The goal of this project is to develop and implement a life saving system which alerts in case a child drowns in a pool. It´s a known fact that drowning is the second leading cause of unintentional injury-related death of children ages 14 and under. A temporary lapse in supervision is a common factor in most drowning and near-drowning. Child drowning can happen in a matter of seconds, in the time it takes to answer the phone. There is often no splashing of warn of trouble.

Parents whose children have drowned say the day of the tragedy started out just like any other day. No matter how the drowning happened or where it happened, i.e. pool, sea, or any other body of water – one thing was the same; the seconds that claimed their child’s life slid by silently, without warning, and can never be brought back. The system is composed by three main parts. The first part is named "Watch", which is worn by the child on the wrist like an ordinary watch. The "Watch" detects a situation of drowning and sends a distress signal to the second part called the "Bridge" located at the edge of the pool. The "Bridge" is the second part of the system. Its aim is to receive and interpret a distress signal from the "Watch" and transmit it forward to the third part called "Base". The moment the "Base" receives a distress signal from the "Bridge" it alerts the water´s (i.e. pool, sea etc.) surroundings so that the drowning child be pulled out of the water before he´d be critically injured or god forbid die.

This system works with radio frequency (RF) and underwater ultrasonic frequencies. The communication between the "Watch" and the "Bridge" is via ultrasonic communication when the child is in the water and via RF communication when the child is outside the water. The communication between the "Bridge" and the "Base" is via RF communication.

In this system a state of drowning is to be detected using moving sensors. Entering and exiting the pool should be detected using water sensors. When transmitting the data between the three stations they should be synchronized with one another. Also, a demodulation circuit needs to be designed based on the selected modulation of the ultrasonic communication. The system must be reliable and mustn´t report false alarms. Great emphasis must be put on choosing the correct communication protocol between the "Watch" and the "Bridge" when using ultrasonic communication in order to prevent cases when the "Bridge" receives nothing from the "Watch" or when the "Bridge" detects a distress signal from the "Watch" even though nothing was actually broadcasted.

Other aspects that need to be considered in this project are the water sealing of the "Watch", the power consumption of the "Watch", the charging ability of the batteries inside the "Watch" and the way they are charged. In the "Base" station a terminal should be added which shows the status of the children i.e. in the water or out of the water. The "Base" is responsible for alerting the pool´s surroundings in case of a drowning incident by activating an alarm and by automatically calling the emergency services.