Insignia 450TX - Manual (Page 13)

Second Returns. When a sonar signal is reflected off the bottom back to
the transducer, there is often enough energy left in the signal to be reflected
off the surface of the water back to the bottom a second time. Second
returns appear as a slightly weaker bottom representation exactly twice the
depth of the primary bottom return. The second return is most likely to
occur in shallow water and in areas of relatively hard bottom.
Fish ID. The 450TX uses advanced signal processing to further evaluate any
sonar return between the surface and the bottom. For instance, a small
school of bait fish usually appears as a dense cluster of individual dots. If the
return meets certain additional
criteria, a fish symbol will be
assigned. There are three
different size fish symbols used
to indicate the intensity of the
sonar return. While signal
intensity is a good indicator of
relative fish size, different
species of fish have different
sonar characteristics, so it is not
always possible to distinguish
fish size between varying
species. The signal intensity is
"normalized" for depth so that
a small fish close to the boat
does not appear as a large fish symbol.
ID+ adds an additional piece of information to help the user locate fish. On
selected fish symbols, the digital depth of the designated fish is drawn to help
locate the fish vertically. This is especially helpful in setting bait depths or for
downrigger operation.
The specific fish symbol indicates the type of sonar beam the fish is detected
in. This gives you a reliable indicator of side to side location relative to boat
movement. Fish symbols which are hollow are detected in the outside two
beams. Hollow fish symbols facing to the right are in the right beam and
therefore are to the right side of the boat (as viewed from the driver seat facing
forward). Hollow fish symbols facing to the left are detected in the left beam,
and thus the fish is to the left side of the boat. Solid fish symbols represent fish
in the single center beam, and these fish are directly under the boat.
11
USING THE 450TX
CONTROL FUNCTIONS
Fish in Center Beam ID+ Fish Depth
Fish in Left Beam Fish in Right Beam
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