Multipath propagation of acoustic signal in a swimming pool

Abstract

The paper deals with a problem of severe multipath propagation of underwater acoustic signal in a swimming pool. The problem appeared during a study of a system for signalling an emergency situation (pre-drowning symptoms detected by a swimming pool user wearable device) and locating the signal source. A swimming pool acoustic environment is characterized by the presence of large flat reflecting planes surrounding a small volume of water. Then, the reflections are more numerous and much stronger than in typical hydroacoustic applications. The paper presents an attempt to create a model of the swimming pool response, suitable for simulation experiments with detection and localization of emergency signal. Then, a study of possible remedies for the localization system, applied on the transmit side (waveform design) and on the receive side (receiver placement and signal processing) is presented.