Babu Madhav Institute of Information Technology, UTU 2015 Five years Integrated M.Sc. (I.T.) -­‐ Semester 5 060010506 – Satellite Communication Question Bank Orbit, Orbital Slots, Frequencies, Footprints and Coverage Short answer questions 1. How satellite stays in orbit only and orbiting the earth? 2. Which effect slightly pulls the satellite out of its intended orbit and orbital slot? 3. Give one example of circular orbit. 4. Define the term – altitude. 5. What is called to orbits with less than 90 degree of inclination? 6. What is called to orbits with greater than 90 degree of inclination? 7. If the orbit is circular, the satellite motion is at a constant speed. – Comment. 8. For elliptical orbit, at which point satellite move faster and at which point satellite move slower? 9. Does size or mass of the satellite determine the period? Why? 10. What is the exact time required for earth to turn west to east in one day? 11. Which satellites are called geosynchronous? 12. To become geostationary, which three conditions must be satisfied by orbits? 13. What is the circumference of Clarke orbit? 14. It would take only three GSO satellites to cover almost all of the earth with much overlap. – Comment. 15. Time taken for a radio signal to travel between the station and the satellite will vary from 0.119 sec to 0.139 sec. – Comment. 16. What is called quasi-­‐zenith satellites and figure-­‐eight orbits? 17. What is the need of system called string-­‐of-­‐pearls? 18. Define the term – constellation. 19. What is Virtual GEO? Write two advantages of it. 20. What is Geosynchronous transfer orbit? 21. Comment on “limited natural resource” in the context of orbits. 22. What is the equivalent degree E for Satellite at 39.5 degree W? 23. What is to be called to orbits with inclination less than 90 degree? 24. To become truly geosynchronous, what is the distance of satellite from the center of earth? 25. Which band is used for fixed and mobile services? 26. Give two advantages and disadvantages of GSO. 27. Where foci are located in circular orbit? 28. How many Non-­‐geostationary orbits are possible? 29. For Clarke orbit, 5 degree is equal to how many km? 30. Why heater is mounted on satellite? 31. Give the method by which approximate location of the satellite can be known. 32. Give the second law of Kepler. 33. What is the normal time taken by radio signal to travel from earth station to satellite? 34. What is to be called to longitude position of GSO satellite? 35. What is frequency coordination? 36. Give the longitude ranges which are most crowded portions. 37. How much area can be covered by global beam? 38. LEO and MEO systems pass across the earth along, that is called what? 39. Which period of the year is called satellite eclipse season? 40. Which radio transmitter sends signals that earth station receive to accurately determine Mr. Sapan Naik Page 1 Babu Madhav Institute of Information Technology, UTU 2015 the satellite’s position? What is Lockheed Martin A2100? Which device is used to transfer interior heat of satellite to outside? Newer satellites are using more expensive gallium arsenide cells. Why? Write a name of satellite’s angle above the horizon, which is used for pointing a dish. List out any four major subsystems of a communication satellite. Give one advantage and disadvantage of three-­‐axis-­‐stabilized structure. Differentiate station keeping and attitude control. There is a tradeoff between total battery capacity and some other massive items on board. How? 49. Write the eccentricity of Clarke orbit. 41.
