CVS-842/852/843 Chapter 5
Operation Manual Basic Operation
93132692-00 5-7
5.2.4 Setting the receiver gain
Turn the H FREQ GAIN or L FREQ GAIN control as appropriate to make the bottom echo displayed in
red.
For High Frequency gain control
CVS-842/852
For Low Frequency
gain control
CVS-843
5.2.5 Setting the STC
The STC (Sensitivity Time Control) is used to reduce the receiver gain in proportion to time, which is
useful to eliminate nearby unwanted echoes like plankton, jelly fish, etc. There are two STC controls
provided, STC Depth and STC Amplitude. Refer to the following descriptions of these controls before
attempting the operation.
5.2.5.1 Setting the STC Depth
In this mode, you are reducing receiver sensitivity against depth in time proportional law with STC
amplitude fixed. This mode is useful in deep sea fishing to locate school of fish and the species.
Operational notes for STC amplitude adjustment
(1) STC law A: STC is not enough, causing noise and unwanted residual weak echoes in shallow
and mid depth zone to be shown.
(2) STC law B: STC is appropriate, causing unwanted echoes to be perfectly reduced while schools
of fish are shown without degradation.
(3) STC law C: STC is too much, causing the echoes from fish school to be reduced too much.
STC Amplitude
STC
Depth
A
C
B
Max
Max
Figure 5.10 Adjusting the STC depth
Figure 5.9 Receiver gain controls and the images varied by the gain control
Receiver gain is appropriate Receiver gain is short
200
43
130
0
50
100
150
2001/05/23
Image Speed
1/1
14:22:56
Shift 000 0
High
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