SATELLITE COMMUNICATION (KEC-062)
B.Tech Semester VI – Theory Examination (2022–23)
SATELLITE-COMMUNICATION-KEC-062
Satellite Communication is a vital branch of communication engineering that deals with the use of artificial satellites to provide long-distance communication services such as television broadcasting, telephony, internet connectivity, navigation, meteorology, and disaster management. This subject combines concepts of orbital mechanics, electromagnetic propagation, antennas, link budget analysis, satellite subsystems, and multiple access techniques. The given question paper is structured to test both theoretical understanding and numerical problem-solving skills related to satellite systems. To score well, answers must be written in a descriptive, logically connected paragraph format, supported by correct terminology, derivations, and explanations.
SECTION A – BASIC CONCEPTS AND TERMINOLOGY
Section A focuses on fundamental concepts and definitions that form the base of satellite communication systems.
The advantages of satellite communication technologies should be explained by highlighting their ability to provide wide area coverage, global connectivity, reliable communication in remote regions, rapid deployment, and support for broadcasting and navigation services. Unlike terrestrial systems, satellites can cover large geographical areas with minimal infrastructure.
Orbital effects must be explained as deviations in satellite motion caused by factors such as earth’s oblateness, gravitational attraction of the sun and moon, atmospheric drag, and solar radiation pressure. These effects cause orbital perturbations and require correction through station-keeping maneuvers.
The look angle and azimuth angle are important for earth station antenna alignment. The look angle refers to the elevation angle above the horizon at which the satellite is observed, while the azimuth angle represents the horizontal direction measured clockwise from true north.
Rain and cloud effects should be explained as atmospheric attenuation phenomena that primarily affect higher frequency bands such as Ku and Ka bands. Rain causes signal absorption and scattering, leading to fading and reduced link reliability.
The INSAT system must be explained as India’s multipurpose satellite system used for telecommunications, broadcasting, meteorology, disaster warning, and navigation services.
The concept of EIRP (Effective Isotropic Radiated Power) should be explained as a measure of transmitted power that combines transmitter power and antenna gain, indicating the effective power radiated in the direction of maximum gain.
Noise-related questions, such as noise figure and equivalent noise temperature, require explanation of how internal noise affects system performance and how noise temperature represents noise power in thermal terms.
Terms like apogee and perigee, timing accuracy, and access control protocols must be explained clearly with reference to satellite orbits, synchronization requirements, and channel sharing among multiple users.
SECTION B – ORBITS, ANTENNAS, AND SATELLITE SYSTEMS
Section B demands detailed explanations and numerical application of satellite communication principles.
The TTCM (Tracking, Telemetry, and Command) system should be explained as an essential subsystem used to monitor satellite health, control its operation, and maintain proper orbit and attitude.
The question on geostationary orbit requires explanation of its advantages such as continuous coverage and fixed earth station antennas, along with disadvantages like signal delay and limited coverage at high latitudes. Numerical problems involving Molniya orbits require application of orbital mechanics to compute time period and velocities at apogee and perigee.
Kepler’s laws of planetary motion must be explained as fundamental laws governing satellite motion. The explanation of ascending and descending nodes should describe how satellite orbits intersect the equatorial plane.
Questions on satellite antennas require explanation of different antenna types such as horn antennas, parabolic reflectors, phased array antennas, and their applications in uplink and downlink communication.
Space qualification and space debris should be explained in terms of reliability testing of satellite components and challenges posed by debris to operational satellites.
SECTION C – LINK BUDGET, ORBITS, AND SATELLITE APPLICATIONS
Section C evaluates analytical depth and system-level understanding. Answers here must be written with proper derivations and explanations.
Orbit perturbations must be explained along with the significance of the G/T ratio, which is a critical figure of merit for earth station performance, combining antenna gain and system noise temperature.
The question on uplink and downlink design requires explanation of factors such as frequency selection, power requirements, atmospheric losses, antenna characteristics, and noise considerations. The difference between uplink and downlink design must be clearly highlighted.
Derivation of the Carrier-to-Noise (C/N) ratio is one of the most important numerical topics. Students must explain each term in the equation and apply it correctly in numerical problems related to satellite TV systems.
The DBS-TV system design requires explanation of direct broadcast satellites, their link budget, and system components.
Topics like satellite signal acquisition, GPS and satellite navigation, and radio navigation principles should be explained with emphasis on positioning accuracy and timing synchronization.
Questions on satellite altitude and stabilization methods require explanation of gravity gradient, spin stabilization, and three-axis stabilization techniques.
The concept of VSAT (Very Small Aperture Terminal) must be explained along with its distinguishing features such as small antenna size, low power, and widespread use in data communication networks.
Finally, satellite subsystems such as power supply and thermal control must be explained, along with brief notes on Indian launch vehicles PSLV and GSLV, highlighting their roles in satellite deployment.
HOW TO WRITE SATELLITE COMMUNICATION ANSWERS IN THE EXAM
In Satellite Communication, never write answers in short bullet points. Always begin with a clear introduction, followed by detailed explanation, derivations where required, and practical relevance. Numerical problems must include assumptions, formula derivation, and step-by-step calculation. Use correct technical terms such as EIRP, G/T, C/N ratio, orbit perturbations, and link budget. Examiners focus heavily on clarity of explanation, correct application of formulas, and logical presentation.
