Furuno 1933C - Manual (Page 156)

4. VIDEO SOUNDER OPERATION
4-10
4.4 Manual Sounder Operation
Manual operation is useful for observing fish schools and bottom using a fixed
gain setting.
The gain, range and range shift functions used together give you the means to
select the depth you can see on the screen. The basic range can be thought of
as providing a “window” into the water column and range shifting as moving the
“window” to the desired depth.
4.4.1 Selecting the manual mode
1. If not displayed, press the [HIDE/SHOW] key to show the sounder soft keys.
2. Press the AUTO/D. BOX soft key to show the mode/frequency window.
3. Select OFF (MANUAL).
4. Press the RETURN soft key.
4.4.2 Selecting display range
Press the [RANGE +] or [RANGE -] key to select a range. The default ranges in
feet, meters, fathoms and passi/braza are as below. Note that the range cannot
be changed in the automatic sounder mode.
Default sounder ranges
Range 8 Range 1 Range 2 Range 3 Range 4 Range 5 Range 6 Range 7
ETR-6/10N ETR-30N
15 ft 30 ft 60 ft 120 ft 200 ft 400 ft 1000 ft 4000 ft 4500 ft
5 m 10 m 20 m 40 m 80 m 150 m 300 m 1200 m 1500 m
3 fa 5 fa 10 fa 20 fa 40 fa 80 fa 150 fa 650 fa 900 fa
3 P/B 5 P/B 10 P/B 30 P/B 50 P/B 100 P/B 200 P/B 700 P/B 900 P/B
4.4.3 Adjusting the gain
Normally, set the gain to the point where excessive noise does not appear on the
screen. Use a higher gain setting for greater depths and a lower setting for
shallow waters.
Gain too high Gain proper Gain too low
Examples of proper and improper gain