Initial coastline sampling data , racon position data and sart position data are acquired from sea chart by digitizer . all of the initial data are saved with predefined data structure in data files 雷达回波中的海岸线、雷康和sart的原始数据是通过数字化仪从海图中采样获取的，获取后的数据按照预先设计好的数据结构保存在了特定类型的文档中。
3.
Radar echoes include echoes of lands , islands , all kinds of moving targets , racon , sart and sea , etc . arpa marks consist of fixed range marker , variable range marker , electronic bearing line , guard zone , heading - line , parallel index ( 4 navigation lines ) , vector lines ( or pad ) and past track information of tracked target ships , marks of trial manoeuvres , ect 雷达回波包括陆地、岛屿回波，各种活动目标的回波，雷康、 sart回波，海杂波等。 arpa符号包括包括固定距标圈、活动距标圈、电子方位线、警戒圈、船首线、 pi线、已录取目标的矢量线以及历史航迹(或pad ) 、试操船符号等。
