Harsh environment magnetostrictive displacement sensor

A magnetostrictive displacement sensor comprising:

• a target magnet;
• a sensor assembly comprising
• a waveguide;
• a pickup sensing element configured to generate a high impedance sensor response signal through a positive pickup terminal and a negative pickup terminal in response to a magnetostrictive response in the waveguide corresponding to the target magnet;
• a signal conditioner comprising a balanced line driver circuit including:
• a positive response signal circuit configured to produce a positive response signal at a low impedance based on the high impedance sensor response signal at the positive pickup terminal;
• and
• a negative response signal circuit configured to produce a negative sensor signal at a low impedance based on the high impedance sensor response signal at the negative pickup terminal;
• and
• a cable connector including a positive sensor terminal coupled to the positive sensor signal, a negative sensor terminal coupled to the negative sensor signal, and a waveguide terminal coupled to the waveguide;
• a cable attached to the cable connector and including a positive response wire connected to the positive sensor terminal, a negative response wire connected to a negative sensor terminal, and a waveguide wire coupled to the waveguide terminal;
• and
• sensor electronics comprising:
• an excitation generator configured to generate a current pulse that is delivered to the waveguide through the waveguide wire of the cable;
• a receiver circuit configured to receive the positive sensor signal from the positive response wire and the negative sensor signal from the negative sensor wire and output a received sensor signal;
• and
• a controller configured to generate a position estimate of the target magnet relative to the waveguide based on the received sensor signal.

A method of operating magnetostrictive displacement sensor, the magnetostrictive displacement sensor comprising:

• a target magnet;
• a sensor assembly comprising
• a waveguide;
• a pickup sensing element;
• a signal conditioner comprising a balanced line driver circuit including:
• a positive response signal circuit;
• and
• a negative response signal circuit;
• and
• a cable connector including a positive sensor terminal, a negative sensor terminal and a waveguide terminal;
• sensor electronics comprising:
• an excitation generator;
• a receiver circuit;
• and
• a controller,
• the method comprising:
• connecting a positive response wire of a cable to the positive sensor terminal, a negative response wire of the cable to the negative sensor terminal, and a waveguide wire of the cable to the waveguide terminal;
• delivering a current pulse generated using the excitation generator to the waveguide through the waveguide wire and the waveguide terminal;
• generating a magnetostrictive response in the waveguide at a location of a target magnet in response to the current pulse in the waveguide;
• generating a high impedance sensor response signal to the magnetostrictive response through a positive pickup terminal and a negative pickup terminal of the pickup sensing element;
• converting the high impedance sensor response signal at the positive pickup terminal to a low impedance positive sensor signal using the positive response signal circuit;
• converting the high impedance negative sensor signal to low impedance negative sensor signal using the negative response signal circuit;
• delivering the low impedance positive sensor signal to the receiver circuit through the positive response wire and the low impedance negative sensor signal to the receiver circuit through the negative response wire;
• generating a received sensor signal based on the low impedance positive sensor signal and the low impedance negative sensor signal using the receiver circuit;
• and
• determining a position estimate of the location of the target magnet relative to the waveguide based on the received sensor signal using the controller.