# US 2014/0191897 A1 · Low Frequency Magnetic Induction Positioning System And Method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0191897 A1 - Document ID: US20140191897A1 - Status: Published application - Kind: A1 - Application number: 13/792,195 - Filed: 2013-03-11 - Published: 2014-07-10 - Earliest claimed: 2012-05-08 - Assignees: Awarepoint Corporation - Inventors: Matthew R. Perkins; Anthony Truscott; Wei Geng - Web page: https://patentgrep.com/patent/US20140191897A1 ## CPC - G01S 3/02: using radio waves - G01B 11/14: for measuring distance or clearance between spaced objects or spaced apertures (G01B11/26 takes precedence; rangefinders G01C3/00) - G01S 3/80: using ultrasonic, sonic or infrasonic waves - G07C 9/28: the pass enabling tracking or indicating presence - G01S 5/12: by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G07C: TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE ## Abstract A method and system for determining a real-time location of an object or person in a facility using low frequency magnetic induction positioning is disclosed herein. Each of the plurality of low frequency receivers is configured to receive a signal packet from a low-frequency magnetic induction transmitter, decode the signal packet, and estimate a distance from the low-frequency magnetic induction transmitter to the low-frequency receiver based on the decoded signal packet. ## Claims ### Claim 1 A method for determining a real-time location of an object within a facility, the method comprising: transmitting a signal packet from at least one low-frequency magnetic induction transmitter of a plurality of low-frequency magnetic induction transmitters, each of the plurality of low-frequency magnetic induction transmitters comprising at least one orthogonally oriented transmit coil, the signal packet comprising a unique transmitter identifier code and a coil orientation code; receiving the signal packet at at least one low-frequency receiver; decoding the signal packet at the at least one low-frequency receiver to generate a decoded signal packet data; and estimating a distance from the at least one low-frequency magnetic induction transmitter to the at least one low-frequency receiver based on the decoded signal packet data. ### Claim 2 (depends on 1) The method according to claim 1 further comprising sending distance information to a processor, wherein the processor determines a location of an object. ### Claim 3 (depends on 2) The method according to claim 2 wherein the processor is a context aware location engine. ### Claim 4 (depends on 1) The method according to claim 1 wherein the distance drives a workflow. ### Claim 5 (depends on 1) The method according to claim 1 wherein the estimated distance provides context for at least one of an interaction, a workflow milestone and a departure. ### Claim 6 (depends on 1) The method according to claim 1 wherein the at least one low-frequency magnetic induction transmitter comprises at least one of a radiofrequency transmitter, an ultrasound transmitter and an infrared transmitter. ### Claim 7 (depends on 1) The method according to claim 1 wherein the at least one low-frequency magnetic induction transmitter comprises a WiFi transmitter, a BLUETOOTH transmitter and a ZIGBEE transmitter. ### Claim 8 (depends on 1) The method according to claim 1 wherein the estimating the distance comprises combining a received signal strength intensity for the signal packet and the coil orientation code to remove the effects of relative coil orientation; and estimating a position of the at least one low-frequency receiver. ### Claim 9 (depends on 1) The method according to claim 1 wherein the estimating the distance comprises utilizing a link intensity estimate. ### Claim 10 (depends on 1) The method according to claim 1 further comprising transmitting a signal from the at least one low-frequency receiver to a mesh network, the mesh network comprising a plurality of sensors within a facility. ### Claim 11 A system for determining a real-time location of an object within a facility, the system comprising: a plurality of low-frequency magnetic induction transmitters, each of the plurality of low-frequency magnetic induction transmitters comprising at least one orthogonally oriented transmit coil, each of the plurality of low-frequency magnetic induction transmitters configured to transmit a signal packet comprising a unique transmitter identifier code and a coil orientation code; and a plurality of low-frequency receivers, each of the plurality of low frequency receivers configured to receive the signal packet, decode the signal packet, and estimate a distance from the low-frequency magnetic induction transmitter to the low-frequency receiver based on the decoded signal packet. ### Claim 12 (depends on 11) The system according to claim 11 further comprising a processor, the processor configured to receive the distance information and determine a location of an object. ### Claim 13 (depends on 12) The system according to claim 12 wherein the processor is a context aware location engine. ### Claim 14 (depends on 11) The system according to claim 11 wherein the distance drives a workflow. ### Claim 15 (depends on 11) The system according to claim 11 wherein the estimated distance provides context for at least one of an interaction, a workflow milestone and a departure. ### Claim 16 (depends on 11) The system according to claim 11 wherein the at least one low-frequency magnetic induction transmitter comprises at least one of radiofrequency transmitter, an ultrasound transmitter and an infrared transmitter. ### Claim 17 (depends on 1) The system according to claim 1 wherein the at least one low-frequency magnetic induction transmitter comprises a WiFi transmitter, a BLUETOOTH transmitter and a ZIGBEE transmitter. ### Claim 18 (depends on 11) The system according to claim 11 wherein each of the plurality of low-frequency magnetic induction transmitters is configured to drive each coil with multiple power levels; each plurality of low-frequency receivers is configured to determine an effective signal strength by correlating a number of signal packets received from each transmit coil with a corresponding power level of each of the plurality of low-frequency magnetic induction transmitters; and a resulting value is a threshold for reception and is related to an effective RSSI. ### Claim 19 (depends on 11) The system according to claim 11 wherein each of the plurality of low-frequency magnetic induction transmitters is configured to encode both a unique device code and a transmit power level indication, and each plurality of low-frequency receivers is configured to estimate a link strength using the lowest power level indication code received from a particular low-frequency magnetic induction transmitter of the plurality of low-frequency magnetic induction transmitters. ### Claim 20 (depends on 11) The system according to claim 11 wherein the receiver has a variable gain amplifier and automatic gain control to automatically adjust a gain to maintain a constant output level, and an adjusted gain level is inversely proportional to the received signal strength and is used for RSSI calculation. ### Claim 21 (depends on 11) The system according to claim 11 wherein the combination of two or more signal packets received from two or more transmitter orientations located at a common point are combined in vector magnitude form to produce an orientation invariant signal strength. ### Claim 22 (depends on 11) The system according to claim 11 wherein each of the plurality of low-frequency magnetic induction transmitters synchronizes the signal packet transmissions to reduce over-the-air collisions. ### Claim 23 (depends on 11) The system according to claim 11 wherein each of the plurality of low-frequency magnetic induction transmitters uses motion activation to trigger signal packet transmissions by each of the plurality of low-frequency magnetic induction transmitters in an area. ### Claim 24 (depends on 11) The system according to claim 11 further comprising a plurality of sensors positioned within a facility. ### Claim 25 (depends on 24) The system according to claim 24 wherein the plurality of sensors forms a mesh network. ### Claim 26 (depends on 25) The system according to claim 25 further comprising at least one position engine in communication with the mesh network.