Humminbird ] 981 - Manual (Page 57)

SENSITIVITY
Sensitivity controls how much detail is shown on
the display. Increasing the sensitivity shows more sonar returns from small baitfish and
suspended debris in the water; however, the display may become too cluttered. When
operating in very clear water or greater depths, increased sensitivity shows weaker
returns that may be of interest. Decreasing the sensitivity eliminates the clutter from
the display that is sometimes present in murky or muddy water. If Sensitivity is adjusted
too low, the display may not show many sonar returns that could be fish.
To adjust the Sensitivity:
1. Highlight Sensitivity on the Sonar X-Press™
menu.
2. Use the LEFT or RIGHT 4-WAY Cursor Control
keys to increase or decrease the Sensitivity
setting. (Low = 1, High = 20, Default = 10)
UPPER RANGE
(Advanced: Sonar, Split Sonar and Active Sonar Side Views only)
Upper Range sets the shallowest depth range that will be displayed on the Sonar, Split
Sonar and Big Digits Views. The Upper Range menu choice is available when User
Mode is set to Advanced (see Setup Menu Tab: User Mode) and can only be accessed
from the Sonar, Split Sonar and Big Digits Views. Upper Range is often used with Lower
Range.
NOTE: A minimum distance of 10 feet will be maintained between the Upper and Lower
Range regardless of the manual settings entered.
To adjust the Upper Range:
1. Make sure you are in Advanced Mode, then highlight Upper Range on the Sonar
X-Press™ Menu.
2. Use the LEFT or RIGHT 4-WAY Cursor Control keys to increase or decrease the
Upper Range setting. (0 to 2990 feet, 3 to 927 meters [International Models
Only], Default = 0).
For example, if you are only interested in the area between 20 and 50 feet deep, you should
set the Upper Depth Range to 20 and the Lower Depth Range to 50. The Sonar View will then
show the 30 foot area between 20 and 50, and will not show the surface or the bottom
(assuming the bottom is deeper than 50 feet), and will show greater detail for that area
between 20 and 50 feet.
Sensitivity at Low
Sensitivity at Medium
Sensitivity at High
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