A very small number (perhaps three) of pressure measur- 

 ing packages will be required to indicate the depth of the 

 temperature sensors. The pressure gage will control the 

 frequency of an oscillator and the package will be scanned 

 in the same manner as the temperature packages. To obtain 

 the required accuracy of pressure measurement pressure 

 transducers of a precision strain gage type may be required. 

 For use with these, precision sxob-carrier type oscillators, 

 commercially available, will be modified to suit the require- 

 ments of the system. 



The signal amplifier contained in each package serves 

 a double purpose: it amplifies the FM carrier generated by 

 the signal oscillator in its own package and , when a gage 

 farther down the chain is being sampled, transmits the PM 

 signal from below on up the chain. The fail-safe feature 

 afforded by the use of transformers in the power, control, 

 and calibration circuits is provided in the signal amplifier 

 by isolation resistors. If, for example, one gage package 

 becomes flooded the signal from the lower gages will feed 

 around that amplifier through resistor R , The next ampli- 

 fier will be able to raise the signal to the standard level. 



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