Near field electromagnetic positioning calibration system and method

• US 7,592,949 B2
• Filed: 11/19/2007
• Issued: 09/22/2009
• Est. Priority Date: 08/19/2002
• Status: Expired due to Term

• Current Assignee: GaN Corporation
• Original Assignee: Q-Track Corporation
• Inventors: Schantz, Hans Gregory, Langford, David Wesley
• Primary Examiner(s): Lobo; Ian J
• Application Number:
  US11/986,319
• Publication Number:
  US 20080165050A1
• Time in Patent Office: 673 Days
• Field of Search: 342/165, 342/174
• 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 5/24 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 method for calibrating an electromagnetic position determination system, said position determining system determining an unknown position of a beacon transmitter within a predefined region by generating a positioning data set and matching said positioning data set with a plurality of calibration data sets;

said unknown position determined based on a position corresponding to a calibration data set of said plurality of calibration data sets, that most closely matches said positioning data set;

said method for calibrating said position determination system comprising;

1) generating a calibration database containing said plurality of calibration data sets, each calibration data set of said plurality of calibration data sets generated by;

a) transmitting a calibration transmission from a respective known transmitter position of a plurality of transmitter positions within said predefined region;

b) receiving said calibration transmission at a plurality of known receiver positions and producing said calibration dataset, each said calibration data set comprising a plurality of comparison values comparing two received signal characteristics of said calibration transmission at each receiver position of said plurality of known receiver positions;

c) associating each said calibration dataset with said respective known transmitter position; and

d) storing each said calibration dataset and said respective known transmitter position in said calibration database.

2. The method of claim 1, wherein said two received signal characteristics of said calibration transmission are near field signal characteristics.

3. The method of claim 1, wherein said two received signal characteristics of said calibration transmission include measurements of an E field phase and an H field phase.

4. The method of claim 1, wherein said two received signal characteristics of said calibration transmission include an E field magnitude and an H field magnitude.

5. The method of claim 1, wherein said step of transmitting a calibration transmission from a known transmitter position corresponding to each said calibration data set includes moving at least one calibration transmitter between at least two positions of said known positions.

6. The method of claim 1, wherein said step of receiving said plurality of calibration transmissions from said plurality of known receiver positions includes moving at least one receiver between at least two positions of said plurality of known receiver positions.

7. A method for calibrating an electromagnetic position determination system, said position determining system determining an unknown position of a beacon transmitter within a predefined region by generating a positioning data set and matching said positioning data set with a plurality of calibration data sets;

said unknown position determined based on a position corresponding to a calibration data set of said plurality of calibration data sets, that most closely matches said positioning data set;

said method for calibrating said position determination system comprising;

1) generating a calibration database containing said plurality of calibration data sets, each calibration data set of said plurality of calibration data sets generated by;

a) transmitting a calibration transmission from a respective known transmitter position of a plurality of transmitter positions within said predefined region;

b) receiving said calibration transmission at a plurality of known receiver positions and producing said calibration dataset, each said calibration data set comprising a plurality of measurements of at least one near field signal characteristic of said calibration transmission at each receiver position of said plurality of known receiver positions;

c) associating each said calibration dataset with said respective known transmitter position; and

d) storing each said calibration dataset and said respective known transmitter position in said calibration database.

8. The method of claim 7, wherein said at least one near field signal characteristic of said calibration transmission comprises a comparison of two other received signal characteristics of said calibration transmission.

9. The method of claim 7, wherein said at least one near field signal characteristics of said calibration transmission comprises a measurement of an E field phase.

10. The method of claim 7, wherein said at least one near field signal characteristic of said positioning transmission comprises an E field magnitude.