Side lobes, Indirect (false) echoes – Raymarine Marine GPS System User Manual
Page 102

Advanced Navigator Functions
5-11
Side Lobes
A small part of the RF energy from each transmitted pulse is radiated
outside the single narrow beam. This produces side lobe patterns,
shown in Figure 5-2. Side lobes have no effect on distant or small
surface objects; however, the echo from a large object at short range
may produce an arc on the radar screen similar to a range ring or a
series of echoes forming a broken arc. Side-lobe echoes normally
occur at ranges below 3nm, and can be reduced by adjusting the SEA
control.
Figure 5-2. Radar Side Lobe Echo Affects
Indirect (False) Echoes
There are several types of indirect echoes or ghost images (Figure 5-3).
These sometimes have the appearance of true echoes, but in general
they are intermittent and poorly defined.
Figure 5-3 Radar Indirect Echo Affects
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