This is the Multiple Choice Questions in Chapter 20: Satellite Communications from the book Electronic Communication Systems by Roy Blake
Start Practice Exam Test Questions
Choose the letter of the best answer in each questions.
MULTIPLE CHOICE
1. The height of the geosynchronous orbit above the equator is about:
- a. 3,578 km
- b. 35,780 km
- c. 357,800 km
- d. depends on satellite velocity
ANS: B
2. The high and low points of a satellite's orbit are called, respectively,:
- a. apogee and perigee
- b. perigee and apogee
- c. uplink and downlink
- d. downlink and uplink
ANS: A
3. The area on the earth that is "covered" by a satellite is called its:
- a. earth station
- b. downlink
- c. footprint
- d. plate
ANS: C
4. The velocity required to stay in orbit:
- a. is constant
- b. is zero (freefall)
- c. is lower close to the earth than far from the earth
- d. is higher close to the earth than far from the earth
ANS: D
5. An antenna is aimed by adjusting the two "look angles" called:
- a. azimuth and elevation
- b. azimuth and declination
- c. declination and elevation
- d. apogee and perigee
ANS: A
6. The power per transponder of a typical Ku-band satellite is in the range:
- a. 5 to 25 watts
- b. 50 to 250 watts
- c. 500 to 2500 watts
- d. depends on its orbit
ANS: B
7. The power level for an earth station to transmit to a satellite is on the order of:
- a. 101 watts
- b. 102 watts
- c. 103 watts
- d. 104 watts
ANS: C
8. The "payload" on a communications satellite consists of:
- a. transponders
- b. batteries
- c. solar cells
- d. all of the above
ANS: A
9. "Station-keeping" refers to:
- a. antenna maintenance
- b. power-level adjustments
- c. orbital adjustments
- d. none of the above
ANS: C
10. DBS stands for:
- a. decibels of signal
- b. down-beam signal
- c. direct-broadcast system
- d. direct-broadcast satellite
ANS: D
11. LNA stands for:
- a. low-noise amplifier
- b. low north angle
- c. low-noise amplitude
- d. low-noise array
ANS: A
12. A reduction in TWT power for linearity is called:
- a. backdown
- b. backoff
- c. power-down
- d. EIRP drop
ANS: B
13. TVRO stands for:
- a. television receive only
- b. television repeater only
- c. television remote origin
- d. none of the above
ANS: A
14. TDMA stands for:
- a. transponder-directed multiple antennas
- b. television distribution master antenna
- c. time-division multiple access
- d. transmit delay minimum aperture
ANS: C
15. VSAT stands for:
- a. video satellite
- b. video signal antenna terminal
- c. very small antenna terminal
- d. very small aperture terminal
ANS: D
16. On the uplink from a terminal, a VSAT system uses:
- a. high power to a small antenna
- b. low power to a small antenna
- c. low power to a large antenna
- d. LEO satellites
ANS: B
17. A typical VSAT system is configured as a:
- a. star
- b. mesh
- c. ring
- d. repeater
ANS: A
18. LEO stands for:
- a. long elliptic orbit
- b. low-earth orbit
- c. lateral earth orbit
- d. longitudinal earth orbit
ANS: B
19. For real-time communication, LEO systems require:
- a. a constellation of satellites
- b. tracking dish antennas
- c. very high power
- d. all of the above
ANS: A
20. The frequency bands used by Ku-band satellites are:
- a. 4 GHz and 6 GHz
- b. 12 GHz and 14 GHz
- c. 20 GHz and 30 GHz
- d. none of the above
ANS: B
COMPLETION
1. A satellite in geosynchronous orbit takes ____________________ hours to complete one orbit.
ANS: 24
2. The ____________________ is the signal path from the earth station to the satellite.
ANS: uplink
3. The ____________________ is the signal path from the satellite to the earth station.
ANS: downlink
4. A satellite in a ____________________ orbit appears to stay directly above one spot on the equator.
ANS: geostationary
5. Non-geostationary satellites are sometimes called ____________________ satellites.
ANS: orbital
6. A geosynchronous orbit is about ____________________ km above the earth.
ANS: 35,780
7. A ____________________ is an outline of the area on the earth's surface that a satellite broadcasts to.
ANS: footprint
8. All satellite orbits are ____________________ in shape.
ANS: elliptical
9. The ____________________ is the distance of a satellite's closest approach to the earth.
ANS: perigee
10. The ____________________ is a satellite's farthest distance from the earth.
ANS: apogee
11. An antenna's ____________________ is its angular direction between east and west.
ANS: azimuth
12. An antenna's ____________________ is its vertical angle with respect to the earth's surface.
ANS: elevation
13. An antenna's ____________________ is the angle by which it is offset from the earth's axis.
ANS: declination
14. Satellites using the ____________________ band operate on 12 GHz.
ANS: Ku
15. The time for a signal to make a round trip via satellite is about ____________________ milliseconds.
ANS: 500
16. A ____________________ is a type of repeater used on communications satellites.
ANS: transponder
17. Both the gain and the beamwidth of a dish antenna depend on its ____________________.
ANS: diameter
18. VSAT systems commonly use a ____________________ network configuration.
ANS: star
19. To date, LEO satellite systems have been a financial ____________________.
ANS: failure
20. C-band antennas are ____________________ than Ku-band antennas.
ANS: larger
SHORT ANSWER
1. A receiving antenna with a gain of 44.4 dBi looks at a sky with a noise temperature of 15 K. The loss between the output of the antenna and the input of the LNA is 0.4 dB, and the LNA has a noise temperature of 40 K. Calculate the G/T.
ANS:
25 dB
2. A receiver has a noise figure of 1.7 dB. Find its equivalent noise temperature.
ANS:
139 K.
3. A receiving antenna with a G/T of 25 dB is used to receive signals from a satellite 38,000 km away. The satellite has a 100-watt transmitter and an antenna with a gain of 30 dBi. The signal has a bandwidth of 1 MHz at a frequency of 12 GHz. Calculate the C/N at the receiver.
ANS:
38 dB
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