Location of emergency service workers

Apparatus for determining the present location, at a designated site, of a mobile user that carries the apparatus inside or outside buildings and structures, the apparatus comprising:

• FM subcarrier means, carried by the user, for determination of the present location of the user, the FM means comprising:
• an FM signal antenna and associated FM signal receiver/processor to receive FM subcarrier signals transmitted from at least three spaced apart FM subcarrier signal sources, with each of these FM subcarrier signals having a subcarrier source indicium that identifies the source for that FM subcarrier signal, to receive relative phase information on the FM signals received by the FM signal antenna, to determine the present location of the FM antenna from knowledge of the relative phases of signals received from the FM subcarrier sources, to determine an FM signal indicium that is a measure of at least one of the determined present location of the FM antenna, signal robustness and signal quality of these FM subcarrier signals, and to issue information on the FM antenna present location and the FM signal indicium as output signals;
• and
• phase information means for receiving information on the relative phases of signals transmitted from the FM subcarrier signal sources and for passing this information to the FM receiver/processor;
• outdoor location determination (LD) means, carried by the user, for determination of the present location of the user, the outdoor LD means comprising:
• an outdoor LD signal antenna and associated outdoor LD signal receiver/processor to receive outdoor LD signals transmitted from at least three spaced apart outdoor LD signal sources, with each of these outdoor LD signals having an LD source indicium that identifies the source of that outdoor LD signal, to determine the location of the outdoor LD antenna from analysis of these LD signals, to determine an outdoor LD signal indicium that is a measure of at least one of the determined present location of the outdoor LD antenna, signal robustness and signal quality of these outdoor LD signals, and to issue the outdoor LD antenna present location information and the outdoor LD signal indicium as output signals;
• controller means, for receiving the FM receiver/processor output signals and the outdoor LD receiver/processor output signals, for comparing the FM signal indicium with a selected FM signal indicium threshold, for comparing the outdoor LD signal indicium with a selected outdoor LD signal indicium threshold, for selecting from these comparisons at most one of the FM antenna present location information and the outdoor LD antenna present location information as user present location information, and for issuing the selected user present location information as a controller means output signal;
• and
• transceiver means, connected to the controller means, for receiving the controller means output signal, for receiving at least two location interrogation signals, spaced apart in time, that command the transceiver means to transmit information on the present location of at least one of the FM signal antenna and the outdoor LD signal antenna, and for transmitting the controller means output signal to a selected receiver spaced apart from the user when at least one of a specified group of conditions is present.

A method for monitoring the location of a general service worker or emergency service worker at a designated site, the method comprising the steps of:

• selecting a designated site where the general or emergency service worker will perform services;
• positioning a first location-determining (LD) unit on the body or the garments of the worker, the first LD unit including an antenna and receiver/processor for receiving a sequence of radiowave signals from three or more electromagnetic signal transmitters whose transmitter locations are spaced apart from the designated site and are known with high accuracy, where these electromagnetic signals contain information that allows the present location of the first LD unit to be determined;
• positioning a second LD unit on the body or the garments of the worker, the second LD unit operating independently of the first LD unit and including an antenna and receiver/processor for receiving a sequence of radiowave signals from three or more electromagnetic signal transmitters whose transmitter locations are spaced apart from the designated site and are known with high accuracy, where these electromagnetic signals contain information that allows the present location of the second LD unit to be determined, where the carrier frequencies for the electromagnetic signals used by the second LD unit are chosen so that these signals can be received, within a building-like structure having at least one aperture as well as outside such a structure, without substantial signal attenuation or distortion;
• providing attachment .means for attaching the first LD unit and the second LD unit to at least one of the worker's body and the worker's garments so that the first LD unit and the second LD unit do not interfere with performance of the worker's services;
• providing a central station, having a signal receiver and processor, a signal transmitter, and an electronically sensible map of a selected portion of the Earth's surface that includes the coordinates of the designated site;
• providing the first LD unit and the second LD unit with a sequence of two or more selected, spaced apart interrogation times;
• causing the first LD unit receiver/processor and the second LD unit receiver/processor to determine, at each interrogation time, the present location of the first LD unit and the second LD unit, respectively;
• transmitting information on the present location of at least one of the first LD unit and the second LD unit to the central station receiver;
• causing at least one of the central station processor, the first LD unit and the second LD unit to determine the coordinates of the present location of at least one of the first LD unit and the second LD unit from the information received and to compare these coordinates with the coordinates of the designated site;
• and
• causing the central station transmitter to communicate an alarm signal, which is perceptible by at least one person other than the worker at the designated site, if one or more of a specified group of conditions is present, based on this comparison.