Multi-hazard alarm system using selectable power-level transmission and localization

Abstract

A personal alarm system includes a monitoring base station and one or more remote sensing units in two-way radio communication. An electronic handshake between the base station and each remote unit is used to assure system reliability. The remote units transmit at selectable power levels. In the absence of an emergency, a remote unit transmits at a power-conserving low power level. Received field strength is measured to determine whether a remote unit has moved beyond a predetermined distance from the base station. If the distance is exceeded, the remote unit transmits at a higher power level. The remote unit includes sensors for common hazards including water emersion, smoke, excessive heat, excessive carbon monoxide concentration, and electrical shock. The base station periodically polls the remote units and displays the status of the environmental sensors. The system is useful in child monitoring, for use with invalids and with employees involved in activities which expose them to environmental risk. Alternative embodiments include a panic button on the remote unit for summoning help, and an audible beacon on the remote unit which can be activated from the base station and useful for locating strayed children. In another embodiment, the remote unit includes a Global Positioning System receiver providing location information for display by the base station.

What is claimed is: 
     
         1 . A mobile remote unit comprising:
 a radio transmitter and receiver configured to communicate with a cellular telephone network using a two-way radio communication link;   a navigational receiver configured to receive navigational information;   a detection circuitry configured to detect an emergency input;   wherein   the detection circuitry is coupled to the radio transmitter and receiver for providing an emergency identifier according to the emergency input;   the navigational receiver is coupled to the radio transmitter and receiver for providing location information relating to the location of the mobile remote unit based on the navigational information; and   the radio transmitter and receiver is configured to send the emergency identifier and the location information to the cellular telephone network for processing.   
     
     
         2 . A mobile remote unit according to  claim 1 , wherein the radio transmitter and receiver is further configured to receive a message from the cellular telephone network requiring the location information of the mobile remote unit. 
     
     
         3 . A mobile remote unit according to  claim 1 , wherein the navigational receiver comprises a GPS receiver. 
     
     
         4 . A mobile remote unit according to  claim 1 , wherein the detection circuitry comprises an emergency switch and the emergency input is defined according to the switch status. 
     
     
         5 . A mobile remote unit according to  claim 1 , wherein the detection circuitry comprises at least one manually operated switch and the emergency input is defined according to the status of the at least one manually operated switch. 
     
     
         6 . A mobile remote unit according to  claim 1 , wherein the detection circuitry comprises at least one sensor and the emergency input is defined according to the status of the at least one sensor. 
     
     
         7 . A mobile remote unit according to  claim 1 , wherein location information of the mobile remote unit comprises demodulated navigational information. 
     
     
         8 . A mobile remote unit according to  claim 1 , wherein the location information comprises location of the mobile remote unit. 
     
     
         9 . A mobile remote unit according to  claim 1 , further comprising a timing circuitry configured to provide time-of-day information, wherein the timing circuitry is coupled to the radio transmitter and receiver for sending the time-of-day information to the cellular telephone network for processing. 
     
     
         10 . A mobile remote unit according to  claim 1 , wherein the radio transmitter and receiver is configured to send the emergency identifier and the location information of the mobile remote unit to at least one network element of the cellular telephone network for processing. 
     
     
         11 . A mobile remote unit according to  claim 1 , wherein the processing comprises computing, by the cellular telephone network, the location of the mobile remote unit based on the location information sent by the mobile remote unit. 
     
     
         12 . A mobile remote unit according to  claim 1 , wherein the processing comprises converting, by the cellular telephone network, coordinates provided in the location information sent by the mobile remote unit. 
     
     
         13 . A mobile remote unit according to  claim 1 , wherein the processing comprises comparing, by the cellular telephone network, the location information sent by the mobile remote unit with a threshold. 
     
     
         14 . A mobile remote unit according to  claim 1 , wherein the processing comprises initiating, by the cellular telephone network, a connection to emergency personnel in response to receiving the emergency identifier sent by the mobile remote unit.