Furuno CHS-5LMARK-2-55, Operator'S Manual

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2. FINE TUNING THE SONAR PICTURE
2-3
2.3.2 Pulse length
The pulse length control determines the length of the transmission pulse emitted into
the water. While a longer pulse is advantageous for long-range sounding, it has the
disadvantage of being poor in discrimination of targets, i.e., ability to separate several
closely located targets. When searching bottom fish, therefore, it is useful to shorten
the pulselength in order to separate fish echoes from bottom reflections. For search of
surface and midwater fish in which bottom reflections are not so strong, the longest
pulse length "10" should be used.
1. Press the MENU key.
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 [PULSE LENGTH].
5. Use the GAIN control to set pulse length. The setting range is 0-10 and the higher
the setting the longer the pulse length.
6. Press the MENU key to close the menu.
2.3.3 2ND AGC
While it is ideal to suppress bottom echoes with the AGC alone there are some fishing
grounds where this is not possible. (The high power sonar has the advantage of long-
range detection but this can also be a disadvantage, since weaker echoes may be hid-
den in strong, unwanted echoes such as the bottom.)
If you cannot suppress bottom echoes or sea surface reflections by the AGC function
alone, use the 2ND AGC feature. Normally a setting of 1 or 2 is suitable. For especially
strong echoes, use a setting of 3 or 4.
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 [2ND AGC].
5. Use the GAIN control to set 2ND AGC. The setting range is 0-10 and the higher
the setting the greater the 2ND AGC effect.
6. Press the MENU key to close the menu.