Patent US5977909A successfully refreshed from Google Patents.
US5977909A
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Method and apparatus for locating an object using reduced number of GPS satellite signals or with improved accuracy
Assignee: General Electric Co
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Filing: 1998-03-13
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Granted: 1999-11-02
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Expires: 2018-03-13
Abstract
Abstract The number of simultaneous equations needed to find the location solution of an asset being tracked, such as a railcar, or, in the alternative, to improve the localization accuracy of any of several positioning methods used to track assets, is reduced by using a railway track database. Known railway track locations are used to constrain the railcar (i.e., asset) location solutions. This constraint makes the Cartesian coordinate location x, y and z values interdependent and reduces the number of simultaneous equations needed to find the location solution. Since all relevant railcars must be supported on railway tracks, and railway track locations and elevations throughout North America are available in a database, the number of satellite signals required is reduced. The railway track database represents a complex set of railway tracks. Instead of forming the complete set of function factors that make up the railway track data base every time a railcar location solution is needed, a start is made from a previous solution and only those railway tracks and/or branches that are feasible (i.e., nearby) are tried. Thus, the complexity of forming all railway track function terms is reduced to forming only those needed in a short railway track "tree search".
Inventors
- 👤 Daniel David Harrison
- 👤 Glen William Brooksby
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 10:51
CPC Classifications
G; G01; G01S; G01S19/00; G01S19/38; G01S19/39; G01S19/42; G01S19/50; G01S19/01; G01S19/03; G01S19/09; G01S5/00; G01S5/0009; G01S5/0018; G01S5/0027
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
114 words
A method for identifying a location of an object to be tracked comprising the steps of: measuring at said object to be tracked data related to propagation time differences between signals transmitted from a plurality of satellites and received at said object to be tracked; transmitting said data by said object to be tracked to a central station; and calculating at said central station the location of said object to be tracked based upon the transmitted data, a predetermined database containing information constraining the location of the object to be tracked, and data derived from at least one receiver apart from said object to be tracked receiving said signals from said plurality of satellites.
Claim 2
Independent Claim
114 words
A method for identifying a location of an object to be tracked comprising the steps of: measuring at said object to be tracked data related to propagation time differences between signals transmitted from a plurality of satellites and received at said object to be tracked; transmitting said data by said object to be tracked to a central station; and calculating at said central station the location of said object to be tracked based upon the transmitted data, a predetermined database containing information constraining the location of the object to be tracked, and data derived from at least one receiver apart from said object to be tracked receiving said signals from said plurality of satellites.
Claim 3
Dependent Claim
56 words
The method of claim 1 wherein said satellites transmit respective identification data, said object to be tracked further transmitting received satellite identification data with said data related to propagation time differences to said central station and the step of calculating the location of said object to be tracked is further based upon the satellite identification data.
Claim 4
Dependent Claim
52 words
The method of claim 2 wherein said plurality of satellites comprises at least two global positioning system (GPS) satellites and said data related to propagation time differences comprises code word phase measurements simultaneously derived from the signals transmitted from said plurality of GPS satellites and received at the object to be tracked.
Claim 5
Dependent Claim
51 words
The method of claim 2 wherein said plurality of satellites comprises at least two global positioning system (GPS) satellites and said data related to propagation time differences comprises bit phase measurements simultaneously derived from the signals transmitted from said plurality of GPS satellites and received at the object to be tracked.
Claim 6
Dependent Claim
34 words
The method of claim 1 wherein the step of calculating the location of said object comprises calculating a point of intersection of curves defined by said arrival time measurements and by said predetermined database.
Claim 7
Dependent Claim
30 words
The method of claim 5 wherein said object to be tracked is a railcar constrained to rail tracks, and the database is a track database indicating known feasible railcar location.
Claim 8
Dependent Claim
33 words
The method of claim 6 including the steps of: assuming a railcar location that moves along the tracks; and using the tracks connectivity to constrain the railcar location to points along the tracks.
Claim 9
Dependent Claim
24 words
The method of claim 6 including the steps of: assuming a railcar speed limitation; and using the speed limitation to constrain the railcar location.
Claim 10
Dependent Claim
15 words
The method of claim 6 wherein the track database comprises a set of track segments.
Claim 11
Dependent Claim
25 words
The method of claim 9 wherein each track segment is associated with one or more representative points for testing proximity to the measurement induced curve.