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Long answer questions 1. List outs three Kepler’s Laws and explain in detail. 2. Differentiate Geosynchronous and Geostationary orbits. 3. Discuss the advantages and disadvantages of satellites in geostationary orbit for communication. 4. Write short note on Little and Big LEOs. 5. Describe Molniya orbits. 6. Explain orbit insertion or circularization or apogee firing procedure. 7. Give Kepler’s second law. How it is useful for satellite communication? 8. There is only one truly Geostationary orbit. Why? 9. Write the name of the orbit, which is 90 degree to Clarke orbit. How Molniya orbit is good alternative for Clarke orbit? 10. Give two disadvantages of Clarke orbit. How Geosynchronous transfer orbit is used to satellite in Clarke orbit? Multiple choice questions 1. If the eccentricity is exactly zero, it is special case of a. Elliptical orbit b. Circular orbit c. Rectangle orbit d. None of the above 2. To be truly geosynchronous, the satellite must lie ____ km above the surface of the earth. a. 35,786 b. 42,164 c. 35,687 d. 42,416 3. Exactly how many truly geostationary orbits are possible? a. 0 b. 1 c. 100 d. Infinite 4. What do you mean by HEO? a. High End Orbit b. Highly Elliptical Orbit c. Highly Effective Orbit d. Highest Effective Orbit Mr. Sapan Naik Page 2 Babu Madhav Institute of Information Technology, UTU 2015 Fill in the blanks with appropriate answer 1. Range of eccentricity is from ______ to ______. 2. If the orbit is elliptical, the object the satellite is orbiting is at _____ of the ellipse. 3. The outermost tip of the ellipse, where the satellite is farthest from earth, called ____ and the closest point to earth, called ____. 4. GSO satellite is about ____ Earth radii away from its sub satellite point. 5. LEO operates in the ____ part of the radio spectrum. 6. After the satellite is checked out and the spacecraft reaches its apogee, a command is sent to fire a solid fueled motor built into the satellite, called the ____ . 7. Location on earth’s surface directly below any satellite is called _____________. 8. The position of GSO satellite in orbit, denoted by its longitude is called __________. 9. Some satellites operate in two or more frequency bands, these are often called ____. 10. Range of eccentricity is from ______ to ______. State whether the below given statements are true or false 1. Closed orbits have the shape of an ellipse, and the ellipse lies in a single plane. 2. The period of the orbit depends only on the average distance of the satellite. 3. Non geostationary orbits are internationally regulated. 4. All the satellites operating in a given service and frequency band use the same range of frequencies. 5. LEO and MEO satellites will have shorter operational lives than GSO satellites. 6. GSO satellite can see 20% of the entire surface of the planet. Applied answer questions 1. Write any two major causes of depolarization. Sometimes signal does not enter to dish directly from the satellite but may have bounced in after reflection from various objects of earth. What this phenomenon is called? 2. Which measurement is used for signal quality? Write “triple whammy” effect. 3. Write the name of the orbit, which is 90 degree to Clarke orbit. How Molniya orbit is good alternative for Clarke orbit? 4. Write two disadvantages of Clarke orbit. How geosynchronous transfer orbit is used to put satellite in Clarke orbit? 5. “Elevation angle and path length effect the signal strength” – Comment. 6. Which are the points need to keep in mind while placing satellite into orbit? Mr. Sapan Naik Page 3 Babu Madhav Institute of Information Technology, UTU 2015 Satellite Systems and Construction Short answer questions 1. By which method, one can identify approximate location of GSO? 2. Which are the services provided by satellite and which frequencies are used for each services? 3. Four spots along the GSO where all forces balance out. Give the name of these longitudes. 4. What do you mean by subsatellite point and satellite slot? 5. What is the location of satellite in Greenwich Meridian Eastward if satellite at position 37.5 degree west? 6. How Skyplex is used for onboard processing in satellite? 7. How to characterize transponder? 8. What is called to the downlink power measured in dB? 9. What do you mean by spot beam? 10. Give any two steps that can be taken in solar outage. 11. What do you mean by satellite neighborhood? 12. Closest point of ellipse to Earth is called what? 13. Which antenna is used for global beam? 14. Write the satellite system name, which uses crosslink antennas. 15. Write the name of compass direction towards satellite, which is used for pointing a dish. 16. List out any four specification of communications payload. 17. Which arrangement of motors and mechanical flywheels can partially correct the deviations in orientation? 18. In which structure, satellite looks like a tin can? Long answer questions 1. Discuss the parameters on which types and functions of satellites depend. 2. Hybrid satellite adds to the difficulty of minimizing interference between satellites. Give your comments. 3. Write two solutions for perturbation effect. 4. How hybrid satellites add more difficulties in minimizing interference between satellites? 