Ultrasonic liquid flow controller

A method of determining a rate of flow of a fluid in a conduit, the method comprising acts of:

• sending first and second ultrasonic signals along a length of the conduit using a pair of ring-shaped transducers disposed at first and second positions spaced apart along the length of the conduit;
• receiving the first and second ultrasonic signals;
• cross-correlating the first received ultrasonic signal and the second received ultrasonic signal to generate a resulting time-domain signal;
• analyzing the resulting time-domain signal to determine a difference in transit time between the first received ultrasonic signal and the second received ultrasonic signal;
• calculating the rate of flow of the fluid in the conduit based upon the determined difference;
• and
• providing the calculated rate to another device for use as the determined rate of flow of fluid in the conduit;
• wherein the act of cross-correlating comprises:
• performing a Fourier transform on each of the received ultrasonic signal and the second received ultrasonic signal to generate a first frequency-domain representation and a second frequency-domain representation, respectively;
• multiplying the first and second frequency-domain representations together to generate a resulting frequency-domain representation;
• and
• performing an inverse Fourier transform on the resulting frequency-domain representation to generate the resulting time-domain signal.

An ultrasonic flow meter comprising:

• a conduit;
• a first ring-shaped ultrasonic transducer, disposed at a first position along a length of the conduit, to transmit a first ultrasonic signal and to receive a second ultrasonic signal;
• a second ring-shaped ultrasonic transducer, disposed at a second position along the length of the conduit that is spaced apart from the first position, to transmit the second ultrasonic signal and to receive the first ultrasonic signal;
• and
• a controller configured to cross-correlate the first received ultrasonic signal and the second received ultrasonic signal and generate a resulting time-domain signal, to analyze the resulting time-domain signal to determine a difference in transit time between the first received ultrasonic signal and the second received ultrasonic signal, and to calculate a rate of flow of a fluid in the conduit based upon the determined difference;
• wherein the controller is further configured to:
• perform a Fourier transform on the first received ultrasonic signal to generate a first frequency-domain representation;
• perform a Hilbert transform and a Fourier transform on the second received ultrasonic signal to generate a second frequency-domain representation;
• multiply the first and second frequency-domain representations together to generate a resulting frequency-domain representation;
• and
• perform an inverse Fourier transform on the resulting frequency-domain representation to generate the resulting time-domain signal.