Navigation and positioning system and method using uncoordinated beacon signals in conjunction with an absolute positioning system
First Claim
1. A positioning system for determining location of a mobile unit, said system making use of a multiplicity of transmitters, at known locations, each of which transmits a beacon signal having a phase that is at least partially un-synchronized with the phases of the beacon signals of the other transmitters, each of said beacon signals being of a predetermined repetition rate, said system comprising:
- an uncoordinated beacon positioning subsystem (UBS), said subsystem including a UBS receiver for receiving said beacon signals and for providing a UBS location of said mobile unit;
an absolute positioning subsystem (APS) including an APS receiver for receiving APS signals and for providing an APS location of said mobile unit; and
a processor for determining uncertainty of location information provided by said beacon signal receiver and said APS receiver, and updating a current location of said mobile unit based on said UBS and APS locations and said uncertainty of said location information;
wherein the processor determines the uncertainty of location information for the APS receiver by measuring and evaluating at least one signal parameter associated with the APS signals, and determines the uncertainty of location information for the UBS receiver by measuring and evaluating at least one signal parameter associated with the received beacon signals.
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Accused Products
Abstract
A navigation system in which an uncoordinated beacon positioning system (UBS) is used in conjunction with an absolute positioning system (APS) is described herein. The UBS employs a multiplicity of transmitters, at known locations, each of which transmits a beacon signal having a phase that is at least partially un-synchronized with the phases of the beacon signals of the other transmitters. Within a mobile unit, separate receivers are provided for receiving these beacon signals and for receiving APS signals. The absolute positioning system (APS) receiver is disposed to receive the APS signals, and to estimate an initial position of the mobile unit therefrom. The mobile unit processor is disposed to modify the estimated mobile unit position on the basis of the detected beacon signal phases. The mobile unit processor may also be programmed to determine the uncertainty of location information provided by the beacon signal receiver and by the APS receiver. This allows the current location of the mobile unit to be updated by selecting the location estimate having associated therewith the least amount of location uncertainty, or by weighting each estimate based on its uncertainty and combining the two weighted location estimates. In another implementation, the mobile unit includes an estimator operative to compute an estimate of mobile unit position on the basis of selected pseudorange measurements from the UBS and APS receivers. The estimator may include a Kalman filter configured to process residual pseudorange information provided by the UBS and APS receivers.
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Citations
36 Claims
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1. A positioning system for determining location of a mobile unit, said system making use of a multiplicity of transmitters, at known locations, each of which transmits a beacon signal having a phase that is at least partially un-synchronized with the phases of the beacon signals of the other transmitters, each of said beacon signals being of a predetermined repetition rate, said system comprising:
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an uncoordinated beacon positioning subsystem (UBS), said subsystem including a UBS receiver for receiving said beacon signals and for providing a UBS location of said mobile unit; an absolute positioning subsystem (APS) including an APS receiver for receiving APS signals and for providing an APS location of said mobile unit; and a processor for determining uncertainty of location information provided by said beacon signal receiver and said APS receiver, and updating a current location of said mobile unit based on said UBS and APS locations and said uncertainty of said location information; wherein the processor determines the uncertainty of location information for the APS receiver by measuring and evaluating at least one signal parameter associated with the APS signals, and determines the uncertainty of location information for the UBS receiver by measuring and evaluating at least one signal parameter associated with the received beacon signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A positioning system for determining position of a mobile unit, comprising:
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a multiplicity of transmitters, at known locations, each of which transmits a beacon signal having a phase that is at least partially un-synchronized with the phases of the beacon signals of the other transmitters;
