Emergency alarm method and system utilizing cross cueing and ranging techniques
First Claim
1. A method of operating an emergency signalling unit worn by a fireman or other worker in a potentially dangerous environment, which emits at least audio and visible alarm signals, comprising,arranging said audio alarm signals to occur in a cyclical manner, wherein each cycle comprises a first interval consisting of a predetermined number of successive tone emissions occurring in predetermined time relationship to each other and a second interval which is longer than said first interval during which no tone emissions occur, andarranging said visible alarm signal to be emitted immediately following a predetermined one of said successive tone emissions.
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Accused Products
Abstract
An alarm signalling method and system utilizing cross cueing between radio, audio and visible alarm signals which are emitted by an alarm signalling unit. A method and system for measuring the range between the alarm signalling unit and a receiver carried by a rescuer wherein the differences in the time of receipt at the receiver of simultaneously emitted radio and audio signals is used as a measure of range.
14 Citations
12 Claims
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1. A method of operating an emergency signalling unit worn by a fireman or other worker in a potentially dangerous environment, which emits at least audio and visible alarm signals, comprising,
arranging said audio alarm signals to occur in a cyclical manner, wherein each cycle comprises a first interval consisting of a predetermined number of successive tone emissions occurring in predetermined time relationship to each other and a second interval which is longer than said first interval during which no tone emissions occur, and arranging said visible alarm signal to be emitted immediately following a predetermined one of said successive tone emissions.
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6. In emergency signalling in which an alarm signalling unit carried by a fireman or endangered worker emits audio alarm signals and radio alarm signals which are received by a rescuer trying to move towards the fireman or worker, the method comprising,
arranging said radio and audio signals to be emitted by said signalling unit at the same time, and measuring the time delay at the rescuer between the receipt of the radio and audio signals, which delay is a measure of the distance between the rescuer and the fireman or endangered worker who is carrying the signalling unit.
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7. An emergency signalling system comprising,
an emergency signalling unit for being carried by a fireman or endangered worker, said signalling unit being comprised of, means for emitting an audio alarm signal, and means for emitting a radio alarm signal at the same times that said audio alarm signal is emitted, a receiving unit for being carried by a rescuer, which is comprised of, a signal receiving means for receiving said radio signal, audio signal receiving means for receiving said audio signal, means for measuring the time difference between receipt of said radio and audio signals, and means for displaying a number derived from said measured time which is representative of the distance between the rescuer and the fireman or worker carrying the signalling unit.
Specification