Function

The fall detector had to meet the following requirements:

1. Daily activities of old people should not trigger the detector. These activities including walking, going up /down stairs, turning around, sitting down and standing up. 

2. Falling down should trigger the detector. 

3. In the case of trigger, the device should send notification to someone's mobile phone.

4. In the case of trigger, the device should use some signals to let the user know a falling has been detected. 

5. In the case of false trigger, for example, a drop of the device, the user should be able to cancel the device before the notification is sent.