초록 ▼

A security system is provided wherein a portable locator (10) is disposed on a protected person and, with the use of an alarm switch (88), an individual can set the locator (10) to continuously transmit an alarm signal. This alarm signal is comprised of a pseudonoise (PN) code ORed with data and tra

A security system is provided wherein a portable locator (10) is disposed on a protected person and, with the use of an alarm switch (88), an individual can set the locator (10) to continuously transmit an alarm signal. This alarm signal is comprised of a pseudonoise (PN) code ORed with data and transmitted over a carrier frequency. This carrier frequency is then transmitted to a plurality of fixed receivers (14). The fixed receivers (14) note the time of arrival and then determine via this time of arrival the approximate location of the locator (10). During this time, the locator (10) operates in a high power mode that is sufficient to reach each of the receivers (14). This occurs for a short time and then the locator (10) goes into a low power mode to conserve the battery. During this low power mode, a portable monitor (62) is provided that has two receivers (66) and (68). Two antennas (70) and (72) are associated therewith. The system operates on an angle of arrival method. This basically gives left-right direction to the portable monitor (62). The portable monitor (62) is moved into the general location of the locator (10) to further refine and determine the exact location of the locator (10).

대표청구항 ▼

A personal security system for locating a person within a predetermined locale, comprising: a plurality of receivers disposed about the predetermined locale for receiving an alarm transmission; one or more portable transmitters for being carried on a person, each said portable transmitter having: an

A personal security system for locating a person within a predetermined locale, comprising: a plurality of receivers disposed about the predetermined locale for receiving an alarm transmission; one or more portable transmitters for being carried on a person, each said portable transmitter having: an alarm switch for being activated by the person, a battery for supplying power, a processor for generating an alarm signal and encoding said alarm signal onto a carrier as an encoded alarm signal, and a transmitter for transmitting said encoded alarm signal as said alarm transmission at first and second power levels, at said first power level, said alarm transmission reaching the closest ones of said plurality of receivers and, at said second power level, to an area proximate to said portable transmitter, said transmitter powered by said battery; a control system for controlling said transmitter to operate at said first power level for a predetermined duration of time and, thereafter, at said second power level until the power in said battery is drained; a central control system for interfacing with each of said receivers and receiving the information received thereby, each of said plurality of receivers operable to determine the time that said alarm transmission is received by said receiver, said central control system operable to determine a location of said locator by a time-of-arrival method; and a portable monitoring system having associated therewith a directional receiver for receiving said alarm transmission when said control system for said portable transceiver forces said transmitter to operate at said second power level, said portable monitoring system operable to determine a relative position when said portable monitoring system is in the RF field of each said transmitter at said second power level to more specifically locate each said portable transmitter.