A lifeguard alarm system for swimmers, capable of detecting whether a swimmer is moving forward or drowning. The system includes a detecting device, an accelerometer disposed on the detecting device and a computing unit; the accelerometer configured to output respective acceleration values along X, Y, and Z axes of the detecting device and of gravity, the computing unit configured to calculate a sum of squares of the X, Y and Z acceleration values of the accelerometer as a first value and square of an acceleration of gravity as a second value and to compare the first value with the second value. A relationship between the first value and the second value can be used to control the warming unit.
展开▼
