B.Sc Nautical Science

Subject Code: UG21T2404

Subject : Nautical Electronics III


Answer Any Seven

1.(a)Explain the terms sampling, quantisation ,quantizing error and encode.

(5 Marks)


(b) What is straight receiver? What are the drawbacks of a straight receiver?                        How  are they overcome in a TRF? Explain TRF receiver.                      (5 Marks)


  1. (a) Explain pulse amplitude modulation with neat waveform and block diagram (5)

(b) A message signal has a sine tone of 500Hz, sound tone of 1000Hz and a high frequency component of 2000Hz. What is minimum sampling frequency?                  (5)


3.(a) Explain PCM generation and demodulation with suitable block diagram     (6)

(b) For a minimum line speed with 8bit PCM for speech signal of 1V

calculate resolution and quantisation error                                                                 (4)

  1. (a)Explain the working of a communication receiver with help of a block diagram.                                                                                                                         (5 Marks)


(b)With the aid of appropriate diagram, explain the operation of Yagi Uda

antenna.                                                                                                                        (5 Marks)


5.(a) With neat sketch explain a tuned RF receiver                                                           (5)

(b) Explain a super hetro-dyne receiver                                                                      (5)


6.(a) Briefly explain types of noises                                                                                 (5)

(b) An amplifier with a bandwidth of 20MHz has a 10kΩ input resistor. What is the rms noise voltage at the input to this amplifier if ambient temperature is 27°C                      (3)

(c) Define signal to noise ratio                                                                                    (2)


7.(a)Explain a transmission line with proper equivalent circuit                           (6)

(b) Define characteristic impedance of a transmission line                                        (4)


8.(a)Explain resonant and non resonant antennas using proper radiation patterns (6)

(b) If antenna resistance is 100Ω and radiation refficiency is 75%, what is the antenna radiation resistance                                                                                                           (4)


  1. (a) Explain a basic radar system with neat block diagram. (6)

(b) Calculate maximum range of a radar system which operates at 3cm wavelength with a peak pulse power of 500kW, if its minimum receivable power is 10-13W, the capture area of its antenna is 5m2 and the radar cross sectional area of the target is 20m2.                                                                                                               (4)