TABLE 10.7 SELECTED SURFACE POSITIONING SYSTEMS [FROM REF. (18)] 



*P: Pulse 



Ph: Phase Comparison 

 CW: Continuous Wave 



proach is all on the part of the submersible 

 operator and, once underwater, is independ- 

 ent of the surface ship. Between both of 

 these extremes (surface-dependent versus 

 independent positioning) are a number of 

 variations. For convenience, the surface-de- 

 pendent methods are categorized as Surface 

 Tracking and the independent methods as 

 Submerged Navigation. A third aspect of 

 navigation, intermediate between where do 

 we go and where have we been, concerns 

 locating a target and going to it; this func- 

 tion is termed "Homing," and is also dis- 

 cussed. 



It is very difficult to speak of navigation 



without discussing accuracy and within the 

 confines of this section it is impossible to 

 discuss adequately the many factors in- 

 volved in navigational accuracy. Accuracy is 

 defined as the degree of conformance with a 

 correct value. But, in regards to an object's 

 location on the planet Earth, even the "cor- 

 rect value," in terms of its latitude and longi- 

 tude, is accompanied with inaccuracies un- 

 der the most exacting measurements. Navi- 

 gation, according to Bowditch, is not an ex- 

 act science and a number of the approxima- 

 tions used by the conventional navigator 

 would be unacceptable in careful scientific 

 work. The navigator, however, is a pragma- 



495 



