Abstract: An interface system (5) for connection to a fluid flow monitoring assembly is described. The monitoring assembly comprises a signal generating assembly and a signal receiving assembly (8,9) for transmitting signals into a flowing fluid and for receiving the signals after transmission through the fluid respectively; and a monitoring assembly (1) for controlling the transmission of signals by the signal generating assembly, sensing the signals received by the signal receiving assembly, and thereby monitoring the fluid flow. The signal generating and receiving assemblies (8,9) are adapted to transmit and receive signals passing through the fluid along at least two paths and the monitoring assembly (1) has one communication port for each transmission path.

Abstract: A method and an apparatus for (a) monitoring fluid flow by transmitting acoustic signals in opposite directions through a fluid with components in the direction of flow; (b) receiving the transmitted signals; (c) providing a first signal representing acoustic velocity; (d) time-integrating the first signal to produce a ramp signal, the rate of change of which represents acoustic velocity in the fluid; (e) transmitting a first acoustic signal in one direction through a fluid; (f) transmitting a second acoustic signal in the opposite direction through the fluid; and (g) initiating integration of the first signal. The ramp signal is compared with a second signal representing fluid flow velocity to generate first and second arrival signals according to the direction of the transmitted acoustic signal; expected arrival times for the transmitted acoustic signals are compared with the actual arrival times of the transmitted acoustic signals, and the results of the comparisons are stored.

Abstract: A meter for measuring the velocity of a fluid by ascertaining propagation periods of acoustic wave packets transmitted therein, the meter including a pair of transducers for disposition in the fluid, a transmitter for transmitting a packet between the transducers in an upstream or downstream direction designated by an up/down signal at each time designated by a transmit signal and a receiver for developing a received signal marking the time of receipt by a transducer of each packet, the times being marked so as to avoid amplitude and half-cycle ambiguity errors.