OCEAN ELECTRONIC NAVIGATIONAL AIDS 



49 



Figure 4-6.- 



-PPI picture showing sea return when no anticlutter or sea return suppression 

 devices are in use (special 3 cm. Radar). 



Other factors which more or less impose limitations on Radar are tabulated 

 and briefly discussed below : 



(1) Objects cannot be readily identified unless additional electronic 



devices (Radar aids) are used in conjunction with the Radar itself. 

 Identification, however, can quite often be accomplished by impli- 

 cation such as movement, relation to other objects, shape (coast- 

 line) , and sometimes initial range of detection. 



(2) Radar chart presentation on the scope requires interpretation due to 



line-of-sight characteristics which give shadow effects. In other 

 words, larger intervening objects may blank out objects behind 

 them. 



(3) Radar can be used reliably for only slightly over line-of-sight 

 distance. 



