EC1351 Digital Communication Techniques Question Bank : kings.ac.in
Name of the College : Kings College Of Engineering
Department : Electronics & Communication Engineering
Subject : Digital Communication Techniques
Website : kings.ac.in
Document Type : Question Bank
Download Model/Sample Question Paper : https://www.pdfquestion.in/uploads/ki…TECHNIQUES.pdf
Kings Digital Communication Techniques Question Paper
Part A (2 Marks)
Unit – I
Pulse Modulation :
1. Define Dirac comb or ideal sampling function. What is its Fourier Transform?
2. Give the interpolation formula for the reconstruction of the original signal g(t) values {g(n/2W)}.
3. State sampling theorem.
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4. Define Quadrature sampling.
5. What is aliasing?
6. Give the expression for aliasing error and the bound for aliasing error.
7. What is meant by PCM?
8. Define quantizing process.
9. What is meant by idle channel noise?
10. What is meant by prediction error?
11. Define delta modulation.
12. Define adaptive delta modulation.
13. Name the types of uniform quantizer?
14. What you mean by non-uniform quantization?
15. What is the disadvantage of uniform quantization over the non
16. What do you mean by companding? Define compander.
17. Draw the block diagram of compander? Men
18. What is PAM?
Part B :(16 Marks)
1. a) State and prove sampling theorem. (10)
b) Explain about PAM scheme. (6)
2. a) Define aliasing and derive an expression for it. (10)
b) Explain Adaptive delta modulation system. (6)
3. a) Write short notes on (12)
i)Flat sampling ii)Natural sampling,
iii)Instantaneous sampling.
b) Write short notes on modified Duo Binary scheme. (4)
4. a) Explain in detail the TDM. (8)
b) Explain about the noise in PCM. (8)
5. a) Explain in detail the PCM. (12)
b) Write short notes on Duo Binary signaling scheme. (4)
Unit – II
Baseband Pulse Transmission :
Part A :( 2 Marks)
1. How are the predictor coefficients determined?
2. Define adaptive sub band coding?
3. Define Adaptive filter?
4. Define data signaling Rate.
5. Define modulation rate.
6. State Polar format, NRZ unipolar format, NRZ bipolar format, Manchester format, Biphase.
7. What is an eye pattern?
8. What does the width of the eye define?
9. From the eye pattern how the sensitivity on the system can be determined?
10. What is the margin over noise?
11. What is Inter symbol interference?
12. How an eye pattern is obtained?
Part B : (16 Marks)
1. Explain in detail about the optimum demodulation of Digital signals in the presence if ISI and AWGN. Also, explain the various equalization techniques. (16)
2. Explain in detail the operation of Non Coherent Receivers in the presence of Random Phase Channel and implement the receiver. (16)
3. Explain in detail the operation of Non Coherent Receivers in the presence of Random amplitude and phase Channel and implement the receiver. (16)
4. a. Explain the In phase and Quadrature Modulation systems. (8)
b. With necessary diagrams explain the operation of Quadrature Amplitude Modulation systems. (8)
5. a. Derive the SNR of the matched filter. (10)
b . Explain the LMS algorithm of adaptive equalization, (6)
Unit – III
Passband Data Transmission :
Part – A : (2 Marks)
1. State the properties of matched filter.
2. Define antipodal signals.
3. Explain how QPSK differs from PSK in terms of transmission bandwidth and bit information it carries?
4. Define QPSK.
5. What are the three broad types of synchronization?
6. What is carrier synchronization?
7. What are the two methods for carrier synchronization?
8. What is called symbol or bit synchronization?
9. What are the disadvantages of closed loop bit synchronization?
10. What is called frame synchronization?
11. Why synchronization is required?
Part B : (16 Marks)
1. Explain the Binary Phase Shift Keying and obtain an expression for its probability of error. (16)
2. Explain the Quadrature Phase Shift Keying and obtain an expression for its probability of error. (16)
3. Explain the Minimum Shift Keying and obtain an expression for its probability of error. (16)
4. Explain the Continuous Phase Frequency Shift Keying and obtain an expression for its probability of error. (16)
5. a) Brief about carrier and symbol synchronization. (8)
b) Compare digital modulation systems using single carrier. (8)