2. RADAR OBSERVATION
2-7
5. Close the menu.
The indication "SART" appears at the bottom of the alert box, in yellow text, when this
feature is active. Be sure to turn this feature off when SART detection is no longer your
objective.
2.3.3 General remarks on receiving SARTs
SART range errors
When responses from only the 12 low frequency sweeps are visible (when the SART
is at a range greater than about 1 nm), the position at which the first dot is displayed
can be as much as 0.64 nm beyond the true position of the SART. When the range
closes so that the fast sweep responses are seen also, the first of these will be no
more than 150 meters beyond the true position.
Radar bandwidth
This is normally matched to the radar pulselength and is usually switched with the
range scale and the associated pulselength. Narrow bandwidths of 3-5 MHz are used
with long pulses on long range scales and wide bandwidths of 10-25 MHz with short
pulses on short ranges.
A radar bandwidth of less than 5 MHz will attenuate the SART signal slightly, so it is
preferable to use a medium bandwidth to ensure optimum detection of the SART.
Radar sidelobes
As the SART is approached, sidelobes from the radar antenna can show the SART
responses as a series of arcs or concentric rings. These can be removed by the use
of the anti-clutter sea control although it can be operationally useful to observe the
side lobes as they may be easier to detect in clutter conditions and also they will con-
firm that the SART is near to own ship.
Note: SART information excerpted from IMO SN/Circ 197 OPERATION OF MARINE
RADAR FOR SART DETECTION.
Setting Changed to
Range 12 NM
Pulselength Long
Echo Stretch Off
Noise Rejector Off
Echo Averaging Off
Interference Rejector Off
Performance Monitor Off
A/C RAIN Off
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