Multipath Propagation of Acoustic Signal in a Swimming Pool—Source Localization Problem

Abstract

This paper explores the problem of severe multipath propagation of underwater acoustic signals in a swimming pool. The problem appeared in a study that examined a system used to signal emergency situations (i.e, pre-drowning symptoms detected by a wearable device on a pool user’s wrist) and locate the signal source. A swimming pool acoustic environment is characterized by the presence of large flat reflecting planes surrounding a small volume of water. The reflections are numerous and much stronger than in typical hydroacoustic applications. In this paper, we attempted to create a model of the swimming pool response, one that is suitable for simulation experiments with detection and localization of emergency signals. Then, we explore the possible remedies for the localization system, applied on the transmit side (waveform design) and on the receive side (receiver placement and signal processing). Finally, we present an algorithm for object localization, considering the possible reflections with a multi-hypothesis approach.

Wearable Pulse Oximeter for Swimming Pool Safety

“…The presented algorithm is suitable as a drowning condition detector part of a whole safety system, which integrates the threat detection and transmission of the alarm signal to the lifeguards, or which reacts automatically by itself. Some systems of this type are proposed in [ 28 , 29 , 30 , 31 ].…”

An Improved YOLOv5 Algorithm for Drowning Detection in the Indoor Swimming Pool

“…Additionally, wearable devices utilize methods like the transmission of acoustic signals, which present inevitable challenges. Swimming pools suffer from severe multipath propagation of underwater acoustic signals, potentially weakening their transmission [12]. Furthermore, the presence of strong noise in a pool can negatively affect the detection and accurate positioning of emergency signals, leading to positioning deviations [12].…”

“…Swimming pools suffer from severe multipath propagation of underwater acoustic signals, potentially weakening their transmission [12]. Furthermore, the presence of strong noise in a pool can negatively affect the detection and accurate positioning of emergency signals, leading to positioning deviations [12]. Hence, there is a pressing need for the development of an automated, unsupervised drowning detection and identification system.…”