Digital Communication full notes.pdf

EC8501 - DIGITAL COMMUNICATION FULL NOTES

1. EC8501

DIGITAL
COMMUNICATION






Page 1 of 258
Prepared by
KABILESH.S.K
AP/ECE
Jai Shriram Engineering College

2. EC8501 DIGITAL COMMUNICATION

OBJECTIVES:


ion schemes



UNIT I INFORMATION THEORY
Discrete Memoryless source, Information, Entropy, Mutual Information – Discrete Memoryless channels –
Binary Symmetric Channel, Channel Capacity – Hartley – Shannon law – Source coding theorem – Shannon
– Fano & Huffman codes.
UNIT II WAVEFORM CODING & REPRESENTATION
Prediction filtering and DPCM – Delta Modulation – ADPCM & ADM principles-Linear Predictive Coding-
Properties of Line codes- Power Spectral Density of Unipolar / Polar RZ & NRZ – Bipolar NRZ –
Manchester
UNIT III BASEBAND TRANSMISSION & RECEPTION
ISI – Nyquist criterion for distortion less transmission – Pulse shaping – Correlative coding – Eye pattern –
Receiving Filters- Matched Filter, Correlation receiver, Adaptive Equalization
UNIT IV DIGITAL MODULATION SCHEME
Geometric Representation of signals – Generation, detection, PSD & BER of Coherent BPSK, BFSK &
QPSK – QAM – Carrier Synchronization – Structure of Non-coherent Receivers – Principle of DPSK.
UNIT V ERROR CONTROL CODING
Channel coding theorem – Linear Block codes – Hamming codes – Cyclic codes – Convolutional codes –
Viterbi Decoder.
Page 2 of 258

