Patent ID: 7539587

Claim:
A method for determining a rate of change of a physical or environmental parameter Φ at a time t, the method comprising the steps of: (a) sensing a voltage rate dV/dt representative of the rate of change of the physical or environmental parameter Φ at the time t using a sensor that is operable to detect variations in the physical or environmental parameter Φ; (b) determining a calibration factor dΦ/dV which relates an incremental change in the physical or environmental parameter Φ to a corresponding incremental change in voltage V; (c) multiplying the voltage rate dV/dt by the calibration factor dΦ/dV to determine the rate of change dΦ/dt of the physical or environmental parameter Φ at the time t; and (d) using an information processor to store data representing one or both of the voltage rate dV/dt and the rate of change dΦ/dt of the physical or environmental parameter Φ.