Abstract: An electrical conductor forming a grid only partially circumferentially surrounds the path of the outer portion of a rotatable member. The member has a magnet coupled thereto for influencing the grid to produce a signal indicative of vibration of the member whenever the magnet is within a predetermined distance of the grid. During the interval that the magnet does not influence the grid, a synthesis signal, indicative of vibration of the member during the previous influence portion of the revolution, is generated. The influence signal and the synthesis signal may be provided to processing apparatus for obtaining vibration information. Providing both an influence signal and a synthesis signal substantially simplifies processing apparatus that would otherwise be needed should only an essentially null signal be available during the interval in which the magnet does not influence the grid.

Abstract: An apparatus is provided for obtaining data from sensor measurements made on a body moving rotationally with respect to a stationary observer. Radio frequency energy is reactively coupled between an energy source fixed with respect to the observer and load varying means located on the moving body. The load variance is dependent upon measurement data provided by sensors located on the moving body. The variation in load is reflected back through the reactive coupler to a detector which is fixed with respect to the observer. The detector operates to provide signals indicative of the measurement data provided by the sensors. The apparatus of the present invention may be easily retrofitted to rotational devices such as turbines, motors and generators to provide relevant, continuous, on-line measurements of important parameters associated with such rotating systems. These parameters include such measurements as temperature, pressure, strain and torque.

Abstract: A multichannel data acquisition system for physical measurements on rotating members of operating machinery avoids slip rings and radio telemetry for data transfer by providing a capacitive coupling link between rotating and stationary members. Electronic circuitry mounted on the rotating member provides a pulse-code modulated signal containing the measured information for transmission through the capacitive coupling link. Power required to operate the rotating circuitry is inductively coupled from a stationary high-frequency source. The rotating circuitry includes a digital counter whose count is incremented by a momentary power interruption and whose digital output corresponds to a particular measuring range, allowing a range selection to be made during machinery operation.

Abstract: A self-calibrating subcarrier telemetry system for measuring strain on rotating members of a turbine under operating conditions. A rotor mounted portion of the system includes a strain gage transducer bridge excited by a subcarrier alternating current derived from an induced power source. The transducer bridge produces an output signal, amplitude modulated by the strain signal whereby the modulation shifts the strain signal into a higher frequency portion of the spectrum away from low-frequency noise related to the rotational speed of the turbine. A calibration signal is introduced by automatically unbalancing the bridge transducer periodically at a rate related to the subcarrier frequency. The strain signal is recovered in a stationary data reception portion of the system by a synchronous detector. A reference calibration signal is provided against which receiver gain is adjusted to achieve a null, leaving only the calibrated strain signal and achieving indpendence of variations in system gain.