3. Page 3 of 258

4. Page 4 of 258

5. Page 5 of 258

6. Page 6 of 258

7. Page 7 of 258

8. Page 8 of 258

9. Page 9 of 258

10. Page 10 of 258

11. Page 11 of 258

12. Page 12 of 258

13. Page 13 of 258

14. Page 14 of 258

15. Page 15 of 258

16. Page 16 of 258

17. Page 17 of 258

18. Page 18 of 258

19. Page 19 of 258

20. Page 20 of 258

21. Page 21 of 258

22. Page 22 of 258

23. Page 23 of 258

24. Page 24 of 258

25. Page 25 of 258

26. Page 26 of 258

27. Page 27 of 258

28. Page 28 of 258

29. Page 29 of 258

30. Page 30 of 258

31. Page 31 of 258

32. Page 32 of 258

33. Page 33 of 258

34. Page 34 of 258

35. Page 35 of 258

36. Page 36 of 258

37. Page 37 of 258

38. Page 38 of 258

39. Page 39 of 258

40. Page 40 of 258

41. Page 41 of 258

42. Page 42 of 258

43. Page 43 of 258

44. Page 44 of 258

45. Page 45 of 258

46. Page 46 of 258

47. Page 47 of 258

48. Page 48 of 258

49. Page 49 of 258

50. Page 50 of 258

51. Page 51 of 258

52. Page 52 of 258

53. Page 53 of 258

54. Page 54 of 258

55. Page 55 of 258

56. Page 56 of 258

57. Page 57 of 258

58. Page 58 of 258

59. Page 59 of 258

60. Page 60 of 258

61. Page 61 of 258

62. Page 62 of 258

63. Page 63 of 258

64. Page 64 of 258

65. Page 65 of 258

66. Page 66 of 258

67. Page 67 of 258

68. Page 68 of 258

69. Page 69 of 258

70. Page 70 of 258

71. Page 71 of 258

72. Page 72 of 258

73. Page 73 of 258

74. Page 74 of 258

75. Page 75 of 258

76. Page 76 of 258

77. Page 77 of 258

78. Page 78 of 258

79. Page 79 of 258

80. Page 80 of 258

81. Page 81 of 258

82. Page 82 of 258

83. Page 83 of 258

84. Page 84 of 258

85. Page 85 of 258

86. Page 86 of 258

87. Page 87 of 258

88. Page 88 of 258

89. Page 89 of 258

90. Page 90 of 258

91. Page 91 of 258

92. Page 92 of 258

93. Page 93 of 258

94. Page 94 of 258

95. Page 95 of 258

96. Page 96 of 258

97. Page 97 of 258

98. Page 98 of 258

99. Page 99 of 258

100. Page 100 of 258

101. Page 101 of 258

102. Page 102 of 258

103. Page 103 of 258

104. Page 104 of 258

105. Page 105 of 258

106. Page 106 of 258

107. Page 107 of 258

108. Page 108 of 258

109. Page 109 of 258

110. Page 110 of 258

111. Page 111 of 258

112. Page 112 of 258

113. Page 113 of 258

114. Page 114 of 258

115. Page 115 of 258

116. Page 116 of 258

117. Page 117 of 258

118. Page 118 of 258

119. Page 119 of 258

120. Page 120 of 258

121. Page 121 of 258

122. Page 122 of 258

123. Page 123 of 258

124. Page 124 of 258

125. Page 125 of 258

126. Page 126 of 258

127. Page 127 of 258

128. Page 128 of 258

129. Page 129 of 258

130. Page 130 of 258

131. Page 131 of 258

132. Page 132 of 258

133. Page 133 of 258

134. Page 134 of 258

135. Page 135 of 258

136. Page 136 of 258

137. Page 137 of 258

138. Page 138 of 258

139. Page 139 of 258

140. Page 140 of 258

141. Page 141 of 258

142. Page 142 of 258

143. Page 143 of 258

144. Page 144 of 258

145. Page 145 of 258

146. Page 146 of 258

147. Page 147 of 258

148. Page 148 of 258

149. Page 149 of 258

150. Page 150 of 258

151. Page 151 of 258

152. Page 152 of 258

153. Page 153 of 258

154. Page 154 of 258

155. Page 155 of 258

156. Page 156 of 258

157. Page 157 of 258

158. Page 158 of 258

159. Page 159 of 258

160. Page 160 of 258

161. Page 161 of 258

162. Page 162 of 258

163. Page 163 of 258

164. Page 164 of 258

165. Page 165 of 258

166. Page 166 of 258

167. Page 167 of 258

168. Page 168 of 258

169. Page 169 of 258

170. Page 170 of 258

171. Page 171 of 258

172. Page 172 of 258

173. Page 173 of 258

174. Page 174 of 258

175. Page 175 of 258

176. Page 176 of 258

177. Page 177 of 258

178. Page 178 of 258

179. Page 179 of 258

180. Page 180 of 258

181. Page 181 of 258

182. Page 182 of 258

183. Page 183 of 258

184. Page 184 of 258

185. Page 185 of 258

186. Page 186 of 258

187. Page 187 of 258

188. Page 188 of 258

189. EC8501
DIGITAL COMMUNICATION
QUESTION BANK
Page 189 of 258

190. Page 190 of 258

191. Page 191 of 258

192. Studentsfocus.com Page 192 of 258

193. Studentsfocus.com Page 193 of 258

194. Studentsfocus.com
Page 194 of 258

195. Studentsfocus.com Page 195 of 258

196. Studentsfocus.com Page 196 of 258

197. Studentsfocus.com Page 197 of 258

198. Studentsfocus.com Page 198 of 258

199. Studentsfocus.com Page 199 of 258

200. Studentsfocus.com
Page 200 of 258

201. STUDENTSFOCUS.COM Page 201 of 258

202. STUDENTSFOCUS.COM Page 202 of 258

203. STUDENTSFOCUS.COM Page 203 of 258

204. STUDENTSFOCUS.COM Page 204 of 258

205. STUDENTSFOCUS.COM Page 205 of 258

206. STUDENTSFOCUS.COM
Page 206 of 258

207. STUDENTSFOCUS.COM Page 207 of 258

208. STUDENTSFOCUS.COM Page 208 of 258

209. STUDENTSFOCUS.COM Page 209 of 258

210. STUDENTSFOCUS.COM Page 210 of 258

211. STUDENTSFOCUS.COM Page 211 of 258

212. STUDENTSFOCUS.COM Page 212 of 258

213. STUDENTSFOCUS.COM Page 213 of 258

214. STUDENTSFOCUS.COM Page 214 of 258

215. STUDENTSFOCUS.COM Page 215 of 258

216. STUDENTSFOCUS.COM Page 216 of 258

217. STUDENTSFOCUS.COM Page 217 of 258

218. STUDENTSFOCUS.COM
Page 218 of 258

219. Sri Vidya College of Engineering and Technology Cou rse Material [Question Bank]

EC6501 Digital Communication Unit 4 Page 1

STUDENTSFOCUS.COM
Page 219 of 258

220. Sri Vidya College of Engineering and Technology Cou rse Material [Question Bank]

EC6501 Digital Communication Unit 4 Page 2

STUDENTSFOCUS.COM
Page 220 of 258

221. Sri Vidya College of Engineering and Technology Cou rse Material [Question Bank]

EC6501 Digital Communication Unit 4 Page 3

STUDENTSFOCUS.COM
Page 221 of 258

222. Sri Vidya College of Engineering and Technology Cou rse Material [Question Bank]

EC6501 Digital Communication Unit 4 Page 4

STUDENTSFOCUS.COM
Page 222 of 258

