Fish Id; Fish Id Sensitivity - Humminbird 931C Installation And Operation Manual

93x_Man_531370-1_A - vs4.qxd 2/18/2005
FISH ID+™
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.
DualBeam PLUS™ sonar models represent targets detected in the 200 kHz narrow
beam as orange fish symbols, and represent targets detected in the 50 kHz wide beam
as blue fish symbols.
200 kHz, narrow beam
orange fish symbols
When Fish ID+™ is turned off, the 900 Series™ 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.
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50 kHz, wide beam blue fish symbols
(937c DF Combo and 931c DF models only)
56
Transducer Cone and Fish Arches
To turn Fish ID+™ on or off:
1. Highlight Fish ID+ on the Sonar main menu.
2. Use the LEFT or RIGHT 4-WAY Cursor Control keys to turn the Fish ID+™
setting On or Off. (Off, On, Default = Off)

FISH ID SENSITIVITY

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 Sensitivity is used in conjunction with Fish ID+™.
Fish ID+™ must be On for Fish Sensitivity to affect the ability of the 900 Series™ to
identify sonar returns as fish.
To change the Fish ID Sensitivity setting:
1. Highlight Fish ID Sensitivity on the Sonar main menu.
2. Use the LEFT or RIGHT 4-WAY Cursor Control keys to change the Fish Sensitivity
setting. (Low = 1, High = 10, Default = 5)