Location system adapted for use in multipath environments

The location system of claim further comprising:

• at least one calibration transmitter, positioned at a known location, for transmitting calibration transmissions receivable by each of the receivers;
• each receiver being responsive to a calibration transmission for providing a corresponding calibration TOA detection packet, including the associated time-of-arrival TOA count, to the location processor;
• and
• the location processor determines calibration coefficients from the calibration TOA detection packets and the known locations of the receivers, and uses those coefficients to calibrate location computations from TOA-detection packets associated with TAG transmissions.

A location system for locating objects within a tracking environment using area-detection by receivers that receive electromagnetic transmissions from assigned areas, comprising:

• for each object, a TAG transmitter for transmitting, at selected intervals, TAG transmissions that include a unique TAG ID;
• an array of receivers distributed within the tracking area, with each receiver being configured to receive TAG transmissions from an assigned area of a predetermined size;
• each receiver including a data communications controller responsive to the receipt of a TAG transmission for providing a corresponding area-detection packet that includes the received TAG ID;
• and
• a location processor for receiving the area-detection packets, and for determining the location of each TAG, and its associated object, based on the identity of the receiver receiving the TAG transmissions for that TAG.

A method for locating of objects within a tracking environment using time-of-arrival differentiation for electromagnetic transmissions received at multiple receivers, comprising the steps:

• for each object, transmitting, at selected intervals, TAG transmissions that include a unique TAG ID;
• providing an array of receivers distributed within the tracking environment such that a TAG transmission is received by at least three receivers;
• in response to the arrival of a TAG transmission at a receiver, providing a TOA count corresponding to the time-of-arrival of the most direct path for such TAG transmission, with the TOA count being synchronized to a system synchronization clock provided to each receiver;
• in response to the receipt of a TAG transmission, providing a corresponding TOA-detection packet that includes the associated TAG ID and TOA count;
• and
• using the TOA-detection packets, determining the location of each TAG, and its associated object, from at least three corresponding TOA-detection packets received from different receivers.

A method of locating objects within a tracking environment using area-detection by receivers that receive electromagnetic transmissions from assigned areas, comprising:

• for each object, providing a TAG transmitter for transmitting, at selected intervals, TAG transmissions that include a unique TAG ID;
• providing an array of receivers distributed within the tracking area, with each receiver being configured to receive TAG transmissions from an assigned area of a predetermined size;
• each receiver being responsive to the receipt of a TAG transmission for providing a corresponding area-detection packet that includes the received TAG ID;
• and
• determining the location of each TAG, and its associated object, based on the identity of the receiver receiving the TAG transmissions for that TAG as represented by the area-detection packet provided by such receiver that received the TAG transmissions.

A transmitter including:

• transmitter circuitry for transmitting information;
• and
• a motion detection circuit for detecting motion and lack of motion of the transmitter, said motion detection circuit enabling the transmit circuitry to transmit information at first selected intervals when the transmitter is in motion and enabling the transmit circuitry to transmit information periodically at second selected intervals in response to detecting lack of motion,
• wherein said second selected intervals are at a low duty cycle relative to said first selected intervals.

A transmitter including:

• transmitter circuitry for transmitting information;
• and
• a periodicity control circuit for causing the transmitter circuitry to transmit information at selected intervals in response to the transmitter being moved,
• wherein the periodicity control circuit causes the transmitter circuitry to transmit at relatively short intervals while the transmitter is in motion, and at relatively long intervals while the transmitter is stationary.

A location system for locating objects within a tracking environment using area-detection by receivers that receive transmissions from assigned areas, comprising:

• for each object, a TAG transmitter for transmitting, at selected intervals, TAG transmissions that include a unique TAG ID, each said TAG transmitter further including a motion detection circuit for detecting motion of the object, and for enabling the TAG transmitter to transmit TAG transmissions while the object is in motion;
• an array of receivers distributed within the tracking area, with each receiver being configured to receive TAG transmissions from an assigned area of a predetermined size;
• each receiver including a data communications controller responsive to the receipt of a TAG transmission for providing a corresponding area-detection packet that includes the received TAG ID;
• and
• a location processor for receiving the area-detection packets, and for determining the location of each TAG, and its associated object, based on the identity of the receiver receiving the TAG transmissions for that TAG.

