Patent ID: 9378636
Filing Date: 2016-06-28
CPC Classification: G01P,G08B

Claim Text:
1. A social alarm system, comprising: a social alarm server apparatus; a social alarm client unit which is configured to connect with the social alarm server apparatus over a communications network in response to an alarm event and to signal the social alarm server apparatus concerning the alarm event; a fall detector unit, arranged to be carried by a user, comprising an accelerometer arranged to measure acceleration forces to provide an acceleration signal and a barometer arranged to measure atmospheric pressure to provide a pressure signal; a controller which, upon the acceleration signal exceeding a wake-up threshold, is arranged to determine whether or not a fall event has occurred based on the acceleration signal and the pressure signal; and an alarm signal unit which is arranged to generate a fall alarm signal in response to the controller determining that the fall event has occurred; wherein the controller is arranged to determine a compensated height difference for determining the fall event by: reading the pressure signal over a pressure examination period to derive a first pressure difference value, wherein the first pressure difference value is determined by taking a difference between at least two readings from the pressure signal in the examination period, reading the pressure signal over a subsequent compensation period to derive a second pressure difference value, wherein the second pressure difference value is determined by taking a difference between at least one pressure reading of the pressure signal in the compensation period and at least one other pressure reading of the pressure signal in the examination period or in the compensation period, and modifying the first pressure difference value using the second pressure difference value.