Icom MR-1200RII - 7 Basic Radar Theory; Side-Lobe Echoes; Indirect Echoes

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BASIC RADAR THEORY
■ Indirect echoes
Indirect echoes may be returned from either a passing
ship, or returned from a reecting surface, such as a
mast on your own ship.
Target
Scanner
Mast or
similar obstruction
An echo is reflected at this point.
Your ship
Target
Bridge
An indirect echo from a reective surface will appear
on a different bearing from the direct (true) echo, but
the distance will be approximately the same for both.
Tr ue echo
False echo
Indirect echo
Tr ue echo
■ Side-lobe echoes
Radiation can escape on each side of the beam inside
the lobes. If a target reects this radiation, it will be
displayed on the screen as an echo.
Main beam
Side lobes
Side-lobe echoes usually occur at short ranges and
as a result of large (strongly reective) targets. They
can be reduced with proper adjustment of the [SEA]/
[ ] control.
See page 9 for the [SEA]/[ ] control.
False
echoes
Tr ue
echo
Radar uses a form of electromagnetic radiation which, like light, can be reected. 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 other metal object is in proximity. Operators should be famil-
iar with the effect of this phenomena. In some cases, echoes can be reduced.