DIGITAL PRESSURE MEASURING SYSTEM

摘要

Digital pressure measuring system including a primary pressure transducer [24] with a pressure sensitive capacitor [Cs] and a pressure insensitive reference capacitor [Cr]; these capacitors [Cs, Cr] are excited by out-of-phase signals and their outputs combined at a summing junction [12]; the output of the summing junction [12] controls the incrementation of a counter [16] whose output is converted to a nonlinear negative feedback signal by means of a digital-to-analog converter [26] and a feedback pressure transducer [105] including a pressure sensitive capacitor [Cfs] and a pressure insensitive reference capacitor [Cfr] which are excited by out-of-phase signals from said converter [26]; a closed loop is formed by applying the nonlinear negative feedback signal appearing at the output of feedback pressure transducer [105] to the summing junction [12]; the counter [16] is incremented in a direction to null the loop such that its output is representative of the measured pressure.