5. What to call a satellite system, which uses two types of fuels? Multiple choice questions 1. Satellite is at 349.50 degree E is equal to what degree W? a. 11.50 b. 11.00 c. 10.50 d. 10.00 2. What kind of problem occurs for below arrangement? Earth-­‐Satellite-­‐Sun(All are in same line with given order) a. Solar outage b. Sun outage c. Sun transit d. All of above 3. LEO and MEO systems pass across the earth is _____. Mr. Sapan Naik Page 4 Babu Madhav Institute of Information Technology, UTU 2015 a. Satellite neighborhood b. Orbital spacing c. Orbital shaming d. Ground track 4. ___________ band use for broadcast services. a. Ka-­‐band b. C-­‐band c. Ku-­‐band d. None of the above 5. 37.5 degree W and 322.5 degree E, over ___________ . a. Indian Ocean b. Pacific Ocean c. Atlantic Ocean d. None of the above 6. Smaller region of earth called a. Global beam b. Regional beam c. Stat beam d. All of the above 7. What is the full form of DARS? a. Digital audio radio from satellite b. Digital audio radio from system c. Data audio radio from satellite d. Digital atomic radio from satellite 8. What is the full form of PSTN? a. Provider-­‐switched telnet network b. Public-­‐switched telnet network c. Public-­‐switched telephone network d. Public-­‐switched telephone noise 9. Which one of below is not type of earth station? a. single-­‐purpose station b. gateway station c. teleports d. none 10. A typical x-­‐y mount 9.3-­‐m diameter dish used for which band? a. Ka-­‐Band b. C-­‐Band c. Both (a) And (b) d. none 11. A relative azimuth, the value will always be less than________degree? a. 90 degree b. 95 degree c. 80 degree d. 10 degree Fill in the blanks with appropriate answer 1. ____________ band use for mobile services. 2. FM radio stations in United States broadcast in the _________ to__________MHz band of frequencies, each station. 3. ___________ or ___________ periods are eclipse season. 4. Eclipse season lasts ________ if you consider only the dates. Mr. Sapan Naik Page 5 Babu Madhav Institute of Information Technology, UTU 2015 5. In ___________ season earth station cannot do any thing. 6. The complex and continues topic of minimizing interference is called____________ . 7. ____________Was Very First Commercial Communication Satellite.(Telstar) 8.A___________mounted on a van to provide telemedicine services in rural areas. 9. The satellite 's angle above the horizon called_____________. 10. ______________and ________________ are types of antenna mountings. 11. ___________ is a major constant environmental factor for unprotected dishes. 12. ______________and ________________ways are available for measured azimuth. State whether the below given statements are true or false 1. A completely dark inner part called penumbra. 2. In solar outage can increase the signal quality. 3. In eclipse season satellite can use battery or fuel. 4. Global beam covers full said of antenna. 5. One satellite can operate in two or more frequency bands. 6. L-­‐band can use for connect with mobile user. 7. Most earth station antenna are located in open air. 8. Telstar was not in geostationary orbit. 9. A small wire located at the focus of the dish, while the British usually refer to them antennas. 10. Gateway earth stations serve as the interface points between terrestrial networks and satellites. 11. The three numbers you need to point a dish are the compass direction toward the satellite called azimuth. 12. A mount has one major axis of rotation, called a polar axis. Applied answer questions 1. How much number of days, GSO satellite remains in full sunlight? 2. What is the actual need of satellite spacing? 3. What kind of problem occurs and how to solve for below arrangement? Earth – Satellite – Sun (All are in same line with given order) Mr. Sapan Naik Page 6 Babu Madhav Institute of Information Technology, UTU 2015 Satellite Operations Short answer questions 1. What is called to the sensitivity of incoming signals measured in dB? 2. Write any two advantages of solid-­‐state power amplifiers. 3. Write the name of process, which integrate satellite onto the top stage of the launch vehicle. 4. The basic components (structure and capability) of a typical commercial communication satellite is called what? 5. Give one advantage and disadvantage of spinner structure. 6. Write any two functions of repeaters. 7. Transponder redundancy is needed in satellite system. Why? 8. In which situation, SSL is useful? 9. Two closely spaced satellites have same frequency antenna beam pattern pointed at different region of the earth. What this arrangement is called? 10. Can satellites using different frequency be put at same orbital slot? 11. If the satellite has enough battery capacity aboard to keep its communication going throughout an eclipse, what is it called? 12. In which situation, inter satellite link is useful? 13. How ion thrusters work? 14. Write any two functions of transponders. 15. List any two disadvantages of traveling wave tubes amplifiers. Long answer questions 1. Which are the points need to keep in mind while putting satellite into orbit? 2. Explain satellite station keeping and orientation operations. 3. Differentiate penetrating and non-­‐penetrating antenna mounts. 4. List and explain four characteristics of transponder. 