytes d) 10 billion bytes15. What is the ASCII value of space?a) 32 b) 48 c) 96 d) 6516. Which block or device does the data compression?a) Channel encoder b) Source encoder c) Modulator d) None of the given17. What is code rate?a) k/n b) n/k c) All of the mentioned d) None of the mentioned18. Pulse shaping is done by which block or system? a) Encoder b) Baseband modulator c) Pulse code modulator d) Demodulator19. Equalizer is used for ?a) Filtering b) Diminish distortion c) All of the mentioned d) None of the mentioned20. Source coding block is used for?a) Compressing b) Digitizing c)A/D conversion d) All of the mentioned


UNIT III - SOURCE CODES, LINE CODES & ERROR CONTROL



QUESTION BANKPrimary communication – entropy, properties, BSC, BEC, source coding: Shanon Fano, Huffman coding: noiseless coding theorem, BW – SNR trade off codes: NRZ, RZ, AMI, HDBP, ABQ, MBnB codes : Efficiency of transmissions, error control codes and applications: convolutions & block codes.

PART-AS.No Questions Knowledge

LevelBooks

1. Define lossless channel. Remember R12. Define Deterministic channel Remember T23. Define noiseless channel. Remember T24. What are the types of Correlation? Remember T25. What is the difference between Correlation and

Convolution?Remember R1

6. Define Signal. Remember T27. Define Shannon’s capacity theorem for a power and band

limited channel.Remember T2

8. Define entropy. Remember R19. Define mutual information. Remember R110. List the properties of mutual information. Remember T211. Relate the relation between the different entropies. Remember T212. Define information rate. Remember T213. What is data compaction? Remember T214. Define the property of entropy. Remember T215. What is differential entropy? Remember T216. What is the channel capacity of a discrete signal? Remember T217. What is source coding and entropy coding? Remember T218. Define Shannon Hartley theorem. Remember T119. What is the entropy of a binary memory-less source? Remember T120. What happens when the number of coding alphabet

increases?Understand T1

21. What is information theory? Remember T122. What is the channel capacity of a BSC and BEC? Remember T123. List the properties of H mming distance. Remember R124. What are the popular coding sequences of CDMA syst m. Remember R125. Prove Shannon noiseless coding theorem Understand R126. Explain Shannon-Fano coding. Understand R127. A source generates 3 messages with probability 0.5, 0.25

and 0.25. Calculate the entropy.Understand R1

28. What are the types of characters used in data communication codes?

Remember R1

29. Prove that I (xi xj) = I(xi) + I(xj) if xi and xj are independent.

Remember T2

30. Differentiate between lossless and lossy coding. Understand T331. How is the efficiency of the coding technique measured? Understand T3









QUESTION BANK32. Calculate the Entropy of the source with symbol

probabilities 0.6, 0.3, 0.1.Understand T1

33. What is information rate? Remember T234. An event has six possible outcomes with probabilities {1/2,

1/4, 1/8,1/16, 1/32, 1/32}. Calculate the entropy of the system.

Understand T2

35. A source transmits messages Q1 to Q5 having probabilities ½, ¼,1/8, 1/16, 1/16 respectively. Estimate the average information of thesource.

Understand R1

36. An analog signal is band limited to B Hz, sampled at the Nyquistrate, and the samples are quantized into 4 levels. The quantizationlevels Q1, Q2, Q3 and Q4 are assumed to be independent and occur with probabilities p1=p4=81 and p2=p3=83. Calculate the information rate of the source.

Understand R1

37. What is BSC? Remember T238. Classify the types of characters used in data communication

codes.Understand

39. Evaluate the Hamming distance between the following code wordsC1={1,0,0,0,1,1,1} and C2={0,0,0,1,0,1,1}.

Understand T2

40. List the properties of Hamming distance. Understand T241. Show how many errors can be detected and corrected by a

(7, 4)Hamming code?Understand T2

42. What is the significance of source coding? Remember T243. Analyze about the working rule of AMI code. Understand T244. Illustrate the significance of AMI code. Understand T245. Name the error control schemes used in Modems. T146. Differentiate error detection from error correction. Understand T147. List the different error control methods. Understand T148. List out the two general categories of error control. Understand T149. Define the Redundancy in Error control. Remember T150. Listw2FD out the inferences of vertical redundancy

checking.Understand T2

51. Compare block and convolution codes. Understand T2PART-B

S.No Questions Knowledge Level

Books

1. Explain the BSC and BEC with their channel diagram and transition matrix.

Understand T1

2. (i) Brief the properties of entropy. (ii) Give the procedure for Shannon Fano coding and use the procedure to obtain the code for the source symbols S0, S1, S2,S3, S4, S5 with their respective probabilities ½, 1/3, 1/12, 1/15,1/120, 1/120.