223. Sri Vidya College of Engineering and Technology Cou rse Material [Question Bank]

EC6501 Digital Communication Unit 4 Page 5

STUDENTSFOCUS.COM
Page 223 of 258

224. Sri Vidya College of Engineering and Technology Cou rse Material [Question Bank]

EC6501 Digital Communication Unit 4 Page 6

STUDENTSFOCUS.COM
Page 224 of 258

225. Sri Vidya College of Engineering and Technology Cou rse Material [Question Bank]

EC6501 Digital Communication Unit 4 Page 7

STUDENTSFOCUS.COM
Page 225 of 258

226. Sri Vidya College of Engineering and Technology Cou rse Material [Question Bank]

EC6501 Digital Communication Unit 4 Page 8

STUDENTSFOCUS.COM
Page 226 of 258

227. STUDENTSFOCUS.COM Page 227 of 258

228. STUDENTSFOCUS.COM Page 228 of 258

229. STUDENTSFOCUS.COM Page 229 of 258

230. STUDENTSFOCUS.COM Page 230 of 258

231. STUDENTSFOCUS.COM
Page 231 of 258

232. Download STUCOR App for all subject Notes & QP's STUCOR APP Page 232 of 258

233. Access 3,000+ Study Materials for Semester Exams via STUCOR App STUCOR APP Page 233 of 258

234. Download STUCOR App for all subject Notes & QP's STUCOR APP Page 234 of 258

235. Access 3,000+ Study Materials for Semester Exams via STUCOR App STUCOR APP Page 235 of 258

236. Download STUCOR App for all subject Notes & QP's STUCOR APP Page 236 of 258

237. Access 3,000+ Study Materials for Semester Exams via STUCOR App STUCOR APP Page 237 of 258

238. Download STUCOR App for all subject Notes & QP's STUCOR APP Page 238 of 258

239. Access 3,000+ Study Materials for Semester Exams via STUCOR App STUCOR APP Page 239 of 258

240. Download STUCOR App for all subject Notes & QP's STUCOR APP Page 240 of 258

241. Access 3,000+ Study Materials for Semester Exams via STUCOR App STUCOR APP Page 241 of 258

242. Download STUCOR App for all subject Notes & QP's STUCOR APP Page 242 of 258

243. Access 3,000+ Study Materials for Semester Exams via STUCOR App STUCOR APP Page 243 of 258

244. Download STUCOR App for all subject Notes & QP's STUCOR APP Page 244 of 258

245. UNIT I – SAMPLING & QUANTIZATION
Low pass sampling – Aliasing- Signal Reconstruction-Quantization - Uniform & non-uniform quantization - quantization
noise - Logarithmic Companding of speech signal- PCM - TDM
PART A

Q.No

Questions

BT
Level


Competence
1.
List the advantages and disadvantage of digital communication system.
BTL 1 Remembering
2.
Define Band pass sampling.
BTL 1 Remembering
3.
State sampling theorem for band limited signals and the filters to avoid aliasing.
BTL 1 Remembering
4.
Distinguish natural and flat top sampling.
BTL 2 Understanding
5.
Interpret the use of pre-filtering done before sampling.
BTL 3 Applying
6.
What is meant by aliasing?
BTL 1 Remembering
7. How would you show your understanding of the components required for signal
reconstruction?
BTL 3 Applying
8.
Write about non uniform quantization.
BTL 1 Remembering
9.
Interpret the two fold effects of quantization process.
BTL 2 Understanding
10.
Illustrate the difference between uniform and non-uniform quantization.
BTL 3 Applying
11. In a PCM system the output of the transmitting quantizer is digital. Generalize,
Why is it further encoded?
BTL6 Creating
12. A signal is sampled at Nyquist rate of 8 KHz and is quantized using 8 bit uniform
quantizer. Assuming SNR for a sinusoidal signal, calculate the bit rate, SNR and
BW.
BTL 4 Analyzing
13. A certain low pass bandlimited signal x(t) is sampled and the spectrum of the
sampled version has the first guard band from 1500Hz to 1900Hz.How will you
determine the sampling frequency and the maximum frequency of the signal?
BTL 5 Evaluating
14.
Outline the input-output characteristic of a compressor and expander.
BTL 1 Remembering
15.
Point out the μ-law of compression.
BTL 4 Analyzing
16.
State in your own words the application of pulse communication system.
BTL 2 Understanding
17.
Express the Quantization noise of a PCM system.
BTL 2 Understanding
18.
Formulate the concept of PAM and PCM.
BTL 6 Creating
19.
Outline the concept of TDM.
BTL 4 Analyzing
Page 245 of 258

246. 20.
Summarize the advantages and disadvantages of TDM.
BTL 5 Evaluating


PART –B
1.
(i) Explain the following terms with respect to sampling:

(a) Aliasing and Signal Reconstruction (b) Aperture effect distortion

(ii) Explain Time division multiplexing system for N- number of channels.

(6)

(7)

BTL
1


Remembering
2. What is the main idea of quadrature sampling of band-pass signals? Derive
the expression for SDR.
(13) BTL
2
Understanding
3.
(i) Can you find the sampling rate for the following signal
m(t)=2[cos(500*pi*t).cos(1000*pi*t)]
(ii) Can you find the the Nyquist Rate for
m(t)=5*cos(5000*pi*t).cos²(8000*pi*t)
(7)


(6)

BTL
3

Applying
4. Let the maximum spectral frequency component (fm) in an analog
information signal be 3.3khz .Can you identify the frequency spectra of
sampled signal under the following relationships between the sampled
frequency (fs) and maximum analog signal frequency (fm)
(i) fs=2fm
(ii) fs>2fm & fs<2fm



(5)

(8)


BTL
4


Analyzing
5.
(i) Point out the sampling rate for the signal given
M(t)=(1/2*pi) * cos(4000*pi*t)*cos(1000*pi*t)
(ii) A T1 signal uses flat topped sampling with 1 µsec. Calculate the
spacing of samples if fm=3.4 Hz and fs=8KHz
(7)


(6)

BTL
4

Analyzing
6. How would you determine the magnitude spectrum of the ideally sampled
version of the signal m(t)=2*cos(200*pi*t)+40*sin(290*pi*t).Assuming
that the sampling rate is 1khz.
(13) BTL
5
Evaluating
7. A signal m(t) band limited to 4 KHz is sampled at the rate of 50% higher
than Nyquist rate , the maximum acceptable error in the sample amplitude
is 1% of peak amplitude. The quantized samples are binary coded. Find
minimum bandwidth of a channel required to transmit the encode binary
signa
(13)
BTL
2


