satellite communication question

Electronics and Communication Engineering

EC 2045— SATELLITE COMMUNICATION

Time : Three hours                                                                                                  Maximum : 100 Marks

Answer ALL questions

         PART A — (10 x 2 = 20 Marks)

1.      State kepler’s first and second law of planetary motion..

2.      Enlist the traditional orbital keplerian elements.

3.      State the condition of visibility of satellite to an observer standing on the earth surface.

4.      Define mean anomaly and true anomaly.

5.      What is line of apsides?

6.      Mention the perigee and apogee height.

7.      What are geo-stationary satellites?

8.      Define sun transit outage.

9.      Define figure of merit.

10.  How the attitude of a satellite is controlled through active control? 

                                                  PART B — (5 x 16 = 80 Marks)

11    (a)What are look angles? Explain how look angles are determined using sub satellite points?

      Explain the necessary expressions for the look angles.                                                     (16)

(OR)

                   (b) Give a detailed note on launching vehicle and the procedure employed for launching

                           Spacecraft in GEO orbits.                                                                                 (16)        

12    (a) A satellite is orbiting the equatorial plane with a period from perigee to perigee of 10h.

     Given that the eccentricity is 0.002 and the earth equatorial radius is 6378.1414Km.How

     Will you calculate the semi-major axis.                                                                            (16)

(OR)

                     (b)(i) How will you determine the sub satellite point?                                              (8)

                     

                          (ii)Determine the limits of visibility for an earth station situated at mean sea level,at

                             latitude 48.42 degrees N, and longitude 89.26 degrees W. Assume a minimum angle

                             of elevation of 10deg.                                                                                                 (8)

             13 (a)  With a neat sketch, explain the various modules of attitude and orbit control (AOCS)

                              subsystem.                                                                                                     (16)

 (OR)

                  (b)  (i) Explain the various structure of a spacecraft system.                                                   (8)

                        (ii) Determine the angle of tilt required for a polar mount used with an earth station at

                              latitude of 38degrees north.Given,radius of earth is 6371Km..                                   (8)

              14 (a) With necessary equations estimate the primary power of a satellite system.                (16)

(OR)

                   (b) Explain in detail about the geocentric-equatorial co-ordinate system which is based on

                              earth’s equatorial plane.                                                                                 (16)

 15 (a) (i) Draw the block diagram of TT&C and explain the various sub modules.        (10)

            (ii) Write short notes on thermal control mechanism.                                               (6)

(OR)

       (b)  Explain the construction and working principle of a transponder in a communication

              subsystem.                                                                                                                (16)