These characteristics include useful range, positional accuracy, conditions of 

 operation, ease and cost of operation, maintenance requirements, reliability, 

 and geographical coverage. Important mechanical and electrical characteris- 

 tics which affect the performance of each system are tabulated. 



The sources of this information were the available literature, con- 

 tractors' reports, and private communications . None of the material in this 

 report is classified. Relevant reference material is cited following each sys- 

 tem description. 



artbur ai-ILittlclnr. 