Understand T2

3. (i)Given states S={S0,S1,S2,S3,S4} and their probabilities P={0.4,0.2,0.2,0.1,0.1}. Find coding efficiency and entropy for Huffman coding. ii)Describe the concept of noiseless coding theorem and state its significance.

Remember T2





QUESTION BANK4. (i)Five symbols of the alphabet of discrete memory less source and

their probabilities are given below.S = { S0, S1, S2, S3, S4}P(S) = {0.4, 0.2, 0.2, 0.1, 0.1}Obtain code symbols using Huffman coding.ii)Discuss the Bandwidth-SNR trade off of a communication system.

Remember T2

5. (i)State and prove Shannon noiseless coding theorem.ii)Consider that a source is transmitting equiprobable 1/0 at the rate of 103 b/s and the probability error of Pe = 1/16. Determinethe rate of transmission.

Remember T1

6. For the given 8 bit stream 11010100, plot the NRZ, RZ, AMI,HDBP and Differential Manchester codes.

Remember T1

7. (i)Apply the following coding technique and obtain the output wave form for the bit stream 10011100 on NRZ, RZ, AMI,HDBP, ABQ and MBnB.ii)Draw the plots for the polar, unipolar, bipolar and Manchester NRZ line code format for an information {1 0 1 1 0 0}.

Apply T3

8. Explain in detail about error control codes and their applications. Understand T29. (i)Explain in detail about various error control codes with one

example for convolution code. ii)Describe in detail about convolutional coder of constraint length 6 and rate efficiency ½.

Understand R1

10. Explain about the viter bi algorithm by showing the possible path through the trellis of a coder. Assume the state diagram of any coder.

Understand T2

11. Explain the concept of coding and decoding methods of block codes with its mathematical framework and diagram.

Understand T2

12. (i)Develop how cyclic redundancy checking is used for detection ii) Explain Bandwidth-SNR trade off in source coding.

Apply T2

13. Illustrate with suitable example, any one of the decoding methods of convolutional coding precisely.

Understand T3

14. Construct the Block check sequence (BCS) for the following data and cyclic redundancy check(CRC) generating polynomials: data G(x) =x7+ x5+ x4+ x2+ x1+ x0, CRC P(x) = x5+ x4+ x1+ x0. Also Explain the Concept of block codes and coding efficiency.

Apply T3

PART – C15. i) Solve a problem for binary PCM if“0” occur with probability p

and “1” occur with Probability , then calculate amount of information conveyed by each binit.ii) If there are M equally likely and independent messages, then prove that amount of information carried by each message will be, I = N bits.Where M = 2N and N is an integer.

Apply T1

16. Build an analog signal is bandlimited to B Hz and sampled at Nyquist rate.The samples are quantized into 4 levels. Each level represents one message. Thus there are 4 messages. The probabilities of occurrence of these 4 levels information rate of the source.

Apply T2

17. Solve a problem of black and white TV picture consists of about 2X106 picture elements with 1 different brightness levels, with equal probabilities. If pictures are repeated at the rate of 32 per second, calculate average rate of information conveyed by this TV picture Source. If SNR is 30 db, what is the maximum bandwidth

Apply T2



QUESTION BANKrequired to support the transmission of the resultant video signal?

18. Construct a discrete memory less source has five symbols x1, x2, x3, x4 and x5 with probabilities 0.4,0.19, 0.16, 0.15 and 0.15 respectively attached to every symbol.

Apply T2

19. Build the generator polynomial of a (7, 4) cyclic code is G (p) = p3+p+1 Find all the Code vectors for the code in non systematic form.

