Tracking, safety and navigation system for firefighters

An apparatus for locating people and objects in a difficult to see environment, the apparatus comprising:

• a beacon including an ultrasonic transmitter and an ultrasonic receiver coupled to an omnidirectional antenna, the ultrasonic transmitter including a pulse modulator and an audio input coupled to the modulator, the ultrasonic transmitter providing a voice modulated ultrasonic beacon signal having a first beacon frequency to the omnidirectional antenna for transmission therefrom, the ultrasonic receiver including a pulse demodulator and an audio output coupled to the demodulator, the ultrasonic receiver receiving the voice modulated ultrasonic signal having a first tracker frequency via the omnidirectional antenna and demodulating the received ultrasonic signal and providing an audio output;
• a tracker including an ultrasonic transmitter and an ultrasonic receiver coupled to a directional antenna, the ultrasonic transmitter including a pulse modulator and an audio input coupled to the modulator, the ultrasonic transmitter providing a voice modulated ultrasonic tracker signal having a first tracker frequency to the to the directional antenna for transmission therefrom, the ultrasonic receiver including a pulse demodulator and an audio output coupled to the demodulator, the ultrasonic receiver receiving the voice modulated ultrasonic beacon signal having a first beacon frequency via the directional antenna and demodulating the received ultrasonic signal and providing an audio output.

A method for a first person to track the position of a second person in a difficult-to-see environment, the method comprising the steps of:

• providing the second person with an ultrasonic beacon unit providing an omnidirectional ultrasonic beacon signal;
• providing the first person with an ultrasonic tracking unit capable of receiving in a predetermined directional beamwidth the ultrasonic beacon signal and providing an indicia of the signal strength of the received ultrasonic signal;
• having the first person rotate through a range of azimuth angles while observing the indicia of the signal strength of the received ultrasonic signal;
• and
• 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;
• determining the azimuth angle as corresponding to the direction indicated by the indicia of signal strength corresponding to the maximum received signal strength.

A method of a first individual in communication with a second individual, over a communication link, to navigate in a difficult-to-see environment, the method comprising the steps of

• providing the second person with an ultrasonic beacon unit providing an omnidirectional ultrasonic beacon signal;
• providing the first person with an ultrasonic tracking unit capable of receiving in a predetermined beamwidth the ultrasonic beacon signal and providing an indicia of the signal strength of the received ultrasonic signal;
• having the first person cause the tracker unit to interrogate the beacon unit with an interrogation pulse;
• responding to the interrogation pulse by the beacon unit by providing an answer pulse;
• measuring the time of arrival by the tracker unit of the answer pulse;
• determining the distance to the beacon unit from the tracker unit as a function of the measured time of arrival;
• providing indicia of the determined distance to the first person;
• having the first individual rotate through a range of azimuth angles while observing the indicia of the signal strength of the received ultrasonic signal;
• determining the azimuth angle to the beacon as a function of the received signal strength;
• and
• providing directions by the first individual over the communications link to the second individual to reduce the distance to the first individual.