System, method, and apparatus for detecting air in a fluid line using active rectification
A circuit for detecting air, a related system, and a related method are provided. The circuit for detecting air includes a receiver connection and an air-detection circuit. The receiver connection is configured to provide a receiver signal. The air-detection circuit is in operative communication with the receiver connection to process the receiver signal to generate a processed signal corresponding to detected air. The air-detection circuit includes one or more active-rectifying elements configured to actively rectify the receiver signal to provide the processed signal.
1. A method of detecting air, the method comprising:
transmitting ultrasonic energy;
receiving the ultrasonic energy;
transducing the received ultrasonic energy into a receiver signal;
actively rectifying the receiver signal to provide a processed signal by inverting the receiver to provide an inverted receiver signal;
determining whether the processed signal is less than a predetermined threshold;
inverting the receiver signal to provide an inverted receiver signal;
switching between the receiver signal and the inverted receiver signal in accordance with a first switching signal to provide a first switch output; and
integrating the first switch output to provide a first integrated output for a predetermined number of cycles.
2. The method according to claim 1 , further comprising:
switching between the receiver signal and the inverted receiver signal in accordance with a second switching signal to provide a second switch output.
3. The method according to claim 2 , further comprising:
integrating the second switch output to provide a second integrated output for a predetermined number of cycles.
4. The method according to claim 1 , further comprising:
calculating a magnitude using the first and second integrated outputs.
5. The method according to claim 4 , wherein the magnitude defines the processed signal.
6. The method according to claim 1 , wherein the act of actively rectifying the receiver signal comprises:
activating a first switching network configured to switch between the receiver signal and an inverted receiver signal to provide a first switching network signal.
7. The method of claim 6 , wherein the act of actively rectifying the receiver signal further comprises:
activating a second switching network configured to switch between the receiver signal and an inverted receiver signal to provide a second switching network signal.
8. The method of claim 7 , wherein the act of actively rectifying the receiver signal further comprises:
integrating the second switching network signal to provide a second integrated output.
9. The method according to claim 1 , wherein the act of actively rectifying the receiver signal comprises:
switching between the receiver signal and the inverted receiver signal in accordance with a first switching signal to provide a first switching network signal.
10. The method of claim 1 , wherein the act of actively rectifying the receiver signal comprises:
integrating the first switching network to provide a first integrated output.
11. The method of claim 1 , wherein the act of actively rectifying the receiver signal further comprises:
switching between the receiver signal and the inverted receiver signal in accordance with a second switching signal to provide the second switching network signal.
12. The method of claim 11 , wherein the second switching signal is about 90 degrees out of phase with the first switching signal.
13. The method of claim 11 , wherein the act of actively rectifying the receiver signal comprises:
filtering the second switch output to provide a second filtered output.
14. The method of claim 11 , wherein the act of actively rectifying the receiver signal comprises:
filtering the first switch output to provide a first filtered output; and
filtering the second switch output to provide a second filtered output.
15. The method of claim 14 , wherein the act of actively rectifying the receiver signal further comprises:
generating a processed signal using the first filtered output and the second filtered output.
16. The method of claim 15 , wherein the processed signal is a square root of a squared of the first filter output summed with a square of the second filtered output.
17. The method of claim 15 , further comprising:
determining a presence of an air bubble within a fluid tube when the processed signal is below a predetermined threshold.
18. The method of claim 17 , further comprising:
estimating a volume of the air bubble.
19. The method of claim 18 , wherein the estimation of the volume of the bubble is based on a flow rate of fluid within the tube and a period of time that the processed signal is below the predetermined threshold.
20. The method of claim 1 , wherein the act of actively rectifying the receiver signal comprises:
filtering the first switch output to provide a first filtered output.