Understanding
8. Illustrate and describe the types of Quantizer? Describe the mid tread and
midrise type characteristics of uniform quantizer with suitable diagram.
(13) BTL
3
Applying



Page 246 of 258

247. 9. (i) Deduce the expression for signal to noise ratio of uniform
quantizer.
(ii) A PCM system has a uniform quantizer followed by a „v’
bit encoder. Estimate that the rms signal to noise ratio is
approximately given by (1.8 + 6v) dB assuming a
sinusoidal input.
(7)


(6)

BTL
4


Analyzing
10. (i) Elaborate in detail about logarithmic companding of speech
signals
(ii) Show that the signal to noise power ratio of a uniform
quantizer is PCM system increases significantly with increase
in number of bits per sample. Also determine the signal to
quantization noise ratio of an audio signal s(t) = 3 cos (2π 500t)
which is quantized using a 10 bit PCM.
(4)


(9)


BTL
6


Creating
11. (i) Can you recall PCM system with neat block diagram
(ii) What is TDM and mention its applications. Explain the difference
between analog TDM and digital TDM
(7)

(6)
BTL
1

Remembering
12.

How would you show your understanding on PCM waveform coder and
decoder with neat sketch and list the merits compared with analog coders.
(13) BTL
1
Remembering
13. The bandwidth of TV, Video + audio signal is 4.5 MHz If the signal is
converted to PCM bit stream with 1024 quantization levels. Determine the
number of bits per second generated by the PCM system. Assume that
signal is sampled at the rate of 20% above nyquist rate.
(13)
BTL
1

Remembering
14. (i) Illustrate the principle of quantization and obtain the expression for the
signal to quantization noise ratio in PCM system.
(ii) The information in an analog signal with maximum frequency of 3
KHz is required to be transmitted using 16 quantization levels in PCM
systems. Interpret (a) The maximum number of bits per sample that should
be used
(b) The minimum sampling rate required and
(c) The resulting transmission data rate
(8)


(5)



BTL
2



Understanding



PART – C
1 (i) Compare Natural Sampling and Flat-top Sampling and explain the
concept of Sample and Hold circuit
(ii) Summarize the Pseudo noise sequences importance with examples.
(8)

(7)
BTL
5

Evaluating
2 (i) What is low pass sampling theorem and discuss the reconstruction of the
signal from its samples.
(ii) The signal x(t)=4cos(400πt) + 12cos(360 πt) is ideally sampled at a
frequency of 300 samples per second. The sampled signal is passed through
unit gain LPF with a cut off frequency of 220hz .Estimate the frequency
components present at the output of the LPF?
(8)


(7)


BTL
6



Creating

Page 247 of 258

248. 3 (i) What is low pass sampling theorem and discuss the reconstruction of the
signal from its samples.
(ii) The signal x(t)=4cos(400πt) + 12cos(360 πt) is ideally sampled at a
frequency of 300 samples per second. The sampled signal is passed through
unit gain LPF with a cut off frequency of 220hz .Estimate the frequency
components present at the output of the LPF?
(8)


(7)


BTL
6



Creating
4
Propose the digital hierarchy with examples.
(15) BTL
6
Creating



UNIT II - WAVEFORM CODING

Prediction filtering and DPCM - Delta Modulation - ADPCM & ADM principles-Linear Predictive Coding
PART A
Q.No Questions
BT
Level
Competence
1.
What is linear predictor? On what basis are predictor coefficients are determined.
BTL 1 Remembering
2.
Identify the need of prediction filtering.
BTL 1 Remembering
3.
List the 2 properties of linear prediction.
BTL 1 Remembering
4.
State in your own words prediction gain and its significance.
BTL 2 Understanding
5.
Why Delta Modulation is superior to Differential Pulse Code Modulation?
BTL 1 Remembering
6.
Distinguish PCM and DPCM.
BTL 2 Understanding
7.
Discuss about delta modulation and its limitations.
BTL 2 Understanding
8. Demonstrate the techniques to overcome slope overload and granular noise in
delta modulation system.
BTL 2 Understanding
9.
Interpret the principle of DM and ADM.
BTL 3 Applying
10.
Illustrate the difference between DM and ADM.
BTL 3 Applying
11.
Point out the slope overload distortion in delta modulation systems.
BTL 4 Analyzing
12.
Recall the advantages of delta modulator.
BTL 1 Remembering
13.
Inspect the concept of ADPCM.
BTL 4 Analyzing
14.
Outline the theory of APB and APF .
BTL 4 Analyzing


Page 248 of 258

249. 15.
Identify the objectives of speech coding.
BTL 3 Applying
16.
Write about temporal waveform coding.
BTL 1 Remembering
17.
Assess the principle of linear predictive coder .
BTL 5 Evaluating
18.
Summarize the applications of LPC.
BTL 5 Evaluating
19.
Formulate the model of LPC.
BTL 6 Creating
20.
Compose a theory for adaptive sub-band coding.
BTL 6 Creating


PART –B
1.
(i) Evaluate the structure of linear predictor.
(ii) Assess the process of prediction error.
(8)

(5)
BTL
5

Evaluating
2. (i) Summarize adaptive delta modulator with continuously variable step size
and explain with block diagram.
(ii) Explain the difference between PCM systems and delta modulation
systems.
(8)

(5)
BTL
2

Understanding
3. (i) How would you explain delta modulation and its quantization error?

