Sky wave-ground wave interference producing large LOP errors has 

 been noted under some conditions of operation at ranges between 150 and 600 

 nautical miles. At ranges shorter than 150 miles, the ground wave predominates; 

 at ranges greater than 600 miles, the sky wave predominates, and errors due to 

 interference of the two modes of propagation become negligible. The errors are 

 maximum when the two waves are of equal strength. 



It is clear that the reliability of reception at a given range is dependent 

 upon taking such data under standard conditions and in large groupings, so that 

 statistical calculations can be made. The positional accuracy of Consol LOP have 

 been determined with enough data to calculate statistical error information. The 

 data include all random (equipment failure, etc.) as well as systematic (miscount 

 of dots and dashes, etc.) errors. Table IV-3 shows the 95% confidence Consol 

 LOP errors. 



TABLE IV-3 



CONSOL LOP ERRORS, 95% CONFIDENCE LEVEL 



Error in Day Range Error in Night Range 

 Angle from Normal Over Sea Over Sea 







(nm) 







(nm) 







200 



500 



1000 



100 



300-1000 



1500 



On Normal 



1.5 



3 



6 



.5 



10 



18 



60° 



3 



6 



12 



1 



20 



36 



75° 



6 



12 



24 



2 



40 



72 



Operator errors also arise from faulty sector identification or poor 

 counting accuracy resulting in lost counts. In practice, under less than maximum 

 S/N conditions the equisignal line may appear broadened, with a resultant loss of 

 both dots and dashes. The recommended method of counting dots and dashes is to 

 count both dots and dashes, subtract the sum of the two from 60 (German cycle), 

 and add half the difference to whichever is heard first. This method assumes an 

 equal number of dots and dashes are lost. 



41 



arthur Zn.UittlcJnr. 



