Abstract: A differential pressure sensor senses a difference in pressure between a first input (low) pressure or "reference pressure" and a second input (high) pressure and provides a differential sensor signal representative of the difference in pressure. The reference pressure is sensed by a reference pressure sensor which provides a reference signal representative of the reference pressure. The differential sensor signal and the reference signal are provided to a correction circuit. The correction circuit, which is preferably a digital computer, adjusts the reference signal and provides an improved output signal as a function of the differential sensor signal and the adjusted reference signal.

Abstract: A sensor providing an output indicating pressure including means to excite a vibrating beam at its natural frequency, and means to load the beam in response to pressure to alter the natural frequency of the beam. The frequency output is sensed by a capacitor pick off mounted on the same side of the beam as the means to excite the beam. Changes in the output frequency provides an indication of the pressure being measured.