each of said beacon signals having a frequency which is approximately equal to a predetermined target frequency;a first receiver, at a known location relative to the locations of said multiplicity of transmitters, which (A) receives said beacon signals, (B) determines the relative phases of said beacon signals, and (C) broadcasts phase data representing said relative phases; a second receiver, disposed within said mobile unit, which receives said broadcast phase data from said first receiver and at least three of said beacon signals, said second receiver including phase detection circuitry for detecting the phases of said beacon signals at the location of said mobile unit, and data processing circuitry for computing a first estimated location of said mobile unit based on said broadcast values and said detected phases; an absolute positioning system (APS) receiver, disposed within said mobile unit, for receiving APS signals and for providing a second estimated location of said mobile unit; and a processor for evaluating positional uncertainty in said first and second estimated locations, and for updating a current position of said mobile unit based on said first and second estimated locations of said mobile unit and said positional uncertainty; wherein the processor determines the uncertainty of the first estimated location by measuring and evaluating at least one signal parameter associated with the beacon signals, and determines the uncertainty of the second estimated location by measuring and evaluating at least one signal parameter associated with the received APS signals. - View Dependent Claims (11)
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12. A positioning system, comprising:
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a multiplicity of transmitters, at known locations, each of which transmits a beacon signal having a phase that is at least partially un-synchronized with the phases of the beacon signals of the other transmitters;
each of said beacon signals having a frequency which is approximately equal to a predetermined target frequency; anda mobile unit including; a beacon signal receiver for receiving at least three of said beacon signals, said beacon signal receiver including phase detection circuitry for detecting the phases of the at least three of said beacon signals received thereby, an absolute positioning system (APS) receiver for receiving APS signals and for estimating an initial position of said mobile unit therefrom, and a processor for computing a current location of said mobile unit based on; (i) said detected phases of the at least three of said beacon signals, and (ii) said estimate of said initial position; said processor including; a memory for storing estimates of location of said mobile unit made by said APS receiver at first and second calibration times, and for storing phases and frequencies of said beacon signals received from a plurality of said transmitters at said first and second calibration times, and software for determining phase and frequency drift of said beacon signals based on said stored estimates of location of said mobile unit and said stored phases and frequencies of said beacon signals. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. In a positioning system which makes use of:
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(i) an uncoordinated beacon positioning subsystem (UBS), said subsystem including a multiplicity of transmitters, at known fixed locations, each of which transmits a beacon signal having a phase that is at least partially un-synchronized with the phases of the beacon signals of the other transmitters, each of said beacon signals having a frequency which is approximately equal to a predetermined target frequency, and (ii) global positioning system (GPS) signals transmitted by a multiplicity of GPS satellites, a method for determining location of a mobile unit, said method comprising the steps of; receiving a plurality of said beacon signals and determining a UBS location of said mobile unit therefrom; receiving a plurality of said GPS signals and determining a GPS location of said mobile unit therefrom; and determining uncertainty of said GPS and UBS locations, and updating a current location of said mobile unit based on said UBS and GPS locations and said uncertainty thereof; wherein the determining step includes determining the uncertainty of GPS location by measuring and evaluating at least one signal parameter associated with the GPS signals, and determining the uncertainty of UBS location by measuring and evaluating at least one signal parameter associated with the received beacon signals. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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28. In a positioning system which makes use of an uncoordinated beacon positioning subsystem and an absolute positioning subsystem (APS), said uncoordinated beacon positioning subsystem including a multiplicity of transmitters, at known fixed locations, each of which transmits a beacon signal having a phase that is at least partially un-synchronized with the phases of the beacon signals of the other transmitters, each of said beacon signals having a frequency which is approximately equal to a predetermined target frequency,
a method for determining location of a mobile unit comprising the steps of: -
at a known location relative to the locations of said multiplicity of transmitters, receiving said beacon signals, determining the relative phases of said beacon signals, and broadcasting phase data representing said relative phases; at said mobile unit, receiving said broadcast phase data and receiving at least three of said beacon signals, detecting the phases of said beacon signals received at said mobile unit, and computing a first estimated location of said mobile unit based on said broadcast values and said detected phases; at said mobile unit, receiving APS signals generated at known locations within a coordinated system of said APS subsystem, and providing a second estimated location of said mobile unit using said received APS signals; and evaluating positional uncertainty in said first and second estimated locations, and updating a current position of said mobile unit based on said first and second estimated locations of said mobile unit and said positional uncertainty; wherein the evaluating step includes determining the uncertainty of the first estimated location by measuring and evaluating at least one signal parameter associated with the beacon signals, and determining the uncertainty of the second estimated location by measuring and evaluating at least one signal parameter associated with the received APS signals. - View Dependent Claims (29, 30)
