Pickupless magnetostrictive position measurement apparatus

DETAILED DESCRIPTION What is claimed is: 1.
A magnetostrictive position measurement apparatus comprising: a circuit including a magnetostrictive wire having first and second opposed ends, the circuit transmitting an electrical excitation pulse and detecting a return signal indicative of the position of a first magnet along the magnetostrictive wire on the basis of the time delay between the detection of the return signal relative to the transmission of the electrical excitation pulse; the first magnet displaceable relative to the magnetostrictive wire, the first magnet interacting with the electrical excitation pulse and generating first and second oppositely propagating torsional waves in the magnetostrictive wire; and means for reflecting the second torsional wave from the second end of the magnetostrictive wire to the first magnet wherein the magnetic field of the first magnet interacts with the second torsional wave to induce an electrical current in the magnetostrictive wire, the electrical current acting as the return signal.
2.
The apparatus of claim 1 further comprising: a dampener coupled to the first end of the magnetostrictive wire, dampening the first torsional wave at the first end of the emagnetostrictive wire.
3.
The apparatus of claim 1 wherein the circuit further comprises: means, coupled to the circuit for determining the position of the first magnet along the length of the magnetostrictive wire based on the time differential between the application of the electrical excitation to the pulse wire and the detection of the return signal in the magnetostrictive wire.
4.
The apparatus of claim 1 wherein the reflecting means comprises: a reflective termination coupled to the second end of the magnetostrictive wire.
5.
The apparatus of claim 1 further comprising: a first magnetically transmissive tube spacedly surrounding the magnetostrictive wire.
6.
The apparatus of claim 5 further comprising: a second magnetically transmissive tube surrounding the first magnetically transmissive tube