Liquid flow meter

The present invention relates broadly to an electronic liquid flow meter and, in particular to a liquid flow meter for domestic and commercial use. A liquid flow meter for directly measuring the velocity of a liquid is disclosed. The liquid flow meter includes a pair transducers arranged facing each other in a conduit through which the liquid flows. The liquid flow meter also includes a transmitter means for causing the transducers to simultaneously transmit an acoustic wave packet directed for reception at the other transducer. A differential receiver means is also included whereby the differential receiver means has inputs each coupled to a corresponding one of the transducers for detecting an acoustic signal received thereby and determining a difference between the two received signals. The difference being related to the velocity of the liquid within the conduit. The transmitter means and the differential receiver means are each matched to the transducers to ensure substantial reciprocity to thereby substantially avoid phase and/or amplitude variations in the received signal. A method for measuring the velocity of a liquid is also disclosed. The method involves transmitting an acoustic wave packet between a pair of transducers that face each other, detecting an acoustic signal received by a pair of amplifiers and determining the time difference between the two received signals where the receiver amplifiers are matched to the transducers through resistive components.