Furuno CSH-5L/CSH-8L - Manual (Page 32)

2. FINE TUNING THE SONAR PICTURE
2-4
2.4 Suppressing Bottom and Sea Surface
Reflections in Shallow Fishing Grounds
In shallow fishing grounds with hard or rocky bottom, bottom reflections often
interfere with wanted fish echoes and they can not be eliminated sufficiently with
the aforementioned TVG and AGC, especially when the tilt angle is large in
order to track fish schools approaching within 400 m. In such cases try to reduce
the output power without turning down the gain. The picture becomes clearer
when the output power is reduced rather than when the gain is decreased as
illustrated below.
1. Press the MENU key. The last-used menu appears.
2. Use the [RANGE] control to choose [MENU MODE] at the top of the screen.
3. Use the [GAIN] control to choose SONAR to display the SONAR menu.
4. Use the [RANGE] control to choose TX OUTPUT.
5. Use the [GAIN] control to set TX output. The higher the setting (setting range:
0-10) the greater the TX power.
6. Press the [MENU] key to close the menu.
For long-range detection, set TX OUTPUT to 10.
Improper
Proper
TVG and AGC
adjusted, OUTPUT
high.
OUTPUT decreased,
gain maintainted
Fish echo
Fish echo
weakened
Bottom echo masks
fish echo.
How to adjust TX output