Method and apparatus for calibrating a transducer having real and reactive impedance

The method of calibrating a transducer having real and reactive impedance which is excited from an excitation source and which provides an output signal at a transducer output connected by electrical conductor means to a remote load, said method of calibrating comprising the steps of:

• providing a preamplifier having a high impedance input and a low impedance output connected to said electrical conductor means:
• alternatively (a) connecting said transducer output to said preamplifier input for preamplifying said transducer output signal and providing through said conductor to said remote load a low impedance preamplified output signal, and (b) providing a substantially purely resistive calibration signal to said remote load for use in calibrating said transducer;
• providing an auxiliary calibration circuit;
• and selectively causing said calibration circuit to calibrate said auxiliary calibration circuit.

The method of calibrating a transducer having real and reactive impedance which is excited from an excitation source and which provides an output signal at a transducer output connected by electrical conductor means to a remote load, said method of calibrating comprising in combination the steps of:

• providing a preamplifier having a high impedance input and a low impedance output connected to said electrical conductor means;
• providing a power supply for powering said preamplifier;
• and
• alternatively (a) connecting said transducer output to said preamplifier input for preamplifying said transducer output signal and providing through said conductor means to said remote load a low impedance preamplified output signal, and (b) providing a substantially purely resistive calibration signal to said preamplifier input for use in calibrating said transducer.

The method of calibrating a transducer having real and reactive impedance which is excited from an excitation source and which provides an output signal at a transducer output connected by electrical conductor means to a remote load, said method of calibrating comprising the steps of:

• providing a preamplifier having a high impedance input and a low impedance output connected to said electrical conductor means;
• providing a power supply for powering said preamplifier;
• alternatively (a) connecting said transducer output to said preamplifier input for preamplifying said transducer output signal and providing through said conductor means to said remote load a low impedance preamplified output signal, and (b) providing a substantially purely resistive calibration signal to said preamplifier input for use in calibrating said transducer;
• providing an auxiliary calibration circuit;
• and selectively causing said calibration circuit to calibrate said auxiliary calibration circuit.

The method of calibrating a transducer having real and reactive impedance which is excited from an excitation source and which provides an output signal at a transducer output connected by electrical conductor means to a remote load, said method of calibrating comprising the steps of:

• providing a preamplifier having a high impedance input and a low impedance output connected to said electrical conductor means;
• providing a power supply for powering said preamplifier;
• alternatively (a) connecting said transducer output to said preamplifier input for preamplifying said transducer output signal and providing through said conductor means to said remote load a low impedance preamplified output signal, and (b) providing a substantially purely resistive calibration signal to said preamplifier input for use in calibrating said transducer;
• providing means for removably connecting said power supply to said excitation source;
• providing an auxiliary calibration circuit;
• and
• selectively causing said calibration circuit to calibrate said auxiliary calibration circuit.

Apparatus for calibrating a transducer having real and reactive impedance which is excited from an excitation source and which provides an output signal at a transducer output connected by electrical conductor means to a remote load, said apparatus comprising:

• a preamplifier having a high impedance input and a low impedance output connected to said electrical conductor means;
• means for alternatively (a) connecting said transducer output to said preamplifier input for preamplifying said transducer output signal and providing through said conductor means to said remote load a low impedance preamplified output signal, and (b) providing a substantially purely resistive calibration signal to said preamplifier input for use in calibrating said transducer;
• an auxillary calibration circuit;
• and
• means for selectively causing said calibration circuit to calibrate said auxiliary calibration circuit.