Patent ID: 9518958
Filing Date: 2016-12-13
CPC Classification: G01N

Claim Text:
1. A system for detecting air, the system comprising: a transmitter configured to transduce a driver signal to ultrasonic vibrations; a receiver configured to receive the ultrasonic vibrations and transduce the ultrasonic vibrations to provide a receiver signal; an air-detection circuit in operative communication with the receiver to process the receiver signal to generate a processed signal corresponding to detected air, the air-detection circuit comprising at least one active-rectifying element configured to actively rectify the receiver signal to provide the processed signal; a first conductive path to provide a first polarity of the receiver signal from the receiver; a second conductive path to provide a second polarity of the receiver signal from the receiver; a first switch electrically coupled to the first and second conductive paths, the first switch configured to switch a first switch output to between the first and second polarities of the receiver signal, the first switch defining the at least one active-rectifying element; a second switch electrically coupled to the first and second conductive paths, the second switch configured to switch a second switch output to between the first and second polarities of the receiver signal; a first amplifier having a positive input and a negative input, wherein the positive input is coupled to the first switch output and the negative input is coupled to the second switch output, wherein the first amplifier provides a first amplifier output in accordance with the positive and negative inputs; and a first filter electrically coupled to the first amplifier output of the first amplifier to provide a first filter output.