ALGORITHM FOR CALCULATING AMPLITUDES, PHASE- OR TIME DIFFERENCES

The present invention relates to a method for calculating the flow in a gas or a liquid by an ultrasonic flow meter. It is the object of the pending patent application to achieve a very fast calculation of fluid flow, gas or liquid, in a flow channel. A further object is to achieve calculation of flow with extremely low power consumption of the system calculating the fluid flow. This can be achieved by performing condensing and summarizing of the data by use of a mathematic model in order to fit data to the following general model function g(t) = h(t; a4, a5,..., aM). sin(a1. t + a2) + a3. and by calculating the flow by using either the digital Constant Fraction Discriminator, DCFD, using a part of, or all, of the data frame or by Least Square Fit (LSQF) by fitting measured data to a model function of the type g(t) = h(t; a4, a5,..., aM). sin(a1 . t + a2) + a3, or a combination of DCFD and LSQF for achieving at least Ta, Tb and DT. The use of a mathematical model calculating further in the system using the model will give a function that still contains the necessary transmission times Ta and Tb as well as time difference DT.