4. SUMMARY 



a . Type of System 



(1) Hyperbolic phase comparison multi-user system. 



(2) Number of shore stations required: master and three 

 slave stations (red, green, and purple) are generally 

 arranged in a star pattern . 



(3) Length of base line; 60-100 nautical miles (nominal) . 



(4) Frequency range: 70-130 kcps. 



(5) Transmitted power: 1200 watts for Decca Navigator 

 600 watts for mobile survey equipment. 



(6) Transmitter power requirements: 2 kw for mobile survey 

 equipment . 



(7) Mobile antenna; 70 or 100 ft in tubular sections . 



(8) Decca Navigator range;: 200-500 nautical miles. 



(9) Receiver power requirements: 80-140 and 165-260 v, 

 47-63 cps, 22-30 v dc 250 watts 



do) Receiver readout: 3 dial (navigation); 2 dial (survey) 

 Decometer Unit - Marine Automatic Track Plotter 

 provides continuous position plot in rectilinear coordinates . 



5 . RANGE AND ACCURACY 



(1) Usable service distance 

 (nautical miles) 



(2) Approx. 95% rms radial 

 error at maximum range 



(3) Approx. 95% rms radial 



error at 150 nautical miles 1/4 1 1-1/2 



Daytime 



Nighttime 





Summer 



Winter 



500 



240 



200 



2 



4 



3 



(4) Approx. 95% rms radial 



// 



error at 40 nautical miles 1/20 



56 



^Irthur ZD.ItittlcKnr. 



