758 THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1952 



120° 90° 60° 



Fig. 6 — Contours of constant autocorrelation for Scene A. In general there are 

 no preferred directions of correlation. 



1.0 



AS IN ELEMENTS 

 5 10 15 



I I I I I I I I I I I I I I I I 



q 5 10 



I I I I I I I 1 1 1 T" 



AS IN ELEMENTS 

 VERT. 5 10 15 



I II I I I 



HOR. 



VERT. 



I I I I I I I 1 I 

 5 10 HOR. 



A(S) 



20 40 60 60 too 20 40 60 SO 100 



SHIFT, As, IN MILS SHIFT, AS, IN MILS 



Fig. 7— Plots of autocorrelation for small shifts. Aio is the autocorrelation for 

 a shift of one horizontal elemental distance, A20 for two horizontal elemental dis- 

 tances, and Aoi for one vertical elemental distance. Alternatively Aio may be 

 described as the average correlation between horizontally adjoining elements, 

 etc. 



