Furuno FR-2105-B - Manual (Page 35)

-1.18-
1.14 Suppressing Precipitation Clutter
In adverse weather conditions, clouds, rain or snow produce a lot of spray-like spurious
echoes and impairs target detection over a long distance. This situation can be improved by
using a function key provided that it is so programmed. If the function key fails to offer a
favorable suppression of the rain clutter, adjust the A/C RAIN control on the front control
head.
BRILLIANCE A/C RAIN A/C SEA GAIN
STBY
TX
RANGE
OFF ON
EBL
1 2
3 4
A/C RAIN CONTROL
A/C RAIN control
OFF A/C RAIN control
adjusted
The A/C RAIN control adjusts the receiver sensitivity as the A/C SEA control does but rather
in a longer time period (longer range). Clockwise rotation of this control increases the anti-
clutter effect.
1.15 Interference Rejector
Mutual radar interference may occur in the vicinity of another
shipborne radar operating in the same frequency band (9 GHz for
X-band, 3 GHz for S-band). It is seen on the screen as a number of
bright spikes either in irregular patterns or in the form of usually
curved spoke-like dotted lines extending from the center to the edge
of the picture. This type of interference can be reduced by activating
the interference rejector circuit.
The interference rejector is a kind of signal correlation circuit. It
compares the received signals over successive transmissions and
suppresses randomly occurring signals. There are three levels of
interference rejection depending on the number of transmissions that
are correlated. These are indicated by the legends IR1, IR2 and IR3
at the upper-left position of the screen.
Radar interference