Topic: Communications (All)
1. The effective refraction index of the ionosphere for radio
waves is:
less than unity (Correct Answer)
2. If a fiber optic system has a rise time of 16ns, the source
rise time is 1.5ns and the detector rise time is 2ns, what is the
cable rise time?
14 ns (Correct Answer)
3. Earth station uses what type of antenna.
Cassegrain antenna (Correct Answer)
4. The minimum number of turns a helix antenna must have.
3 (Your Correct Answer)
5. A local area network in which, rather than all users sharing
the media, a central switch routes traffic between only those
parts that require it:
Switched LAN (Correct Answer)
6. A method of snooping through the internet for files and
retrieving them.
Gopher (Correct Answer)
7. A tag based ASCII programming language that is used to
specify and links to other documents on the World Wide Web
servers on the Internet (HTML for short).
Hypertext markup language (Your Correct Answer)
8. A passive circuit, usually consisting of capacitance and/or
inductance, that is inserted in series with the a-c power cord of
an electronic device which will allow the 60 - Hz current to
pass and suppressed high-frequency noise components.
noise filter (Your Correct Answer)
9. Transmission for the cell site to receive calls from the users:
Reverse Link (Correct Answer)
10. Which of the following network access methods sends a
signal indicating its intent to transmit data on the wire?
[Choose the best answer]
CSMA/CA (Correct Answer)
11. Frequencies in the UHF range propagate by means of
which of the following?
Ans: Space waves
12. Digital modulation scheme that represents a bit pattern by
a change in phase from the previous state.
Ans: DPSK
13. How much does the radiated power of an antenna
increases if its current increases by 3.3 times?
Ans: 10.89 times
14. A process using uudecode to decode a file encoded for
network transmission by uuencode, a UNIX utility program.
Ans: extraction
15. Which statement is true?
Ans: changing the length of the wire will have no effect on the
SWR
16. What is the ratio of the power radiated by the antenna to
the total input power?
Ans: antenna efficiency
17. For proper operation, a magnetron must be accompanied
by a
Ans: permanent magnet
18. Parabolic and lens are extremely used for
Ans: microwaves
19. A GSM criterion that is measured as the number of
simultaneous conversations per MHz per km2.
Ans: Spectral Efficiency
20. In the _____ layer, translation from one character code to
another occur.
Ans: presentation
21. ______ detects the satellite signal relayed from the feed
and converts it to an electric current, amplifies and lower its
frequency.
Ans: LNA
22. Quantizing noise is present in ______ system.
Ans: PCM
23. What is the function of a redirector?
Ans: Forwards requests to local or remote resource hosts
24. Data services that provide the capacity necessary to
transmit appropriate data signals between two access points.
Ans: Bearer Services
25. A feature of PCS that notifies users that they have voice
mail messages.
Ans: Message Waiting Indicator (MWI)
26. The center of a network which is based on a star
TOPOLOGY.
Ans: Hub
27. ____ is the central office for mobile switching.
Ans: MTSO
28. It is fictitious resistance that dissipates as much power as
an antenna is radiating if it were connected to the same
transmission line.
Ans: radiation resistance
29. The published rates, regulations, and descriptions
governing the provision of communications service for public
use.
Ans: Tariff
30. Provide post equalization to the received analog signal.
Ans: Adaptive equalizers
31. One of the reasons why FDM is being replaced by TDM
Ans: Noise is amplified with voice when an FDM system is used
32. ______ is the measurement of unilateral antenna
properties of directivity.
Ans: beamwidth
33. In a klystron amplifier, velocity modulation of the electron
beam is produced by the
Ans: catcher cavity
34. Refers to a type of beam antenna that uses two or more
straight elements arranged in line with each other.
Ans: Yagi antenna
35. A type of array antenna which consists of one half-wave
driven dipole, one reflector and one director.
Ans: Yagi-Uda
36. What is the modulation rate of the CCITT V.26 modem?
Ans: 1200 bauds
37. The distance between the two antennas of a geostationary
satellite system is 22,300 miles and is operating at a downlink
frequency of 12.2 GHz, what is the free space loss in dB?
Ans: 205 dB
38. It covers links between satellites and fixed earth stations.
Ans: Fixed Satellite service (FSS)
39. Maximum Ethernet segment length for thick wire.
Ans: 500 m
40. You are measuring noise in a voice channel at a-4 dB test
point level, the meter reads -73 dBm, convert the reading into
dBrnCO.
Ans: 21
41. AMPS is the short for ____, an analog cellular standard
developed in the USA and primarily employed there and in
Asia-Pacific.
Ans: Advanced Mobile Phone System
42. Antenna that is not properly terminated
Ans: Non-resonant
43. Noise that is generated from our galaxy.
Ans: galactic noise
44. Electrical noise inherent to a particular device, circuit, or
system that remains when no other signal is present.
Ans: background noise
45. Which is not a method of data compression?
Ans: Winzip
46. Typical ac signal drive for a 19-in. picture tube.
Ans: 140 Vp-p
47. This is a requirement for linearity:
homogeneity
additivity
shift invariance
all of these (Correct Answer)
48. If the bandwidth is 3000 Hz and the S/N ratio of 1024, the
expected channel capacity of the line according to Shannon's
theorem is about:
Ans: 30,000 bps
49. When an antenna is loaded, its physical length remains
unchanged but increases the effectiveness of the electrical
length. What is (are) the technique(s) used in loading ?
Ans: Loading coil
50. Known as the Cellular Mobile Telecommunication System
Policy, issued last November 11, 1992.
Ans: DOTC Mem. Cir. No. 92-269
