Abstract: A low power apparatus for measuring various process parameters and/or physical properties of a fluid or gas medium by measuring the change of a wave signal or time dependent signal as it traverses the fluid or gas medium, the apparatus comprising: at least one transmission transducer for providing a transmitted wave or time dependent signal for injection into the fluid or gas medium; at least one reception transducer, displaced from the transmission transducer for receiving a received wave or time dependent signal from the fluid or gas medium; and an analog signal processor, coupled to the reception transducer, for processing of the received wave or time dependent signal such that a short interval of the processed received wave or time dependent signal is extracted.

Abstract: A sensor communication system uses a shared analog signal to duty cycle converter for producing a comparison between a predetermined free-running triangular waveshape and a selected output signal from a plurality of analog signal sources such as process sensors, to convert the amplitude of the analog signal to a variable duty cycle signal. The variable duty cycle signal is subsequently converted to a digital signal which may be represented by a count stored in a counter counting clock pulses during the occurrence of the pulse width waveshape of the variable duty cycle signal. The digital signal is utilized as a digital word by a microprocessor operating in accordance with a stored program to produce a characterized digital output signal for use in a communication after conversion to a 4-20 ma control signal for communication and control in an industrial process control system.

Abstract: A high pressure electrical feedthru uses a ceramic circuit assembly which has a metalized bonding area on the surface of the ceramic to enable the ceramic assembly to be brazed to an outer support housing. The ceramic structure has embedded therein electrical conductors which extend from electrical connection terminals at one end of the feedthru to electrical connection terminals at the other end of the feedthru with the brazing area being located therebetween. The ceramic structure is arranged to support a pressure sensor which is connected to the electrical connection terminals at one end of the ceramic structure. The sensor and the adjacent end of the feedthru are located in a high pressure environment within a pressure tight housing.