Near field electromagnetic calibration system

• US 7,859,452 B2
• Filed: 09/21/2009
• Issued: 12/28/2010
• Est. Priority Date: 08/19/2002
• Status: Expired due to Fees

• Current Assignee: GaN Corporation
• Original Assignee: Q-Track Corporation
• Inventors: Schantz, Hans Gregory, Langford, David Wesley
• Primary Examiner(s): Lobo; Ian J
• Application Number:
  US12/563,960
• Publication Number:
  US 20100103025A1
• Time in Patent Office: 463 Days
• Field of Search: 342/125, 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 calibration system for a position determination system, the calibration system includes, in one embodiment, a calibration transmitter producing a calibration signal, a plurality of calibration receivers for receiving the calibration signal, each of the calibration receivers of the plurality of calibration receivers having a respective known calibration receiver position, and each of the calibration receivers of the plurality of calibration receivers including 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. In various embodiments, signal comparisons may be differences between electric and magnetic field phase or may utilize signal amplitude differences. A system utilizing a receiver and multiple transmitter locations is disclosed. Position may be determined using existing wiring.

Claims

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

a plurality of positioning transmitters for transmitting a plurality of respective beacon signals;

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

a positioning receiver located with an object, said positioning receiver configured to receive said plurality of respective beacon signals;

said positioning receiver comprising;

means for receiving a first signal characteristic of each signal of said plurality of respective beacon signals;

means for receiving a second signal characteristic of each signal of said plurality of respective beacon signals; and

a positioning comparison unit for comparing said first signal characteristic and said second signal characteristic of each signal of said plurality of respective beacon signals to generate a plurality of positioning comparison results;

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

said calibration system comprising;

a plurality of calibration transmitters for transmitting a plurality of respective calibration signals;

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

a calibration receiver for receiving said plurality of respective calibration signals;

said calibration receiver comprising;

means for receiving a first signal characteristic of each signal of said plurality of respective calibration signals;

means for receiving a second signal characteristic of each signal of said plurality of respective calibration signals; and

a comparison unit for comparing said first signal characteristic and said second signal characteristic of each signal of said plurality of respective calibration signals to generate a plurality of calibration comparison results;

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

said calibration receiver producing a calibration comparison result of said plurality of calibration comparison results for each said calibration transmitter for each calibration receiver position of said plurality of calibration receiver positions;

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