問題一覧
1
How many radar transponder (SART) are required to be carried on board a ship for use in survival crafts?
2 on new- builds only. old ships have to comply by August-95
2
When using the ARPA in heavy rain, which action should you take?
navigate as though the effective range of the radar has been reduced
3
Which vector generated by arpa as greater likelihood of errors?
true vector
4
What is the modulation frequency of most radar system?
between 60 and 500 Hz
5
What is the best land target to be used for radar ranging?
a cliff face
6
What should be the typical radar range discrimination?
not less than 50 metres
7
What happened when radar waves are trapped in the atmospheric duct?
increase of radar range
8
In radar principle, what determines the number of pulises that strike a target?
The scanner rotational speed, aperture size of the aerial & PRF of the transmitter.
9
What type of target would give the best radar echo?
A 600-foot freighter beam on
10
What is the operational check you should carry out when a radar set is installed?
check the accuracy of the heading marker
11
You are underway at five knots and you observe from your radar a target with a range of 10 miles directly astern of you, twelve minutes later, the target is 8 miles directly astern of you. What is the estimated speed of the contact?
15 knots
12
What is the difference between a 10 cm radar compared to a 3 cm radar?
a wider horizontal beam with
13
What is the most accurate determination that are radar can make?
distance to a target
14
Which of the following radar presentation feature can be used to advantage for position fixing?
an off-centered display
15
Which of the following statements concerning operational requirement for the radar system is true?
a minimum of four independent parallel index lines, with a means to truncate and switch off individual lines, should be provided.
16
Which of the most correct statement containing the parameters which control the size of product target echo?
transmitted power, antenna effective area, transmit and receive losses, radar cross section of the target, range to target.
17
All ships /crafts of 500 gross tonnage and upwards but less than 10,000 gross tonnage, what is the radar minimum operational display area in the performance requirements?
250 mm
18
In fog, you observe your radar and determine that risk of collision exist with a vessel with is 2 miles of your port bow. Which action should you take?
take avoiding action as soon as possible
19
An S-band radar operates in which frequency band?
2 - 4 GHz
20
When you examine the radar, you notice that there is no target video in the center of CRT. The blank spots get smaller in diameter as you increase the range scale. What operator front panel control could be misadjusted
sensitivity time control (STC)
21
What is the radar control to be adjusted so that echoes from rain can be reduced?
differentiator control
22
In calm and clutter free conditions, what is the minimum detection range for X-Band radar if the target is a 10-meter tall SOLAS ship (more than 5,000 gross tonnage)
11 nm
23
Which determine the minimum range at which a target can be detected?
pulse length
24
Which of the following is the approximate time a radar pulls travel out to and the echo return from a target at 24 miles?
400 microsec
25
What is one good practice of a navigator fixing a vessel position by means of radar?
can use radar information from one object to fix the position
26
The ship speed indication on the arpa display can be set manually but does not change with changes in the vessels speed. What other indication would point to a related equipment failure?
"LOG OUT"is displayed on the arpa indicator
27
The detection range of surface target is decreased when radar waves touch the earth's surface at point closer than the standard horizon. What type of refraction is this?
sub refraction
28
Your vessel is making 10 knots. After several observation of a target, it remain in the same position relative to yours, what could be the possible analysis of the situation?
the target is on the same course and speed as your vessel
29
What purpose in the function brilliance/intensity/brightness on the radar?
regulation of the light on PPI
30
Your power driven vessel is fitted with radar and is underway in poor visibility. At what speed should you proceed?
a safe speed
31
Under rule 5 of the colregs, when should the radar be used for keeping a proper lookout?
whenever it may help
32
When can you determine the closest point of approach (CPA) of a contact on a relative motion radar?
after the contact has been marked at least twice
33
When using the arpa in heavy rain, which action should you take?
increase the FTC setting to reduce close in spurious signal
34
What is the function of the heading flash when the sweep line is momentarily intensified on the PPI presentation?
to inform the operator of the dead-ahead position on the PPI scope.
35
What do you call the marker in the radar PPI which the operator can put in any direction to watch the incoming target?
guard zones
36
What is the approximate wavelength of X-Band radar operating on a frequency of approximately 95000MGHz?
3 cm
37
If the gyro fails, in which display would the arpa default into?
Head-up
38
What do you call a radar display which is oriented so that north is always at the top of the screen?
stabilize display
39
Which radar control is used to shorten all echoes on the display and reduces the clutter caused by the snow or rain?
fast time constant
40
What should be recorded in the radar log?
the details of repairs and services carried out.
41
What is the name of the movable guideline used to measure direction on a radar?
cursor
42
When two ships are on reciprocal courses, what is meant by the "approaching vessels relative speed"?
the sum of the speed of the two vessels
43
Your arpa as automatic speed inputs from the log. Due to current, the log is indicating a faster speed than the speed over the ground. What should you expect under this circumstances?
the target true course vector will be in error
44
What is one good practice of a navigator fixing a vessel position by means of radar?
can use radar information from one object to fix the position
45
Which of the following has the most effect on the size and shape of small radar targets?
pulse length
46
How long will it takes for the radar to be fully operational from the standby position?
within 5 seconds
47
What will happen to the power of radar beam as distance from the scanner increases?
decreases rapidly
48
Which radar control that shortens on echoes on the display and reduces clutter caused by rain or snow?
fast time constant (differentiator)
49
Which of the following radar representation future is useful in radar pilotage?
true motion
50
Which of the following situation will cause the ARPA to emit a visual alarm, audible alarms, or both?
