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US 5,334,933 AGranted
Variable rejection method for improved signal discrimination in a magnetostrictive position transducer
AssigneeMTS Systems Corporation
InventorJacob Tellerman
Life of this patent
Estimating the term…
Abstract
A variable rejection level system for a magnetostrictive transducer which improves the detectability of magnetostrictive pulses along a waveguide in the presence of background noise on the waveguide.
Claims10
A magnetostrictive transducer, comprising:
- a ferromagnetic delay line;
- a pulse generator coupled to said ferromagnetic delay line for generating a current excitation pulse in said ferromagnetic delay line;
- magnet means located proximate said ferromagnetic delay line for converting said current excitation pulse propagating in said ferromagnetic delay line into an acoustic pulse propagating in said ferromagnetic delay line;
- mode convertor means coupled to said ferromagnetic delay line for detecting said acoustic pulse and converting said acoustic pulse into a corresponding representative mode convertor signal;
- comparator means coupled to said mode convertor means for comparing said mode convertor signal to a rejection signal reference level thereby generating a comparator output signal;
- circuit means, coupled to said comparator means and to said pulse generator, for generating an interrogation pulse which causes the pulse generator to generate said current excitation pulse, and for measuring a time interval between generation of said interrogation pulse and reception of said acoustic pulse by said mode convertor as indicated by the occurrence of said comparator output signal, said circuit means including position determination means for determining, responsive to a value of said ferromagnetic delay line;
- rejection signal generation means coupled to said circuit means and said comparator means for generating said rejection signal initiated by said interrogation pulse;
- said reference level of said rejection signal, having a DC amplitude varying in direct proportion to the level of said mode convertor signal so that for any magnet means location along said ferromagnetic delay line, the ratio of said rejection signal level to said mode convertor signal level is substantially constant;
- and
- wherein said rejection signal generation means further includes buffer means, coupled to said circuit means and said comparator means, for adjusting said reference level of the rejection signal, the buffer means electrically connecting to a capacitor which provides a charging/discharging signal responsive to the interrogation pulse.
7 more elements
A magnetostrictive transducer, comprising:
- a ferromagnetic delay line (18) forming a gauge;
- a pulse generator (17), electrically couple to said delay line (18) for generating a plurality of DC electrical excitation pulses (15) in said delay line (18);
- a position indicating magnet (16) proximate said delay line (18) for converting a first one of aid DC electrical excitation pulses (15) into an acoustic pulse (20) propagating in said ferromagnetic delay line, from the location of said position indicating magnet (16) on said gauge;
- a mode convertor (22) proximate said ferromagnetic delay line (18) for converting said acoustic pulse (20) into a mode convertor output signal (36);
- logic (11) for generating an inhibit signal (38), said inhibit signal (38) substantially coincident with said first one of said excitation pulses (15), said logic (11) for generating an output (13) indication of the location of said position indicating magnet (16) along said gauge based upon the time interval between (16) along said gauge based upon the time interval between said first one of said excitation pulses (15) and a comparator output signal (35);
- a comparator (25) coupled to said mode convertor (22) for generating said comparator output signal (35) when said mode convertor output signal (36) exceeds a DC reference level output signal (37);
- reference level means (26) responsive to said inhibit signal (38) for generating said reference level output signal (37), said reference level output signal (37) having a time varying value which varies from an initial value to a terminal value, to compensate for acoustic pulse (20) attenuation in said delay line (18), said reference level means (26) including buffer means (112, 113, 114, 115, 116), coupled to said logic (11) and said comparator (25), for adjusting said reference level output signal (37), the buffer means electrically connecting to a capacitor (111) which provides a charging/discharging signal responsive to said inhibit signal (38).
4 more elements
Dependencies are inferred from the claim text.