1. Define Dirac comb or ideal sampling function.
2. State sampling theorem.
3. What is aliasing or foldover?
4. What is meant by PCM?
5. Define quantizing process.
6. What is meant by idle channel noise?
7. Define delta modulation
8. Name the types of uniform quantizer
9. What is the need for speech coding at low bit rates?
10. What is PAM?
11. Define modulation rate.
12. State NRZ unipolar format
13. State Manchester format.
14. What is Inter symbol interference?
15. Which criterion makes ISI Zero?
16. What is matched filter receiver ?
17. What is maximum likelihood detector
18. Define antipodal signals.
19. Give the two basic operation of DPSK transmitter
20. Define deviation ratio in MSK
21. What are the three broad types of synchronization ?
22. What are the disadvantages of closed loop bit synchronization.
23. Define code efficiency
24. Define pseudo-noise (PN) sequence.
25. What does the term catastrophic cyclic code represent ?
26. Define a random binary sequence.
27. Give the correlation property of random binary sequence.
28. What is called processing gain ?
29. What is called jamming effect ?
30. What is Anti jamming ?
31. What are the three codes used for the anti jamming application ?
32. What is called frequency hop spread spectrum ?
33. What are the two function of fast frequency hopping?
34. What are the features of code Division multiple Accesses?
35. What is called multipath Interference?
36. What is the advantage of a spread spectrum technique?
37. What is called frequency hop spread spectrum ?
38. BPFSK is more efficient than BFSK in presence of noise. Why?
39. What is inter symbol interference?
40. What is raised cosine pulse?
41. Compare the bandwidth efficiency of the M-ary FSK and M-ary PSK modulation schemes
42. . If x(t) = cos (2pt / T) sin (4 pt / T) is to be sampled, what is the maximum sampling interval?
43. A PCM system uses a uniform Quantiserfollowed by a 7-bit encoder.The rate of system is 50Mbits\second. Determine message bandwidth for system to operate satisfactorily
44. Which modulation technique has best utilization of bandwidth?
45. In which modulation scheme probability is maximum
46. In which modulation scheme probability is minimum
47. What is Nyquist rate?
48. What is advantage of digital communication over analog communication?
49. Which are the channels used for digital communication?
50. Which kind of multiplexing used in digital communication?
51. Define Aperture effect . How it can be avoided
52. Why is Sample & Hold circuit used?
53. An Analog signal is given as
X(t) = 3cos 50πt + 10 sin 300 πt + cos 100πt
Calculate Nyquist rate
54. The spectrum of a signal g(t) has bandwidth 0.8KHZ and centered around 
10 KHZ. Find Nyquist Rate
10 KHZ. Find Nyquist Rate55. What is requirement for Transmission Bandwidth?
56. Difference between Coherent and Non-coherent detection
57. Signal constellation diagram of all modulation schemes
58. A PCM system uses a uniform quantizer followed by a 7 bit encoder,with bit rate 50Mbps.What is the message bandwidth for system to operate satisfactorially?
59. Properties of Matched filter?
60. Difference between CDMA & TDMA
61. What is Pulse code modulation(PCM)?
62. How the performance of a PCM is corrupted?
63. What are the two types of Spread spectrum technique?
64. We need to send 3 bits at a time at a bit rate of 3Mbps.The carrier frequency is 10MHz.Calculate No of levels and Bandwidth
65. What is a Constellation Diagram?
66. Which modulation is a combination of other 2 schemes
67. Name two principles by which spread spectrum achieves its goal
68. Which of the 3 multiplexing techniques is common for fibre optic links
69. What is the minimum number of bits in a PN sequence if we use FHSS with a channel bandwidth of 5kHz and Bss=120kHz?
70. Which theorm gives Maximum Data Rate of a channel
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