Radar Terminology

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Because you probably know how to read (you made it this far onto the site)

ARPA - automatic radar plotting aid; a computerized system that displays info such as range, bearing, and relative motion automatically
CPA - closest point of approach; tells you how the range an object will be at when it is at it's absolute closest point to you
EBL - electronic bearing line; a line displayed on the screen from you (center) to the bearing or object of your choice
FTC - (aka Rain) fast time constant; allows the radar to remove some of the clutter caused by rain by shortening the part of the radar pulse that it displays
Gain - a measure of how sensitive the radar is to the signals it receives; a low gain will only display strong returns, a high gain will display weaker returns
HDG - your heading at that time, (note this is not your course)
LP - long pulse; the radio pulse that the radar sends out will be longer, enabling you to use greater range scales
MP - medium pulse; modifies the radio pulse that the radar sends out to be more efficient on medium range scales
Parallel Indexing - a method of establishing a line, parallel to your course, a set distance away from you so that, when an object is in view, you can visibly see if you are drifting off course due to wind, current, etc. Also useful in maneuvering, see section on parallel indexing for more
RADAR - Radio Detection and Ranging
Rain - (FTC) rain and clouds will sometimes display on the screen, use this feature to reduce the effect of these on the screen by reducing the length of the pulse displayed (it gets complicated but essentially it only displays the strongest part of the radio pulse received)
Range - the distance something is from you
Range Rings - a series of concentric rings set at different distances from you; useful in obtaining a rough range of an object with no calculations
RM - relative motion; images display relative to your movements, ie. all vectors are of the objects motion relative to your own
Sea - (aka STC) removes clutter caused by the radar pulses bouncing off the waves nearby
SP - short pulse; modifies the pulse that the radar sends out so that it will be more efficient on small range scales
STC - (aka Sea) sensitivity time control; reduces the gain for nearby targets only, thus removing some sea clutter
TCPA - time until CPA; the time it will take for you and an object to reach your CPA
TM - true motion; images on screen display as they would in real life, ie. all vectors are of the objects true heading
VRM - variable range marker; a ring or cross-hair cursor that allows you to find the distance to whatever you're looking at