Kongsberg Simrad ST90, Reference Manual

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Related topics
Improving the recognition of fish and schools using receiver filters, page 117
Functions and dialog boxes, page 416
Active menu; Functions and dialog boxes, page 466
Noise Filter function
The
Noise Filter
removes unwanted acoustic noise from the display presentation. It reduces
the interference from other acoustic systems (sonars and echo sounders), as well as the
noise from the propellers.
How to open
You open this function from the
Active
menu.
Description
The
Noise Filter
is used to minimize the interference from other acoustics systems (sonars
and echo sounders) on your own and/or other vessels. The filter also suppresses noise from
your propellers, and from other similar noise sources. The
Noise Filter
is very effective if
you are bothered by strong noise or interference, especially from your own vessel, or even
from other vessels operating near you.
The four filter settings are used to control the "efficiency" of the filter. To disable the filter,
set it to
Off .
Tip
Use weak filtering - or turn the filter off - if you have strong echoes on short ranges. The
filter may then be too powerful, and distort the echo presentation.
Select the middle of the button to open a small menu with the available options. Select the
left side of the button to select a "lower"' menu choice. Select the right side of the button
to select a "higher"' menu choice.
Additional information for the technically minded :
The filtering is done by overriding the automatic function for the preamplifiers. The number
of amplifier stages used is a function of range instead of signal level. There is a total of six
amplifier stages. By forcing the ST90 system to use (for example) three amplifier stages
at a certain distance, interference will be clipped at this specific range. This is better than
suppressing all other echoes at the same range.
Simrad ST90 Reference Manual