航海英语航海仪器使用说明书章节练习(2019.04.20)

单项选择题
The number of pulses of energy transmitted per second is call the（）.
A.carrier frequency
B.pulse repetition rate
C.pulse length
D.pulse repetition time
单项选择题
A Doppler log in the volume reverberation mode indicates（）.
A.speed being made good
B.speed through the water
C.the set of the current
D.the depth of the water
单项选择题
An indirect radar echo is caused by a reflection of the main lobe of the radar beam off the observer’s vessel. Which of the following is NOT a characteristic of indirect echoes?（）.
A.Their bearing is almost constant，even when the true bearing of the contact changes appreciably
B.They always appear on a bearing of 90°from the true bearing of the contact
C.The indirect echoes usually appear in shadow sectors
D.When plotted，their movements are usually abnormal
单项选择题
There is a possibility that small vessel，ice and other floating objects may not be（）by radar at an adequate range.
A.reflect
B.shown
C.detected
D.defected
单项选择题
A deadhead is a(n)（）.
A.tree or log awash in a nearly vertical position
B.crew member who refuses to work
C.upstream end of a land wall
D.buoy that is adrift
单项选择题
What will NOT induce errors into a doppler sonar log?（）
A.Increased draft
B.Pitch
C.Roll
D.Change in trim
单项选择题
（）should be used during the poor visibility if the radar’s screen shows heavy sea returns.
A.Gain Control
B.Brilliant Control
C.Anti-clutter Sea Control
D.Sweep Intercept
单项选择题
The principal purpose of adjustment of the magnetic compass is to eliminate（）as far as possible.
A.variation
B.compass error
C.deviation
D.earth's magnetic force
单项选择题
If a magnetic compass is not affected by any magnetic field other than the Earth’s，which statement is TRUE?（）.
A.Compass error and variation are equal
B.Compass north will be true north
C.Variation will equal deviation
D.There will be no compass error
单项选择题
If the compass heading and the magnetic heading are the same then（）.
A.the deviation has been offset by the variation
B.there is something wrong with the compass
C.the compass is being influenced by nearby metals
D.there is no deviation on that heading