Method and apparatus for communicating the existence of an emergency situation without uniquely identifying the source of the communication
First Claim
Patent Images
1. A method for communicating an emergency signal comprising:
- varying a repetition rate of an unmodulated long-wave carrier in an on/off keyed manner in a predetermined sequence and at a predetermined phase angle;
generating an electromagnetic wave with a resulting signal in which a primary propagation mode is a magnetic field with a reduced electric field; and
transmitting a resulting signal as the emergency signal.
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Accused Products
Abstract
A system in which one or more alarm sources (10), can wirelessly communicate with a receiver (30), to activate an alarm and does not contain any identification that indicates the communication'"'"'s source (10). The system may include “repeaters” (40), whose function is to relay the communication from one station to another over distances longer than can be reached by a single transmitter (10), Apparatuses for transmitting (10), repeating (40), and receiving (30), are also disclosed, as well as a communication system comprised of various elements of these.
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Citations
24 Claims
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1. A method for communicating an emergency signal comprising:
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varying a repetition rate of an unmodulated long-wave carrier in an on/off keyed manner in a predetermined sequence and at a predetermined phase angle; generating an electromagnetic wave with a resulting signal in which a primary propagation mode is a magnetic field with a reduced electric field; and transmitting a resulting signal as the emergency signal. - View Dependent Claims (2, 3, 4)
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5. A method for communicating an emergency signal comprising:
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transmitting an alarm sequence as a predetermined repeating on/off sequence of a predetermined unmodulated longwave frequency at a predetermined phase angle using a magnetic field as a primary mode of propagation and with a reduced electric field; identifying by one or more repeaters the alarm sequence; synchronizing the one or more repeaters to the alarm sequence; and rebroadcasting the alarm sequence from the one or more repeaters in synchronism with a source of the alarm sequence. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An apparatus for transmitting an emergency signal comprising:
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a signal generator to generate an unmodulated longwave carrier signal at a predetermined frequency and a predetermined phase angle; a switch coupled to the signal generator to interrupt the carrier signal in a predetermined sequence while maintaining the predetermined phase angle; and an antenna to radiate the interrupted carrier signal in the predetermined sequence and predetermined phase angle as the emergency signal using a magnetic field as a primary mode of propagation and with a reduced electric field.
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19. An apparatus for receiving an emergency signal comprising:
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a shielded antenna to receive a transmission at an unmodulated predetermined longwave carrier, said shielded antenna designed to generate a current primarily from a changing magnetic field, and said shielded antenna designed to limit electric fields around the antenna; a receiver to monitor a predetermined longwave frequency and to output a digital sequence upon receiving a transmission on the predetermined longwave frequency, which digital sequence represents an on/off sequence detected in the predetermined frequency; and a processor to correlate the digital sequence against a predetermined sequence to identify the emergency signal. - View Dependent Claims (20, 21, 22)
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23. An apparatus for repeating an emergency signal comprising:
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a receiver to monitor a predetermined longwave frequency and to output a digital sequence upon receiving a transmission on the predetermined longwave frequency, which digital sequence represents an on/off sequence detected in the predetermined frequency, said receiver including a processor to correlate the received digital sequence against a predetermined sequence to identify the emergency signal; a transmitter including; a signal generator coupled to the processor to generate a signal at the predetermined longwave frequency and a predetermined phase angle upon an identification of the emergency signal by the processor; a switch coupled to the signal generator to cause a signal output by the signal generator to be switched on and off in the predetermined sequence and the predetermined phase angle; and an antenna to reradiate the predetermined signal in the predetermined sequence as the emergency signal using a magnetic field as a primary mode of propagation and with a reduced electric field; and a synchronizer coupled to the switch in the transmitter to synchronize the predetermined sequence generated at the output of the switch with the received digital sequence and to synchronize a phase of the carrier signal output from the signal generator with a phase of a carrier signal received by the receiver.
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24. A communication system for communicating an emergency signal comprising:
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a transmitter for transmitting an initial emergency signal, said transmitter including; a signal generator to generate a signal at a predetermined longwave frequency and a predetermined phase angle; a switch coupled to the signal generator to cause the signal to be interrupted in a predetermined sequence and the predetermined phase angle; and an antenna to radiate the interrupted signal in the predetermined sequence and predetermined phase angle as the emergency signal at a longwave frequency using a magnetic field as a primary mode of propagation and with a reduced electric field;
one or more repeaters, each of said one or more repeaters including;a receiver to monitor the predetermined longwave frequency and to output a digital sequence upon receiving a transmission on the predetermined longwave frequency, which digital sequence represents an on/off sequence detected in the predetermined longwave frequency, said receiver including a processor to correlate the received digital sequence against a predetermined sequence to identify the emergency signal; a transmitter including; a signal generator coupled to the processor to generate a signal at the predetermined longwave frequency and the predetermined phase angle upon an identification of the emergency signal by the processor; a switch coupled to the signal generator to cause the signal output by the signal generator to be interrupted in the predetermined sequence and the predetermined phase angle; and an antenna to reradiate the predetermined signal in the predetermined sequence and predetermined phase angle at a longwave frequency using a magnetic field as a primary mode of propagation and with a reduced electric field as the emergency signal; and a synchronizer coupled to the switch in the transmitter to synchronize the predetermined sequence generated at the output of the switch with a received digital sequence and to synchronize a phase of a carrier signal output from the signal generator with a phase of a carrier signal received by the receiver; and an alarm receiver to receive the emergency signal, said alarm receiver to monitor the predetermined longwave frequency and to output a digital sequence upon receiving a transmission on the predetermined longwave frequency, which digital sequence represents an on/off sequence detected in the predetermined longwave frequency, said receiver including a processor to correlate the received digital sequence against a predetermined sequence to identify the emergency signal.
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Specification