Updated SATELLITE COMMUNICATION (S.Com) Lab Viva Questions



Updated SATELLITE COMMUNICATION (S.Com) Lab Viva Questions
Updated SATELLITE COMMUNICATION (S.Com) Lab Viva Questions


Kepler’s Laws, Newton’s law, orbital parameters, orbital perturbations, station keeping, Geo stationary and non-Geo-stationary orbits – Look Angle Determination- Limits of visibility – eclipse-Sub satellite point –Sun transit outage-Launching Procedures - launch vehicles and propulsion.

1 What is Satellite?

2 What is the limit of visibility? 

3 State Kepler’s first law. 

4 State Kepler’s second law.

5 State Kepler’s third law.

6 Define apogee.

7 Define Perigee. 

8 What are the geostationary satellites?

9 Differentiate geostationary and geosynchronous satellite. 

10 Define ascending node.

11 Define descending node.

12 Define mean anomaly.

13 Define true anomaly.

14 Mention the apogee and perigee height

15 Identify the basic factors affecting satellite position.

16 The limit of visibility depends on what factors? Considering an earth station at the equator, with the antenna pointing either west or east along the horizontal calculate the limiting angle. 

17 Write short notes on station keeping.

18 What is look angle?

19 Write short notes on station keeping.

20 Which parameters decide the system reliability?

21 A satellite moving is orbiting in the equatorial plane with a period from period from perigee to perigee of 12hrs.Given the eccentricity is 0.02. Calculate the semimajor axis. The earth’s equatorial radius is 6378.1414 km.

22 Differentiate ascending node from descending node.

23 Find the viewing angle of a geostationary satellite orbiting at 42000km from an earth station making an elevation angle of 25 degrees.

24 List the differences between LEO and MEO satellites.

25 What are the features of LEO? 

26 Define orbital period.

27 What is prograde orbit direct orbit?

28 What is a geostationary orbit?

29 Distinguish between LEO system and GEO system. 

30 Name the Keplerian element set.

31 What is meant by sun transit outage?

32 A satellite is in an elliptical orbit with eccentricity of 0.6 and perigee altitude 1000 Km. Determine: a) The semi major axis b) The period of revolution

33 Assume a circular orbit: Using Newton’s law of gravitation and Newton’s second law, determine the acceleration of a satellite.


Spacecraft Technology- Structure, Primary power, Attitude and Orbit control, Thermal control and Propulsion, communication Payload and supporting subsystems, Telemetry, Tracking and command-Transponders-the Antenna Subsystem. 

1 Give the two segments of basic satellite communication.

2 Write short notes on altitude control system.

3 What is declination?

4 Formulate uplink and downlink equation of a satellite access

5 Define payload and transponder?

6 Why should an omnidirectional antenna be used aboard a satellite for telemetry and command during the launch phase? 

7 What is meant by Pitch angle?

8 What is a propellant?

9 What is Yaw?

10 What is an zero ‘g’?

11 Write short notes on the spin stabilized satellites.

12 Mention about the functions of AOCs.

13 What is meant by momentum wheel stabilization?

14 Define sky noise.

15 What is the function of Telemetry Tracking and Command (TT&C)?

16 Examine why noise temperature is a useful concept in communication receiver 

17 What is noise weighting?

18 What is an OMT?

19 A satellite downlink at 12 GHz operates with a transmit power of 6W and an antenna gain of 48. 2dB.Calculate the EIRP in dBW

20 What is split body stabilization?

21 Write the objective with the downlink of any satellite communication system must be designed.

22 How do you characterize uplink and downlink?

23 What is the need for thermal control and propulsion?

24 What are the effects to which the displacement in association with tracking feeds gives rise?

25 Why is thermal control necessary in a satellite?

26 Why is the satellite link probably the most basic in microwave communications? 

27 Write the relationship between EIRP and antenna gain?

28 What is the use of frequency reuse technique in communication subsystem and how it is employed?

29 Give the formula for reliability of hardware.

30 What does the term ‘bus’ refer in TT & C?

31 Draw the block diagram of antenna subsystem.


Basic link analysis, Interference analysis, Rain induced attenuation and interference, Ionospheric characteristics, Link Design with and without frequency reuse.

1 What are the earth station parameters affecting C/N ratio?

2 Why is the cassegrain antenna popular for large earth station.

3 An antenna has a noise temperature of 35K and it is matched into a receiver which has a noise temperature of 100K.Claculate the noise power density and the noise power for a BW of 36MHz.

4 What is terrestrial interface?

5 Define antenna gain. 

6 A satellite downlink at 10 GHz operates with a transmit power of 6 W and an antenna gain of 48.2 dB. Calculate the EIRP in dBW. 

