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Adjusting the TVG (Time Variable Gain) setting
When an acoustic pulse is sent through the water, it will gradually lose its energy. The
greater the distance between the transducer and the target(s), the greater the loss of
energy.
(Time Variable Gain) compensates for the loss of acoustic energy due to
TVG
geometric spread and absorption.
Context
The TVG (Time Variable Gain) compensation is designed to counteract the natural
phenomena of geometric spread and absorption loss. In the SN90, the TVG
compensation is made using digital signal processing software. The TVG compensation
is expressed as a logarithmic curve. Each curve has a different slope creating a different
gain compensation. Each curve is identified with the equation X log TVG. The coefficient
"X" is an integer. Typical values for "X" are 10 to 40.
Procedure
1
Click in the view you want to activate.
The setting you choose will only be valid for the active view. The active view is
identified with a thicker border.
2
Open the
Active
3
Locate the
TVG
4
Select [+] or [-] to choose the requested setting.
Related topics
Controlling the gain and range settings, page 63
Adjusting the sonar range
The sonar range setting defines how "far" you wish the SN90 to detect echoes: the
distance from the vessel to the outer edge of the search area.
Context
The
setting defines how "far" you wish the SN90 to detect echoes. In other
Range
words, you specify the horizontal or vertical distance from the vessel to the outer edge
of the search area.
381295/B
menu.
button.
Operating procedures
65
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