Lowrance HOOK-4 Operation Manual page 21

NOTE: You can make minor (+/-40%)
changes to sensitivity with Auto Sensitivity
turned on. You will have to turn it off to
make significant adjustments.
Range
Selects the deepest range shown on
the display. Range settings display
the section of the water column from
the water surface to the selected
depth range.
If you select too shallow a depth range, the unit will
not be able to lock onto the bottom.
Custom range — Upper and Lower limits
Used to select the upper limit and lower limit of
a section of the water column. That allows you to
view a section of the water column that does not
include the water surface or the bottom. Upper
and lower limits must be at least 6.5 ft (2 m) apart.
NOTE: When using a custom range, you
may not receive any digital depth read-
ings, or you may receive incorrect depth
information.
Frequency
Controls the transducer frequency used by the
unit. This unit supports conventional, CHIRP and
DownScan sonar frequencies.
Only frequencies supported by
your transducer will appear on the
Frequency menu.
21
Custom range
menu
Sonar Operation | HOOK series