Simrad ARGUS FMCW 3G, User Manual

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Radar presentation and video processing | Argus Radar Operator Manual
remain under the clutter, while if the setting is too high, both sea clutter and targets will dis-
appear from the display. In case of a too strong suppression of clutter, the dark area displayed
around own ship may not show potentially dangerous nearby targets. The proper setting
of the sea clutter should be such that the clutter is seen as small dots, and small targets will
become distinguishable around the ship.
The sea control reduces the gain level in the areas near your vessel, extending up to 3-5 NM
depending on the wave and sea conditions. This is the main reason why the use of the gain
control to reduce sea clutter effect is not correct. The gain control produces the same effect at
all ranges, causing for example loss of targets at 5 NM, when wishing to remove clutter at
1 NM.
In order to reduce the sea clutter effects, the operator has to place the trackball cursor over
the “SEA” labelled progress bar. Use the SKs in order to increase, decrease or switch the Anti
Sea Clutter control to Automatic mode.
The Help line changes when the list is closed, when the list is opened and in automatic STC
mode.
Sea State
The sea clutter attenuation curve depends on the antenna size and height, and especially the
sea state. The list permits selecting the optimal curve for every sea state.
The sea progress bar will indicate the sea state selected, as shown in the previous left figure
(Sea 5). Placing the mouse pointer over the sea progress bar and pressing the centre SK, the
list shown in the previous right figure will appear, giving the possibility to select a different
sea state or the Auto Adaptive Sea Control. Selecting one of the possible items, the indication
in the progress bar will change consequently and the sea shape correspondent to sea state
selected will be loaded by the system.
After the sea state has been selected, the clutter residuals reduction can be optimized operat-
ing on the sea clutter bar. Increasing the bar, reduces the sea clutter, decreasing works in the
opposite way.
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Note:
The sea state STC curves should have been created for each transceiver by instructed
service personnel. For more details regarding how to build the sea state STC curves, refer to
the ARGUS Radar - Installation and Service Manual.
When rain and clutter is present at the same time as sea clutter, both detection losses are
operating at the same time. Sea clutter is always a short range problem, depending of the
sea waves’ height, so when a precipitation bank is distinct from the sea clutter reflection, the
picture will experience detection losses in the precipitation bank and farther in range (on the
angle covered by the rain clutter) and the usual losses in the sea clutter area.
The worst situation is when the precipitation is over the ship position and the detection losses
caused by the two different types of clutter affect the presentation in such a way that it is
hard to discern near echoes in the clutter and farther, because attenuated by the rain absorp-
tion.
The best strategy is to avoid using long pulse transmission, depending of the rainfall rate. The
X-Band will be useful only for near range detection, using only the short pulse.
Warning:
while adjusting gain, tune, sea or rain, verify that trail mode is not in use.
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Note:
The sea and rain clutter do not affect the AIS targets.