Transit time determination in a measurement system, with effects of transducers

In the use of precision multi-beam ultrasonic flowmeters of the transit time type for fiscal measurements of natural gas, accurate initial and operational calibrations at representative zero flow conditions may be required. A simplified system model for only one beam of such a flowmeter is used to analyze how the transmitting and receiving transducers in addition to the transmission through the medium are affecting the transit times. The resulting pulse forms are seen to be connected to the variations in transit times as determined from zero crossings at different locations in the pulses. For the steady state regions of long CW bursts, the transit times can be related to the phase of the transfer functions, but with some transitions occurring in particular frequency bands at frequencies further removed from resonance