Process measurement instrument with target rejection

摘要

A process measurement instrument with target rejection comprises a sensor circuit. The sensor circuit comprises a drive circuit for transmitting a pulse signal at a target of interest and a receive circuit receiving reflected echoes of the pulse signal and developing an analog receive signal representative of the reflected echoes. An analog processing circuit receives the analog receive signal and comprises a summer subtracting an analog target rejection signal from the analog receive signal to develop a corrected receive signal. A programmed digital processing circuit is operatively coupled to the analog processing circuit and comprises a memory storing target rejection signal value data representing false target reflections and developing the analog target rejection signal for transfer to the analog processing circuit.