Spatial position determination system

• US 7,215,247 B1
• Filed: 03/14/2005
• Issued: 05/08/2007
• Est. Priority Date: 07/25/2001
• Status: Expired due to Fees

• Current Assignee: Quarterhill Inc. (f/k/a Wi-LAN Inc.)
• Original Assignee: Quarterhill Inc. (f/k/a Wi-LAN Inc.)
• Inventors: Radin, Lon B.
• Primary Examiner(s): Pope; Daryl C
• Application Number:
  US11/079,965
• Time in Patent Office: 785 Days
• Field of Search: 340/539.13, 340/539.1, 340/539.11, 340/539.23, 340/539.21, 340/573.1
• US Class Current: 340/539.13
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: G08B 21/0244 System arrangements wherein the alarm criteria uses signal delay or phase shift

Abstract

A system is disclosed that determines a spatial position of a tracker device relative to an object sending a return signal to the tracker. Such a system advantageously maintains phase accuracy between a forward signal from the tracker device and the return signal from the object. The system can include, as part of a tracker device, a reference signal generator, a transmitter, a receiver, and a spatial position computer. The reference signal generator is responsive to and phase-stabilized by a broadcast signal, e.g., a signal received from a commercial AM broadcast transmitter. The transmitter and receiver are both coupled to and phase-stabilized by the tracker reference signal generator. Variations and methods with different advantageous features are also described.

Claims

1. A spatial position determination system comprising:

(a) a tracker unit comprising;

(1) a reference signal generator responsive to and phase-stabilized by a broadcast signal;

(2) a transmitter coupled to and phase-stabilized by the reference signal generator; and

(3) a receiver coupled to and phase-stabilized by the reference signal generator and responsive to a return signal from a transponder unit that is coupled via field radiation to the tracker unit, which return signal is triggered by a signal from the transmitter; and

(b) a spatial position computer coupled to the receiver and at least one of the reference signal generator and the transmitter, responsive to indicia of a phase relationship between an output signal from the transmitter and the return signal;

whereby the spatial position computer determines a spatial position of the tracker unit relative to the transponder.

2. The system of claim 1 wherein the reference signal generator is responsive to a commercial broadcast signal.

3. The system of claim 2 wherein the reference signal generator is responsive to a commercial broadcast signal in a frequency range between about 500 kHz and about 1600 kHz.

4. The system of claim 1 wherein, during operation:

(a) the spatial position computer includes a memory cell that includes indicia of a previous spatial position; and

(b) responsive to the indicia, the spatial position computer determines the spatial position of the tracker unit relative to a source of the return signal, the spatial position being expressed as an offset from the previous spatial position.

5. The system of claim 1 wherein, during operation:

(a) the spatial position computer includes a memory cell that includes indicia of wavelength of at least the return signal; and

(b) responsive to the indicia, the spatial position computer determines the spatial position of the tracker unit relative to a source of the return signal, the spatial position being expressed as a physical measure of distance.

6. The system of claim 1 wherein, during operation:

(a) the spatial position computer includes memory cells that include indicia of a plurality of previous spatial positions; and

(b) responsive to the indicia, the spatial position computer determines the spatial position of the tracker unit relative to a source of the return signal, the spatial position being expressed as an azimuthal angle from the tracker unit.

7. The system of claim 1 further comprising a controller coupled to the transmitter and configured to periodically enable and disable signal transmission therefrom.

8. The system of claim 1 further comprising a digital signal processing subsystem that, during operation, implements at least portions of the reference signal generator, transmitter, and receiver of the tracker unit.

9. The system of claim 8 further comprising a control subsystem that, during operation, implements at least portions of the spatial position computer.