Adjusting the gain (echo sensitivity)
Some echoes are weak while others are stronger. To compensate for this it is often necessary to adjust the sensitivity of the CS90. This adjustment is commonly referred to as gain.
Context
You can compare this gain setting with the volume control on your car radio. When the gain is increased, the echoes will appear stronger. Weak echoes will be easier to see. However, since you also increase the acoustic noise in the reception, the CS90 presentations will also show this noise. Too much gain may therefore "distort" the presentation.
Comparing the gain function with the volume control on your car radio is not very accurate. In fact, the gain in the CS90 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.
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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 Varied 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.
4 Select Gain.
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5 Make the necessary adjustment.
6 Open the button and select Apply to all if you wish to use the chosen setting in all the views in the current presentation mode.