Abstract: A system and method for sensing the periodic position of one or more objects, such as rotating blades of a turbine. The system includes a passive eddy current sensing unit having one or more magnets and first and second cores around which first and second coils are wound, respectively, which together generate first and second magnetic fields. The sensing unit is positioned so that the object periodically passes through the first and second magnetic fields in succession, and the first and second coils consequently produce first and second output signals, respectively. Each coil is individually connected to a processing circuitry that receives each of the first and second output signals. The circuitry electronically combines the first and second output signals so that common mode signals thereof electronically subtract from each other to eliminate from output of the circuitry any electromagnetic interference noise present in the first and second output signals.

Abstract: A system and method for sensing the periodic proximity of one or more objects, such as the rotating blades of a gas turbine. The system includes a passive eddy current sensing unit having first and second magnets and first and second coil-wound cores coupled to generate and detect first and second magnetic fields. The sensing unit is positioned relative to the object such that the first and second coil-wound cores produce outputs in response to the object periodically passing through the first and second magnetic fields, respectively. Circuitry electronically combines the outputs of the first and second coil-wound cores to produce output signals corresponding to the proximity and timing of the object as it periodically passes through the first and second magnetic fields. Electromagnetic interference noise present in the outputs of the first and second coil-wound cores is eliminated from the output signals of the circuitry.

Abstract: A system and method for sensing the periodic position of one or more objects, such as rotating blades of a turbine. The system includes a passive eddy current sensing unit having one or more magnets and first and second cores around which first and second coils are wound, respectively, which together generate first and second magnetic fields. The sensing unit is positioned so that the object periodically passes through the first and second magnetic fields in succession, and the first and second coils consequently produce first and second output signals, respectively. Each coil is individually connected to a processing circuitry that receives each of the first and second output signals. The circuitry electronically combines the first and second output signals so that common mode signals thereof electronically subtract from each other to eliminate from output of the circuitry any electromagnetic interference noise present in the first and second output signals.

Abstract: A system and method for sensing the periodic proximity of one or more objects, such as the rotating blades of a gas turbine. The system includes a passive eddy current sensing unit having first and second magnets and first and second coil-wound cores coupled to generate and detect first and second magnetic fields. The sensing unit is positioned relative to the object such that the first and second coil-wound cores produce outputs in response to the object periodically passing through the first and second magnetic fields, respectively. Circuitry electronically combines the outputs of the first and second coil-wound cores to produce output signals corresponding to the proximity and timing of the object as it periodically passes through the first and second magnetic fields. Electromagnetic interference noise present in the outputs of the first and second coil-wound cores is eliminated from the output signals of the circuitry.