| 2. | 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。 |
