Patent ID: 7289914

Claim:
An ultrasonic flowmeter comprising: a trigger oscillating unit configured to output trigger signals; a pulse receiver configured to output ultrasonic pulse oscillation signals according to the trigger signals from the trigger oscillating unit; a transducer configured to cast an ultrasonic pulse along a measurement line in a fluid flowing in a flow tube, due to the ultrasonic pulse oscillation signals from the pulse receiver; a signal processing unit configured to receive ultrasonic echo signals corresponding to a reflected wave from an ultrasonic reflector suspended in the fluid, due to the ultrasonic pulse cast from the transducer, and configured to perform signal processing for the ultrasonic echo signals; and a signal analyzing unit configured to calculate a position and a speed of the ultrasonic reflector positioned along the measurement line by performing signal analysis for ultrasonic echo signals subjected to signal processing by the signal processing unit, wherein said trigger oscillating unit is configured to control signal transmission/reception timing between the pulse receiver and an AD converter by transmitting to the pulse receiver and the AD converter, with one cycle of the signal transmission/reception timing being formed of three consecutive sets of ultrasonic pulse oscillation signals and ultrasonic echo signals and a predetermined waiting period of time, so that said signal transmission/reception timing is adjusted, wherein said signal processing unit includes the AD converter configured to perform AD conversion of said ultrasonic echo signals from the pulse receiver to form digitized ultrasonic echo signals, and wherein said signal analyzing unit calculates two independent flow-speed distributions of the fluid based upon the two independent flow-speed distributions of a plurality of ultrasonic reflectors suspended in the fluid calculated by making cross-correlation between a pair of two adjacent digitized ultrasonic echo signals selected from the three consecutive digitized ultrasonic echo signals reflected from the ultrasonic reflector, due to three consecutive ultrasonic pulses cast from the transducer.