COMMUNICATIONS ENGINEERING PART 14 the times of arrival of pulses from widely spaced,
NAVIGATIONAL AIDS synchronized transmitting stations.
Multiple Choice: Encircle the letter that corresponds to your a. LORAN
answer. b. TACAN
c. DME
1. An area directly above a radio range station where d. VOR
practically no signal is heard.
a. radio range
b. cone of silence 5. A measure of the ability of the receiver to detect
c. coverage area transmission
d. RDF area
a. selectivity
2. A shipboard equipment which measures the distance b. sensitivity
between the ships bottom and the ocean floor by c. detector
sending the ultrasonic pulses via a transducer which d. demodulator
are reflected at the sea bottom and received with the
same transducer. 6. Radio range stations in LFR operate on frequencies
between
a. echosounder
b. SONAR a. 20KHz & 40 KHz
c. Compandor b. 200 KHz & 400 KHz
d. Hydrophone c. 30 KHz & 300 KHz
d. 2 MHz & 4 MHz
3. The ratio of the pulse width to the time between the
beginning of 2 pulses 7. The fifth center tower in an LFR is used for transmitting
_____ reports
a. duty cycle
b. doppler shift a. hazard
c. blind speed b. range
d. tracking error c. weather
d. direction
4. A navigation system from which hyperbolic lines of
position are determined by measuring the difference in
8. The direction of one terrestrial point from another, d. transceiver
expressed as angular distance from a reference
direction. 13. The speed of sound through water
a. heading a. 4800 m/sec
b. bearing b. 1463 m/sec
c. relative bearing c. 4800 miles/sec
d. true bearing d. 5000 ft/sec
9. DME operates in the ________ frequency band. 14. What is an electronic measuring equipment used in
navigation operating in 1 GHz band which provides
a. LF bearing and distance indication?
b. HF
c. VHF a. TACAN
d. UHF b. VOR
c. ILS
10. SONAR equipment feature which enlarges all echoes d. DME
on the screen.
15. An instrument used to measure one location in terms of
a. grayline coordinates.
b. zoom
c. sensitivity a. Global positioning system
d. ASP b. Hydrometer
11. A major obstacle in achieving high speed operation in c. Altimeter
a SONAR manifested by turbulent water flow. d. Increductometer
a. transom
b. cavitation
c. thru-hull
d. shoot thru
12. Considered to be the SONAR units antenna 16. The distance in angular degrees in a clockwise
direction from magnetic north.
a. crystal
b. transducer a. phase difference
c. localizer b. azimuth
c. latitude
d. longitude
17. _______ is used with a localizer station to indicate the
desired approach path of an aircraft. 21. The coho in MTI radar operates at the
a. glide slope system a. intermediate frequency
b. marker b. transmitted frequency
c. LORAN chart c. received frequency
d. OBI d. pulse repetition frequency
18. _______ is a 30 Hz signal which has a constant phase at 22. If the target cross section is changing , the best system
all points around the VOR station. for accurate tracking is
a. reference signal a. lobe switching
b. variable signal b. sequential lobing
c. ID signal c. conical scanning
d. voice modulation d. monopulse
19. If the peak transmitted power in a radar system is 23. The number of pulses that occur per second in a radar
increased by a factor of 16, the maximum range will be is called
increased by a factor of
a. PRR
a. 2 b. pulse train
b. 4 c. pulse width
c. 8 d. duty cycle
d. 16
24. The phenomenon evidenced by the change in the
20. After a target has been acquired, the best scanning observed frequency of a sound or a radio wave
system for tracking is caused by the time rate of change in the magnitude of
the radial component of relative velocity between the
a. nodding source and the point of observation.
b. spiral
c. conical a. tunnel effect
d. helical b. doppler effect
c. gunn effect
d. end effect 29. The time from the transmission of a radar pulse to its
reception is 0.12 msec. The distance to the target is
25. _______ are non-directional transmitters that operate in _________ nautical miles.
the LF and MF bands.
a. 4.85
a. radio beacons b. 11.2
b. DME c. 9.7
c. ILS d. 7.9
d. LORAN
30. The pulse duration of a radar signal is 600 nanoseconds.
The PRF is 185 pulses per second. The duty cycle is
26. When a single antenna is intended to be used for a. 0.01%
transmitting and receiving , it is necessary to use a b. 5.5%
c. 31%
a. duplexer d. 97%
b. diplexer
c. combiner
d. translator
27. The most commonly used component in a RADAR 31. Doppler effect allows which characteristic of a RADAR
transmitter is the _______ tube. target to be measured?
