Module 1

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Module 1

1.What device measures the angle
between two radio frequency and also
the direction of propagation of a wave
-Goniometer
2. What is the frequency range of an
aircraft’s Very High Frequency (VHF)
communications
-118.00MHz to 136.975MHz
3. What is the frequency range of an
aircraft’s radio altimeter
-4250MHz to 4350MHz
4. Tropospheric scatter is method of
sky wave propagation for which of the
following frequency bands
-300MHz to 3GHz
5.Which of the following terrain types
permits a ground wave to travel the
farthest
-salt water
6. Best describe a dip-meter
-a variable LC oscillator with
metered feedback current
7.Which of the following systems is not
used in radio detection and ranging
-amplitude modulation

10. What consists the front-end circuit
of a VHF TV superheterodyne receiver
-local oscillator, mixer and RF
amplifier
11. What phenomenon causes the
radio-path horizon distance to exceed
and the geometric horizon
-radio waves may be bent
12. What is meant by the term
modulated index
-the ratio between the deviation
of a frequency modulated signal and
the modulating frequency
13. The bending of radio waves
passing over the top of a mountain
range that disperses a weak portion of
the signal behind the mountain
-knife-edge diffraction
14. Which of the following is not one of
the natural ways a radio wave may
travel from transmitter to receiver
-micro wave
15. If the modulation index of an AM
wave is doubled, the antenna current
is also
-doubled
16. What is the advantage of a
sidetone
-assures that the telephone is
working

8. Considered as the main source of an
internal noise
-thermal agitation

17. Which transmit only one sideband
-A3E

9. What is the cause of atmospheric or
static noise
-thunderstorms

18. Transmission of printed material
over telephone lines
-facsimile

19. When testing transmitter to
prevent interfering with other stations,
which type of antenna must be used
-dummy antenna
20. If the modulation index of an AM
wave is doubled, the antenna current
is also doubled, the AM system being
used is
-A3J
21. What is the reason why
compounding is employed in PCM
systems
-to protect small signals in PCM
from quantizing distortion
22. What is the local oscillator
frequency range in commercial AM
broadcast if it is equal to
-995 to 2055 kHz
23. Modulation in which no signal is
present between pulses
-pulse modulation
24. An increase in the effective power
radiated by an antenna in a certain
desired direction at the expense of
power radiated in other directions
-antenna gain
25. How can the antenna efficiency of
an HF grounded vertical antenna be
made comparable to that of a half
wave antenna
-by installing a good ground
radial sytem
26. One type of pulse communications
system uses pulse that appear as a
group, an which vary in number
according to the voice. This type of
pulse modulation is called
-pulse duration modulation

27. A device to be connected across
the headset in telephone receivers to
reduce the effects of acoustic shock
-two rectifiers in parallel with
opposite polarities
28. What is meant by antenna gain
-the numeric ratio relating the
radiated signal strength of an antenna
to that of another antenna
29. Which determines the number of
sideband components in FM
-modulation index
30. What is the baseband frequency of
standard FDM basic supergroup
-312 to 552 kHz
31. An electromagnetic wave consist
of
-both electric field and magnetic
field
32. When electromagnetic waves are
propagated through a waveguide, they
-are reflected from the walls but
do not travel along them
33. Transmission sent in both direction
simultaneously
-duplex
34. Reference noise temperature
-290 K
35. A pi-network is
-a network consisting of one
inductor and two capacitors
36. What type of emission is produced
when a frequency modulated

transmitter is modulated by a
facsimile signal
-F3C
37. Which of the following antennas is
used for testing and adjusting a
transmitter for proper modulation,
amplifier operation and frequency
accuracy
-dummy antenna
38. Which improves antenna
directivity
-parasitic element
39. Where are the current nodes in a
half-wave antenna
-at the ends
40. Which of the following is the ferrite
device that buffers a microwave
source from the effects of a varying
load, and thereby prevents the
formation of standing waves
-isolator
41. Point on the satellite orbit closest
to the earth
-perigee
42. What is the purpose of beat
frequency oscillator (BFO)
-generates a 1kHz note for
Morse code reception
43. The capture area of an antenna is
directly proportional to the ____
-gain of the antenna
44. What is a trap
-a parallel LC network inserted
in an antenna
45. Pulse width modulation
-

