Furuno FSV-30 Operator's Manual page 180

ORIGINAL SETTING
Note: 1) Dual multi-mode can't be used, when the INT SUPPRESS is set
2) Combination of INT SUPPRESS "3" and SIDEROBE
10. To emphasis the difference between a week and strong signal with
multi-color, adjust the color setting properly.
11 . Increasing the POST GAIN setting is effective for displaying the week
echo such as echo of skipjack, or tuna, however, it also emphasis the
unexpected echo such as sea-surface echo, bottom echo, DSL and the
echo caused by the side-lobe.
12. To suppress the side-lobe echo, select SIDE-LOBE SUPPRESSION "1"
or "2", or lower the horizontal beam setting.
13. Too high NEAR GAIN setting, over 33dB approx., makes the control
range of the GAIN controller on the control unit narrow. Do not increase
NEAR GAIN so much except detecting the fish, such as skipjack or tuna,
of which detection is difficult with low frequency.
14. Setting of the MIN BANDWIDTH "200 Hz" is for improving the
performance of detecting the fish school at quick-turn of the ship. Except
this situation, narrowing bandwidth, 60 to 120 Hz, is better to suppress
the noise.
15. Basically, set the REVERBRATION, BOTTOM SUPPRESS, and
PRETVG CORRECT settings to "0". Use these functions under deep
understanding.
Horizontal mode "H2" setting.
Horizontal H2 settings are the same setting as the horizontal H1
except the settings of FREQ SHIFT. In order to avoid the
interference between H1 and H2 signals with multi-transmission
mode, the frequency is shifted down to 22.4 kHz (-16).
When use the individual transmission mode, shifting frequency
is not required.
Vertical mode "V" setting.
All settings, P1 to P10, are common settings except the setting of the
frequency shift.
Purpose of this setting is as follows;
1. Narrow the bottom echo in vertical direction.
2. Smooth the upper edge of bottom echo in order to distinguish the
bottom fish.
3. Observe the form of the fish school clearly in both horizontal and vertical
direction.
Tips of this setting are the settings of TX PULSE LENGTH, BEAMWIDTH,
SMOOTH ECHO, ECHO AVERAGE, and COLOR RESPONSE.
AP-6
to "3".
SUPPRESSION "1 or 2" cause low sensitivity at the range less
than 600m.