JRC JMA-3400 Series, Instruction Manual, Page: 98 / 314

Chapter 3 ADJUST THE RADAR ECHO
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3.4 RAIN/SNOW CLUTTER SUPPRESSION (RAIN)
Rain/Snow clutter suppression level suitable Rain/Snow clutter suppression level excessive
(fine weather) (some targets become small)
The [RAIN] control can make targets hidden by rain/snow clutter appear on the radar display.
Be careful that excessive suppression may cause small targets to be overlooked.
When using the rain/snow clutter suppression function, never set the
suppression level too high canceling out all image noises from the rain or
snow at close range. Detection of not only echoes from the rain or snow
but also targets such as other ships or dangerous objects will become
inhibited. When using the rain/snow clutter suppression function, make
sure to choose the most appropriate image noise suppression level.
It is necessary to adjust the rain/snow clutter suppression level in order to use
the radar exactly. Failure to do so, it is impossible to obtain an accurate radar
echo.
The rain/snow clutter suppression level is
displayed at the lower part of the screen when the
RAIN control is turned left or right.
Turning the control right increases the value, and
turning it left decreases the value.
About the RAIN control : please refer to the number 13 in Chapter 2.2.