Interview questions answers Satcom | Satellite Communication

This page covers top Satcom interview questions and answers will help interviewee pass the job interview for satcom (satellite communication) engineer job position. This Satcom questions are written by specialists in satellite communication domain.

Question -1: What is the major function of a satellite transponder ?
Answer -1: The main function of a satellite transponder is frequency conversion and amplification of received signal. For C band transponder, it receives 6 GHz from Ground and converts it to 4 GHz for transmission towards the ground (i.e. Earth).

Question -2: Which are the frequency bands used by satellite to connect with Ground Stations or Earth Stations with the help of VSATs ?
Answer -2: Following bands are used by satellite for different applications.
L band : 1 to 2 GHz
S band : 2 to 4 GHz
C band : 4 to 8 GHz
X band : 8 to 12 GHz
Ku band : 12 to 18 GHz
K band : 18 to 26.5 GHz
Ka band : 26 to 40 GHz

Question -3: Which are the name of orbits in which satellites are being placed ?
Answer -3: The different satellite orbits include Geostationary circular orbit (at 35786 Km), Molnya orbit (at apogee of 40000 Km and perigee of 1000 Km), Tundra orbit (apogee of 46300 Km and perigee of 25250 Km) and Low Earth Circular Orbit (at height of 500 to 800 Km).

Question -4: Mention different parts of a satellite and describe their functions.
Answer -4: The major satellite parts are transponder, antenna, solar cell, battery backup, camera and thrusters. Following are the functions of each of these parts.
Transponder : It does frequency conversion. Amplifier may be internal to transponder or external which performs amplification of signal before relaying it to the Earth.
Antenna : It performs EM waves transmission and reception to and from the air (i.e. free space).
Solar cell : It converts solar energy to electrical energy for use as power supply for operation of a satellite.
Battery : It provides power to the satellite when sufficient power is not produced by satellite solar cells.
Camera : It is used for capturing images as and when needed.
Thrusters : They are used to keep the satellite in the orbit. They are fired from the Earth as and when needed.

Question -5: What are the different types of satellites in use today ?
Answer -5: The satellites are categorized into active satellite and passive satellite. Further satellite types include Geostationary satellite, LEO satellite and MEO satellite.
➨Refer Satellite types >> for detailed description of each of these satellite types.

Question -6: Mention different applications of a satellite.
Answer -6: The typical applications of a satellite are TV signal relaying, satellite radio, surveillance, navigation, satellite phone, weather information relaying, satellite images, satellite maps and so on.

Question -7: What are the functions of satellite TTC (Telemetry, Tracking and Control) ?
Answer -7: The telemetry system is used to report status of on-board subsystems to the ground station. Tracking is used to know the position of the satellite all the time. A command and control system permits ground station to control the satellite position.

Question -8: What is the difference between SCPC and MCPC in satellite communication ( Satcom ) ?
Answer -8: SCPC stands for Single channel per carrier where as MCPC stands for Multiple channels per carrier. These channels can carry voice, data or control or monitoring commands.

Question -9: Explain the full form of BUC and LNB and their functions.
Answer -9: BUC stands for Block Up Converter where as LNB stands for Low Noise Block Converter. BUC houses RF Up converter and RF Amplifier. LNB houses RF LNA and RF Down converter.

Question -10: Draw block diagram of VSAT and describe the functions of its modules.
Answer -10: As shown VSAT consists of two main portions viz. RF and baseband. RF part houses RF Transceiver, Power Amplifier, LNA and OMT. Baseband part houses MUX/DeMUX, Encryption/Decryption, MODEM and interface (voice line/data line).

➨Refer article on VSAT system overview >> for more information VSAT and its working with satellite.

This set of Satcom interview questions and answers are useful for freshers and experienced level of satcom job positions. Refer following links on Satellite communication (Satcom) for more information.

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