| 摘要 |
A dedicated correlator receives two noise signals from spaced centers sensing noise in a fluid flow. One of the noise signals in delayed by a variable known amount with respect to the other. The amount of correlation between the delayed and undelayed signal is determined. A sweep voltage generator is connected for variably increasing or decreasing the delay at set rates. A peak lock control is connected to the sweep generator and to the apparatus for establishing correlation for changing the direction of the sweep generator when it is determined that the amount of correlation is decreasing from a maximum. The particular delay amount corresponding to maximum correlation corresponds, in turn, to the amount of time required for the fluid to traverse the two sensors and, thus, the velocity of the fluid. The particular delay amount varies with variations in fluid velocity since the peak lock control follows these variations and controls the sweep voltage generator accordingly. |