Apply T2

Multiple choice questions1. While recovering signal, which gets attenuated more?a) Low frequency component b) High frequency component c) Low & High frequency componentd) None of the mentioned2. Mutual information should bea) Positive b) Negative c) Positive & Negative d) None of the mentioned3. ASCII code is aa) Fixed length code b) Variable length code c) Fixed & Variable length code d) None of the mentioned4. Which reduces the size of the data?a) Source coding b) Channel coding c) Source & Channel coding d) None of the mentioned5. In digital image coding which image must be smaller in size?a) Input image b) Output image c) Input & Output image d) None of the mentioned6. Which coding method uses entropy coding?a) Lossless coding b) Lossy coding c) Lossless & Lossy coding d) None of the mentioned7. Which achieves greater compression?a) Lossless coding b) Lossy coding c) Lossless & Lossy coding d) None of the mentioned8. A code is a mapping froma) Binary sequence to dicrete set of symbols b) Discrete set of symbols to binary sequencec) All of the mentioned d) None of the mentioned9. Which are uniquely decodable codes?a) Fixed length codes b) Variable length codes c) Fixed & Variable length codes d) None of the mentioned10. A rate distortion function is aa) Concave function b) Convex function c) Increasing function d) None of the mentioned11. The measure of the amount of redundancy is given bya) Code size b) Code weightc) Code rated) Minimum distance12. The number of k bit shift over which a single information bit influences the encoder output is given bya) Code rateb) Constraint lengthc) Code lengthd) Code weight13. The method used for representing convolution encoder area) Connection pictorialb) State diagramc) Tree diagramd) All of the mentioned14. Periodic truncation is done bya) Appending zero to end of the input data sequenceb) Appending zero to the beginning of the input data sequencec) Appending one’s to end of the data sequenced) Appending one’s to beginning of the data sequence

15. Finite state machines havea) Past memories also b) Only present and future memories c) Only future memoriesd) Only present memories16. How many number of transitions can be made at each bit time?



QUESTION BANKa) One b) Two c) Three d) Half17. In trellis diagram, the number of nodes ______ at successive branching.a) Increases by 1 b) Doubles c) Triples d) None of the mentioned18. Example for convolution encoder state diagram isa) Tree diagram b) Trellis diagram c) Tree & Trellis diagram d) None of the mentioned19. In maximum likelihood decoding technique, the likelihood function compares thea) Joint probabilities b) Individual probabilities c) Conditional probabilities d) None of the mentioned20. In maximum likelihood detector the error probability isa) Maximum b) Minimum c) Zero d) None of the mentioned


UNIT IV-MULTIPLE ACCESS TECHNIQUES

SS&MA techniques : FDMA, TDMA, CDMA, SDMA application in wire and wireless communication:Advantages (merits)



QUESTION BANKPART_A

S.No Questions Knowledge Level

Books

1. List any four primary applications of FDMA. Understand R12. List out the features of CDMA. Understand R13. Define FDMA. Remember R14. List out the merits of TDMA system. Understand R15. Relate the significance of CDMA techniques. Understand R16. Show the applications of CDMA system. Understand R17. Define near –far problem. Remember R18. Illustrate the popular coding sequences of CDMA system. Understand R19. Define multiple access. Remember R110. Demonstrate the working principle of SDMA. Remember R111. Define the role of modem in communication networks. Remember R112. Illustrate the frame structure of a T1 carrier system. Understand R113. Compare SDMA with CDMA. Understand R114. Explain about the working principle of TDMA. Understand R115. Explain in briefly about FDMA. Understand R116. Summarize the significance of T1 carrier system in

communication networks with an illustration.Understand R1

17. Show the advantages of SDMA technique. Understand R118. List the applications of SDMA in wire and wireless

communication.Understand R1

19. What is the significance of spread spectrum? Remember R120. What is the use of special code in spread spectrum? Remember R121. What is key in spread spectrum? Remember T122. What are averaging system and avoidance systems? Remember T123. Where spread spectrum is used? Remember T124. What are the two types of spread spectrum? Remember T125. What is the meaning of the word jamming and anti-jam? Remember T126. What is jamming margin? Remember T127. What is meant by PN sequence and what are the properties

of PN sequence?Remember T1

28. Define chip duration and chip rate? Remember T129. What is the relationship between chip duration and bit

duration? Tb Remember T1

30. What is the shape of auto-correlation function of PN sequence?

Remember T1

31. Define slow frequency hopping. Remember R132. Define FDMA, TDMA and CDMA? Remember R133. What is an FDMA? Explain it. Remember R134. What is SDMA? What special features it has when

compared to other multiple access techniques? Remember R1






QUESTION BANK35. What are the pros and cons of CDMA technique? Remember R136. What is near – far problem? Remember T137. What are the popular coding sequences of CDMA system. Remember T138. Explain direct sequence spread spectrum. Understand T139. Explain frequency hop spread spectrum Understand R140. Why pseudo-random code is used as special code for

spreading the spectrum? Remember R1

41. Is spread spectrum a modulation technique? Remember R142. How many stages of flip-flops are required to generate PN

sequence of length 31Remember T1

PART-BS.No Questions Knowledge

Level Books

1. Solve a problem of 500 users employ FDMA to transmit 1000-bit packets of data. The channel band width is 100MHz and QPSK is used at each of the 5000 carrier frequencies employed i) What is the maximum bandwidth allocated to each user?ii)What is the bit rate employed by each user?iii)How long does it take to transmit a packet?

