Appendix 

 REDUCTION OF TAPED DATA 



The FM signals containing the deflection, load, and attitude 

 transducer output for each test were multiplexed with a carrier frequency 

 on one channel of a magnetic tape. This taped data was processed by the 

 NCEL analog to digital conversion (ADC) system.^ This facility is capable 

 of sampling analog data such as this at a specified rate over a given time 

 range and storing it as digital data on the disk of an IBM 1620 System. 

 The sampling procedure was as follows: 



1. The tape was played through a discriminator with a time scale 

 of 32 times real time and all of the signals but one (for example, the load) 

 were filtered out. 



2. This signal was in turn modified by a low pass filter which was 

 used to remove some of the noise present. 



3. The point on the tape at which sampling was to be initiated was 

 marked by a key on an unused channel. When this key was reached, the ADC 

 System began sampling at a predetermined rate (usually 25 to 50 samples per 

 32 seconds real time) and continued until a given number of samples had been 

 taken. This number was based on the estimated test length (usually 10 to 



20 minutes). 



This process was continued for all of the data on a channel with each 

 element of data being stored on the disk. The data was then automatically 

 punched on computer cards with a format directly acceptable to the IBM 

 1620 System. Each card had 24 three-digit samples. The first digit of each 

 sample was always flagged (that is, had a minus sign superimposed on it), 

 and the last digit was flagged if the sample were negative. 



A general system of routines (with the acronym SUPER)^° was 

 devised for scaling and subsetting ADC data and plotting one set (for example, 

 load) versus another (for example, displacement). However, because of noise 

 and calibrate phases, the data obtained according to the procedure described 

 above was not in the correct form for accurate plotting. It was necessary to 

 edit out this extraneous information and substitute in its place more appro- 

 priate data. This was accomplished with a program written for this purpose 

 with the acronym ADEDIT." This routine is capable of changing any ADC 

 data element value to any other value and producing a new computer card 

 deck. It was modified so that a series of data elements could be removed at 

 once and replaced by a series of linearly varying elements. In this way a 

 calibrate signal or a region of noise could be replaced by a straight line. 



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