Method for calibrating a transducer for converting pressure variation to frequency variation

A method for calibrating a transducer for converting a pressure variation to a variation in the frequency of an output periodic function, the transducer including a reference signal processing means and a sensor signal processing means as inputs to a mixer signal processing means, the reference signal processing means generating a periodic reference electrical signal as a function of a reference timing capacitor and a reference resistor, the sensor signal processing means generating a periodic sensor electrical signal as a function of a variable sensor timing capacitor responsive to pressure changes and a sensor resistor, the mixer signal processing means generating a mixed periodic electrical signal having a frequency proportional to the difference between the reference and sensor electrical signals, said method including the steps of:

• applying a first reference pressure to the transducer and measuring a first sensor signal frequency;
• applying a second reference pressure to the transducer and measuring a second sensor signal frequency;
• measuring the reference signal frequency during at least one of the applications of the first reference pressure or the second reference pressure;
• calculating the actual, uncalibrated transfer function defining the mixed signal frequency as a function of pressure;
• altering the slope of the actual transfer function to a desired, calibrated slope by changing the magnitude of the sensor resistor;
• and
• altering the frequency axis intercept to a desired, calibrated frequency intercept by changing the magnitude of the reference resistor.