(ii) Explain how adaptive delta modulation performs better than gains more
SNR than delta modulation.
(7)

(6)

BTL
1

Remembering
4.
Describe delta modulation system in detail with a neat block diagram. Also
illustrate two forms of quantization error in delta modulation.
(13)
BTL
1
Remembering
5.
Construct a DPCM system. Derive the expression for slope overload noise
Of the system.
(13) BTL
3
Applying
6. (i) State in your own words the functioning of ADPCM system with block
diagram.
(ii) A delta modulator with a fixed step size of 0.75v is given a sinusoidal
message signal. If the sampling frequency is 30 times the Nyquist rate, what
is the best maximum permissible amplitude of the message signal if slope
overload is to be avoided?
(8)


(5)

BTL
2


Understanding
7.
How would you show your understanding of
(i) Adaptive quantization schemes
(ii) Adaptive prediction schemes.
(7)

(6)
BTL
3

Applying
8. A signal having bandwidth of 3kHz is to be encoded using 8 bit PCM and DM
system. If 10 cycles of signal are digitized, state how many bits will be digitized
in each case if sampling frequency is 10 kHz? Also find bandwidth required in
each case.
(13)
BTL
6

Creating
9. Outline the concept of temporal waveform coding and spectral waveform
coding.
(13) BTL
1
Remembering

Page 249 of 258

250. 10.
(i) What is model based coding?
(ii) How would you explain the performance of various source coding
methods?
(8)

(5)
BTL
1

Remembering
11.
What is the function of LPC model and explain with diagrams.
(13) BTL
4
Analyzing
12. (i) Differentiate the speech coding methods.

(ii) Distinguish time domain coders from the frequency domain coders.
(8)

(5)
BTL
2

Understanding
13. (i) Can you identify low bit rate speech coding?
(ii) What is the function of adaptive sub-band coding scheme for speech
signal and explain with block diagram.
(5)

(8)
BTL
4

Analyzing
14.
How would you classify the various types of speech encoding techniques?
(13) BTL
4
Analyzing



PART-C
1
A television signal with a bandwidth of 4.2 MHz is transmitted using binary
PCM. The number of quantization level is 512. Calculate
(i) determine the code word length and transmission bandwidth
(ii) Can you find Final bit rate and Output signal to quantization noise ratio.


(8)
BTL
5
Evaluating
(7)
2
In a single integration DM scheme the voice signal is sampled at a rate of 64
kHz, the maximum signal amplitude is 1v, voice signal bandwidth is 3.5 kHz .
(i) Determine the minimum value of step size to avoid slope overload
(ii) Determine the granular noise No.
(iii)Assuming the signal to be sinusoidal, calculate the signal power and signal
to noise ratio.


(5)
(5)
BTL
5

Evaluating

(5)

3
A 1 kHz signal of voice channel is sampled at 4kHz using 12 bit PCM and a
DM system. If 25 cycles of voice signal are digitized. Solve in each case
(i) Signaling rate
(ii) Bandwidth required
(iii) No of bits required to be transmitted.


(5)
(5)
BTL
6

Creating

(5)

4
Develop an adaptive time domain coder with an encoder that codes the speech
at low bit rate and compare it with frequency domain coder.
(15) BTL
6
Creating



UNIT III - BASEBAND TRANSMISSION
Page 250 of 258

251. Properties of Line codes- Power Spectral Density of Unipolar / Polar RZ & NRZ – Bipolar NRZ - Manchester- ISI – Nyquist
criterion for distortion less transmission – Pulse shaping – Correlative coding – M-ary schemes – Eye pattern – Equalization

PART A

Q.No

Questions
BT
Level
Competence
1.
Identify the properties of line coding.
BTL 1 Remembering
2.
Summarize the need of Line Codes.
BTL 2 Understanding
3.
Recall Manchester coding.
BTL 1 Remembering
4.
Express the data 10011 using the Manchester code format.
BTL 2 Understanding
5. Interpret what do the various autocorrelation coefficients represent in the power
spectral density expression of a line code. Given the values of R10, R8, R50 and
R200, arrange them in the increasing order.
BTL 2 Understanding
6.
Apply unipolar and RZ code for the binary data 01101001.
BTL 3 Applying
7.
Point out duo binary system. What are the drawbacks of it?
BTL 4 Analyzing
8.
State Nyquist criteria.
BTL 1 Remembering
9.
Utilize Nyquist second and third criteria to realize zero ISI.
BTL 3 Applying
10.
Discuss how pulse shaping reduce ISI.
BTL 2 Understanding
11.
List four applications of eye pattern.
BTL 1 Remembering
12.
Examine correlative level coding.
BTL 4 Analyzing
13.
Outline the causes for ISI.
BTL 1 Remembering
14.
Justify the statement „ISI can-not be avoided‟.
BTL 5 Evaluating
15.
Compare the coherent and non-coherent receivers.
BTL 4 Analyzing
16.
Illustrate Eye pattern with diagram.
BTL 3 Applying
17.
Define Equalization.
BTL 1 Remembering
18.
Assess the need for adaptive equalization in a switched telephone network.
BTL 5 Evaluating
19.
Propose the methods used to implement adaptive equalizer.
BTL6 Creating



