Racon (Radar Beacon) - Furuno FR-1710 Operator's Manual

Radar side lobes
As the SART is approached, side lobes from
the radar scanner may show the SART re-
sponses as a series of arcs or concentric
rings. These can be removed by the use of
the anti-clutter sea control although it may
be operationally useful to observe the side
lobes as they may be easier to detect in clut-
ter conditions and also they will confirm that
the SART is near to the ship.
Gain
For maximum range SART detection the nor-
mal gain setting for long range detection
should be used, that is, with background
noise speckle visible.
A/C SEA control
For optimum range SART detection, this con-
trol should be set to the minimum. Care
should be exercised as wanted target in sea
clutter may be obscured. Note also that in
clutter conditions the first few dots of the
SART response may not be detectable, irre-
spective of the setting of the anti-clutter sea
control. In this case, the position of the SART
may be estimated by measuring 9.5 nm miles
from the furthest dot back towards own ship.
Some sets have automatic/manual anti-clut-
ter sea control facilities in which case the op-
erator should switch to manual.
A/C RAIN control
This should be used normally (to break up
areas of rain) when trying to detect a SART
response which, being a series of dots, is not
affected by the action of the anti-clutter rain
circuitry. Note that Racon responses, which
are often in the form of a long flash, will be
affected by the use of this control.
Some sets have automatic/manual anti-clut-
ter rain control facilities in which case the op-
erator should switch to manual.
Note: This SART information is excerpted
from IMO SN/Circ 197 Operation of Marine
Radar for SART Detection.

2.4 RACON (Radar Beacon)

A racon is a radar transponder which emits
a characteristic signal when triggered by a
ship's radar (usually only the 3 centimeter
band). The signal may be emitted on the
same frequency as that of the triggering ra-
dar, in which case it is superimposed on the
ship's radar display automatically.
The racon signal appears on the PPI as a
radial line originating at a point just beyond
the position of the radar beacon or as a
Morse code signal (figure below) displayed
radially from just beyond the beacon.
Figure 2-9 Appearance of RACON signal
on the radar display
Racon
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