Humminbird 858 HD DI, Operation Manual

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90 Sonar Menu Tab
Fish ID+™
Settings: Off, On; Default = Off
Fish ID+™ uses advanced signal processing to interpret sonar returns and
will display a Fish Symbol when very selective requirements are met. When
a fish is detected, a fish icon and its depth are displayed above the return
that has been classified as being a fish. Three different fish size icons
represent the intensity of the sonar return and provide an indicator of
relative fish size.
In DualBeam PLUS™ models (858c HD, 958c HD, 898c HD SI, and 998c
HD SI), targets detected in the 200 kHz narrow beam are represented as
orange fish symbols, and targets detected in the 83 kHz wide beam are
represented as blue fish symbols.
In Down Imaging™ models (858c HD DI and 958c HD DI) , targets detected
in the 455 kHz conical beam are represented as blue fish symbols, and targets
detected in the 200 kHz conical beam are represented as orange fish symbols.
In the Xtreme Depth models (858c HD XD and 958c HD XD) , targets
detected in the 200 kHz narrow beam are represented as orange fish
symbols and targets detected in the 50 kHz wide beam are represented as
blue fish symbols.
When Fish ID+™ is turned off , the Fishfinder shows only the raw sonar
returns on the display. These returns will often result in “arches“ forming on
the display, indicating potential targets. Due to the transducer beam angle,
the distance to a fish decreases as the fish moves into the beam, and then
increases as it moves out again, creating a Fish Arch when this distance
change is shown on the display. Boat speed, chart speed, and the position
of the fish within the sonar beam greatly affect the shape of the arch.
Fish ID Sensitivity
Settings: Low = 1, High = 10; Default = 5
Fish ID Sensitivity adjusts the threshold of the Fish ID+™ detection
algorithms. Selecting a higher setting allows weaker returns to be displayed
as fish. This is useful for identifying smaller fish species or baitfish. Selecting
a lower setting displays fewer fish from weak sonar returns. This is helpful
when seeking larger species of fish.
Fish ID Sensitivity is used in conjunction with Fish ID+™. Fish ID+™ must be
On for Fish ID Sensitivity to affect the ability of the Fishfinder to identify
sonar returns as fish.
Transducer Cone and Fish Arches
Narrow beam
Orange Fish Symbols
Wide beam
Blue Fish Symbols