A location system for locating objects within a tracking environment using area-detection by receivers that receive transmissions from assigned areas, comprising:

• for each object, a TAG transmitter for transmitting, at selected intervals, TAG transmissions that include a unique TAG ID;
• an array of receivers distributed within the tracking area, with each receiver being configured to receive TAG transmissions from an assigned area of a predetermined size;
• each receiver including a data communications controller responsive to the receipt of a TAG transmission for providing a corresponding area-detection packet that includes the received TAG ID;
• a location processor for receiving the area-detection packets, and for determining the location of each TAG, and its associated object, based on the identity of the receiver receiving the TAG transmissions for that TAG;
• and
• wherein each receiver provides an adjustable level of noise sensitivity for
• differentiating TAG transmissions from noise.

A location system for locating objects within a tracking environment using area-detection by receivers that receive transmissions from assigned areas, comprising:

• for each object, a TAG transmitter for transmitting at selected intervals, TAG transmissions that include a unique TAG ID;
• an array of receivers distributed within the tracking area, with each receiver being configured to receive TAG transmissions from an assigned area of a predetermined size;
• each receiver including a data communications controller responsive to the receipt of a TAG transmission for providing a corresponding area-detection packet that includes the received TAG ID;
• a location processor for receiving the area-detection packets, and for determining the location of each TAG, and its associated object, based on the identity of the receiver receiving the TAG transmissions for that TAG;
• and
• a local area network, said array of receivers being coupled to the location processor by said local area network, with each receiver including a LAN interface, such that the area detection packets are communicated to the location processor over said LAN.

A method of locating objects within a tracking environment using area-detection by receivers that receive transmissions from assigned areas, comprising:

• for each object, providing a TAG transmitter for transmitting, at selected intervals, TAG transmissions that include a unique TAG ID;
• providing an array of receivers distributed within the tracking area, with each receiver being configured to receive TAG transmissions from an assigned area of a predetermined size;
• each receiver being responsive to the receipt of a TAG transmission for providing a corresponding area-detection packet that includes the received TAG ID;
• determining the location of each TAG, and its associated object, based on the identity of the receiver receiving the TAG transmissions for that TAG as represented by the area-detection packet provided by such receiver that received the TAG transmissions;
• said receivers being distributed within the tracking environment with a predetermined spacing;
• and
• the transmitter power for each TAG transmitter and the spacing between adjacent receivers being cooperatively chosen such that a TAG transmission is almost always received by a single receiver to which the TAG is most proximate.

A method of locating objects within a tracking environment using area-detection by receivers that receive transmissions from assigned areas, comprising:

• for each object, providing a TAG transmitter for transmitting, at selected intervals, TAG transmissions that include a unique TAG ID;
• providing an array of receivers distributed within the tracking area, with each receiver being configured to receive TAG transmissions from an assigned area of a predetermined size;
• each receiver being responsive to the receipt of a TAG transmission for providing a corresponding area-detection packet that includes the received TAG ID;
• determining the location of each TAG, and its associated object, based on the identity of the receiver receiving the TAG transmissions for that TAG as represented by the area-detection packet provided by such receiver that received the TAG transmissions;
• and
• wherein the set of transmitting TAG transmissions further comprises detecting the motion of the object, and enabling TAG transmissions while
• the object is in motion.

A method of locating objects within a tracking environment using area-detection by receivers that receive transmissions from assigned areas, comprising:

• for each object, providing a TAG transmitter for transmitting, at selected intervals, TAG transmissions that include a unique TAG ID;
• providing an array of receivers distributed within the tracking area, with each receiver being configured to receive TAG transmissions from an assigned area of a predetermined size;
• each receiver being responsive to the receipt of a TAG transmission for providing a corresponding area-detection packet that includes the received TAG ID;
• determining the location of each TAG, and its associated object, based on the identity of the receiver receiving the TAG transmissions for that TAG as represented by the area-detection packet provided by such receiver that received the TAG transmissions;
• and
• wherein the step of transmitting TAG transmissions comprises the step of transmitting TAG transmissions at selected intervals each time an object
• is being moved.

A method of locating objects within a tracking environment using area-detection by receivers that receive transmissions from assigned areas, comprising:

• for each object, providing a TAG transmitter for transmitting, at selected intervals, TAG transmissions that include a unique TAG ID;
• providing an array of receivers distributed within the tracking area, with each receiver being configured to receive TAG transmissions from an assigned area of a predetermined size;
• each receiver being responsive to the receipt of a TAG transmission for providing a corresponding area-detection packet that includes the received TAG ID;
• determining the location of each TAG, and its associated object, based on the identity of the receiver receiving the TAG transmissions for that TAG as represented by the area-detection packet provided by such receiver that received the TAG transmissions;
• and
• wherein the receivers are coupled to the location processor by a local area network, with each receiver including a LAN interface, such that the TOA detection packets are communicated to the location processor over the LAN.