(10) Shipboard antenna: one-quarter wave loaded flat top. 



(11) Shore station antenna: one-quarter vertical dipole and ground 

 plane. 



(12) Ground station transmission: time separated by a controlled 

 and precise delay. 



(13) Number of ships handled by ground station: 1 ship or 2 ships 

 (time sharing). 



(14) Readout: pulse matching on shipboard cathode -ray tube. 

 Distance is read on a vernier to 0. 1 microsecond and digital 

 counters to 9999.9 microseconds. Time is converted to dis- 

 tance using C = 299,690 km per second. 



b. Range and Accuracy 



(1) Usable service distance: 15-500 nautical miles. 



(2) Approximate accuracy of distance measurement: 50-200 feet at 

 distances out to 250 miles. 



(3) Accuracy of LOP: dependent upon absolute magnitude of errors 

 and angle at which distance arcs intersect. Area of uncertainty 

 is negligible when angles of intersection are between 30 and 150' 



REFERENCES 



1. Cmdr. Clarence A. Burmister, "Electronic Position Indicator (EFI, " Journal , 

 Coast and Geodetic Survey, 1953. 



2. Cmdr. Clarence A. Burmister, "Electronics in Hydrographic Surveying, " 

 Journal, Coast and Geodetic Survey, Jan. 1948. 



3. Capt. Gilbert R. Fish, Electronic Control Systems Used on Hydrographic 

 Surveys, Coast and Geodetic Survey, Dept. of Commerce. 



4. Rear-Admiral Robert F. A. Studds, Coast & Geodetic Survey, "Shoran 

 and EPI in Offshore Hydrographic Surveying, " paper given at the Inter- 

 national Hydrographic Conference, Monaco, April-May 1952. 



116 



artbur ZD.lLittleJnr. 



