Satcom Interview Questions and Answers

This page covers top Satcom interview questions and answers to help interviewees pass job interviews for satcom (satellite communication) engineer positions. These Satcom questions are written by specialists in the 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 the received signal. For a C band transponder, it receives 6 GHz from the ground and converts it to 4 GHz for transmission towards the ground (i.e., Earth).

Question 2: Which are the frequency bands used by satellites to connect with Ground Stations or Earth Stations with the help of VSATs?

Answer 2: The following bands are used by satellites 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: What are the names of orbits in which satellites are 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)
• Low Earth Circular Orbit (at a 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. Here are the functions of each:

• Transponder: Performs frequency conversion. An amplifier may be internal to the transponder or external, performing amplification of the signal before relaying it to Earth.
• Antenna: Performs EM wave transmission and reception to and from the air (i.e., free space).
• Solar Cell: Converts solar energy to electrical energy for use as a power supply for the operation of a satellite.
• Battery: Provides power to the satellite when sufficient power is not produced by the satellite’s solar cells.
• Camera: Used for capturing images as and when needed.
• Thrusters: Used to keep the satellite in orbit. They are fired from Earth as and when needed.

Question 5: What are the different types of satellites in use today?

Answer 5: Satellites are categorized into active satellites and passive satellites. Further satellite types include Geostationary satellites, LEO satellites, and MEO satellites.

Question 6: Mention different applications of a satellite.

Answer 6: 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 reports the status of on-board subsystems to the ground station. Tracking is used to determine the position of the satellite at all times. A command and control system permits the ground station to control the satellite’s position.

Question 8: What is the difference between SCPC and MCPC in satellite communication (Satcom)?

Answer 8: SCPC stands for Single Channel Per Carrier, whereas MCPC stands for Multiple Channels Per Carrier. These channels can carry voice, data, 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, whereas LNB stands for Low Noise Block Converter.

BUC houses the RF Up Converter and RF Amplifier. LNB houses the RF LNA and RF Down Converter.

Question 10: Draw a block diagram of VSAT and describe the functions of its modules.

Answer 10: As shown, VSAT consists of two main portions: RF and baseband.

The RF part houses the RF Transceiver, Power Amplifier, LNA, and OMT.

The baseband part houses the MUX/DeMUX, Encryption/Decryption, MODEM, and interface (voice line/data line).

This set of Satcom interview questions and answers are useful for freshers and experienced candidates seeking Satcom job positions.