AC excited transducer having stabilized phase sensitive demodulator circuit

摘要

A signal conditioning circuit (30) using an oscillator (32) which feeds a counter (34) whose output addresses a programmable memory (42). The output of the programmable memory (42) provides a selected processed signal which is used for excitation of a transducer (12). The processed signals can have various phase shifts, frequencies, or amplitudes. The transducer (12) has a mechanical input (14) and provides a modulated signal output which is a function of the mechanical input. The output of the transducer (12) is fed to a phase sensitive demodulator (36). Demodulator (36) provides an output signal in response to the signal from transducer (12) and an appropriate demodulator drive signal. The output signal from demodulator (36) is indicative of the mechanical input to transducer (12). Averaging means (40) is connected to the output of the demodulator (36) to provide a DC signal which is proportional to the mechanical input to transducer (12).