Radio signal transmitter with multiple antennas for improved position detection

• US 7,190,309 B2
• Filed: 09/26/2005
• Issued: 03/13/2007
• Est. Priority Date: 09/24/2004
• Status: Active Grant

• Current Assignee: Position Imaging, Inc.
• Original Assignee: Edward L. Hill
• Inventors: Hill, Edward L.
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US11/235,508
• Publication Number:
  US 20060066486A1
• Time in Patent Office: 533 Days
• Field of Search: 342/442, 342/443, 342/457, 342463-465, 455/456.1, 455/456.5, 455/456.6, 455/457
• US Class Current: 342/465
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence

Abstract

A radio frequency (RF) signal transmission device (the “device”) is used as a tracked target in a position tracking system (the “system”). In the preferred embodiments, the device'"'"'s position is determined by analyzing the time difference of arrival of the device'"'"'s RF signals received at multiple receivers which are part of the system. The device has two antennas spaced a known distance apart and the device alternately transmits on these antennas or can use code-division multiplexing for individual antenna'"'"'s signal detection. The system detects the position of both antennas at their respective phase center and determines the distance between the two calculated antenna positions. By comparing the calculated distance to actual known distance the system can assess the quality of the calculated positions.

Claims

1. A system for tracking an object, comprising:

a transmitter carried on or embedded within the object, each transmitter transmitting an electromagnetic signal either through physically separated antennas on or within the object or through the use of code-division multiplexing;

using multiple, physically separated antennas on or within the object;

a plurality of receiver stations operative to receive the electromagnetic signal from the antennas; and

a processor operative to determine the position of the object in multiple dimensions based upon the time difference of arrival of the signals transmitted by the transmitter and assess the quality of the calculated positions based upon the phase center of the received signals.