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44 Cards in this Set

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Radar surface-angular measurements are referenced to true north and measured in what plane?
Horizontal plane.
The distance from a radar set to a target measured along the line of sight is identified by what
term?
Range.
What is the speed of electromagnetic energy traveling through air?
Approximately the speed of light (162,000 nautical miles per second).
How much time is required for electromagnetic energy to travel 1 nautical mile and return to the
source?
12.36 microseconds.
In addition to recovery time, what determines the minimum range of a radar set?
Pulse width.
Atmospheric interference with the travel of electromagnetic energy increases with what rf energy characteristic?
Frequency
How is prt related to prf?
1/PRT= PRF
What type of radar transmitter power is measured over a period of time?
Average power.
What term is used to describe the product of pulse width and pulse-repetition frequency?
Duty cycle.
What type of target bearing is referenced to your ship?
Relative bearing.
What type of radar detects range, bearing, and height?
Three-dimensional.
What characteristic(s) of radiated energy is (are) altered to achieve electronic scanning?
Frequency or phase.
What term is used to describe the ability of a radar system to distinguish between targets that are close together?
Target resolution.
The degree of bearing resolution for a given radar system depends on what two factors?
Beam width and range.
What happens to the speed of electromagnetic energy traveling through air as the altitude
increases?
Speed increases.
What term is used to describe a situation in which Atmospheric temperature first increases with altitude and then begins to decrease?
Temperature inversion.
What radar subsystem supplies timing signals to coordinate the operation of the complete
system?
Synchronizer.
When a transmitter uses a high-power oscillator to produce the output pulse, what switches the oscillator on and off?
High-voltage pulse from the modulator.
What radar component permits the use of a single antenna for both transmitting and receiving?
Duplexer.
What is the simplest type of scanning?
Single lobe.
How does the operator of a single-lobe scanning system determine when the target moves off the lobe axis?
The reflected signals decrease in strength.
What are the two basic methods of scanning?
Mechanical and electronic.
Rotation of an rf-feed source to produce a conical scan pattern is identified by what term?
Nutation.
The Doppler effect causes a change in what aspect of rf energy that strikes a moving object?
Frequency.
The Doppler variation is directly proportional to what radar contact characteristic?
Velocity
The Doppler method of object detection is best for what type objects?
Fast-moving targets.
The beat frequency in a swept-frequency transmitter provides what contact information?
Range
What factor determines the difference between the transmitted frequency and the received frequency in an fm transmitter?
Travel time.
What type of objects are most easily detected by an fm system?
Stationary
What transmission method does NOT depend on relative frequency or target motion?
Pulse modulation.
What transmission method uses a stable cw reference oscillator, which is locked in phase with the transmitter frequency?
Pulse-Doppler.
What type of radar provides continuous range, bearing, and elevation data on an object?
Track radar.
Radar altimeters use what type of transmission signal?
Frequency modulated (fm).
A surface-search radar normally scans how many degrees of azimuth?
360 degrees.
What limits the maximum range of a surface-search radar?
Radar horizon.
What is the shape of the beam of a surface-search radar?
Wide vertically, narrow horizontally.
Air-search radar is divided into what two basic categories?
2D and 3D.
What position data are supplied by 2D search radar?
Range and bearing.
Why do 2D air-search radars use relatively low carrier frequencies and low pulse-repetition rates?
Increased maximum range.
Why is the range capability of 3D radar usually less than the range of 2D radar?
Higher operating frequency.
Fire-control tracking radar most often radiates what type of beam?
A narrow circular beam.
Tracking radar searches a small volume of space during which phase of operation?
Acquisition.
What width is the pulse radiated by fire-control tracking radar?
Very narrow.
Which beam of missile-guidance radar is very wide?
Capture beam.