Apply R1

2. Develop an operation of a typical TDMA system with the time pattern and compare with FDMA.

Apply T1

3. Explain the principle of FDMA with neat diagram. Understand T14. Draw and explain the block diagram of transmitter and receiver of

CDMA.Understand R1

5. (i)Demonstrate the operation of a typical TDMA system with neat block diagram.ii)Distinguish TDMA with FDMA. Understand

R1

6. (i)What is CDMA? Explain in detail.ii)List the basic features of CDMA systems. Explain soft handover.

Understand R1

7. Explain with a neat block diagram the SDMA technique. Understand R18. Illustrate how interference is avoided by using code

multiplexing.Understand R1

9. Build the wired and wireless communication systems. Apply R110. Develop the BSC and BEC with their channel diagram and

transition matrix.Apply R1

11. (i)With neat block diagram explain the Frequency Multiple Access technique.ii) Discuss the application of FDMA in communication.

Understand T1

12. Develop the allocation of time slot in TDMA and time frequency characteristics of synchronous TDMA.

Apply R1

13. Illustrate the concept of using CDMA scheme in FDD and TDD. Understand R114. Construct the structure of Code Division Multiple Access. Apply R1

PART-C15. Develop the BCS for the following data and CRC

generating PolynomialsApply R1

16. Construct a Data G(x) = 7 + 5+ 4 + 2++ 1+1 and CRC P(x) = 5+ 4 + 1++ 0.

Apply T1




QUESTION BANK17. Solve a problem of 200 users employ FDMA to transmit

400 packets of data. The Channel B>W is 100 MHz and QPSK is used of the 1000 carrier frequencies employed. i) What is the max B, W allocated to each user? ii) What is the bit rate employed by each user? iii) How long does it take to transmit a packet?

Apply R1

Multiple choice questions

1. Multiple access schemes are used to allow ____ mobile users to share simultaneously a finite amount of radio spectrum.a) Many b) One c) Two d) Ten-Fifteen2. The technique that makes possible the task of listening and talking in communication system is called ________a) Simplexingb) Duplexingc) Modulatingd) Multiple access technique3. Frequency division duplexing provides ____ distinct bands of frequencies for _____ user.a) Two, twob) One, twoc) Two, oned) Two, many4. The forward band in FDD provides traffic from the mobile to base station.a) Trueb) False5. The frequency separation between each forward and reverse channel changes throughout the system.a) Trueb) False6. Time division duplexing uses ____ to provide both a forward and reverse link.a) Frequencyb) Timec) Time and frequencyd) Cell spacing7. TDD is effective for _____a) Fixed wireless access and users are stationaryb) Dynamic wireless access and users are stationaryc) Fixed wireless access and users are movingd) Dynamic wireless access and users are moving8. In wideband systems, the transmission bandwidth of a single channel _____ coherence bandwidth of the channel.a) Equal tob) Not related toc) Larger thand) Smaller than9. In narrowband system, the channels are usually operated using TDD.a) Trueb) False10. Narrowband FDMA allows users to share the same radio channel allocating a unique time slot to each user.a) Trueb) False 11. TDMA systems transmit in a continuous way.a) Trueb) False12. Preamble contains _____a) Addressb) Datac) Guard bitsd) Trail bits13. _____ are utilized to allow synchronization of the receivers between different slots and frames.a) Preamble b) Datac) Guard bitsd) Trail bits14. Which of the following is not true for TDMA?a) Single carrier frequency for single userb) Discontinuous data transmissionc) No requirement of duplexersd) High transmission rates15. Because of _______ transmissions in TDMA, the handoff process in _____a) Continuous, complexb) Continuous, simplec) Discontinuous, complexd) Discontinuous, simple16. _____ synchronization overhead is required in TDMA due to _______ transmission.



