問題一覧
1
What is the suitable radio wave length to use at closer range?
Short
2
It is a condition in calm weather with no turbulence where there is an upper layer of warn dry air over a surface layer of cold moist air. This normally occurs in the tropics when warn land breeze blows over the cooler ocean currents.
Super refraction
3
What may occur due to the obstructions close to the site of the aerial which may reflect some of the radar energy on both its outward and return journey?
Indirect echoes
4
When side echoes are observed where they have not been seen before, their cause should be determined the first suspect should be:
dirty antenna
5
How many cm is the wavelength of S-band radars?
10cm
6
It is an expression which attempts to formalize the relationship between the maximum range at which a target can be detected and the parameters on which that range depend
Range equation
7
The phenomena, occurs during extreme cases of super-refraction. Energy radiated at angles of 1 (one) degree or less maybe trapped in a layer of the atmosphere called ______________.
Surface radio duct
8
How many cm is the wavelength of X-band radars?
3cm
9
It is a phenomenon cannot be described as precipitation but, as the effects are similar.
Dry sand and dust haze
10
What is the suitable radio wave to use, at farther range?
Long
11
What is the maximum heading indicator error?
1 degree
12
Interference can be filtered out by comparing the signals present in successive range and rejecting those which do not appear on successive lines or by pressing the button IR. What do IR mean?
Interference Reject
13
How do you define Range discrimination?
it is the ability to discriminate between two small objects close together at the same bearings
14
The radar rays are reflected downwards to the surface of the sea, then reflected upward reflected downwards again within the duct, and so on continuously.
Surface duct
15
What does RADAR stand for?
Radio Detection and Ranging
16
What do occur when the radiation from the aerial is intercepted by obstructions such as the mast, funnel, etc. onboard the vessel?
Blind and shadow sectors
17
The maximum duration set by the IMO performance standards which requires that, after switching on from cold, the equipment should become full operational______________.
within 4 minutes
18
It is caused by starting the sweep on the indicator before the energy leaves the antenna.
Fixed range error
19
It is a free running oscillator, which generates a continuous succession of low voltage pulses known as synchronizing pulses or trigger pulses; commonly they are referred to as simply triggers
trigger generator
20
What is Range resolution?
It is a measure of the capability of the radar to display as separate indication the echoes of two contacts which are on the same bearing and close together.
21
Which band is recommended to use when it is raining?
S-band
22
It occurs when a target is close and the energy bounces back and forth between the hulls of the target and by the observing ship, with some of the energy entering the antenna at each return.
Multiple echoes
23
How do you define Bearing discrimination?
It is the ability to discriminate between two small objects close together at the same range
24
The amount of energy which is returned towards the antenna, as opposed to that energy which is absorbed and scattered by the target is dependent upon the following five (5) prime characteristics of the target.
aspect, surface texture, materials, shape and size
25
The importance of minimum range detection is recognized by the IMO performance standard. What is the range required by the IMO performance standard that specific target types be clearly displayed
down to a minimum range of 50 meters.
26
For long range targets, which radar band is recommended?
s-band
27
What pulse settings is recommended with targets beyond the rain?
Long pulse
28
Which of these precipitations has the most effect on radar range and target detection?
rain
29
The standard on minimum range and range performance continues to be met even if the vessel is rolling and pitching up to _____________.
10 degrees
30
What is the effect of sub-refraction on your RADAR?
The effect of sub- refraction is to bend the radar rays upward and thus decreases the maximum range at which the contacts maybe detected.