5. Differentiate penetrating and non-­‐penetrating antenna mounts. Multiple choice questions 1. ___________ is to track a satellite to know where it is. (a) Telemetry (b) Satellite Control (c) Tracking (d) Relocation 2. TT&C stands for ________________. (a) Tracking, Monitoring & Control (b) Tracking, Telemetry & Control (c) Telemetry, Tracking & Center (d) Timing, Tracking & Center 3. Four spots along with GSO where all forces balance out. These longitudes called ____________. (a) Orbital spacing (b) Equilibrium point (c) Perturbations (d) Poles 4. _____________ is used in repositioning satellite in another orbital slot. (a) Spot beam (b) Equator Mr. Sapan Naik Page 7 Babu Madhav Institute of Information Technology, UTU 2015 (c) RCS (d) Fuel 5. To control the satellite is to command the satellite to do what you want it to is known as ______________. (a) delta-­‐V (b) order wires (c) satellite control (d) orientation pointing 6. Solution of perturbation is _____________. (a) polar orbit (b) Relocation (c) RCS thruster (d) tracking 7. ________________ are designed to provide low-­‐speed data services and operate in the VHF part of the radio spactrum. (a) Virtual (b) NGSO (c) Little LEOs (d) Big LEOs 8. After the satellite is checked out and the spacecraft reaches its apogee, a commanis sent to fire a solid-­‐fueled motor built into the satellite called________________ . (a) Perigee Kick Motor (b) Apogee Kick Motor (c) Orbital Motar (d) Satellite Kick Motar 9. Which orbital satellite sees only a small fraction of Earth's surface, often only 2% to 15%. (a) Little LEOs (b) Big LEOs (c) LOW orbits (d) MEO orbits 10. Kepler’s first law states (a) The path followed by a satellite around the primary will be an ellipse. (b) The path followed by a satellite around the primary will be an circle. (c) The path followed by a satellite around the primary will be an sphere (d) None of the above 11. When an Earth satellite makes a circular orbit, it has constant (a) speed (b) distance from the Earth (c) force of gravity on it (d) all of the above 12.____________ or ____________ satellites can provide service to 100% of the earth’s surface, including polar regions. (a) MEO, GEO (b) LEO, MEO (c) GEO, LEO (d) Molniya, LEO Fill in the blanks with appropriate answer 1. A satellite is controlled from a _________ which receives & sends TT&C information to dedicated TT&C earth stations that communicate with satellite. 2. The amount by which satellite’s motion is altered is measured in meter per second & called______________. Mr. Sapan Naik Page 8 Babu Madhav Institute of Information Technology, UTU 2015 3. Effect of the pressure of sunlight on the satellite; it’s major effect is to slightly alter the ___________ of the orbit. 4. _____________ is the information on satellite systems status sent back to earth for controllers to monitor. 5. The satellite would appear to move up & down , above & below the Clarke orbit , & slightly east & west describing a small “figure-­‐8” in the sky. The technical name for this “figure-­‐8” is an ______________. 6. SCC stands for ________________. 7. GSO satellite can see about _______% of the entire surface of the planet. 8. ___________ satellite’s distance from the surface of the earth. 9. If the plane of the orbit is not the same as the equator, the angle the plane makes with the equator is called the ______________ . 10. _________________orbit can provide telephony services. 11. ______________degree Equator of “Virtual GEO”. 12. ______________ satellite cannot be seen from Polar Regions. State whether the below given statements are true or false 1. Telemetry is to track a satellite to know where it is. 2. Relocation a satellite reduces its operational lifetime. 3. Satellite Control is to control the satellite is to command the satellite to do what you want it to. 4. Satellites are typically kept within 2 degree to 5 degree of their assigned position. 5. Four spots along with GSO where all forces balance out. These longitudes called poles. 6. Comsat maneuver is the technique simply tilts the antenna pattern down when the satellite moves up above the equatorial plane, and tilts is up when the satellite is below this plane. 7. MEO satellites are usually smaller, liter and easier to launch. 8. Geostationary satellites, once placed in their correct orbit, remain correctly positioned until the lifetime of their equipment expires. 9. Geostationary orbit must be circular. 10. Molniya orbit can cover both Polar Regions. 11. Orbits with I less then 90 degree called direct. 12. In Clarke orbit a satellite will not move uniformly. Applied answer questions 1. There is a tradeoff between total battery capacity and some other massive items on board. How? 2. How electric propulsion works? 3. Why backup systems are required in satellite? 4. What is used for stabilization, which uses the unequal forces of gravity on a long boom or antenna to approximately maintain altitude? Mr. Sapan Naik Page 9 Babu Madhav Institute of Information Technology, UTU 2015 Atmospheric effects on Signals Short answer questions 1. Which kind of interference is created because of beam width is seen by more than one satellite? 2. What are the chances of eclipse for LEO satellites? 3. What is eclipse in the context of satellite? Satellite is at 359.5 degree E is equal to what degree W? 4. Extra amount of signal provided to overcome rain effect is called what? 5. Give the name of atmospheric effect on signal caused because of difference in the density of air and its components. 