MITRC REFRESHER COURSE Communications 1.
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ANSWER KEY
The first passive satellite a. Telstar b. Early Bird c. Sputnik I d. Moon
10. A transponder is a satellite equipment which a. Receives a signal from earth station and amplifies it b. Changes the frequency of the received signal c. Retransmit the received signal d. All of the above
The first active satellite a. Sputnik I b. Telstar c. INTELSAT I d. Explorer I
11. Multiple repeaters in communications satellites are known as a. Transponders b. Detectors c. Modulators d. Transceivers
The first geostationary satellite launched in 1965 is a. Syncom I b. Sputnik I c. Explorer I d. Early Bird
12. Satellite-to-satellite link is also called a. Uplink b. Downlink c. Crosslink d. Weakest link
The average lifetime of geosynchronous satellites is about __________ years. a. 5 b. 10 c. 15 d. 20
13. The expression for satellite link frequencies such as 14/12 GHz denotes that a. 12 GHz is the uplink frequency and 14 GHz is the downlink frequency b. the system is operating at a mean frequency of 13 Ghz c. 14 GHz is the uplink frequency and 12 GHz is the downlink frequency d. the 14 GHz frequency is backup for 12 GHz frequency or vice versa
A communication satellite is a repeater between a. A transmitting station and receiving station b. Many transmitting stations and many receiving stations c. A transmitting station and many receiving stations d. Many transmitting stations and a receiving station
14. The most widely used microwave bands for commercial applications are a. C band and X band b. X band and S band c. C band and Ku band d. S band and Ku band
One of the main applications of satellite communications is monitoring the ecological situation of the earth. This is known as a. Navigation b. Surveillance c. Remote control d. Remote sensing
15. At present, the RF band mainly used by most satellites is a. EHF b. UHF c. SHF d. VHF
What vacuum tube used to amplify RF signal for transmission through the downlink to station receiver? a. Magnetron b. Klystron c. Twystron d. TWT
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A high power tube used in transmission of RF signal uplink a. Magnetron b. Klystron c. BWO d. TWT
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A stage in transponder and downlink system which amplifies the signal and ensuring that noise is suppressed as possible a. Mixer b. Demodulator c. LNA d. IF amplifier
Satellite
16. The required antenna size __________ as the operating frequency of a system increases, assuming that antenna gain remains unchanged. a. Remains the same b. Increases c. Decreases d. All of the above 17. A 20-m antenna gives a certain up-link gain at frequencies of 4/6 GHz. For getting the same gain in 20/30 GHz band, antenna size requires __________ meters. a. 100 b. 4 c. 1 d. 10 1
MITRC REFRESHER COURSE Communications
ANSWER KEY
Satellite
c. d.
18. Orbital disturbances of a geosynchronous satellite are caused by a. Moon b. Sun c. Earth d. All of the above
A pass from south to north A pass from north to south
27. Satellite rotating in an orbit takes it over the north and south poles is in a. Inclined orbit b. Polar orbit c. Equatorial orbit d. Declined orbit
19. Geosynchronous satellites a. Has the same period as that of the earth b. Has a circular obit c. Rotates in the equatorial plane d. All of the above
28. The farthest point a satellite can reach is a. Apogee b. Perigee c. Altitude d. Attitude
20. To cover all inhabited regions of the earth, the number of geosynchronous satellites required is a. 5 b. 10 c. 2 d. 3
29. Include all earth stations within line-of-sight path of a satellite a. Satellite shadow b. Earth shadow c. Zonal d. Global
21. A geostationary satellite is one which a. Hangs motionless in space about 36,000 km above the earth b. Travels around the earth about 24 hrs. c. Remains stationary above the earth d. Appears stationary above the earth
30. The different multiple accesses which permit many satellite users to operate in parallel through a. A Single Transponder Without Interfering With Each other are b. FDMA c. TDMA d. CDMA e. All of the above
22. Geosynchronous Communication satellites travel around the earth in circular orbits with forward speed of about __________km/hr. a. 100,000 b. 36,000 c. 11,200 d. 22,800
31. A digital technology that uses a low power signal spread across a wide bandwidth. With this technology, a phone call is assigned a code instead of a certain frequency. Using identifying code and a low power signal, a large number of channels can used the entire bandwith a. TDMA b. PCDMA c. PMA d. CDMA 32. The use of the same frequency on the same geographical area a. Frequency reuse b. Roaming c. Homing d. Cellular
23. The period of the satellite is a. The amount of time it takes for a satellite to complete one orbit b. The point on an orbit where satellite to complete one orbit c. The time it takes the satellite to travel from perigee to apogee d. An orbital arc that extends from 60 degrees west longitude to 145 degrees west longitude 24. What is the satellite's period orbiting in a circular pattern with elevation of 1000 km? a. 1 hr 45 mins b. 2 hrs 45 mins c. 2 hrs 30 mins d. 3 hrs
33. In selecting a satellite system, the first determining factor is a. Coverage area b. EIRP c. Antenna size d. Antenna gain 34. The earth's area or region that the satellite can receive from or transmit to a. Footprint b. Skip zone c. Primary area d. Finger print
25. A satellite, orbiting in a circular orbit, a. Has constant velocity b. Has varying velocity c. Is not moving at all d. Both a and b 26. What is a descending pass for a satellite? a. A pass from west to east b. A pass from east to west 2
MITRC REFRESHER COURSE Communications
ANSWER KEY
35. Satellite radiation pattern that covers 1/3 of the earth's surface a. Earth b. Zonal c. Spot d. Global
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c. d.