PART –B
Page 251 of 258

252. 1. (i) Write the comparison of various line coding techniques and list their
merits and demerits.
(ii) Outline the modified Duo binary coding technique and its performance
(7)

(6)
BTL
1

Remembering
by illustrating its frequency and impulse response.
2. (i) Describe the power spectral density of NRZ bipolar and unipolar data
format assume that 1s and 0s of input binary data occur with equal
probability.
(7)

(6)
BTL
1

Remembering
(ii) Recall adaptive equalization with block diagram.
3.
Identify the need for line shaping of signals. Derive the PSD of an unipolar
BZ and NRZ, line cod.e and compare their performance.
(13) BTL
1
Remembering
4.
(i) Illustrate and explain the properties of line codes.
(ii) What is a “raised cosine spectrum”? Discuss how does it help to avoid
ISI?
(7)

(6)
BTL
3

Applying
5.
What is ISI ? List the various methods to remove ISI in s communication
system. Also state and prove Nyquist first criterion for Zero ISI.
(13) BTL
1
Remembering
6.
(i) Outline the benefits of Nyquist pulse shaping.

(ii) Summarize the power spectra of Polar NRZ and bipolar RZ signals.
(7)

(6)
BTL
2

Understanding
7.
Discuss how Nyquist criterion eliminates interference in the absence of
noise for distortion less baseband binary transmission.
(13) BTL
2
Understanding
8.
(i) Describe any one method for ISI control.

(ii) Explain the principle of signal reception using a correlator type receiver.
(7)

(6)
BTL
2

Understanding
9. (i) Interpret the pulse shaping method to minimize ISI.
(ii) Demonstrate how eye pattern illustrates the performance of data
transmission system with respect to Inter Symbol Interference with neat
(7)

(6)
BTL
3

Applying
sketch.
10.
Elaborate how ISI occurs in base-band binary data transmission system.
(13) BTL
6
Creating
11.
Evaluate in detail about the M-ary baseband system
(13) BTL
5
Evaluating
12.
Point out the types of Adaptive Equalizers in detail with neat diagrams
(13) BTL
4
Analyzing
13.
(i) Analyzing adaptive MLSE equalizer with block diagrams.

(ii) Identify the merits and demerits of Duo binary signaling.
(7)

(6)
BTL
4

Analyzing



Part- C
Page 252 of 258

253. 1. For the sequence 10111001, sketch the waveform supporting the following
data formats.
(i) Unipolar RZ
(ii) Polar NRZ
(iii) Alternate mark inversion
(iv) Manchester coding.
Draw the corresponding spectrum of the above formats and explain.



(15)


BTL
5


Evaluating
2. Discuss in detail about inter symbol interference (ISI) and the nyquist
criterion for minimizing ISI. Elaborate the difficulties in implementing it in
a practical system.
(15) BTL
6
Creating
3.
Discuss in detail about correlative coding to eliminate ISI.
(15) BTL
6
Creating
4. (i) Deduce the equation for the impulse response coefficients of the zero
forcing equalizer.
(ii) Explain the two operation modes of adaptive equalizers.
(7)

(8)

BTL
5

Evaluating



UNIT IV - DIGITAL MODULATION SCHEME
Geometric Representation of signals - Generation, detection, PSD & BER of Coherent BPSK, BFSK & QPSK - QAM -
Carrier Synchronization - structure of Non-coherent Receivers - Principle of DPSK.
PART A

Q.No

Questions
BT
Level
Competence
1.
Outline the need for geometric representation of signals.
BTL 2 Understanding
2.
Draw the block diagram of a coherent BFSK receiver.
BTL 1 Remembering
3.
Identify the difference between BPSK and QPSK techniques.
BTL 1 Remembering
4.
What is QPSK? Write down the expression for signal set.
BTL 1 Remembering
5.
Sketch the PSK and QPSK waveforms of the bit stream 10110001.
BTL 1 Remembering
6. A BFSK system employs two signaling frequencies f1 and f2. The lower frequency
f1 is 1200 Hz and signaling rate is 500 Baud. Compute f2.
BTL 3 Applying


7. A BPSK system makes errors at the average rate of 100 errors per day. Data rate is
1 kbps. The single-sided noise power spectral density is 10 W/Hz. Assume the
system to be wide sense stationary, predict the average bit error probability.
BTL 3 Applying
8.
Compare M-ary PSK and M-ary QAM.
BTL 4 Analyzing
9.
Distinguish the error probability for BPSK and QPSK.
BTL 4 Analyzing
Page 253 of 258

254. 10.
Discuss the drawbacks of ASK.
BTL 2 Understanding
11.
Indicate why PSK always preferable over ASK in Coherent detection.
BTL 2 Understanding
12.
Write the special features of QAM.
BTL 1 Remembering
13. Sketch the signal space diagram for QAM signal for M=8. BTL 1 Remembering
14.
Illustrate about the constellation diagram.
BTL 2 Understanding
15.
Design a carrier synchronization using M
th
power loop.
BTL 6 Creating
16.
Formulate the concept of memoryless modulation.
BTL6 Creating
17. Identify the difference between coherent and non-coherent digital modulation
techniques.
BTL 3 Applying
18.
Analyze the concept of spectral efficiency.
BTL 4 Analyzing
19.
Evaluate the error probability of DPSK.
BTL 5 Evaluating
20.
Assess the features of DPSK.
BTL 5 Evaluating
PART –B
1.
(i) What is digital modulation scheme? Derive geometrical representation of
signal.
(ii) Write about the geometric representation of BPSK signal and BFSK signal.
(7)

