Communications: directive radio wave systems and devices (e.g. – Directive – Including a satellite
Reexamination Certificate
2000-10-11
2004-03-16
Blum, Theodore M. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a satellite
C342S357490
Reexamination Certificate
active
06707424
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
FIELD OF THE INVENTION
This invention relates in general to radio positioning
avigation systems. More specifically and in particular, the present invention, hereinafter described in accordance with the current best mode of practice, is such a radio positioning
avigation system that integrates global navigation satellite systems (GNSS) with a time modulated ultra-wide band (TM-UWB) system to provide correlated positioning
avigation data either within a line-of-sight barrier, or in direct line of sight of GNSS beacons. In addition, the present invention overcomes the inherent problems of current radio positioning
avigation systems, such as multi-path signal propagation, the “near-far” problem, and the attenuation of low power signals by a barrier.
BACKGROUND OF THE INVENTION
A common need, and requirement of our society is to accurately track and record positions of aircraft, land vehicles, geographical landmarks, materials, buildings, animals, people, and other objects whether they are located indoors, out of doors, or moving in between. One method currently used to accomplish this goal uses radio positioning
avigation beacons and associated equipment. Radio positioning
avigation can be broadly defined as the use of radio waves to transmit information, which in turn can be received and utilized to determine position and to navigate. Some radio positioning
avigation systems either currently in use or under development, are LORAN, OMEGA, and global navigation satellite systems (GNSS) such as NAVSTAR, GLONASS (the Russian variant), and European systems (GNSS1, GNSS2, NAVSTAT and GRANAS). The radio positioning
avigation systems quickly becoming the standard worldwide are, Global Navigation Satellite Systems (GNSS) including the NAVSTAR Global Positioning System (GPS). The NAVSTAR GPS system is capable of providing real-time, three-dimensional position and navigation data.
The NAVSTAR GPS beacon system presently consists of twenty-four orbiting satellites, spaced in six separate circular orbits, with each accommodating four satellites. Of these, twenty-one are normally operational and three serve as spares. Each NAVSTAR GPS satellite reappears above the same ground reference approximately every twenty-three hours and fifty-six minutes. The spacing of satellites is designed to maximize probability that earth users will always have at least four satellites in good geometrical view for navigational use. The basic method of position determination via radio positioning and navigation signals is derived from the concept of triangulation. The term triangulation used herein refers to the general process of determining distance, a.k.a. range, from the present position to multiple known beacons, and mathematically solving for the point in space which satisfies these conditions. As applied to GNSS, the procedure requires calculation of signal travel time, which, when multiplied by the speed of light, renders distance.
A basic discussion of positioning
avigation as it relates to the NAVSTAR GPS is contained in a document entitled “GPS NAVSTAR Global Positioning System, User's Overview”, Reference Document YEE-82-009D, March 1991, prepared by ARINC Research Corporation. This document particularly describes the background of the NAVSTAR Global Positioning System, as well as technical descriptions, performance characteristics and actual user segments. As noted, this book was published in March 1991, and now nine years later the use of NAVSTAR GPS for practical commercial applications has grown immensely.
A process known as differential global positioning (DGPS or DGNSS) compensates for many of the errors which are common in radio positioning
avigation systems. An antenna at a known location receives line of sight (LOS) GNSS signals and broadcasts a signal with current correction adjustments for each satellite which can be received by any differential receiver within its signal range.
Location accuracy via GNSS is continually evolving. Standard GNSS receivers can typically produce position estimates within +/−100 meter accuracy. Sub-meter position accuracy of location can be achieved using DGNSS. Other techniques for improving accuracy are “Carrier-phase GPS”, “Wide Area Augmented GPS”(WAAS), and GPS Interferometry.
GNSS relies on no visual, magnetic, or other point of reference which is particularly important in applications such as aviation and naval navigation that traverse polar regions where conventional magnetic navigational means are rendered less effective by local magnetic conditions. Magnetic deviations and anomalies common in standard radio positioning
avigation systems do not hinder GNSS. In addition, GNSS equipment is typically fabricated of standard, solid state electronic hardware, resulting in low cost, low maintenance systems, having few or no moving parts, and requiring no optics. GNSS does not have the calibration, alignment, and maintenance requirements of conventional inertial measuring units, and is available 24 hours per day on a worldwide basis.
During the development of the NAVSTAR GPS program, the United States Government made decisions to extend its use to both domestic and international communities. Its applications range from navigation over the land, in the air, and on the seas, to precision surveys, the tracking of trains and trucks, and even locating undetonated mines left behind in the 1991 Gulf War. As GNSS is rapidly becoming the accepted global standard for positioning
avigation applications when in direct line of sight of beacons, the following discussion focuses on GNSS.
One critical limitation of current GNSS systems is that the beacons are required to be in direct line of sight (LOS) of the receiver. In other words, if the GNSS receiver is used in heavily forested areas, in steep and narrow canyons, within a structure, adjacent to the outer walls of buildings, or behind various other line-of-sight barriers (LSB), the receiver will be unable to obtain a good repeatable reading, or in many cases, any reading at all. While GNSS systems have many important uses in wide open spaces, they are not useable within environments separated by line-of-sight barriers (LSB).
What is needed is a system that is globally correlated and provides repeatable, precise sub-centimeter positioning
avigation data for locating objects in direct line of sight (LOS) of GNSS beacons and within line-of-sight barriers (LSB). The result of such an all-encompassing system is accurate, consistent positioning and navigation data for a wide variety of applications that can be used both in direct line of sight (LOS) of GNSS beacons and within environments that do not allow these signals to penetrate.
In addition to the GNSS information discussed above, other related U.S. patents also deal exclusively with radio positioning
avigation within a line-of-sight barrier (LSB). Such references include, for example, U.S. Pat. No. 5,051,741 to Wesby, an invention directed to a system for locating the position of moveable elements in a wide area and U.S. Pat. No. 5,334,974 to Simms et al. which describes an invention that provides a fully automatic personal security system which combines the advantages of worldwide LORAN-C or GPS navigation with the substantially worldwide communication capabilities of a cellular telephone or communication satellite.
U.S. Pat. No. 4,918,425 to Greenberg et al. discloses an invention that provides a radio system and method for monitoring and locating objects, including individuals, animals and articles, both locally and globally using base stations communicating by ID code with portable transponders which are secured to the objects to be monitored. Another example is the device discussed in U.S. Pat. No. 5,311,185 to Hochstein et al, which is directed to a proximity detection device relying on a transponder that periodically transmits a signal. Transceivers are fixed at locations about a structure for receiving and transmitting signals to establish a location. U.S.
Baych Leslie D.
Melick Bruce D.
Snyder David M.
Blum Theodore M.
McKee Voorhees & Sease, P.L.C.
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