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36. A satellite position is measured by its _________ angle with respect to the horizon. a. Elevation b. Depression c. Azimuth d. Incidence
44. A satellite communication link between Pinugay Earth Station, Philippines and Mt. Fucino Earth Station, Italy is to be established. If the assigned uplink frequency at Pinugay Earth Station is 6175 MHz, what is the downlink frequency at Mt. Fucino Earth Station, in MHz? a. 4545 b. 3950 c. 3789 d. 4200
37. The _________ angle measures the satellite position clockwise from the direction of true North a. Elevation b. Depression c. Azimuth d. Incidence
45. "The orbit of any planet is an ellipse with the sun at one focus". This is a. Kepler's First Law b. Kepler's Second Law c. Kepler's Third Law d. Law of universal Gravitation
38. GPS has a total number satellites equal to a. 12 b. 24 c. 36 d. 48
46. When a satellite orbits in the opposite direction as the earth's rotation with an angular velocity less than that of the earth a. Orbital b. Prograde c. Retrograde d. Geostationary
39. How many elliptical orbits does Navstar GPS have? a. 5 b. 6 c. 7 d. 8
47. The actual user information conveyed through the satellite system a. Bus transmission b. Payload c. Prograde d. Retrograde
40. What is the free space attenuation of a satellite system operating at 36,000 km above the earth operating at 5 GHz? a. 180 dB b. 190 dB c. 198 dB d. 189 dB
48. The spatial separation between geosynchronous satellites a. 1-3 degrees b. 3-6 degrees c. 6-8 degrees d. 8-10 degrees
41. The FDMA technique wherein voice band channels are assigned on “as needed" basis. a. PAMA b. DAMA c. SSMA d. CDMA
49. The footprint which covers a very small geographical area. a. Spot coverage b. Zonal coverage c. Earth coverage d. Regional coverage 50. The satellite frequency reuse method which sends different information signals using vertical or horizontal electromagnetic polarization a. Multiple coverage areas b. Dual polarization c. Spatial separation d. Spread spectrum
42. A satellite equipped with electronic devices to receive, amplify, convert, and retransmit signals. a. Passive b. Active c. Uplink d. Downlink 43. An earth station transmits signal to a satellite 38,500 km, directly overhead it. What is the propagation delay when the signal is received back at the same earth station, in milliseconds? a. 257 b. 200
51. __________ detects the satellite signal relayed from the feed and converts it to an electric current, amplifies and lower its frequency. a. Feedhorn b. Satellite dish 3
MITRC REFRESHER COURSE Communications c. d.
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Satellite receiver LNA
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35 degrees
61. The main power sources for satellites are a. Batteries b. Solar cells c. Fuel cells d. Thermoelectric generators
52. Satellites used for intercontinental communications are known as a. Comsat b. Domsat c. Marisat d. Intelsat
62. What is the common up-converter and down-converter IF? a. 36 MHz b. 40 MHz c. 70 MHz d. 500 MHz
53. What is the basic function of a communications satellite? a. To act as a receiving antenna for broadcast FM b. To compensate for the antenna limitations c. To eliminate aerodynamic drag d. To act as a receiving antenna for broadcast AM
63. When the satellites are spaced 4 degrees of the 360 degrees complete circle, how many parking spaces or orbit slots are available? a. 90 b. 85 c. 95 d. 80
54. What do you call of a satellite used to provide satellite services within a single country? a. Orbital satellite b. Geostationary satellite c. Non-synchronous satellite d. Domestic satellite 55. A satellite beam that covers almost 42.5% of the earth's surface. a. Zone beam b. Hemispheric beam c. Spot beam d. Global beam 56. The first Philippine satellite has how many channels? a. 30 b. 24 c. 48 d. 50
64. The first satellite launched for a geosynchronous orbit but unfortunately lost during orbit injection. a. Syncom I b. Telstar I c. Sputnik I d. Early Bird 65. Geostationary satellites are located _______ with respect to the equator. a. 0 deg longitude b. 0 deg latitude c. 90 deg latitude d. 45 deg latitude
57. Aguila I has how many transponders? a. 36 b. 48 c. 24 d. 12
66. Incidentally proposed the geostationary scheme or orbit of satellites in 1940's. a. Clarke b. Gauss c. Morse d. Gray
58. How many satellite orbital slots were requested by the Philippine Government from ITU? a. 2 b. 4 c. 6 d. 8
67. The control routine necessary to keep the satellite in position is referred to as a. Station keeping b. Station tracking c. Station monitoring d. Station maintenance
59. The most common device used as an LNA is a. Zener diode b. Tunnel diode c. IMPATT diode d. Shockley diode
68. A satellite which simply reflects the signal without further amplification. a. Passive b. Active c. Geostationary d. Posigrade
60. The radiation patterns of earth coverage antennas have a beamwidth of approximately a. 21degrees b. 5 degrees c. 17 degrees 4
MITRC REFRESHER COURSE Communications
ANSWER KEY
69. What is the line joining the ascending and descending nodes through the center of the earth? a. Line of apsides b. Line of nodes c. Line of shoot d. Line of sight 70. The line joining the perigee and apogee through the center of the earth. a. Line of sight b. Line of nodes c. Equatorial belt d. Line of apsides
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