• The presence or absence of a vessel in a given 

 area. 



• The position of a detected ship at a point in 

 time. 



• Course and speed of a vessel when a continuity 

 of position updates is available. 



• Estimates of gross shape and size for some high 

 resolution radars. 



Microwave radar, by itself, has almost no potential to 

 perform the classification function of vessel type, nationality, or opera- 

 tions since none of the information that can be obtained from analysis 

 of radar returns from a vessel can be directly related to vessel charac- 

 teristics that are unambiguous indications of its identity or status as 

 a fishing vessel. Frequent or continuous surveillance of an area will 

 permit tracking of vessels in the area, and it is often possible to 

 identify fishing vessels engaged in fishing with reasonable certainty 

 from their movement patterns. However, as a practical matter, unaided 

 microwave radar in aircraft will continue to contribute to classification 

 primarily through guiding the aircraft to a position where identification 

 can be made by visual means. 



The detection of targets in sea clutter with microwave 

 radar can be greatly simplified if the target is equipped with a trans- 

 ponder or beacon that responds to interrogation by the radar with coded 

 signals (often at a frequency other than the radar frequency). This 

 not only facilitates target location but provides, by the use of appro- 

 priate coding of the beacon replies, other information about the target 

 (identity, status, intentions, etc.). Transponder technology is also 

 highly developed, and beacon design is well understood. 



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