a. dynatron a. distance
b. twystron b. speed
c. magnetron c. size of target
d. cyclotron d. azimuth
28. A radar display that sweeps outward of the center of 32. Most radar antennas use
the screen while rotating is known as
a. dipoles
a. CRT b. broadside array
b. PPI c. horn and parabolic antenna
c. D-scope d. discone
d. periscope
33. The following are the components of an ILS except:
b. CAA
a. localizer c. IATA
b. glide slope d. ATO
c. markers
d. goniometer 38. LORAN is a navigation system used primarily for
34. The following are hyperbolic systems except: a. obtaining fixes over large distances
b. approach control
a. LORAN c. blind landing
b. DECCA d. IFF surveillance operation
c. OMEGA
d. TACAN 39. TACAN is a navigational aid providing
35. What do you call an electronic measuring equipment a. speed and height indication
used in navigation which provides runway direction, b. bearing and weather information
distance and height guidance to permit blind landing? c. bearing and distance indication
d. cone of confusion
a. DME
b. VOR 40. Otherwise known as Coastline refraction or the
c. TACAN refraction of waves towards the coastline.
d. ILS
a. Polarization effect
36. A radio aid to navigation that uses a rotatable loop or b. Land effect
other highly directional antenna arrangement to c. Skin effect
determine the direction of a radio signal. d. Luxembourg effect
a. DME 41. Low-power radar uses
b. RDF
c. TACAN a. RIMPATT
d. VOR b. TRAPATT
c. Magnetron
37. An agency of the United Nations, that formulates d. IMPATT
standards and recommended practices for all civil
aviation. 42. RADAR means:
a. ICAO a. Radio Detection and Rating
b. Radio Detection and Ranging
c. Radio Distance and Ranging 47. Navigation principle that depends on the
d. Radio Delay and Ranging measurement of the difference in distance to two fixed
43. A long range navigation system in which two pairs of stations whose separation distance is accurately
ground stations transmit pulsed signal, which are used known.
by aircraft or ships to determine their position.
a. triangulation
a. LORAN b. hyperbolic
b. SHORAN c. elliptic
c. Gee d. pilotage
d. TCAS
44. LORAN stands for 48. In hyperbolic navigation, how many sets of hyperbolas
are needed before a position (fix) is obtained?
a. low radar navigation
b. low range navigation a. 2
c. long range radar navigation b. 4
d. long range navigation c. 6
d. 8
45. LORAN was developed in the United States during
WWII. What system equivalent to LORAN, which was 49. In LORAN system, at least how many ground stations
developed in England and is used for guiding high- are needed before a position (fix) is obtained?
flying bombers over Germany during WWII?
a. 2
a. SHORAN b. 4
b. DECCA c. 6
c. OMEGA d. 8
d. Gee
50. In Gee system, at least how many ground stations are
46. What navigational system that uses the principle known needed before a position or fix is determined?
as hyperbolic navigation?
a. 2
a. Gee b. 3
b. LORAN c. 5
c. OMEGA d. 7
d. All are correct
51. In __________ system, one of the ground stations in each 55. A long-range navigation system that operates at a
pair serves as a master station and synchronizes the frequency of 100 kHz. It operates on the hyperbolic
pulses from the other station. principles.
a. Gee a. LORAN
b. VOR b. LORAN A
c. TCAS c. LORAN C
d. LORAN d. LORAN D
52. In __________ system, all the three stations are 56. Tactical LORAN system
synchronized and both difference distances are
simultaneously acquired. a. LORAN
b. LORAN A
a. Gee c. LORAN C
b. VOR d. LORAN D
c. TCAS
d. LORAN 57. LORAN system used by aircraft that operates
independent of ground stations to prevent unwanted
enemy detection of aircraft position.
a. LORAN
53. Gee system operates at what frequency range? b. LORAN A
c. LORAN C
a. 1850 1950 kHz d. LORAN D
b. 40 80 MHz
c. 118 135 MHz 58. Approximate range of LORAN system
d. 960 1213 MHz
a. 200 to 300 miles
54. Operating frequency of LORAN system b. 500 to 700 miles
c. 800 to 1000 miles
a. 1850 1950 kHz d. 1200 to 1500 miles
b. 40 80 MHz
c. 118 135 MHz 59. Approximate range of Gee system
d. 960 1213 MHz
a. 200 to 300 miles
b. 500 to 700 miles
c. 800 to 1000 miles a. VOR
d. 1200 to 1500 miles b. DME
c. ADF
60. In LORAN system, if the ground station is in error, how d. TACAN
does it inform the users?
a. by blinking the signal 64. TACAN operates at what spectrum?
b. by shutting off the signal
c. by inverting the signal a. LF
d. by reducing the signal b. MF
c. VHF
61. In LORAN, if the ship moves a path such that every d. UHF
pulse from two ground stations arrive at the ship at
exactly the same time, the ship is moving on 65. TACAN operates at what frequency range?
