Simrad SN90, Operator'S Manual

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381295/B
37
Comparing the gain function with the volume control on your car radio is not very
accurate. In fact, the gain in the SN90 is constant. The
Gain
function is used to adjust
the sensitivity. This done by controlling the minimum level of detection. When you
increase the gain level (more positive number) , you reduce the minimum level, and thus
increase the sensitivity.
The echo strength (A) changes with time. The minimum level of detection (B) is adjusted
up or down with the
Gain
function. Increasing the
Gain
with a more positive number
reduces the minimum level, and this increases the sensitivity. Only echoes over the
minimum level are shown in the echogram (C).
Do not confuse this
Gain
setting with the
TVG
(Time Variable Gain) setting.
Tip
During normal operating conditions we recommend that you keep the gain between 15
and 30. If you need to adjust the gain "from scratch" disable AGC (Automatic Gain
Control) and RCG (Reverberation Controlled Gain) to see the immediate effect of the
gain adjustments. While you adjust the gain you may find it useful to have a known
target (for example an island) as reference.
Procedure
1 Click in the view you want to activate.
The active view is identified with a thicker border. Unless you use the
Apply to all
function, all changes you make will only be applied to this view.
2 Turn the relevant rotary switch to make the adjustment.
Tip
The Operating Panel is fitted with three rotary switches. The switches are identified
with numbers. Each switch can be assigned a function related to range, gain or
bearing. Investigate the functionality provided on the
Operating Panel
page. This
page is located in the
Installation
dialog box.
Optionally:
3 Observe the
Main
menu.
Its default location is on the right side of the SN90 presentation.
Getting started