| 摘要 |
For use in detecting the presence of a foreign body in liquid, such as a swimming pool or the like, at least one transducer support is immersed in the swimming pool or other body of liquid to be monitored. The transducer support has a plurality of transducer means mounted on the support which are capable of sending and receiving acoustic energy. The present invention also comprises a control means for sequentially activating the transducers to generate a series of time-spaced acoustic pulses sequentially from the transducers, and a means responsive to changes in a reflected echo pattern received at one of the transducer means for the expiration of a pre-determined time period, and thus indicative of a foreign object in the transmission path for generating an appropriate alarm function such as a visual or audio alarm.
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