46. CCITT
47. Advantage of ASCII to Baudot Code
-can transmit letters in lower
and upper case

48. Operating frequency of Automatic
Direction Finder (ADF)
-190 to 1750kHz
49. Why is nitrogen gas sometimes
used in waveguide
-to keep the wave guide dry
50. Radius of sun
10^8 m
51. The characteristic impedance of a
transmission line does not depend
upon its
-length
52. The term used to refer to the
condition where the signals from a
very strong station are superimposed
on other signals being received
-cross-modulation interference
53. To transmit SSBSC it must ______
carrier and _______ the upper sideband
-cancel, filter
54. Ability of the receiver to receive
the desired signal and reject all others
-selectivity
55.
-folded half wave dipole

56. Reference antenna for which the
gain of practical antenna
-isotropic antenna
57. Size of reflector with respect to the
driven element
-about 5%

58. one supplied with power from the
transmitter usually through
transmission line
-driven element
59. An antenna which is not resonant
at a particular frequencies and so can
be used over a wide band of
frequencies is called
-aperiodic
60. EIRP
-product of radiated RF power of
a transmitter and the gain of the
antenna system
61. A word in telegraphy consist of
_____ characters plus a word space
-7 and ½
62.What is the effect of adding
inductor
-attenuates capacitive
reactances
63.
-45 V RMS
64. SSB transmitter uses a/n _____
wattmeter, AM and FM transmitter
uses ______ wattmeter
65. Maximum voice band of a master
group
-300

66. Use in SSB receiver
-BFO
67. What happen when a marine
sends SSB signal to an aircraft which is
switch on auto piloting
-there will be a sharp turn to left
of right
68. Frequency range of VOR ( VHF
Omnidirectional Range)
-108.05 to 117.95 MHz
69. LORAN
-used to find fixed location
70. ILS transmitter is located at the
end of the runway with what operating
frequency
-108.10 to 111.95 MHz
71. Glide slope transmitter operating
frequency
-329.30 to 335.00 MHz
72. Type of information to be
transmitted of A3C
-facsimile
73.Emission of F3C
-facsimile
74. Frequency modulation of single
analog information to be transmitted
by facsimile
-F3C
75.
-frequency shift keying
76. What is the relation indegrees of
electric field to magnetic field
- 90 degrees

77. Frequency range of UHF
-300 to 3000 MHz
78. Best frequency used to operate a
sky wave
-Optimum Usable Frequency
(OUF)
79. This phenomenon happens
because of ray paths in ionosphere are
different frequencies
-selective fading

-guard band
88. In general typical frequency that
troposcatter wave propagation is
found to be effective
-350MHz to 10 GHz
89.Operating frequency of
troposcatter
-350Mhz to 10GHz
90.
-from early evening to 12:00

80.
-line current and surge
impedance of transmission line
81. Ratio of load impedance to
transmission line impedance
-SWR
82. Most desirable SWR
-1:1
83. Ratio of maximum peak frequency
deviation of the carrier signal to the
maximum modulating frequency
-deviation ratio
84. What is the case of two co-channel
being received at the same time
-capture effect
85. What is the IBM’s asynchronous
data link protocol designation
-83B
86. The sensitivity of a receiver is
determined by its ability to
-receive weak signal
87. What do you call the void band of
frequencies between any two adjacent
groups

91. International Broadcasting ( short
waves) frequency range from _____ in
accordance in the international
agreement.
- 5950 to 26100 kHz
92. When a space wave signal passes
over mountain ridge a small part of
the signal is diffracted down the far
side of the mountain, this
phenomenon is called
- Knife edge diffraction
93. What is the term used to describe
a spread spectrum communications
system where the center frequency of
a conventional carrier is altered many
times per second in accordance with a
pseudo-random list of channels?
-Frequency hopping
94.____ is an electronic instrument
used to show both the carrier and the
sidebands of a modulated signal in
frequency domain
-spectrum analyzer
95. Transequatorial propagation is best
during
-afternoon or early evening

96.What is the usual electrical length
of a driven element in an HF beam
antenna
-1/2 wavelength
97. The number of voice band
channels in a master group per CCITT
standard is ______
-300

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