(6)
BTL
1

Remembering
2.
Explain the generation and detection of a coherent binary PSK signal and derive
the power spectral density of binary PSK signal and plot it.
(13) BTL
1
Remembering
3.
Explain the non-coherent detection of FSK signal and derive the expression for
the probability of error.
(13) BTL
2
Understanding
4. Discuss the transmitter, receiver and signal space diagram of QPSK and describe
how it produces the original sequence with the minimum probability of error
with neat sketch .
(13)
BTL
2

Understanding
5.
Summarize the transmitter, receiver and generation of non-coherent version of
PSK with neat sketch.
(13) BTL
2
Understanding
6.
Outline the generation and detection of a coherent binary FSK signal and derive
the power spectral density of binary PSK signal and plot it.
(13) BTL
1
Remembering


7.
(i) Produce the BER comparison of coherent PSK, coherent QPSK and coherent
FSK.
(ii) Show the difference between coherent and non-coherent scheme
(7)

(6)
BTL
3

Applying
8.
(i) Illustrate Carrier Synchronization in QPSK.
(ii) Calculate the BER for a Binary phase shift keying modulation from first
principles.
(6)

(7)
BTL
3

Applying
Page 254 of 258

255. 9.
(i) List the difference between QAM and QPSK.

(ii) Describe QPSK signaling with diagrams.
(7)

(6)
BTL
1

Remembering
10. (i) Analyzing the transmitter, receiver and signal space diagram of Quadrature
Amplitude Modulation.
(ii) Outline the power spectral density and bandwidth of QAM signal with neat
diagrams and mention its advantages.
(5)

(8)
BTL
4

Analyzing
11.
(i) Analyzing the constellation diagram of QPSK scheme.

(ii) Identify the error performance of coherent detection QAM system.
(7)

(6)
BTL
4

Analyzing
12. (i) Evaluate the Quadrature Receiver structure for coherent QPSK with
appropriate diagram.
(ii) In a QPSK system, the bit rate of NRZ stream is 10 Mbps and carrier
frequency is 1GHz. Tell the symbol rate of transmission and bandwidth
requirement of the channel.
(4)


(9)

BTL
5

Evaluating
13.
(i) Explain the principle of working of an “early late bit synchronizer”.
(ii) Develop the expression for bit error probability of QPSK system.
(8)

(5)
BTL
6

Creating
14.
(i) Identify the principle of DPSK? Explain the transmitter and receiver of DPSK
scheme.
(ii) Point out the Probability of error for coherently detected BFSK.
(7)

(6)
BTL
4

Analyzing


PART-C
1 (i) Explain Carrier and symbol synchronization (7)
(ii) A set of binary data is sent at the rate of Rb= 100 Kbps over a channel with 60
dB transmission loss and power spectral density ??????= 10-12 W/Hz at the receiver.
Evaluating the transmitted power for a bit error probability Pe= 10
-3
for the

(8)
BTL
5

Evaluating
following modulation schemes.
(a) FSK (b) PSK (c) DPSK (d) 16 QAM
2 Draw the signal space diagram of a coherent QPSK modulation scheme
and also find the probability of error if the carrier takes on one of four
equally spaced values 0
o
,90
o
, 180
o
and 270
o
.
(15) BTL
5
Evaluating
3 In digital CW communication system, the bit rate of NRZ data stream in 1 Mbps
and carrier frequency is 100 MHz. Solve for the symbol rate of transmission and
bandwidth requirement of the channel in the following cases of different
techniques used.
(i) BPSK system
(ii) QPSK system
(iii) 16-ary PSK system
(15)

BTL
6


Creating


Page 255 of 258

256. 4 (i) Find the error probability of BFSK system for following parameters.
PSD of white noise No/2 = 10
-10
Watt/Hz
Amplitude of carrier is , A = 1mV at receiver input.
Frequency of baseband NRZ signal is fb=1kHz.
(ii) Binary data is transmitted using PSK at rate 2Mbps over RF link having
bandwidth 2MHz. Find signal power required at the receiver input so that
error probability is less than or equal to 10
-4
Assume noise PSD to be 10
-10

Watt/Hz.
(5)




(10)


BTL
6



Creating



UNIT V - ERROR CONTROL CODING

Channel coding theorem - Linear Block codes - Hamming codes - Cyclic codes - Convolutional codes - Vitterbi Decoder

PART A
Q.No Questions BT
Level
Competence
1. State Channel Coding Theorem and its need. BTL -1 Remembering
2. Analyzing the need for error control codes. BTL -4 Analyzing
3. Outline the features of linear code. BTL -1 Remembering
4. Discuss the code rate of a block code. BTL -2 Understanding
5. Demonstrate the significance of minimum distance of a block code. BTL -3 Applying
6. Express the syndrome properties of linear block code. BTL -2 Understanding
7. Distinguish Hamming Distance and Hamming weight. BTL -4 Analyzing
8. Deduce the Hamming distance between 101010 and 010101. If the minimum
Hamming distance of a (n, k) linear block code is 3, what is the minimum
Hamming weight?