7 What is a single carrier per channel (SCPC)?

8 Write the features of MATV

9 What is outdoor unit?

10 What is LNB?

11 What is the major difference between DBS TV and conventional?

12 TV transmission may be classified as full transponder or half transponder transmission. State what this means in terms of transponder access.

13 State the reason for the high-power amplifier in earth stations deploying some sort of redundancy configuration.

14 What is the basic form of a cassegrain antenna?

15 What is called antenna noise?

16 The range between a ground station and a satellite is 42000 km. Calculate the free space loss a frequency of 6 GHz.

17 What is EIRP?

18 What is noise power spectral density?

19 Define noise factor.

20 Define saturation flux density

21 The range between a ground station & a satellite is 42000km. Calculate the free space loss a frequency of 6GHZ.

22 An antenna has a noise temperature of 35k & its matched into a receiver which has a noise temp of 100k. Calculate the noise power density & the noise power for a BW of 36MHZ.

23 What is TWTA?

24 What is polarization interleaving?

25 What are factors contributing to noise in an earth station receiving channel?

26 List the ionospheric effects on space link.

27 What is MATV and state its purpose?

28 A receiving system has antenna noise temperature of 60K & its receiver noise figure 9dB. Find the system noise temperature if room temperature is 290K.

29 State the basic requirements of an earth station antenna.


Modulation and Multiplexing: Voice, Data, Video, Analog – digital transmission system, Digital video Broadcast, multiple access: FDMA, TDMA, CDMA, DAMA Assignment Methods, compression – encryption, Coding Schemes.

1 What is a single mode of operation?

2 What are the methods of multiple access techniques?

3 What is CDMA?

4 Give the types of CDMA.

5 What is a thin route service?

6 Define postamble.

7 What are the advantages of TDMA over FDMA?

8 What is preamble?

9 Define guard time.

10 What is meant by decoding quenching?

11 What are the types of digital speech interpolation?

12 Distinguish centrally controlled random access for satellite access from distributed controlled random access. 

13 How does the spread spectrum system differ from conventional communication systems?

14 What is a single access?

15 What is multiple access technique?

16 Define Multiplexing.

17 What is meant by space division multiple access?

18 What is an error detecting code?

19 What are the limitations of FDMA-satellite access?

20 Write about demand assigned TDMA satellite access.

21 Write about pre-assigned TDMA satellite access.

22 Write the two basic problem in satellite digital transmission. 

23 What is the need of reference burst in TDMA?

24 Distinguish between pre-assigned and demand assigned traffic 

25 Draw the curve for transfer characteristics of TDM.

26 Draw the spectrum of baseband voice signal.

27 What is single channel per carrier? Or Define SCPC.

28 List the features of spread spectrum communication

29 How does a CDMA receiver function for the purpose of synchronization maintenance and reliable data reconstruction?

30 Differentiate multiple access from single access.

31 What is the use of control bits in the data frame?

32 What is the need for burst position synchronization?


INTELSAT Series, INSAT, VSAT, Mobile satellite services: GSM, GPS, INMARSAT, LEO, MEO, Satellite Navigational System. GPS Position Location Principles, Differential GPS, Direct Broadcast satellites (DBS/DTH).

1 Give the 3 different types of applications with respect to satellite systems.

2 Write the principle behind DTH and GPS.

3 Give the types of satellite services.

4 An intelligent VSAT must use what type of networking to permit the maximum utilization of the satellite capacity?

5 What are the applications of Radarsat?

6 What is ECEF?

7 Define dilution of precision in GPS?

8 What is PDOP?

9 What is DBS? Name any two services

10 Give the frequency range of US DBS systems with high power satellites.

11 Write about bit rates for digital television.

12 Give the satellite mobile services. Or write down the names of any four mobile satellite services.

13 What is INMARSAT?

14 List out the regions covered by INMARSAT.

15 What is INSAT?

16 What is GSM?

17 What is GPRS?

18 Define DAB.

19 What is DVB?

20 What is GRAMSAT?

21 Write the four kinds of communication that network structure of MSAT can accommodate. 

22 Write the two areas of satellite communication which are gaining major thrust from leading satellite industry and organization in recent years.

23 Name the services provided by GSM

24 Outline the three regions to allocate the frequency for satellite services. 

25 List the frequency bands assigned for DTH systems. 

26 List the basic principle of VSAT networks.

27 In what ways, does a satellite transfer TV signal to the particular consumer? 

28 Mention the services of INSAT.

29 Write any two features of GPS.

30 What is the difference between active and passive satellites?

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