Furuno CSH-53 manual Control Function

Control	Function
NORM, E/S, HIST	Select display mode: NORM, normal sonar picture; E/S, Echosounder
(Mode keys)	combination; HIST, Historical display.
	Lamp above a key lights to show current selection.
RECALL, MEMO	RECALL: Replays saved picture.
	MEMO: Saves picture to memory card or internal memory.
RANGE	Selects a picture display range. Range selected appears on the display.
GAIN	Adjusts receiver sensitivity.
NARROW	Sharpens width of Tx beam when turned on (light above key is on).
	The off position provides normal Tx beamwidth.
BOOST	Changes weight of vertical direction during transmission when turned
	on.
SHOOT	Press when net is cast. The net shooting mark, *net sonde marks and
	*current mark appears at the own ship mark. The net shooting mark,
	net sonde marks and current mark moves on the *ship's track as the
	ship moves. The lamp above the switch lights and time *distance run
	appear on the display unitl the net shooting mark is turned off.
	(* Requires external sensor.)
R/B	Provides range and bearing data from own ship to a target. Select
	target with trackball and then press the R/B key. A line connects
	between own ship mark and trackball mark to measure bearing.
TILT	Changes the tilt angle of the sounding beam between -5°and 60°.
AUTO TILT	Automatically tilts the sounding beam up and down in 2° steps within
	the tilt angle selected by the WIDTH key. The lamp above the key
	lights when automatic tilt is on.
WIDTH	Sets tilt width in automatic tilt.
NET COURSE	Marks location of net.
TARGET LOCK	Tracks a fish school.
EVENT 1, 2	Inscribes event mark on the display, to find horizontal, range, depth
	and bearing of a target.
ESTIMATE 1, 2	Compares volume of two fish schools.
FISH	Measures fish school speed.
OFF-CENT	Relocates selected target.
DIM	Adjusts the backlighting of the control panels and the brightness of
	the lamps above keys
CONT	Adjusts screen contrast.
BRILL	Adjusts screen brilliance.
AUDIO	Adjusts volume of built-in loudspeaker, which monitors a target
	appearing along the bearing marker.
TRACKBALL	Follows on-screen movement of trackball mark, to enter marks and
	off-center the screen.

1-3