BTL -5

Evaluating
9. Summarize the advantages and disadvantages of Hamming codes. BTL -2 Understanding
10. Discuss two properties of generator polynomial. BTL -2 Understanding
11. List the properties of cyclic codes. BTL -1 Remembering
12. Illustrate the systematic code word with its structure. BTL -4 Analyzing
13. When a binary code does is said to be cyclic codes? BTL -1 Remembering
14. Propose the generator polynomial of a cyclic codes. BTL -6 Creating
15. Generate the cyclic code for (n, k) syndrome calculator. BTL -6 Creating
16. The code vector [1110010] is sent, the received vector is [1100010]. Identify the
Syndrome.
BTL -3 Applying
17. What is meant by constraint length of a convolutional encoder? BTL -1 Remembering
18. What is convolutional code? How is it different from block codes? BTL -1 Remembering
19. Show how Trellis diagram is used to represent the code generated by
convolutional coder and mention its advantages.
BTL -3 Applying
20. Determine the various techniques/algorithms used. in encoding and decoding of
convolutional code.
BTL -5 Evaluating

PART-B
1. Consider a linear block code with generator matrix BTL
1
Remembering


Page 256 of 258

257. (i) Enumerate the parity check matrix.
(ii) Trace the error detecting and capability of the code.
(iii) Draw the encoder and syndrome calculation circuits.
(iv) Write the syndrome for the received vector r = [1 1 0 1 01 0].

(3)
(3)
(3)
(4)

2. (i) Analyzing the generation of (n, k) block codes and audit how block
codes can be used for error control.
(ii) Consider a (6, 3) block code and explain how error syndrome helps in
correcting a single error for a data 110.
(7)

(6)

BTL
4

Analyzing
3. (i) Cite an example and explain one decoding procedure of linear block
codes.
(ii) Find the (7, 4) systematic and non-systematic cyclic code words of the
message word 1101. Assume the generator polynomial as 1 + x
2
+ x
3
.
(8)

(5)

BTL
1

Remembering
4. (i) Describe the steps involved in the generation of linear block codes.

(ii) Explain the properties of syndrome.
(7)

(6)
BTL
2

Understanding
5. Illustrate how the errors are corrected using hamming code with an
example.
(13) BTL
2
Understanding
6. Examine that the generator polynomial of a (7, 4) cyclic code is 1+X+??????
3.
Discover the correct code word transmitted if the received code word is
(i) 1011011 and (ii) 1101111
(13)
BTL
4

Analyzing
7. (i) Explain how to obtain the code for an (n, k) linear cyclic code and
explain its working.
(ii) Write a note on BCH codes.
(8)

(5)
BTL
1

Remembering
8.
Develop the cyclic codes with the linear and cyclic property. Also represent
the cyclic property of a code word in polynomial notation.
(13)
BTL
3

Applying
9. (i) Determine how Viterbi decoding algorithm is used for convolutional
code.
(ii) Explain the different types of error detected by CRC code.
(8)

(5)
BTL
5

Evaluating
10. Draw the diagram of the ½ rate convolutional encoder with generator
polynomials
G
1
(D)=1+D
G
2
(D)=1+D+D
2

And complete the encoder output for input sequence 101101.
(13)

BTL
2


Understanding
11. (i) Draw the code tree of a Convolutional code of code rate r = 1/2 and
constraint length of K = 3 starting from state table and state diagram for an
encoder which is commonly used.
(ii) Draw and explain the trellis diagram representation of convolutional
codes.
(9)

(4)

BTL
1


Remembering
12. (i) Demonstrate the generation of a code using a convolutional encoder
with k=1, n=2 and r = ½.
(ii) Calculate the encoded output for the input message 10011. (For a
Convolutional encoder of constraint length 3 and rate ½.
(7)

(6)

BTL
3

Applying
13. (i) Identify a block code for a message block of size eight that can correct
for single errors.
(ii) Diagnose a convolutional coder of constraint length 6 and rate
efficiency ½. Draw its tree diagram and trellis diagram.
(7)

(6)

BTL
4


Analyzing


Page 257 of 258

258. PART - C
1. For a systematic linear block code, the three parity check digits P1, P2,P3 are given
101
by Pk,n-k =[
111
]
110
011
(i) Construct generated matrix.
(ii) Assess the t code generated by the matrix.
(iii) Determine error correcting capacity.
(iv) Decode the received words with an example.


(4)
(4)

BTL
5

Evaluating
(4)

(3)

2 For a systematic (6,3) linear block code
1 0 0 1 0 1
G=[0 1 0 0 1 1],
0 0 1 1 1 0
(i) Solve for all the code vectors
(ii) Draw encoder circuit for the above code
(iii) Predict minimum hamming weight


(5)
(5)

BTL
6

Creating

(5)

3 (i) Explain Viterbi algorithm with an appropriate coder and received input word of
length 12. Assume a coder of constraint length 6 and rate efficiency ½.
(ii) Assess a (7,4) binary cyclic code with a generator polynomial g(x) = 1 + x + x
3

draw the syndrome circuit.
(10)

(5)

BTL
5

Evaluating
4
A convolutional code is described by g1=[1 0 0], g2=[1 0 1], g3=[1 1 1]
(i) Build the encoder corresponding to the code.
(ii) Develop the state transition diagram for this code.
(iii) Draw the trellis diagram.
(iv) Estimate the transfer function.
(4)

(4)
(4)
BTL
6

Creating

(3)


Page 258 of 258