A tracked target loss for one radar scan
51
After changing range scales on which the arpa facilities are available, or resetting the display, in what period of time should full plotting information be displayed?
a period of time not exceeding four scans
52
How does height above sea level influence the radar range of detection of a target?
higher objects are detected further away than the lower objects
53
Which of these control is provided to check the overall efficiency of the radar?
performance monitor
54
With regard to arpa, what does the "lost target" warning denotes?
targets can no longer be plotted
55
What is the ability of a radar set to clearly distinguish two targets, on the same range and slightly different bearings, as two separate targets on the PPI?
bearing discrimination
56
What is the radar front panel control that reduces weak echoes out to a limited distance from the ship?
sensitivity time control ( sea-clutter control)
57
What is the minimum sleeping target capacity of an arpa?
200 targets
58
How are sea clutter echoes appear on the radar screen?
a mass of small echoes around the screen center
59
Which of the following an arpa must make available past track history?
tracked targets by ARPA
60
What is radar presentation future which is useful in radar pilotage?
true motion
61
An indirect radar echo is caused by a reflection of the main lobe of the radar beam of the observer's vessel. Which of the following is a characteristic of indirect echoes?
The bearing is almost constant, even when the true bearing of the contact changes appreciably.
62
By what reason that edges of land should be avoided if possible when position fixing by radar?
their poor definition
63
When is the transmitted signal of the SART will be most conspicuous on the radar screen?
when the receiver is not fined tuned
64
Regarding performance standards for navigational radar, what are the requirements for a scanner?
It should rotate at a constant RPM of not less than 12 in relative wind speed up to 100 knots
65
What is the required frequency of radar to be fitted on a 10,000 gross tonnage ship as SOLAS V regulation 19?
9 GHz frequency band
66
In what time frame must an arpa produce a relative motion with 95% accuracy and CPA/TCPA?
1 minute
67
What circuit controls the suppression of sea clutter?
STC circuit
68
According to rule 19 of the COLREGs, what must be your action if you detect another vessel by radar alone?
determine if risk of collision exist
69
When navigating in thick fog with the radar on, which action should you take?
station a look-out as low down and far forward as possible
70
When using a radar in an unstabilized mode, how can you determine fixes easily?
from ranges
71
How can a rescue personnel detect that a SART is transmitting in the immediate vicinity?
The SART's blips on the PPI will become arcs and eventually become concentric circle
72
What is the range discrimination of a radar set of pulse length 60 meters?
30 meters
73
Which of the following has the most effect on the definition of small target on the radar display?
horizontal beam width
74
The radar has display has sectors of solid video (spoking). What would be the first thing to check?
for interference from nearby ships
75
You have another ship overtaking you close a board to starboard. You have three radar targets bearing 090°, relative ranges 0.5 nm, 1 nm and 1.5 mm. In this case, what do you call the unwanted echoes?
multiple echoes
76
What is true when operating in fog and other vessels are detected by radar?
you should maneuver in ample time if a closed quarter situation is developing
77
What is the radar control that reduces weak echoes out to a limited distance from the ship?
sensitivity time control (sea clutter control)
78
What is the minimum acquired radar target capacity in the performance requirements for all ships/crafts or less than 500 gross tonnage?
20
79
What is the radar control that shortens all echoes on the display and reduces clutter caused by rain and snow?
fast time constant (differentiator)
80
What ratio would be used by a typical arpa before writing a target into the final switch register?
5 returns to 10 pulses
81
During navigation while arpa running, you have the option to have two guide zones at the same time. What is the purpose of the inner guard zone?
to give warning on small targets that are not initially detected by the outer guard zone
82
What is the purpose of the function "Anti-sea clutter" in the radar?
reduce the sea echoes
83
After 3 minutes of tracking, ARPA should provides CPA to what accuracy?
within 0.3 miles
84
You are using aradar in which your own ship is shown at the center and the heading flash always points to 000 degrees. Bearing are measured in relation to the flash, what type of bearings are produced?
relative
85
If your vessel, while proceeding south at 10 knots, observe by a radar a vessel proceeding south at 10 knots, what would be the approximate direction and rate of which the pip would move on your PPI scope?
stationary
86
How long must an ARPA produce a relative motion display with 95% accurate CPA/TCPA?
within 1 minute
87
You are using a radar which your own ships is shown at the center, and the heading flash always points to 0 degree. If bearings are measured in relation to the flash, what type of bearings are produced?
relative bearing
88
What is the main concern when using the radar for coastal position fixing?
to obtain the most accurate fix.
89
What caused the side echoes on the radar?
reflection from the side lobes of the radar beam
90
In the radar antenna operates at 60 RPM, how long for a typical arpa will generate a target vector?
15 seconds
91
Which type of radar do most ships commonly operates?
X-Band
92
What is the purpose of radar tracking of other ships?
to receive information about ships in the vicinity
93
Which general statement concerning radar is false?
the ability of radar to detect objects is unaffected by weather conditions
94
If your vessel, while proceeding north at 15 knots, observed by radar a stationary target, what would be the approximate direction and rate at which the pip would move on your PPI scope?
south at 15 knots
95
Which mode of the arpa that when it is used properly, it will produce greater accuracy?
ground stabilized
96
What ideas justify cause the SART to begin a transmission?
after being activated, the SART responds to radar interrogation
97
Which part of the ship must the raider transceiver be kept from at a safe distance?
magnetic compass
98
What is the factor in determining a radar maximum range?
receiver sensitivity
99
What is the radar control used to reduce sea clutter?
sensitivity time control