What Is Rcg; About Tilt - Simrad SH90 - REFERENCE MANUAL REV A Reference Manual

Simrad SH90
Figure 41 Tilt
180
To adjust the gain, see How to adjust the gain on page 41.

What is RCG?

means Reverberation Controlled Gain. This is a
RCG
two-dimensional filtering of the received echoes in order to
suppress unwanted surface and bottom reverberation.
If you select Strong, the bottom echoes will disappear altogether
if the bottom is flat, while schools of fish close to the bottom
will be easier to see.
Note that scattered fish may be more difficult to spot if the RCG
function is active, as these can be misinterpreted as reverberation.
It is therefore important that you use the RCG with great care if
your are searching for scattered fish.

About tilt

The sonar beam can be tilted vertically in steps of 1 degree, and
the chosen tilt is shown on the sonar picture. At 0 degrees tilt
you will transmit the sonar beam in parallel with the sea surface,
while 60 degrees tilt will direct it almost straight down.
The challenge will always be 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 will easily be disguised
by the bottom echoes, but a strong RCG setting will help. As
the distance from the bottom to the fish increases, the fish will
be easier to see when the RCG removes the bottom echoes.
However, this assumes that the fish echoes are considerably
stronger than the bottom echoes.
323775/A