Furuno FR-1710 manual Racon Radar Beacon, Radar side lobes, Gain, SEA control, Rain control

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.

Racon

Figure 2-9 Appearance of RACON signal

on the radar display

2-5