Claim 12
Dependent Claim
37 words
The method of claim 10 further comprising the steps of: testing a distance between said representative segment points and said representative curve points; and keeping only those segments and curve points with small distances for further processing.
Claim 13
Dependent Claim
16 words
The method of claim 10 wherein the representative segment points specify coordinate bounds on the segment.
Claim 14
Dependent Claim
34 words
The method of claim 12 further comprising the steps of: testing coordinate differences between representative segment and curve points; and keeping only those segments and curve points with small coordinate differences for further processing.
Claim 15
Dependent Claim
12 words
The method of claim 10 wherein the track database is hierarchically represented.
Claim 16
Dependent Claim
30 words
The method of claim 10 wherein the measurement induced curve is evaluated at the track segment representative points to determine proximity of said representative points to the measurement induced curve.
Claim 17
Dependent Claim
16 words
The method of claim 15 wherein the representative segment points specify coordinate bounds on the segment.
Claim 18
Dependent Claim
14 words
The method of claim 9 wherein the representative segment points comprise segment end points.
Claim 19
Dependent Claim
30 words
The method of claim 17 including the step of further testing the segment when the evaluation of the measurement induced curve function yields different signs at the segment end points.
Claim 20
Dependent Claim
34 words
The method of claim 5 further comprising the step of compiling the track database by tracking one or more railcars and deriving the track database from a set of position results obtained over time.
Claim 21
Dependent Claim
34 words
The method of claim 5 further comprising the step of updating the track database by tracking one or more railcars and deriving the track database from a set of position results obtained over time.
Claim 22
Independent Claim
152 words
A system for identifying location of an object to be tracked comprising: first means situated at the object to be tracked for measuring data related to propagation time differences between signals transmitted from a plurality of satellites and for receiving each of said signals identifying an associated satellite; a central station; second means situated at the object to be tracked for transmitting said data related to propagation time differences along with associated satellite identification data to a central station; at least one GPS receiver situated apart from the tracked object for receiving said signals from said plurality of satellites; a database at said central station containing information constraining the location of the object to be tracked; and means at said central station for calculating the location of said object to be tracked based upon the transmitted data, the information in said database, and data derived from said at least one GPS receiver.
Claim 23
Independent Claim
152 words
A system for identifying location of an object to be tracked comprising: first means situated at the object to be tracked for measuring data related to propagation time differences between signals transmitted from a plurality of satellites and for receiving each of said signals identifying an associated satellite; a central station; second means situated at the object to be tracked for transmitting said data related to propagation time differences along with associated satellite identification data to a central station; at least one GPS receiver situated apart from the tracked object for receiving said signals from said plurality of satellites; a database at said central station containing information constraining the location of the object to be tracked; and means at said central station for calculating the location of said object to be tracked based upon the transmitted data, the information in said database, and data derived from said at least one GPS receiver.
Claim 24
Dependent Claim
32 words
The system of claim 21 wherein said object to be tracked comprises a railcar constrained to travel on railway tracks, and the database comprises a track database indicating known feasible railcar locations.
Claim 25
Dependent Claim
40 words
The system of claim 22 wherein the track database is divided into a set of track segments, each of said track segments being associated with at least one representative point for testing proximity to a measurement induced curve or surface.
Claim 26
Dependent Claim
13 words
The system of claim 23 wherein the measurement induced curve is hierarchically represented.
Claim 27
Dependent Claim
16 words
The system of claim 23 wherein the representative segment points specify coordinate bounds on the segment.
Claim 28
Dependent Claim
52 words
The system of claim 22 wherein said plurality of satellites comprises at least two global positioning system (GPS) satellites and said data related to propagation time differences comprises code word phase measurements simultaneously derived from the signals transmitted from said plurality of GPS satellites and received at the object to be tracked.
Claim 29
Dependent Claim
51 words
The system of claim 22 wherein said plurality of satellites comprises at least two global positioning system (GPS) satellites and said data related to propagation time differences comprises bit phase measurements simultaneously derived from the signals transmitted from said plurality of GPS satellites and received at the object to be tracked.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-11-01 | 2003-05-03 | 2003-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-11-01 | 2007-05-03 | 2007-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-11-01 | 2011-05-03 | 2011-11-02 | $7700.00 | Window Closed / Lapsed |