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2.3.2 General remarks on receiving SART
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 may 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 and wide bandwidths of 10-25 MHz with short pulses on short ranges.
Any 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 side lobes
As the SART is approached, sidelobes from the radar antenna 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 sidelobes as
they may be easier to detect in clutter conditions and also they will confirm that the SART
is near to the ship.
Gain
For maximum range SART detection the normal 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 control 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, irrespective 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-clutter sea control facilities in which case the op-
erator should switch to manual.