Abstract: An accelerometer with internal electronics is mounted within a Faraday shield and encapsulated within a non-electrically conductive material applied by hot injection molding at a high pressure to form a hermetically sealed case with integral strain-relief, cable bend protection, ground loop isolation and protection against EMI/RFI interference through both conduction and radiation. The accelerometer is shaped as a torus with the center hole providing center hole bolt mounting.

Abstract: An apparatus for monitoring a vibrating structure, such as a bridge, uses multiple motion sensors spaced along the structure, each of which produces an analog raw data signal which is then filtered in anti-aliasing filters to remove substantially all frequency components of the signal above a selected cutoff frequency, f.sub.co. The filter outputs are connected to addressed inputs of an analog multiplexer which then multiplexes the signals in response to a channel address clock which repeatedly generates a sequence of channel addresses to scan the data input channels at the multiplexer corresponding to the addresses in the sequence. The complete sequence of addresses is repeated at a frequency of at least twice the cutoff frequency to obtain substantially simultaneous samples from the sensors so that data from different sensors may be correlated. The multiplexed signal is then converted to digital form and stored.

Abstract: A switch control system particularly well suited for use in a electromechanical vibrator drive. Solid-state switches and diodes are used in combination with a DC power supply to alternately switch energy between the electric field of the power supply filter capacitor and the magnetic field of the actuator coil of a vibrator in a power resonant mode. The control system includes a variable frequency oscillator and a controllable pulse generator which respectively provide signals for controlling the closing and opening of the switches whereby the frequency and amplitude of movement of a vibratory feeder may be adjusted.