flowmeter which operates on the principle that two signals, a known distanve apart, are modulated by perturbations in the fluid flow, and these signals are compared by a correlator, the time taken for a perturbation to travel between the two receivers is identified and hence the flow-rate is calculated, voomõõtur, mis kasutab mõõteprintsiipi, et kahte teadaoleval kaugusel asuvat signaali moduleeritakse vedeliku voo häiringute abil ja neid signaale võrreldakse korrelaatori abil, tuvastatakse häiringu levimiseks kahe vastuvõtturi vahel kuluv aeg ja arvutatakse seejärel voomaht