An ultrasonic flow meter includes a conduit, a first ultrasonic
transducer, a second ultrasonic transducer, and a controller. The first
ultrasonic transducer is disposed at a first position about a first
portion of the conduit to transmit a first ultrasonic signal and to
receive a second ultrasonic signal. The second ultrasonic transducer is
disposed at a second position about a second portion of the conduit that
is spaced apart from the first position along a length of the conduit to
transmit the second ultrasonic signal and to receive the first ultrasonic
signal. The controller is configured to cross-correlate the first and
second received ultrasonic signals and generate a resulting time-domain
signal, analyze the resulting time-domain signal to determine a
difference in transit time between the first and second received
ultrasonic signals, and calculate a rate of flow of a fluid in the
conduit based upon the determined difference.