The document presents a set of important questions related to satellite communications, covering various concepts such as satellite types, orbital mechanics, signal propagation, and subsystem functions. Key topics include differentiation between satellite bands, path loss, satellite stability techniques, and the principles of system design and performance. It also involves practical calculations related to satellite orbits and communications parameters.

1. Sub: Satellite Communications
MID-I Important Questions
1. (a) Differentiate Geostationary and Geosynchronous satellites.
(b) A satellite is in a 322-km high circular orbit. Determine the orbital period in
minutes.
(c) What is the limit of visibility
(d) Differentiate between Ku, Ka and C Bands.
(e) Define ascending node.
(f) What is meant by path loss.
(g) Find the viewing angle of a GEO satellite orbiting at 42000 km from earth
station making an elevation angle of 25◦
(h) What is meant by preamble in a TDMA System.
(i) State Keplers laws of planetary motion.
(j) What is meant by Effective Isotropically radiated power ?
(k) Differentiate between LEO and MEO Satellites.
(l) Differentiate between Uplink and Downlink. Explain why downlink signals are
relatively low frequency signals than the uplink signals.
(m) Identify the basic factors affecting the satellite position.
(n) What are Azimuth and Elevation angles ?
(o) Define Guard Time.
(p) Why is it important of ensure redundancy of devices used in satellites
(q) what is meant by momentum wheel stabilization.
(r) What do you mean by Mean time before failure. How is it related to reliability.
(s) List the advantage and disadvantage of FDMA, TDMA, CDMA.
(t) Explain Doppler shift in connection with LEO Satellites.
(u) A satellite is orbiting in the equatorial plane with a period from perigee to
perigee of 20hrs. The eccentricity is 0.04. Calculate the semimajor axis assuming
equatorial radius to be 6378.1414 km.
(v) Briefly explain about system noise temperature.
(w) Derive the complete expression of look angles along with intermediate angle in
satellite communication.
(x) A satellite is in an elliptical orbit with a perigee of 1000 km and an apogee
of 5000 km. Assuming mean earth radius as 6378.14 km, find the period and
eccentricity of the orbit.
(y) What is meant by Geostationary orbit and explain the conditions required for
an orbit to be Geostationary.

2. (z) Determine the limit of visibility for an earth station situated at mean sea level
at a latitude of 23.45◦
South and longitude 18◦
East. Assume a minimum angle
of elevation 7◦
.
2. Differentiate between Global beam antenna and Orthogonally polarized beam an-
tenna.
3. Explain the spin stabilization and momentum wheel stabilization technique to keep
satellite attitude control.
4. What is meant by apogee kick motor ?
5. What are the various elements used in the space segment of a satellite system ?
Explain the needs and functions of each element in the satellite system.
6. Explain the working of telemetry, tracking and control subsystem with a suitable
diagram.
7. Explain Spin Stabilization and Three axis Stabilization.
8. What is DAMA ?
9. Prove that C/N ratio is directly proportional to G/T ratio.
10. Explain about Intermodulation.
11. Explain the principle of spectrum spreading and despreading.
12. A C-band earth station has a frequency of 6.1 GHz. the signal is received by a
satellite at a distance of 37800 km by an antenna with a gain of 25 dB. Determine
the path loss at 6.1 GHz.
13. How spectrum spreading and despreading is used to minimize interference in CDMA
system.
14. Why downlink design is more challenging than uplink design ?
15. Explain about Satellite launch vehicles.
16. What is Noise figure ? How it is related to System Noise Temperature ?
17. Illustrate the orbital parameters used for positioning a satellite.
18. A satellite at a distance of 40000 km from a point on earth’s surface radiates a power
of 15 W from an antenna with a gain of 13 dB in the direction of the observer. Find
the flux density at the receiving point and the power received by an antenna at this
point with an effective area of 15m2
.
19. Describe in detail the launching procedure of a satellite.
20. Describe link equation in detail. Also express the link equation in dBW.
21. What is subsatellite point. Explain the geometry behind determination of subsatellite
point.
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3. 22. An LEO satellite has an altitude of 1000 km. Each satellite has two multiple beam
antennas that generate 16 beams. One antenna is used to transmit at 2.4 GHz and
the other antenna receives at 1.6 GHz. Find the gain and dimension of each antenna
on the satellite.
23. Draw and explain functions of antenna subsystem.
24. List out the interferences in FDMA system
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