Upper Range (Advanced: Sonar, Split Sonar, Circular Flasher, And Big Digits Views Only); Lower Range - Humminbird 688ci HD DI Operation Manual

Upper Range sets the shallowest depth range that will be displayed on the
Sonar, Split Sonar, Circular Flasher, and Big Digits Views. Upper Range is often
used with Lower Range.
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).
Greater detail will be shown for the area between 20 and 50 feet.
NOTE: A minimum distance of 10 feet will be maintained between the Upper and
Lower Range regardless of the manual settings entered.
The available Upper Range settings are determined by your Humminbird® model
as follows:
• 688ci HD: 0 to 1490 ft, 0 to 497 m (International Models only);
Default = 0
• 688ci HD DI: 0 to 590 ft, 0 to 180 m (International Models only);
Default = 0
• 688ci HD XD: 0 to 2490 ft, 0 to 759 m (International Models only);
Default = 0
Lower Range sets the deepest depth range that will be displayed by the unit.
Auto: The Lower Range will be adjusted by the unit to follow the bottom
automatically. Auto is the default setting.
Manual: You can adjust the Lower Range to lock the unit on a particular depth.
"M" will be displayed in the lower right corner of the screen to indicate the unit
is in Manual mode. Adjust the Upper and Lower Range together to view a
specific depth range, especially when looking for fish or bottom structure.
Upper Range
(Advanced: Sonar, Split Sonar, Circular Flasher,
and Big Digits Views only)
Settings: Various, see below.

Lower Range

Settings: Various, see below.
85 Sonar X-Press™ Menu