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30 Cards in this Set
- Front
- Back
3-90O4
Shipboard RADAR is most commonly operated in what band? |
SHF
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3-90O5
The pulse repetition rate (prr) of a RADAR refers to the: |
Pulse rate of the magnetron
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3-90O6
If the elapsed time for a RADAR echo is 62 microseconds, what is the distance in nautical miles to the object? |
5 nautical miles
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3-90O1
What is the normal range of pulse repetition rates? |
500 to 2,000 pps
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3-90O2
The RADAR range in nautical miles to an object can be found by measuring the elapsed time during a RADAR pulse and dividing this quantity by: |
12.346 µs
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3-90O3
What is the normal range of pulse widths? |
.05 s to 1.0 s.
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3-91O1
The ATR box: |
Prevents the received signal from entering the transmitter
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3-91O2
What is the purpose or function of the RADAR duplexer/circulator? It is a/an: |
Electronic switch that allows the use of one antenna for both transmission and reception
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3-91O3
What device can be used to determine the performance of a RADAR system at sea? |
Echo box
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3-91O4
What is the purpose of a synchro transmitter and receiver? |
Transmits the angular position of the antenna to the indicator unit
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3-91O5
Digital signal processing (DSP) of RADAR signals (compared with analog) causes: |
Improved weak signal or target enhancement
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3-91O6
The component or circuit providing the transmitter output power for a RADAR system is the: |
Magnetron
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3-92O1
When a RADAR is being operated on the 48 mile range setting, what is the most appropriate pulse width (PW) and pulse repetition rate (pps)? |
1.0 s PW and 500 pps
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3-92O2
When a RADAR is being operated on the 6 mile range setting what is the most appropriate pulse width and pulse repetition rate? |
0.25 s PW and 1,000 pps
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3-92O3
We are looking at a target 25 miles away. When a RADAR is being operated on the 25 mile range setting what is the most appropriate pulse width and pulse repetition rate? |
1.0 s PW and 500 pps
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3-92O4
What pulse width and repetition rate should you use at long ranges? |
Wide pulse width and slow repetition rate
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3-92O5
What pulse width and repetition rate should you use at short ranges? |
Narrow pulse width and fast repetition rates
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3-92O6
When a RADAR is being operated on the 1.5 mile range setting, what is the most appropriate pulse width and pulse repetition rate? |
0.05 s PW and 2,000 pps
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3-93O1
How does the gain of a parabolic dish antenna change when the operating frequency is doubled? |
Gain increases 6 dB
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3-93O2
What type of antenna or pickup device is used to extract the RADAR signal from the wave guide? |
J-hook
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3-93O3
What happens to the beamwidth of an antenna as the gain is increased? The beamwidth: |
Decreases as the gain is increased
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3-93O4
A common shipboard RADAR antenna is the: |
Slotted array
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3-93O5
Conductance takes place in a waveguide: |
Through electromagnetic and electrostatic fields in the walls of the waveguide
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3-93O6
To couple energy into and out of a waveguide use: |
A thin piece of wire as an antenna
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3-94O1
The permanent magnetic field that surrounds a traveling-wave tube (TWT) is intended to: |
Prevent the electron beam from spreading
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3-94O2
Prior to testing any RADAR system, the operator should first: |
Assure no personnel are in front of the antenna
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3-94O3
In the term “ARPA RADAR,” ARPA is the acronym for which of the following? |
Automatic RADAR Plotting Aid
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3-94O4
Which of the following is NOT a precaution that should be taken to ensure the magnetron is not weakened: |
Keep the TR properly tuned.
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3-94O5
Exposure to microwave energy from RADAR or other electronics devices is limited by U.S. Health Department regulations to _______ mW/centimeter. |
5.0
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3-94O6
RADAR collision avoidance systems utilize inputs from each of the following except your ship’s: |
Anemometer
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