QUESTION BANKa) High, burstb) High, continuousc) Low, burstd) No, burst17. TDMA allocates a single time per frame to different users.a) Trueb) False18. ______ of TDMA system is a measure of the percentage of transmitted data that contains information as opposed to providing overhead for the access scheme.a) Efficiencyb) Figure of meritc) Signal to noise ratiod) Mean19. A TDMA system uses 25 MHz for the forward link, which is broken into radio channels of 200 kHz. If 8 speech channels are supported on a single radio channel, how many simultaneous users can be accommodated?a) 25b) 200c) 1600d) 100020. What is the time duration of a bit if data is transmitted at 270.833 kbps in the channel?a) 270.833 sb) 3 μsc) 3.692 μsd) 3.692 s

Course Incharge Module Co-ordinator HoD/EEE

UNIT V - SATELLITE, OPTICAL FIBER – POWERLINE, SCADAOrbits : types of satellites : frequency used link establishment, MA techniques used in satellitecommunication, earth station; aperture actuators used in satellite – Intelsat and Insat: fibers –types:sources, detectors used, digital filters, optical link: power line carrier communications:SCADA.

PART_A



QUESTION BANKS.No Questions Knowledge

LevelBooks



QUESTION BANK1. List the channels and their data rate used in optical fiber

systems.Remember T1

2. Name the types of optical fiber mode structure. Remember T13. Solve a problem For an earth station transmitter with an

antenna output power of 40dBW(10,000),a back off loss of 3 dB, a total branching and feeder loss of 3 dB and a transmit antenna gain of 40 dB, evaluate the EIRP.

Understand T1

4. Define numerical aperture. Remember T15. Explain about SCADA. Understand T16. List out the essential components of a satellite system. Understand T17. Summarize about near-far problem. Understand T18. Explain the advantages of optical communication. Understand T19. Explain about the types of optical fiber available. Understand T110. Illustrate the primary advantages of optical fiber systems. Understand T111. Examine whether single mode propagation is impossible

withUnderstand T1

12. Define Apogee,perige and geocenter. Remember T113. Explain Snell’s law. Understand T214. Classify the satellite orbital patterns. Understand T215. Evaluate the carrier to noise density ratio for a receiver with

-7dBW input carrier power, an equivalent noise temperature of 180 degree K and a bandwidth of 20MHz.

Understand T2

16. List the merits and demerits of geosynchronous satellite. Understand T117. Explain the communication satellites along with their band

of frequency allocationUnderstand T1

18. Define the aperture actuators used in satellite Remember R119. Show the uplink and downlink frequency range for satellite

communication. Understand T1

20. List the advantages of fiber optic system. Remember T121. Define Kepler’s second law. Remember T122. Define Kepler’s third law. Remember R123. Define orbital satellite. Remember T224. Define prograde orbit. Remember T225. Define retrograde orbit. Remember R126. Define Geo synchronous satellite. Remember T2

27. Define apogee and perigee. Remember T128. Define angle of inclination. Remember T229. Define Descending node. Remember T130. Define ascending node. Remember T231. Define line of nodes. Remember R132. Define angle of elevation. Remember T133. Define Azimuth angle. Remember T1



QUESTION BANK34. What are the advantages of optical fiber or optical fiber

communication? Remember T1

35. Define a fiber optic system. Remember T136. Define refractive index. Remember T137. Define critical angle. Remember T138. Define single mode and multi mode propagation. Remember T139. Define acceptance angle. Remember T140. Define numerical aperture. Remember T141. Define modal dispersion. Remember T142. What are the advantages of heterojunction LEDs? Remember T143. What are the disadvantages of injection laser diode? Remember T144. List the characteristics of LEO orbit or LEO satellite. Understand T145. List the characteristics of MEO orbit or MEO satellites. Understand T246. List the characteristics of GEO satellite. Understand T247. Show the frequency band designations used for satellites. Understand T248. What are the types of LASER source? Remember T149. What are the special characteristics of LASER? Remember T150. List and explain the characteristics of Light detectors. Understand R151. Classify the communication satellites along with their band

of frequency allocation?Understand T1

52. What is SCADA? Remember T153. What are the major advantages of optical fiber system Remember T154. Define Angle of elevation Remember T155. Show the orbital velocity and round trip propagation delay

of GEO satellite.Understand T1

PART-B


1. (i) Compare optical fiber with RF cable.(ii) What is the relationship among single mode step

multimode step index and multimode graded index optical fibers.

Understand T1

2. Explain briefly and compare the three types of optical fiber configurations.

Understand T2

3. i)Explain the block diagram of satellite link .ii)Describe the concept of INSAT.

Understand T2

4. i)Explain the principle of operation of power line communication.ii)Explain the block diagram of optical fiber communication link and explain.

Understand T2



QUESTION BANK5. i)Develop the concept of satellite link budget.

ii) Demonstrate the uplink and downlink model of communication system.