6. For ellipse, what happens if eccentricity is zero? 7. High latitudes have problem seeing GSO satellites. How to solve this problem? 8. Define altitude. 9. Give the name of effect, which pulls satellite out of its intended orbit by Sun and Moon. 10. Two closely spaced satellites have same frequency antenna beam pattern pointed at different region of the earth. What this arrangement is called? 11. What is to be called a physical separation between two orbits? 12. Why one cant put unlimited batteries on satellite? 13. Which kind of problem occurs during solar outage? 14. Write the name of a test in which satellite is put into a vacuum chamber and heated to the condition close to those it will encounter in space. 15. What a satellite system called, which uses hydrazine alone as fuel? 16. Which antenna is used for smaller beam? 17. Write name of antenna, which is composed of many smaller antennas, may be coils of wire or a flat plate with slots in it. 18. Why Gallium arsenide cells are better than silicon-­‐based cells? Long answer questions 1. What will be the effect of atmosphere on C-­‐band frequency? How different form of water affects the satellite communication? 2. What is eclipse? Explain eclipse in Clarke orbit. 3. “Elevation angle and path length effect the signal strength” – Comment. 4. Give any two major causes of depolarization. When signal not enter to dish directly from the satellite but may have bounced in after reflection from various objects of earth is called what? Multiple choice questions 1. Water vapor is the major absorber between _________and above__________. (a)
20 and 30 GHZ, 40 GHZ (b)
10 and 40 GHZ, 80 GHZ (c)
45 and 65 GHZ, 60 GHZ (d)
30 and 60 GHZ, 20 GHZ 2. Which are the major causes of depolarization? (a)
Raindrops (b)
Ice crystals (c)
Irregularities (d)
All of above 3. Radio propagation engineers measure the amount of depolarization by a number Mr. Sapan Naik Page 10 Babu Madhav Institute of Information Technology, UTU 2015 called the_________. (a)
Scintillation (b)
Scattering (c)
Cross-­‐polarization discrimination (d)
Polarization 4. Circularly polarized waves are affected more than linearly polarized ones by as much as_______ db. (a)
25 (b)
35 (c)
85 (d)
15 5. How many types of scattering affecting satellite? (a)
6 (b)
3 (c)
8 (d)
2 6. Between the spinning part and the Despun platform are very critical components called _________. (a) Bearing and power transfer accountability (b) Bearing and power transfer Assemblies. (c) Bearing and position transfer Assemblies (d) Battery and power transfer accountability 7. There are how many generic structure of GSO Satellite ______. (a) 1 (b) 2 (c) 3 (d) 4 8. Smaller satellites may have only a single _____________. (a) Dish antenna (b) Horn antenna (c) Phased array antenna (d) Inter satellite link antenna. 9. Maintenance of correct orbital position is called __________. (a) Attitude control (b) Station Keeping (c) Beacon (d) Orientation 10. OBP satellite may have some steps such as (a) error correction (b) buffering the data (c) decoding data packet (d) All of the above 11. A transponder is characterized by ___________ (a) Center frequency (b) Bandwidth (c) All of the above (d) None Fill in the blanks with appropriate answer 1. Hail is ______water. 2. The water is comes in the form of ________ and ________. 3. _______ and ______ are types of scattering affects. Mr. Sapan Naik Page 11 Babu Madhav Institute of Information Technology, UTU 2015 4. _________ is sending the same information over the same channel at different time. 5. _________ is the rapid changes in the electrons in the layer of the atmosphere called the___________. 6. The effects on a signal depend on the _______ through the atmosphere. 7. One basic structure looks like tin can, and is called _________. 8. An antenna structure and the communications electronics are part of what is termed _______________. 9. Between the spinning part and the Despun platform are very critical components called _________. 10. One common device called a ____________ is used to transfer heat from the interior to the outside. 11. The electronics aboard the satellite that provide the communication functions are called _________ sometimes abbreviated as _______. 12. The planned _____________ satellites designed for Internet traffic will have complex data handling and switching abilities, sometimes called Internet in the sky. State whether the below given statements are true or false 1. Sleet is another form of snow in the atmosphere. 2. Fog and clouds are of major effect only above about 10GHZ. 3. Path diversity is a sampling to improve the quality of a degraded satellite link. 4. At Ka-­‐band the rain noise is much greater. 5. Scattering is a process that not changes the direction of a wave. 6. The problem caused by the atmosphere is Faraday effect. Applied answer questions 1. In which structure, satellites look boxy and usually have one or two large solar panels like wings? 2. If the satellite has enough battery capacity aboard to keep its communication going throughout an eclipse, what this phenomenon is to be called? 3. Can satellites using different frequency be put at same orbital slot? Mr. Sapan Naik Page 12