Kongsberg Simrad ST90, Reference Manual

Page: 102 / 690

100
442704/A
3 Adjust the setting to fit your requirements.
To change the setting, move the cursor to either
side of the button. Select the
left side of the
button to decrease the value. Select the right side of the button to increase the value.
Select the middle of the button to open it.If you have a keyboard connected to the
ST90 system, type the requested value.
Related topics
Operating procedures, page 79
Controlling the gain and range settings, page 94
Improving the recognition of fish and schools using receiver filters, page 117
Display Gain function, page 444
Changing the tilt
In order to detect fish or schools in the water column you may need to change the angle of
the sonar beams. The transmitted sonar beams can be tilted electronically.
Context
The current tilt is shown with a solid line in the
Vertical
view. In the
Horizontal
view, the
current settings for range, gain and tilt are shown in the top left corner of the view.
With 0° tilt the sonar beam is transmitted in parallel with the sea surface. With +60 degrees
tilt the beam is directed towards the bottom.
The challenge is to find a tilt that prevents the fish echoes to be "buried" in reverberation
and bottom echoes.
• If you use a high tilt value (A) the fish are easily disguised by bottom echoes. A strong
RCG (Reverberation Controlled Gain) setting will remove the bottom echoes. As the
distance from the bottom to the fish increases, the fish echoes become clearer. However,
this assumes that the fish echoes are considerably stronger than the bottom echoes.
Simrad ST90 Reference Manual