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2.7
Detecting Schools of Fish Effectively
2.7.1
Relocating a school of fish for easy observation
When a school of fish is near the edge of the screen and inconvenient for observation,
use the expanded sonar mode and adjust the TRAIN control (off-center function) to
relocate the school of fish close to the screen center.
Expanded forward view
2.7.2
Suppressing bottom and sea surface reflections
In shallow fishing grounds, excessive sea surface and bottom reflections often inter-
fere with wanted fish echoes and they cannot be eliminated sufficiently with the afore-
mentioned TVG controls. In such cases, try to reduce the output power from C to B or
A on the SONAR menu, without turning down the gain. The picture becomes clearer
when output power is reduced rather than when the gain is decreased, as illustrated
below.
TX OUTPUT POWER: HIGH
2.7.3
Suppressing bottom tail
As described earlier, schools of fish near the bottom are sometimes difficult to detect
because you have to discriminate fish echoes from the bottom reflections. To discrim-
inate fish echoes near the bottom, select the short Tx pulse length on the SONAR
menu to decrease the tail of bottom reflection.
2.7.4
Displaying surface fish clearly (TVG adjustment)
Echoes from targets (such as the bottom or a fish) return to the transducer in order of
the distance to them, and when their intensities are compared at the transducer face,
those from nearer targets are generally stronger when their reflecting properties are
Turn clockwise
TRAIN
Own ship
Own ship
(Relocated leftside)
TX OUTPUT POWER: LOW
2. SONAR MODE
School of fish
Note:
Own ship's marker
is not expanded.
Expanded right side view
2-7
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