INDUSTRIAL PROCESS CONTROL INSTRUMENT EMPLOYING A RESONANT SENSOR

摘要

821-106 An instrument for developing at a central control station a signal responsive to the value of a process condition occurring at a field measurement station remote from the central control station wherein a resonant device is used as the instrument basic sensor element. The resonant device which is located at the field station may be excited by either a voltage pulse or a continuous wave. In a particular aspect, the output measurement signal of the instrument is solely dependent upon the value of a desired measured variable, which is representative of a process condition, and is independent of other variables. The resonant device is coupled to excitation and detection circuitry located at the central control station and produces in the detection circuitry when excited with a pulse of energy first and second signals, one of which is dependent upon the desired measured variable and a second variable and the other dependent upon at least the second variable. These two signals are then combined according to known mathematical and physical principles to produce an output dependent upon the value of the desired variable.