where 



R = Resistance output 

 T = Temperature in F 



W = Tension in lbs. 

 P = Pressure in PSI 



K = 21, 500 ohms 

 o 



K = 388.6 ohms/°F. 



K = -3.33 ohms/lb. 



K = 32.5 ohms /PSI 



The time constant is approximately .05 sec. Resolution is 

 about 20 ohms. 



3.3 Data Acquisition Sys-f-'='T^ 



The basic function of the Data Acquisition System is to extract 

 and record information from individual sensors on the Signal Cable/ 

 Sensor Array at regular intervals in time. This information is 

 reduced to numerical form and written (recorded) onto a 7-track 

 IBM-format digital magnetic tape. This tape is referred to as the 

 Primary Data Tape. 



All of the sensors on the Array translate what they measure - 

 temperature, pressure, etc., - into a variable electrical resistance. 

 The information actually recorded on the Primary Data Tape is the 

 electrical resistance of each sensor (plus the resistance of the in- 

 tervening cable). During computer analysis of information from the 

 tape, the resistance of the cable between each sensor and the System's 

 input connections is subtracted from the measured resistance to re- 

 cover the resistance of the sensor itself. This cable resistance has 

 been previously measured to the desired accuracy and can be com- 

 pensated for temperature and other effects by comparison with the 

 measured resistance of a calibration wire in the array. 



213 



