Patent ID: 6504794
Filing Date: 2003-01-07
Classification: G01S

Abstract:
An apparatus for locating people and objects in a difficult to see environment, the apparatus comprising:a beacon including an ultrasonic transmitter coupled to an omnidirectional antenna, the ultrasonic transmitter providing an ultrasonic signal having a first frequency to the omnidirectional antenna for transmission therefrom; a tracker including an ultrasonic receiver coupled to a directional antenna, the ultrasonic receiver capable of receiving the ultrasonic signal having a first frequency via the directional antenna, the tracker further providing an indicia of a measurement of the received signal strength of the received ultrasonic signal, wherein the indicia is selected from the group consisting of a single visual indicator in which the intensity of the single visual indicator is dependent upon the received signal strength, a single visual indicator pulsed on and off at a pulse rate in which the pulse rate of the single visual indicator is dependent upon the received signal strength, an audio signal in which the pitch changes as a function of the received signal strength and an audio signal pulsed on and off at a pulse rate in which the pulse rate is a function of the received signal strength; wherein the approximate azimuth is provided by the direction corresponding to the maximum received signal strength and distance from the tracker to the beacon can be estimated as a function of the maximum received signal strength.