Apply T2

6. Explain the frequency reuse concept of cellular network. Support your answer with the required diagram.

Understand T1

7. (i)Summarize the concept of satellite communication system and its applications. ii)Explain in detail about the operation of any one fibre optic source and detector.

Understand T2

8. Identify the various blocks and its functionalities of a fiber optic communication system.

Apply T1

9. (i)Generalize the concept of Optical sources and detectors?ii)Compose short notes on SCADA and Intelsat.

Apply T1

10. Explain in detail about the frequency reuse concept of network. Support your answer with the required diagram.

Understand T2

11. Explain broadly on the multiple access techniques used in satellitecommunication.

Understand T2

12. Illustrate the following.i)Optical detectors and their types.ii)Digital filters used in satellite systems.iii)Optical link iv)Satellite types.

Understand R1

13. (i)What are the modes of operation suggested in optical fibres?How are optical fibres classified according to this? Discuss elaborately.ii)State the advantages of Fiber Optic Communication.

Understand T1

14. Illustrate how Kepler’s and Newton’s laws are used to describe the orbit of a satellite?

Understand T1

PART-C

15. Explain the orbital velocity and round trip propagation delay of GEO satellite

Understand T1

16. Draw and Explain the optical fiber communication link Understand R1

17. Explain in detail about Satellite communication system. Understand R1

Multiple choice questions1. The satellite that is used as a relay to extend communication distance is called as __________a) Relay satellitesb) Communication satellitesc) Repeater satellitesd) Geosynchronous satellites2. The transmitter-receiver combination in the satellite is known as a _______a) Relayb) Repeaterc) Transponderd) Duplexer3. The downlink frequency is lower than the uplink frequency.a) Trueb) False4. What is the reason for carrying multiple transponders in a satellite?a) More number of operating channelb) Better receptionc) More gaind) Redundancy5. Why are VHF, UHF, and microwave signals used in satellite communication?a) More bandwidthb) More spectrum spacec) Are not diffracted by the ionosphered) Economically viable6. What is the reason for shifting from c band to ku band in satellite communication?



QUESTION BANKa) Lesser attenuationb) Less power requirementsc) More bandwidthd) Overcrowding7. Which of the following bands cannot be used for satellite communication?a) MFb) Kuc) Xd) C8. What is the maximum theoretical data rate if a transponder is used for binary transmission and has a bandwidth of 36MHz?a) 32Mpbsb) 72Mpbsc) 36Mpbsd) 12Mpbs9. Why are techniques like frequency reuse and spatial isolation carried out?a) Reduce traffic loadb) More gainc) High speedd) Error detection10. Which technique uses two different antennas to reduce traffic on the same frequency?a) Spatial isolationb) Frequency reusec) Multiplexingd) Modulation11) Which among the following misalignments give/gives rise to the occurrence of splice loss? a. Longitudinal separation between the end-faces of fiberb. Angular tilt between fiber endsc. Transverse offset between fiber ends d. All of the above12) Which among the following stages is/are adopted in Splice Loss Experiment? a. Translational b. Rotational c. Both a and b d. None of the above13) In chromatic dispersion, which parameter for the modulation of the received signal is measured with the help of a vector voltmeter? a. Amplitudeb. Frequencyc. Phased. Period14) For measuring the shape of input pulse in time-domain intermodal dispersion method, the test fiber is replaced by another fiber whose length is less than ___ of the test fiber. a. 1% b. 5% c. 10% d. 20%15) Why is an electrical isolation required between several portions of an electronic circuit? a. Provision of high voltage protection b. Reduction in noise level c. Both a & bd. None of the above16) Basically, solitons are pulses which propagates through the fiber without showing any variation in ______ a. Amplitude b. Velocity c. Shape d. All of the above17) Which band/s specify/ies the operation range of Erbium doped fiber amplifier (EDFA)? a. By O band b. By C band c. By S band d. All of the above18) In an optical network, increase in the number of lasers ________the bit rate. a. Increases b. Stabilizes c. Decreases d. None of the above 19) Which among the following parameters is/are decided by the front-end of a receiver? a. Sensitivity b. Bandwidth c. Both a and b d. None of the above20) Which nature of charge carriers give rise to the current fluctuations thereby resulting into the generation of shot noise? a. Continuous b. Discrete c. Sampled d. All of the above




QUESTION BANK

eeevcet.files.wordpress.com · web viewa) 2^(n+1) b) 2^(n) c) 2^(n)+1 d) none of the mentioned14....

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