Humminbird 400TX Operation Manual page 31

Units Speed. Units of Speed allows the selection of MPH (statute
miles per hour), or KTS (nautical miles per hour). Use the Arrow
buttons to highlight the desired selection.
Units Depth. Only available on metric versions, the Units Depth
function allows the user to select the units of measurement for the
depth readout. FEET and METERS are available. The 400TX
remembers this selection even when the unit is powered off.
Fish ID. There are three selections available: Off, ID+ ON, and
Adjust. The factory setting is ID+ On. With Fish ID Off, sonar
returns are displayed as "raw" information. There is no
interpretation made by the unit. Selecting ID Off also disables the
fish alarm.
ID+ On enables the 400TX to interpret the raw sonar data and,
using a variety of techniques, depict appropriate target returns as
one of three different size fish symbols. Further identification
shows which beam the fish is detected in. The 400TX also
displays the depth beneath the surface with the corresponding fish
symbol.
Selecting Adjust and making incremental changes enhances the
fishfinder's ability to identify sonar returns as fish symbols.
Increasing the value to a number greater than zero shows more
fish symbols onscreen. In this case smaller sonar returns will be
depicted as fish symbols. This is useful for identifying many
smaller sonar
will be depicted as fish symbols. This is useful for identifying many
smaller sonar returns (such as baitfish) as fish symbols.
Decreasing the value to a number less than zero shows fewer fish
symbols on-screen. In this case smaller sonar returns are
disregarded. This is useful for eliminating many small sonar
returns when seeking larger species of fish.
The 400TX remembers this selection even when the unit is
powered off.
Numeral Size. Two options are available: Big and Small. The factory
setting is Big. With this setting, the digital depth and speed and temp
numerals are drawn large enough to be read from across the boat.
The big numerals occupy space on the display that could be used
for the graphics area. Hence, the small numerals option. With small
numerals selected, a greater amount of the display area is available
for the graphic view. This effectively increases the display resolution
of the unit.
Numeral Size settings are remembered when powered off.