Lowrance Radar Operation Instruction Manual page 60

Heading Line Adjustment: the Heading Line is used to make sure
the green heading line (zero point) on your radar display is lined up the
bow of your vessel.
Heading Up: when your heading is displayed at the top of the screen,
you are in Heading Up mode.
Interference Rejection: filters out signals from other radars close to
your location.
North Up: a stabilized display mode in which North is at the top of the
radar display. This display mode requires a heading sensor.
Offset EBL: an electronic bearing line originating from a location other
than the PPI sweep origin.
Offset Mode: moving the sweep origin (center of the PPI) to a location
other than the center of the radar display.
Open Array Antenna: a radar antenna which has an external rotat-
ing scanner.
PPI (Plan Position Indicator): The PPI provides a map-like repre-
sentation of target echoes.
Radar Overlay: radar image data laid over an electronic chart. This
feature requires a GPS position fix and a heading sensor. Radar Over-
lay is available only on GPS units and Sonar-GPS combo units.
Radome: a single housing containing a radar antenna and transceiver.
Rain Clutter: undesirable echoes caused by rain or snow.
Range: distance to a particular target.
Range Rings: fixed rings on the radar display designed to show the
distance from the antenna.
Sea Clutter: undesirable returns caused by smaller waves and water
movement.
Standby: radar mode that follows warm-up and precedes the start of
transmission.
Sweep Origin: the origin of EBL and VRM, the sweep origin is located
at the center of the PPI.
Target: an item detected by radar.
Target Acquisition: process of locking on and starting to track a tar-
get with an ARPA radar.
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