Icom EX-2714 Fish Finder User Manual


 
Indirect echoes
Indirect echoes may be returned from either a passing
ship, or returned from a reecting surface, such as a
mast on your own ship.
An indirect echo from a reecting surface will appear
on a different bearing from the direct (true) echo, but
the distance will be approximately the same for both.
Indirect echo
True echo
True echo
False echo
An echo is reflected at this point.
Own ship
Target
Bridge
Target
Scanner
Mast or
similar obstruction
Side-lobe echoes
Radiation can escape on each side of the beam inside
the lobes. If a target reects this radiation, it will be dis-
played on the screen as an echo.
Side-lobe echoes usually occur at short ranges and as
a result of large (strongly reective) targets. They can
be reduced with proper adjustment of the
[SEA]/[ ] control.
See p. 10 for the [SEA]/[ ] control.
False
echoes
True
echo
Main beam
Side lobes
Radar uses a form of electromagnetic radiation, which like light, can be reected. Because of this property, some
objects may cause false echoes on the screen where in fact no targets actually exist.
These echoes may appear if a large vessel, bridge, or tank is in proximity. Operators should be familiar with the ef-
fects of these phenomena. In some cases, echoes can be reduced.
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BASIC RADAR THEORY
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