Importance

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Abstract

An infra-red remote personal alarm system consists of a portable transmitter unit (10) which is intended to be worn or to be manually carried by the user, and which is operable by the user at any particular location to transmit an alarm signal in an emergency and which is to be received by a central receiving station (41) so that appropriate action can be initiated in response thereto. The transmitter unit is electrically operable and includes means (15) for transmitting pulsed infra-red alarm signals which can be picked-up by an infra-red signal receiver at the location of the user, and then retransmitted as an oscillating electrical signal via direct wiring (38, 39, 40, 42, 43) to the central receiving station (41) as a warning signal indicative at location monitoring points (43, 44) of the location from which the emergency call has been made. By making the transmitter units capable of transmitting infra-red pulsed warning signals, and suitably designing the receiver units to recognize and to receive the pulse signals for conversion into electrical signals for onward transmission to the central control station, it is possible to obtain transmission units which are robust and reliable in operation. Test facilities are also provided to enable continuous monitoring of the operational status of the transmission units and the receiver units, so as to minimize the risk of initiated emergency action of the transmission units being undetected.

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First Claim