Simrad ARGUS FMCW 3G, User Manual

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Radar presentation and video processing | Argus Radar Operator Manual
radar, the SART immediately transmits a response, which is swept repetitively across the com-
plete radar frequency band. The response is made by a first rapid sweep (0.4 µs) through the
band and a relatively slow sweep (7.5 µs) through the band back to the starting frequency,
repeated for a total of twelve complete cycles. At some point in each sweep, the SART fre-
quency will match the one of the interrogating radar and, being within the pass band of the
radar receiver, the signal will be displayed on the radar as a line of 12 dots equally spaced by
about 0.64 nautical miles.
When the range to the SART is down to about 1 NM the radar display may also show the 12
responses generated during the fast sweeps. These additional dot responses, which also are
equally spaced by 0.64 NM will be interspersed with the original line of 12 dots. They will ap-
pear slightly weaker and smaller than the original dots.
To best detect a SART signal, proceed as follows:
•
Use a range scale between 6 and 24 NM, due to the spacing between responses too small to
be distinguished at higher scales (0.64 NM).
•
Set sea control to minimum in manual.
•
Set rain in manual and use it normally.
•
Set gain control to see some noise dots in background.
•
Turn Off Scan to Scan Correlation.
•
Turn Off Echo Stretch.
Range Scale:
The reason why, when looking for a SART, it is preferable to use from 6 to 24 NM range scale, is
because the length of the SART response of 12 dots may be extended to 9.5 NM beyond the
position of the SART and it is necessary to see more than one response dot to distinguish the
SART from other responses.
Sea Control:
This control shall be set to minimum for optimum SART detection, as the control could cut
the sea clutter as well as the SART response. Note that in this condition (Sea control at the
minimum) ships inside the clutter range may not be visible to the radar. Note also that in case
of strong clutter, the first few dots of the SART response may not be detectable, due to the
sea control at the minimum. In this case, the position of the SART may be estimated by using
the ERBL off centre function and measuring 9.5 nautical miles from the farthest dot back
towards own ship.
Rain Control:
The SART response is not affected by the action of the rain clutter control, so the control shall
be used normally to detect ships in rainy areas, but it shall not be used in automatic.
Gain Control:
For maximum range of SART detection the normal gain setting for long range detection
should be used and a few dots of noise shall be visible in the background (around 80% of the
gain bar).
Scan to Scan Correlation:
The SART response could be weakened by this control and this is why it should be turned off.
Echo Stretch:
The shape and dimension of the dots of the SART response could be modified by this control
and therefore it should be turned off.