Furuno GP-3500F - Manual (Page 174)

11. VIDEO SOUNDER OPERATION
11-2
11.2 Sounder Displays
There are nine display modes from which to choose: single frequency,
dual-frequency, marker zoom, bottom zoom, bottom lock, bottom discrimination,
A-scope, Mix display and plotter/sounder display. For Mix display, see paragraph
11.2.8.
You may select a display as follows.
1. Press the [DISP] key to show the DISPLAY MODE screen.
2. Press the [0] key several times until the desired display appears.
3. Press the appropriate numeric key to select a display.
To show the Mix display, you must set a DISPLAY MODE screen for the mix
display. For further details, see paragraph 11.17.
11.2.1 Single frequency display (50 kHz or 200 kHz)
50 kHz
The sounder uses ultrasonic pulses to detect bottom conditions. The lower the
frequency of the pulse, the wider the detection area. Therefore, the low
frequency is useful for general detection and judging bottom condition.
200 kHz
The higher the frequency of the ultrasonic pulse the better the resolution.
Therefore, the high frequency is ideal for detailed observation of fish school.
200 kHz 50 kHz
Sounding area and transmission frequency