Patent ID: 7832282

Claim:
An ultrasonic measurement system for measuring a flow in a conduit, the system comprising: a first transmitting transducer configured to launch a first ultrasonic beam having a center axis of maximum intensity; a first receiving transducer configured to receive modulated signal energy from the first ultrasonic beam and to produce a first receiver output signal, the first receiving transducer located off the center axis of the first beam so as to not receive signal energy from the center axis of maximum intensity to increase the measured modulation of the signal energy; a second transmitting transducer axially spaced from the first transmitting transducer and configured to launch a second ultrasonic beam also having a center axis of maximum intensity; a second receiving transducer configured to receive modulated signal energy from the second ultrasonic beam and to produce a second receiver output signal, the second receiving transducer located off the center axis of the second beam so as to not receive signal energy from the center axis of maximum intensity to increase the measured modulation of the signal energy; and a processing subsystem configured to correlate the first and second receiver output signals to determine a time delay indicative of the flow velocity in the conduit.