■
Indirect echoes
Indirect echoes may be returned from either a passing
ship, or returned from a reflecting 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 reflective surface will appear
on a different bearing from the direct (true) echo, but
the distance will be approximately the same for both.
True echo
False echo
Indirect echo
True echo
■
Side-lobe echoes
Radiation can escape on each side of the beam inside
the lobes. If a target reflects 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 reflective) targets. They
can be reduced with proper adjustment of the [SEA]/
[
] control.
See page 9 for the [SEA]/[
] control.
False
echoes
True
echo
Radar uses a form of electromagnetic radiation which, like light, can be reflected. 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.
7
BASIC RADAR THEORY
20
