NorthStar 490 Echosounder Operation Manual page 75

A-scope
clutter
current
default
echo sounder
fathom
interference
latitude
longitude
490 Echo Sounder Operations Manual Rev. B2
A horizontally magnified view of each echo, where the
strength is shown by the width as well as the color of the line.
Course-Over-Ground. The actual path of your vessel relative
COG
to the surface of the earth.
Distracting echoes caused by turbulence, plankton, etc. Can be
reduced by the clutter control.
The horizontal movement of water caused by tidal or other
forces.
A choice made automatically by the echo sounder; some
defaults can be overridden in partial automatic mode.
echo The sound returned by either an object below the water's sur-
face or by the seabed, when this object or seabed is detected
by a sound wave.
An instrument that uses sound waves to measure the depth of
a body of water or an object (such as a school of fish) below
the water's surface.
A depth measurement that equals six feet or 1.83 meters of
water.
gain
The amount of amplification given to the received echo before
it is displayed.
GPS
Global Positioning System.
hue
The gradations of a color.
The electromagnetic interruption of a radio signal that causes
a poor signal reception. Interference may originate from exter-
nal sources, such as another nearby echo sounder, or from the
vessel itself, such as alternator noise.
Imaginary lines on the earth's surface running East/West and
expressed in degrees (0-90) north or south of the Equator.
Used in conjunction with the North/South lines of longitude to
determine position.
Imaginary lines on the Earth's surface running North/South
and expressed in degrees (0-180) east or west of the Prime
GGlossary
Page B-1