This is the Multiple Choice Questions in Chapter 17: Terrestrial Microwave Communication Systems 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. Another term for a single microwave link is a:
a. section
b. hop
c. skip
d. jump
ANS: B
2. Microwave systems use:
a. FM
b. SSB
c. QAM
d. all of the above
ANS: D
3. The typical reliability of a microwave system is:
a. 90%
b. 99%
c. 99.9%
d. 99.99%
ANS: D
4. A typical microwave system uses a transmitted power of about:
a. 2 watts
b. 20 watts
c. 200 watts
d. none of the above
ANS: A
5. In analog microwave systems, additional repeaters increase the:
a. reliability
b. noise level
c. jitter
d. all of the above
ANS: B
6. In digital microwave systems, additional repeaters increase the:
a. reliability
b. noise level
c. jitter
d. all of the above
ANS: C
7. LOS stands for:
a. Loss Of Skip
b. Loss Of Signal
c. Line-Of-Sight
d. Line-Of-Signal
ANS: C
8. Too much antenna gain causes:
a. a very narrow microwave beam
b. a very wide microwave beam
c. excessive noise
d. jitter
ANS: A
9. The microwave signal path should clear obstacles by at least:
a. 60% of the Faraday zone
b. 60% of the Fresnel zone
c. 60% of the height of the antenna tower
d. 60% of the highest obstacle height
ANS: B
10. Satisfactory performance of an analog microwave system is defined as:
a. a carrier-to-noise ratio that exceeds a given value
b. an ERP level that exceeds a given value
c. an energy-per-hertz level that exceeds a given value
d. none of the above
ANS: A
11. Satisfactory performance of a digital microwave system requires a:
a. low level of transmitted power
b. high level of ERP
c. good energy per bit per transmitted Watt ratio
d. good energy per bit per noise density ratio
ANS: D
12. Fading is caused by:
a. multipath reception
b. attenuation due to weather
c. ducting
d. all of the above
ANS: D
13. The effects of fading due to multipath reception are often reduced using:
a. diversity
b. power
c. high-gain antennas
d. all of the above
ANS: A
14. Repeaters are used in a microwave system:
a. always
b. when distance exceeds line-of-sight
c. above 10 GHz
d. below 10 GHz
ANS: B
15. Microwave repeaters can be:
a. IF type
b. baseband type
c. regenerative type
d. all of the above
ANS: D
16. An advantage of digital techniques over analog in a microwave system is:
a. less bandwidth is required
b. accumulation of noise is reduced
c. it requires less power
d. all of the above
ANS: B
17. MMDS stands for:
a. Multichannel Microwave Distribution System
b. Multipoint Microwave Distribution System
c. Multichannel Multipoint Distribution System
d. Multiple Microwave Distribution Systems
ANS: C
18. LMDS stands for:
a. Local Microwave Distribution System
b. Local Multipoint Distribution System
c. Local Multichannel Distribution System
d. Low-power Microwave Distribution System
ANS: B
19. LMDS is:
a. bidirectional
b. unidirectional
c. multidirectional
d. none of the above
ANS: A
COMPLETION
1. One microwave link is called a ____________________.
ANS: hop
2. STL stands for ____________________-to-transmitter links.
ANS: studio
3. A typical microwave system has about one hour per ____________________ or less of downtime.
ANS: year
4. Adding more links causes ____________________ in a digital microwave system.
ANS: jitter
5. In microwave systems, it is more convenient to use noise ____________________ than noise figure in calculations.
ANS: temperature
6. In digital microwave systems, the energy per bit per ____________________ is a key parameter.
ANS: noise density
7. Multipath reception can cause 20 dB or more of ____________________.
ANS: fading
8. Two antennas stacked one above the other on a tower is an example of ____________________ diversity in a microwave system.
ANS: space
9. The ability to use two frequencies simultaneously is an example of ____________________.
ANS: diversity
10. Microwave systems generally use less than ____________________ watts of power.
ANS: ten
11. ____________________ are necessary in a microwave system that extends beyond the line-of-sight distance.
ANS: Repeaters
12. Analog microwave systems use both IF and ____________________ repeaters.
ANS: baseband
13. Microwave digital radio techniques reduce the accumulation of ____________________ as a signal goes from link to link.
ANS: noise
14. MMDS is unidirectional, but ____________________ is bidirectional.
ANS: LMDS
SHORT ANSWER
1. If the line-of-sight distance for an optical beam is 12 km, what would it be, approximately, for a microwave beam?
ANS:
16 km
2. A line-of-sight microwave link operating at 4 GHz has a separation of 40 km between antennas. An obstacle in the path is located midway between the two antennas. By how much must the beam clear the obstacle?
ANS:
16.4 meters
3. A transmitter and receiver operating at 1 GHz are separated by 10 km. How many dBm of power gets to the receiver if the transmitter puts out 1 Watt, and both the sending and receiving antennas have a gain of 20 dBi?
ANS:
–42.4 dBm
4. A microwave system has a feed-line loss of 2 dB and sees a sky temperature of 150 K. Calculate the noise temperature of the antenna/feed-line system referenced to the receiver input.
ANS:
201 K
5. A microwave receiver receives –60 dBm of signal. The noise power is –100 dBm. What is the carrier-to-noise power ratio?
ANS:
40 dB
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