Name of the College : Sphoorthy Engineering College
University : JNTUH
Department : ELECTRONICS AND COMMUNICATIONS ENGINEERING
Subject Name : DIGITAL COMMUNICATIONS
Degree : B.Tech
Year/Sem : III/I
Website : sphoorthyengg.com
Document Type : Model Question Paper
Download Model/Sample Question Paper : https://www.pdfquestion.in/uploads/sphoorthyengg.com/4740-RR310405%20-%20DIGITAL%20COMMUNICATIONS.pdf
Digital Communications Question Paper
B. Tech III Year I Semester Examinations, December – 2011
DIGITAL COMMUNICATIONS
(ELECTRONICS AND COMMUNICATIONS ENGINEERING)
Time: 3 hours
Max. Marks: 80
Related : Sphoorthy Software Testing Methodologies B.Tech Question Paper : www.pdfquestion.in/4871.html
Answer any five questions :
All questions carry equal marks :
1.a) Define Sampling Theorem? Prove the Sampling Theorem for Low Pass signals. b) Discuss about Generation & Detection of Pulse Width Modulation (PWM) with neat sketch. [8+8]
2.a) Calculate the Nyquist rate & Nyquist Interval for the given Analog Signal
X(t) = 3Cos 50pt+10 Sin 300pt – Cos 100pt
b) Compare PAM, PWM & PPM with respect to bandwidth, Noise, Power and discuss merits & demerits. [8+8]
3.a) Explain about M-array Signaling Schemes.
b) Explain about DPSK modulation scheme with suitable examples. [8+8]
4.a) What is Quantization Error in PCM System? Derive the Equation for Quantization Noise Power in terms of Step Size?
b) Consider an Audio Signal is given as x(t) = 3 Cos (500pt). Determine
(i) Signal to Quantization Noise ratio when this is quantized using 10 bit PCM
(ii) How many bits of Quantization are needed to achieve a signal to Quantization
Noise ratio at least 40 dB? [8+8]
5.a) Compare PCM, DM and DPCM?
b) Explain the Block diagram of Delta Modulation with Suitable Example. [8+8]
6.a) Write the Comparisons among Binary Signaling Schemes (ASK, PSK & FSK)
b) Discuss about QPSK modulation technique with neat block diagram and explain phasor & Constellation diagrams. [6+10]
7.a) Distinguish Block codes and Convolution codes.
b) Design an encoder for a (7, 4) binary cyclic code generated by g(x) = 1+x+x3 and verify its operation using message vector D = 0101. [8+8]
8. Discuss about the following
a) Companding b) Eye Pattern
c) Parity coding d) Inter symbol interference. [16]
RRCode No: RR310405 SET-2
1.a) Explain about M-array Signaling Schemes.
b) Explain about DPSK modulation scheme with suitable examples. [8+8]
2.a) What is Quantization Error in PCM System? Derive the Equation for Quantization Noise Power in terms of Step Size?
b) Consider an Audio Signal is given as x(t) = 3 Cos (500pt). Determine
(i) Signal to Quantization Noise ratio when this is quantized using 10 bit PCM
(ii) How many bits of Quantization are needed to achieve a signal to Quantization
Noise ratio at least 40 dB? [8+8]
3.a) Compare PCM, DM and DPCM?
b) Explain the Block diagram of Delta Modulation with Suitable Example. [8+8]
4.a) Write the Comparisons among Binary Signaling Schemes (ASK, PSK & FSK)
b) Discuss about QPSK modulation technique with neat block diagram and explain phasor & Constellation diagrams. [6+10]
5.a) Distinguish Block codes and Convolution codes.
b) Design an encoder for a (7, 4) binary cyclic code generated by g(x) = 1+x+x3 and verify its operation using message vector D = 0101. [8+8]
6. Discuss about the following
a) Companding b) Eye Pattern
c) Parity coding d) Inter symbol interference. [16]
7.a) Define Sampling Theorem? Prove the Sampling Theorem for Low Pass signals. b) Discuss about Generation & Detection of Pulse Width Modulation (PWM) with neat sketch. [8+8]
8.a) Calculate the Nyquist rate & Nyquist Interval for the given Analog Signal
X(t) = 3Cos 50pt+10 Sin 300pt – Cos 100pt
b) Compare PAM, PWM & PPM with respect to bandwidth, Noise, Power and discuss merits & demerits. [8+8]
RRCode No: RR310405 SET-3
1.a) Compare PCM, DM and DPCM?
b) Explain the Block diagram of Delta Modulation with Suitable Example. [8+8]
2.a) Write the Comparisons among Binary Signaling Schemes (ASK, PSK & FSK)
b) Discuss about QPSK modulation technique with neat block diagram and explain phasor & Constellation diagrams. [6+10]
3.a) Distinguish Block codes and Convolution codes.
b) Design an encoder for a (7, 4) binary cyclic code generated by g(x) = 1+x+x3 and verify its operation using message vector D = 0101. [8+8]
4. Discuss about the following
a) Companding b) Eye Pattern
c) Parity coding d) Inter symbol interference. [16]
5.a) Define Sampling Theorem? Prove the Sampling Theorem for Low Pass signals. b) Discuss about Generation & Detection of Pulse Width Modulation (PWM) with neat sketch. [8+8]
6.a) Calculate the Nyquist rate & Nyquist Interval for the given Analog Signal
X(t) = 3Cos 50pt+10 Sin 300pt – Cos 100pt
b) Compare PAM, PWM & PPM with respect to bandwidth, Noise, Power and discuss merits & demerits. [8+8]
7.a) Explain about M-array Signaling Schemes.
b) Explain about DPSK modulation scheme with suitable examples. [8+8]
8.a) What is Quantization Error in PCM System? Derive the Equation for Quantization Noise Power in terms of Step Size?
b) Consider an Audio Signal is given as x(t) = 3 Cos (500pt). Determine
(i) Signal to Quantization Noise ratio when this is quantized using 10 bit PCM
(ii) How many bits of Quantization are needed to achieve a signal to Quantization
Noise ratio at least 40 dB? [8+8]