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31. A method of determining a mobile unit'"'"'s current location with respect to the positions of a multiplicity of transmitters that are positioned at known locations, wherein each transmitter transmits a beacon signal having a phase that is at least partially un-synchronized with the phases of the beacon signals of the other transmitters, each of said beacon signals having a frequency which is approximately equal to a predetermined target frequency,
the steps of the method comprising: -
receiving, at said mobile unit, at least three of said beacon signals, and detecting the phases of the at least three of said beacon signals received at said mobile unit; receiving, at said mobile unit, signals provided by an absolute positioning system (APS), and estimating an initial position of said mobile unit using said APS signals received at said mobile unit; and computing said current location of said mobile unit based on;
(i) said detected phases of the at least three of said beacon signals, and (ii) said estimate of said initial position;said step of computing includes the steps of; estimating location of said mobile unit based on APS signals received at said mobile unit at first and second calibration times, and storing phases and frequencies of ones of said beacon signals received from a plurality of said transmitters at said first and second calibration times, and determining phase and frequency drift and drift rates of said beacon signals based on said stored estimates of location of said mobile unit and said stored phases and frequencies of said beacon signals. - View Dependent Claims (32, 33)
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34. In a positioning system which makes use of:
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(A) an uncoordinated beacon positioning subsystem, said uncoordinated beacon positioning subsystem including a multiplicity of transmitters, at known fixed locations, each of which transmits a beacon signal having a phase that is at least partially un-synchronized with the phases of the beacon signals of the other transmitters, each of said beacon signals having a frequency which is approximately equal to a predetermined target frequency, and (B) a multiplicity of global positioning system (GPS) satellites, each of which transmits a GPS signal having a predefined phase relationship to the GPS signals transmitted by the other satellites, wherein each of said GPS signals includes information indicative of a position of the GPS satellite within a GPS coordinate system at the time of transmission of the GPS signal therefrom; a method for determining location of a mobile unit comprising the steps of; at said mobile unit, (i) receiving at least three of said beacon signals and computing a first set of estimated ranges between a current position of said mobile unit within said predefined coordinate system and the three of said beacon signal transmitters from which were transmitted said at least three of said beacon signals; (ii) receiving a plurality of said GPS signals and computing a second set of estimated ranges between a current position of said mobile unit within said GPS coordinate system and said GPS satellites from which were transmitted said plurality of GPS signals; (iii) forming a set of simultaneous position equations based on said first and second sets of estimated ranges, said set of simultaneous position equations being referenced to said GPS coordinate system; and (iv) solving said set of simultaneous equations in order to determine said current location of said mobile unit. - View Dependent Claims (35)
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36. A positioning system for determining location of a mobile unit, said system making use of a multiplicity of transmitters, at known locations, each of which transmits a beacon signal having a phase that is at least partially un-synchronized with the phases of the beacon signals of the other transmitters, each of said beacon signals being of a predetermined repetition rate, said system comprising:
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an uncoordinated beacon positioning subsystem (UBS), said subsystem including a UBS receiver for receiving said beacon signals and for generating a UBS pseudorange residual signal; an absolute positioning subsystem (APS) including an APS receiver for receiving APS signals and for generating an APS pseudorange residual signal, said APS receiving including a code loop detector that generates said APS pseudorange residual signal and a code loop oscillator in a feedback arrangement with said code loop detector; and an estimator for filtering and combining said UBS pseudorange residual signal and said ABS pseudorange residual signal to generate a velocity signal used to control said code loop oscillator in said APS and to generate a change-in-position signal; said feedback arrangement in said APS including apparatus for combining said change-in-position signal with a signal generated by said code loop oscillator to generate an a priori APS pseudorange signal that is feed back to said code loop detector.
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Specification