Near Field Electromagnetic Calibration System

• US 20100103025A1
• Filed: 09/21/2009
• Published: 04/29/2010
• Est. Priority Date: 08/19/2002
• Status: Active Grant

• Current Assignee: GaN Corporation
• Original Assignee: Q-Track Corporation
• Inventors: Schantz, Hans Gregory, Langford, David Wesley
• Granted Patent: US 7,859,452 B2
• Time in Patent Office: Days
• US Class Current: 342/174
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: G01S 13/75 using transponders powered from received waves, e.g. using passive transponders , or using passive reflectors
• CPC Class Codes: G01S 5/0027 of actual mobile position, i.e. position determined on mobile
• CPC Class Codes: G01S 5/0081 Transmission between base stations
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04B 5/0075 using inductive coupling transformers or inductances adapted for inductive coupling H01F38/14
• CPC Class Codes: H04B 5/24 Inductive coupling

Abstract

A system and method for electromagnetic position determination utilizing a calibration process. For calibration, a transmitter is positioned at multiple locations in an area of interest and multiple receivers receive and record signal characteristics from the transmitter to generate a calibration data set. The unknown position of a transmitter may be determined by receiving signals from the transmitter by multiple receivers. A locator data set is generated based on the comparison between two received signal characteristics determined for each receiver. The locator data set is compared with the calibration data set to determine the unknown position. In one embodiment, the signal comparisons are the differences between electric and magnetic field phase. Further embodiments utilize signal amplitude differences. A reciprocal method utilizing a single receiver and multiple transmitter locations is disclosed. A further method is disclosed for determining position by utilizing signals available from existing installed wiring such as power wiring.

Claims

1. A system for calibrating a position determination system, said position determination system comprising:

a positioning transmitter located with an object, said positioning transmitter producing a beacon signal;

a plurality of positioning receivers for receiving said beacon signal;

each of said positioning receivers of said plurality of positioning receivers having a respective known positioning receiver position;

each of said positioning receivers of said plurality of positioning receivers comprising;

means for receiving a first signal characteristic of said beacon signal;

means for receiving a second signal characteristic of said beacon signal; and

a positioning comparison unit for comparing said first signal characteristic and said second signal characteristic of said beacon signal to generate a positioning comparison result;

wherein a position for said object is determined by comparing said positioning comparison result with a calibration database;

said calibration system comprising;

a calibration transmitter producing a calibration signal;

a plurality of calibration receivers for receiving said calibration signal;

each of said calibration receivers of said plurality of calibration receivers having a respective known calibration receiver position;

each of said calibration receivers of said plurality of calibration receivers comprising;

means for receiving a first signal characteristic of said calibration signal;

means for receiving a second signal characteristic of said calibration signal; and

a comparison unit for comparing said first signal characteristic and said second signal characteristic of said calibration signal to generate a calibration comparison result;

wherein said calibration transmitter transmits said calibration signal at a plurality of calibration transmitter positions and each said calibration receiver generates a calibration comparison result associated with each calibration transmitter position;

said calibration database comprising said calibration comparison results associated with each said calibration transmitter position.

2. The system as in claim 1, wherein

said first signal characteristic of said calibration signal is an electric field characteristic, and said means for receiving said first signal characteristic of said calibration signal is responsive to the phase of said electric field characteristic, and

said second signal characteristic of said calibration signal is a magnetic field characteristic, and said means for receiving said second signal characteristic of said calibration signal is responsive to the phase of said magnetic field characteristic.

3. The system as in claim 2, wherein said first comparison result is the difference between said phase of said electric field characteristic and said phase of said magnetic field characteristic.

4. The system as in claim 1, wherein

said first signal characteristic of said calibration signal is an electric field characteristic, and

said means for receiving said first signal characteristic of said calibration signal is responsive to the magnitude of said electric field characteristic, and

said second signal characteristic of said calibration signal is a magnetic field characteristic, and

said means for receiving said second signal characteristic of said calibration signal is responsive to the magnitude of said magnetic field characteristic.

5. The system as in claim 1, wherein said first signal characteristic of said calibration signal and said second signal characteristic of said calibration signal comprise near field signal characteristics.

6. The system as in claim 1, wherein at least one receiver of the plurality of positioning receivers is the same as at least one receiver of the plurality of calibration receivers.

7. The system as in claim 1, wherein at least one position of the known positions for the plurality of positioning receivers is the same as at least one position of the known positions of the calibration receivers.

8. A system for calibrating a position determination system, said position determination system comprising:

a plurality of positioning transmitters for transmitting said beacon signal;

each of said positioning transmitters of said plurality of positioning transmitters having a respective known positioning transmitter position;

a positioning receiver located with an object, said positioning receiver producing a beacon signal;

said positioning receiver comprising;

means for receiving a first signal characteristic of said beacon signal;

means for receiving a second signal characteristic of said beacon signal; and

a positioning comparison unit for comparing said first signal characteristic and said second signal characteristic of said beacon signal to generate a positioning comparison result;

wherein a position for said object is determined by comparing said positioning comparison result with a calibration database;

said calibration system comprising;

a plurality of calibration transmitters for transmitting said beacon signal;

each of said calibration transmitters of said plurality of calibration transmitters having a respective known calibration transmitter position;

a calibration receiver for receiving said calibration signal;

said plurality of calibration receiver comprising;

means for receiving a first signal characteristic of said calibration signal;

means for receiving a second signal characteristic of said calibration signal; and

a comparison unit for comparing said first signal characteristic and said second signal characteristic of said calibration signal to generate a calibration comparison result;

wherein said calibration receiver receives said plurality of calibration signals from said plurality of calibration transmitters from a plurality of calibration receiver positions;

said calibration receiver producing a calibration comparison result for each calibration transmitter at each calibration receiver position;

said calibration database comprising said calibration comparison results associated with each said calibration receiver position.