4. 
A recovery capability for certain system failures 
(ground data system). 
5. Ready access to the most commonly used sub 
routines. 
b. Data Editing and Evaluation. 
This program unit is the first to be used in processing data 
originating on the airborne data recorder. Its functions are basically 
that of decoding the airborne recorder tape, and extracting pertinent 
data bits and characters. It converts these data into a workable form 
for arithmetic or printing operations and tests the data for reasonable 
ness and internal consistency. The program unit then smooths the data 
and evaluates the level of random errors. This routine also provides 
the automatic resolution of SHIRAN ambiguities. Many CW distance 
measuring systems tend to occasionally skip full wavelengths which 
results in an error of the form n , where n is any integer, and 
is a constant of the system. Rather than discarding such data points, 
they are examined for consistency with near by points if a given num 
ber of full wavelengths n are added or subtracted. If the n ambig 
uity is the only error, the proper number of wavelengths are added or 
subtracted and the data are used. 
c. Controlled Mapping Photography. 
This program unit combines SHIRAN data, refractive data, 
altitude, aircraft navigational and heading functions, and other recor 
ded data, and determines the position and orientation of the camera at 
each exposure station. 
d. Precise Mapping Photography. 
The function of this program unit is essentially the same as 
that for controlled mapping photography. However, because SHIRAN 
data are not available, the position of the camera at exposure station 
is obtained from the passive navigation system. 
e. Control Point Photography. 
This program unit is similar to that of the electronically 
controlled mapping photography unit except that redundant measure 
ments are used to position a point on the ground (by using two to six 
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