Furuno GP-3700F, Operator'S Manual

Page: 176 / 224

11. ECHO SOUNDER
11-28
indication. Proper adjustment is important. If the level is too low, weak echoes
may be recognized as the bottom echo. If the level is too high, the depth indication
is not displayed (setting range: -100 to +100).
[ECHO SMOOTHING]: Smooths echoes to present a stable display (options:
[SM1], [SM2], [SM3], [SM4], [OFF], default: [SM2]). The higher the setting the
greater the smoothing.
[DEPTH INFORMATION]: Selects the size of the depth indication at the bottom
left of the screen, [LARGE] (default), [SMALL], or [OFF] (no indication).
[TEMPERATURE GRAPH]: Turns the temperature graph on or off. [GRAPH COL-
ORS] sets the color of the graph from black (default), red, yellow, green, light-blue,
purple, blue or white.
[ZOOM MARKER]: Turns the zoom marker on or off on the single frequency dis-
play for the bottom lock, bottom zoom or marker zoom display.
[COLOR BAR DISPLAY]: Turns the color bar on or off. The color bar shows the
relation between echo intensity and echo color on the screen. The top color (red-
dish-brown) is the strongest color and the lower colors the weakest. The bar can
be used as a reference to estimate density of a school of fish, fish specifies and
hardness of the bottom. The background color can be selected on the [HUE]
menu of the [ECHO SOUNDER SETTINGS] menu (see section 11.11).
[PLAYBACK SNDR IMAGE]: Reviews the past picture. For details, see
section 11.14.
[SPEED CALIBRATION]: Applies an offset to the speed data. See the installation
manual.
[TEMP CALIBRATION]: Applies an offset to the water temperature data. See the
installation manual.
[DEPTH CALIBRATION]: In the default arrangement, the depth is measured from
the transducer. If you would rather measure depth from the sea surface or keel,
enter the vessel's draft. The indication of the sound reference (see page 11-2)
changes depending on the setting value. See the examples in the table below.
[SPEED OF SOUND SETTINGS]: Selects speed of sound from [SEA WA-
TER(1500m/s)] (default) or [PURE WATER(1470m/s)].
[SEABED DETECTION POSITION]: When the zero line (transmission line) is de-
tected as the bottom, set this value deeper than the position of zero line end.
6. Press the DISP key to close the menu.
11.19 Zero Line Rejection
The zero line (transmission line) shows the position of the transducer and its signal
strength is the strongest. When turning the zero line rejection on, the transmission line
disappears, which allows you to see fish echoes near the surface clearly. The length
of the transmission line changes with transducer used and installation characteristics.
If the width of the transmission line is 4.5 ft or more, set the transmission line width
with [Z.L. REJECT RANGE].
1. Press the MENU key to open the main menu.
The depth is the distance from the sea surface when the setting
value (offset) is plus.
The depth is the distance from the transducer when the setting
value is 0.
The depth is the distance from the keel when the setting value (off-
set) is minus.