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diapositive information to be processed. 
Since correlation may be expected to occur when the signals 
from both channels are identical in both frequency components and phase, 
a Boolean truth table may be constructed in the following manner. Let A 
and B represent the electrical signals derived from each diapositive, res 
pectively. Each electrical signal may take a value of positive or nega 
tive, which may be referred to as states 1 or 0, respectively. A truth 
table may be constructed as follows: 
A B f(A, B) 
1 1 1 
0 1 0 
1 0 0 
0 0 1 
This truth table is recognised to be the logical bi-conditional, 
which may be simplified to the following logical forms: 
(A + B) • 
(B + A) 
(1) 
(A • B) + 
(Â * B) 
(2) 
(A • B) + 
(B *A) 
(3) 
Since any of these logical equations may be instrumented with 
equal results, equation (2) represents an instrumentation involving a 
minimum of circuit components and is shown in Figure 6. 
OPERATIONAL STATUS OF STEREOPLOTTER, 
PROJECTION AP-14 
The developmental model of the stereoplotter was completed and 
evaluated. During the evaluation of the instrument, the results, while 
very encouraging, pointed out areas of improvement for future study. 
The speed and accuracy with which stereomodel contours are 
detected and traced are most impressive. In stereomodel areas having 
moderate detail and slope, contour printing speeds of from 5 to 15 inches 
per second, at stereomodel scale, are consistently being recorded. Along 
with these tracing speeds, C factors in excess of 500 are also being