Abstract: A sensor communications system includes different sensor modules which are connected to a master module on a two-wire multidrop transducer bus to provide multiple communication channels. The sensor modules transmit signals to and receive signals from the master module.

Abstract: Apparatus for detecting presence of a sensor includes a signal source for providing an excitation signal for the sensor. A detector circuit detects a response signal from the sensor in response to the excitation signal for presence detection. A switch is responsive to a control signal for switching between a first switch state for coupling the signal source to the sensor and a second switch state for coupling the detector circuit to the sensor. A controller provides the control signal and analyzes the detected response signal. The excitation signal can be a chirp signal that spans a range of frequencies. First and second tests of the sensor are conducted with the presence of the sensor determined from the first and second tests. Parameters of the detection including gain can be changed for the first and second tests to provide a more accurate test result.

Abstract: This invention disclosure describes an intelligent sensor system in which different types of sensors are connected to a network communication bus. Analog and digital signals are transferred bi-directionally on the common communication bus between the distributed sensors and an application specific controller referred to as a bus converter/controller module (BCM). The traditional analog type sensors are connected to the communication bus through interface devices referred to as transducer-to-bus interface modules (TBIM). The TBIM provides sensor identification, self-test and data correction functions.

Abstract: A general biquadratic filter circuit is described which uses operational transconductance amplifiers. A bias current controls the transconductance (gm) of the amplifiers which in turn control the corner frequency (Wo) of the circuit. The circuit is configured with three potential sources which can be preselected to either be at a ground level or at a desired voltage level. By preselecting which of the potentials are grounded and which are at a desired voltage level, the circuit can become either a lowpass, highpass, bandpass or notch filter.