a. a circular course a. 108 112 MHz
b. a hyperbolic course b. 330 335 MHz
c. a perpendicular course bisecting the c. 962 1213 MHz
transmitters baseline d. 1030 1090 MHz
d. a straight course joining the two transmitters
baseline 66. TACAN means
62. In LORAN, if the pilot flies such a path that his a. Tactical Air Navigation
equipment interrogates a ground transponder and b. Traffic Alert Collision and Navigation
receives return pulses which have a constant time c. Traffic Alarm Collision and Navigation
delay between transmission and reception, the aircraft d. Tactical Aircraft Control and Navigation
is flying
67. The TACAN system has how many two-way channels?
a. in circular path
b. in parabolic path a. 33
c. in hyperbolic path b. 63
d. in straight and level flight c. 126
d. 252
63. A navigational system that is normally used by military,
it provides bearing and range. 68. Adjacent channels in TACAN system are separated by
a. 0.1 MHz 73. TACAN provides range or distance similar to that of
b. 1.0 MHz
c. 30 MHz a. Barometric-altimeter
d. 63 MHz b. Radio altimeter
c. LORAN
69. In TACAN system, the transmit and receive frequencies d. DME
are spaced
74. In TACAN system, the main azimuth reference burst is
a. at 1.0 MHz transmitted usually at
b. at 63 MHz
c. at 99 MHz a. magnetic North
d. at 150 MHz b. magnetic South
c. magnetic West
d. magnetic East
70. TACAN system can operate without interference to
over how many aircraft at the same time? 75. The TACAN ground station replies to interrogation
exactly __________ after receiving the interrogation.
a. 10
b. 25 a. 10 sec
c. 50 b. 25 sec
d. 100 c. 50 sec
d. 100 sec
71. Approximate maximum slant-range of TACAN:
76. A TACAN station is identified by means of
a. 100 nmiles
b. 200 nmiles a. Morse code
c. 400 nmiles b. ASCII
d. 600 nmiles c. BCD
d. EBCDEC
72. TACAN provides bearing similar to that of
77. In TACAN system, morse coding is achieved by proper
a. ADF
b. Compass a. spacing of pulse pairs
c. VOR b. variation of pulse amplitude
d. LORAN c. adjustment of pulse repeatation
d. pulse with modulation
b. dual ranging
78. The basic TACAN operates on c. RHO-RHO navigation
d. RHO-THETA navigation
a. ground to ground
b. ground to surface only 83. Navigation system that derives position based on the
c. air to surface only measured distance of two different stations
d. air to air only (DME/DME).
79. Which navigational system that is capable of air-to-air a. RHO-RHO
ranging? b. RHO-RHO-RHO
c. RHO-THETA
a. Radio altimeter d. THETA-THETA
b. TACAN
c. DME 84. A method of navigation that derives position by
d. ADF measurement of distance and bearing from a single
ground station (DME/VOR).
80. Air-to-air TACAN is possible if the system is modified to
receive __________ and by adding a transponding a. RHO-RHO
function to the airborne equipment. b. RHO-RHO-RHO
c. RHO-THETA
a. standby frequency d. THETA-THETA
b. harmonics
c. image frequency 85. Uses hyperbolic principle in position determination.
d. reflected frequency
a. ADF
81. Air-to-air TACAN will provide distance information to b. VOR
c. LORAN
a. the interrogating aircraft only d. DME
b. the transponding aircraft only
c. both aircraft 86. Navigation system that operates at VLF and is originally
d. ground in both aircraft designed for use on ballistic missile submarine.
a. ADF
82. When both aircraft are able to display distance b. IRS
information between them, the operation is known as c. OMEGA
d. NMS
a. bilateral ranging
91. Frequency range of TVOR
a. 108 117.95 MHz
b. 962 1860 kHz
c. 1030 1090 MHz
87. Hyperbolic navigational system that transmits d. 962 1213 MHz
continuous-wave
92. VOR beacons for en-route navigation has a typical
a. LORAN output power of
b. DECCA
c. FMS a. 50 W
d. GPS b. 200 W
c. 50 kW
88. Co-located VOR and TACAN station is called d. 50 MW
a. VORTAC 93. With 200 watts power output VOR station, it can
b. VOR/TACAN provide a service range up to
c. VOR/DME
d. TACVOR a. 25 NM
b. 200 NM
89. A radio navigation whose ground station transmits two c. 600 NM
signals (reference and variable). It operates at VHF d. 5000 NM
band.
94. DME means
a. DME
b. ATC a. altitudes
c. LORAN b. distance
d. VOR c. air speed
d. slant distance
90. VOR uses a sub-carrier of
95. DME operates at a frequency range of
a. 9960 Hz
b. 30 Hz a. 1030 1090 MHz
c. 60 Hz b. 962 1213 MHz
d. 108 MHz c. 329.3 335 MHz
d. 1750 1950 kHz
b. transmitter
96. DME measures distance by using c. transceiver
d. any of these
a. pulse radar principle
b. radar transponder principle
c. continuous-wave radar principle
d. virtual ground principle
97. System that enables navigator or pilot to determine its
time-to-station (TTS) or time-to-go (TTG).
a. VOR
b. DME
c. ADF
d. TCAS
98. The airborne equipment or component used in DME
system is called
a. interrogator
b. transceiver
c. duplexer
d. transponder
99. What do you call the ground equipment used in DME
system?
a. interrogator
b. transceiver
c. duplexer
d. transponder
100. Equipment such as interrogator or transponder
are actually a
a. receiver
