Ultra-wideband radios for time-of-flight-ranging and network position estimation

• US 20100225541A1
• Filed: 12/11/2006
• Published: 09/09/2010
• Est. Priority Date: 04/28/2004
• Status: Active Grant

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Romero, Carlos E., Dallum, Gregory E., Dowla, Farid U., Hertzog, Claudia A.
• Granted Patent: US 7,962,150 B2
• Time in Patent Office: Days
• US Class Current: 342/387
• 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 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308

Abstract

This invention provides a novel high-accuracy indoor ranging device that uses ultra-wideband (UWB) RF pulsing with low-power and low-cost electronics. A unique of the present invention is that it exploits multiple measurements in time and space for very accurate ranging. The wideband radio signals utilized herein are particularly suited to ranging in harsh RF environments because they allow signal reconstruction in spite of multipath propagation distortion. Furthermore, the ranging and positioning techniques discussed herein directly address many of the known technical challenges encountered in UWB localization regarding synchronization and sampling. In the method developed, noisy, corrupted signals can be recovered by repeating range measurements across a channel, and the distance measurements are combined from many locations surrounding the target in a way that minimizes the range biases associated to indirect flight paths and through-wall propagation delays.

Claims

1. An ultra-wideband wireless time-of-flight-ranging and network position estimation method, comprising:

transmitting a first encoded ultra-wideband query;

transmitting a second encoded ultra-wideband query;

subtracting out common signals produced from replies to said first and said second encoded ultra-wideband queries so as to result in one or more desired reply signals;

statistically filtering time of flight information resulting from said desired reply signals so as to produce a plurality of one or more range measurements;

transforming said one or more range measurements into a desired coherent one or more range measurements;

introducing a respective bias correction to said coherent signals; and

calculating a true position estimate of a line-of-sight (LOS) or a non-line-of-sight (NLOS) transmission channel target as a result of processing a predetermined collected number of said filtered and corrected coherent said plurality of range measurements.

2. The method of claim 1, wherein said non-line-of-sight (NLOS) transmission channels comprise at least one target located around corners, inside caves, behind walls, and in buildings.

3. The method of claim 1, further comprising visualizing a floor plan of a building using a ranging device mounted on a moving platform to operate as a transmitter of said encoded ultra-wideband queries.

4. The method of claim 1, wherein said encoded query comprises a single ultra-wideband pulse transmission.

5. The method of claim 1, wherein said encoded query comprises one or more Transmit Reference encoding schemes.

6. The method of claim 1, wherein said position estimation is capable of being determined down to about 1.5 inches.