| 摘要 |
<p>A method of determining the velocity of a flowing material (22), suspended in a liquid and flowing in a conduit (20), including: irradiating the conduit (20) with ultrasonic waves (26, 32); detecting first Doppler-shifted reflections of the waves from the material, which first reflections have a positive Doppler-shift; and detecting second Doppler shifted reflections of the waves from the material, which second reflections have a negative Doppler-shift. The flow velocity is estimated based on the extent (34) of the positive and negative Doppler-shifts. Preferably, the first and second reflections are summed to form a composite signal and the range of Doppler-shifts in the composite signal is used to estimate the flow velocity.</p> |
