| 摘要 |
PCT No. PCT/AU92/00315 Sec. 371 Date Feb. 2, 1994 Sec. 102(e) Date Feb. 2, 1994 PCT Filed Jun. 25, 1992 PCT Pub. No. WO/9300570 PCT Pub. Date Jan. 7, 1993.Disclosed is a method and apparatus with which errors caused by the propagation of high order accoustic modes in ultrsonic flow measurement are reduced. Accoustic wave packets are transmitted between two transducers (1,2) arranged in a duct (3). A ringaround transmission technique is used and implemented by a control device (4) in which every fourth wave packet is inverted with respect to the preceding packets in order to annul the propagation effects of high order modes in the duct (3). This permits increased accuracy in the detection of reception of the wave packets by the transducers (1,2) enabling increased accuracy in flow velocity measurment. |
