4. FALSE ECHOES
Occasionally false echoes appear on the screen at positions where there is no target. In some cases the effects can be reduced or eliminated. The operator should familiarize himself or herself with the appearance and effects of these false echoes, so as not to confuse them with echoes from legitimate contacts.
4.1 Multiple Echoes
Multiple echoes occur when a short range, strong echo is received from a ship, bridge, or breakwater. A second, a third or more ech- oes may be observed on the display at double, triple or other multiples of the actual range of the target as shown in Figure
True echo
Own ship Multiple
echo
Figure 4-1 Multiple echoes
4.2 Side-lobe Echoes
Every time the scanner rotates, some radia- tion escapes on each side of the beam— called
True echo | |
|
Sprious
target
Antenna