SYSTEM OPERATION
SeaBat 8160
Operator‟s Manual
Page 29
October 6, 2011
Version 5
The available types of Gain are:
Fixed:
This mode applies a specified gain amount that does not vary
with time. This is normally only used for very short range operation (less
than 10 meters).
TVG:
The Time Varied Gain (TVG) mode applies a variable gain to the
signal, based upon the following formula:
Receiver Gain = 2
R + Sp log R + G
Where:
= Absorption Loss in dB/km
Sp = Spreading Loss Coefficient
R = Range in meters
G = Extra Gain from RxGain menu item
NOTE
Both the Absorption Loss (
) and Spreading Loss (SP) values may be modified
using the “Absorb” and “Spread” items on the “Ocean” menu (see
section
5.4.7 Activate Automatic Gain (AutoGain)
The Automatic Receiver Gain function analyzes the bottom return and
automatically adjusts the Receiver Gain accordingly. The AutoGain menu item
controls the level of signal amplitude threshold to which the sonar return is
compared.
Settings are “OFF” through “10” in increments of 1. The lower the selected
number the lower the threshold, and the higher the gain setting selected by the
sonar processor.
A typical setting is “4,” however the optimal setting will vary with
bottom type and other environmental conditions.
NOTE
The bottom detect process must have good quality return signals to allow
AutoGain to work properly.
