Data processing: vehicles – navigation – and relative location – Navigation – Employing position determining equipment
Reexamination Certificate
2002-12-10
2004-05-11
Black, Thomas G. (Department: 3663)
Data processing: vehicles, navigation, and relative location
Navigation
Employing position determining equipment
C701S213000, C340S988000, C340S435000, C340S995190, C342S358000, C342S357490, C342S444000, C342S357490
Reexamination Certificate
active
06735524
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to systems and methods for radio navigation, and in particular to a system and method for radio navigation using a spatially resolved antenna.
2. Description of the Related Art
In recent years, there has been an increasing need for remote and mobile location systems. For example, there is a need for cellular telephone (cellphone) systems that can locate users, particularly when the user has dialed 911 or other emergency number. There is also a need to locate large numbers of military or fire personnel who can be located over large areas. Further, this capability must be provided in places where line of sight between locating elements are obscured or compromised by multipath distortions (e.g. environments such as urban locations and rugged terrain). These factors limit the accuracy and hence, the usefulness of the location system.
There is further a need to provide secure communications between large numbers of widely distributed receiving/transmitting agents. One way to accomplish this feat is through the use of narrow beam communication signals directed at the intended recipient of the message. Unfortunately this requires accurate information regarding the location of the intended recipient relative to the location of the transmitting agent
What is needed is an accurate, but inexpensive location system that provides adequate location accuracy and availability even in environments that are ordinarily not suitable for radio location. The present invention satisfies that need.
SUMMARY OF THE INVENTION
To address the requirements described above, the present invention discloses a method, apparatus, article of manufacture, of radio navigation among a plurality of stations S
0
, S
1
, . . . , S
i
. The method comprises the steps of propagating a state &PHgr;
0
of a first station S
0
according to autonomous, or self-contained, inertial measurements, wherein the state &PHgr;
0
includes the position P
0
[x
0
,y
0
] of the first station, wherein x
0
is the position of the first station along a first axis, and y
0
is the position of the first station along a second axis orthogonal to the first axis, receiving a signal in the first station S
0
and resolving the received signal to at least one angular sector &thgr; in a plane formed by the first axis x and the second axis y, the received signal comprising first information describing an estimated state &PHgr;
1
of a second station S
1
, wherein the state &PHgr;
1
includes a position P
1
[x
0
,y
0
] of the second station S
1
, and estimating the state &PHgr;
0
of the first station S
0
at least in part from the propagated state {dot over (&PHgr;)}
0
, the resolved angular sector and the relative range R
10
of the second station S
1
and the first information. The apparatus comprises an inertial reference unit for generating inertial measurements of a state of the first station, a navigation module, for propagating the state &PHgr;
0
of the first station S
0
based upon the inertial measurements wherein the state &PHgr;
0
includes the position P
0
[x
0
,y
0
] of the first station, wherein x
0
is the position of the first station along a first axis, and y
0
is the position of the first station along a second axis orthogonal to the first axis, at least one antenna communicatively coupled to a receiver for receiving a signal comprising first information describing an estimated state &PHgr;
1
of a second station S
1
, wherein the state &PHgr;
0
includes a position P
1
[x
0
,y
0
] of the second station S
2
, a resolver, for resolving the received signal to at least one angular sector &thgr; in a plane formed by the first axis x and the second axis y and radio rangefinder for measuring R
10
, the relative range of the second station S
1
with respect to the first station, S
0
The navigation module further estimates the state &PHgr;
0
of the first station S
0
at least in part from the propagated state {dot over (&PHgr;)}
0
, the resolved angular sector &thgr;, relative range R
10
and the first information.
The foregoing provides location services in environments without a line of sight between elements, and mitigates multipath and signal attenuation problems from nearby structures and terrain features.
REFERENCES:
patent: 4883244 (1989-11-01), Challoner et al.
patent: 5546309 (1996-08-01), Johnson et al.
patent: 6598009 (2003-07-01), Yang
patent: 6639553 (2003-10-01), Lin et al.
patent: 2002/0105461 (2002-08-01), Fukushima et al.
patent: 2002/0133958 (2002-09-01), Noureldin et al.
patent: 2003/0135327 (2003-07-01), Levine et al.
patent: 2003/0167863 (2003-09-01), Denice et al.
Bornholdt James M.
Challoner A. Dorian
Black Thomas G.
Gates & Cooper LLP
The Boeing Company
To Tuan C
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