| 摘要 |
<p>Device 1 for determining the level of fluid 14 within a vessel comprises a plurality of sets of acoustic transmitting and receiving devices such as piezoelectric devices 6a-6f spaced along the vessel. The transmitters simultaneously generate an acoustic signal, to be reflected from a stepped reflector plate 10 for reception, only for those signal paths which pass through the fluid. The stepped reflector provides different signal path lengths between each transmitter and receiver, thereby providing a time delay between the returning signals so that different fluid levels can be measured. Circuitry is provided (figs. 18 & 19) to balance the amplitude of the response signals. The required number of connection pins, and hence the cost of manufacture, is reduced. Alternative arrangements for providing different acoustic path lengths are shown (figs. 5, 10, 12 & 13).</p> |
