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US5339246A
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Apparatus for correcting vehicular compass heading with the aid of the global positioning system
Assignee: TomTom International BV
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Filing: 1992-03-17
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Granted: 1994-08-16
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Expires: 2012-03-17
Abstract
Abstract An apparatus for compensating a magnetic heading as indicated by a vehicle's magnetic compass so that the magnetic heading corresponds to a true heading as indicated by signals received in the vehicle from the Global Positioning System. The apparatus includes a computer for calculating compensation factors from successive positions occupied by the vehicle as it travels.
Inventors
- 👤 Wei-Wen Kao
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 20:46
CPC Classifications
G; G01; G01C; G01C21/00; G01C21/26; G01C21/28; G01C17/00; G01C17/38
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
87 words
A vehicle navigation system comprising: a GPS receiver; means for transforming outputs of said GPS receiver into a true heading; means for indicating as magnetic heading and for transmitting said magnetic heading to a computing means; said computing means, responsive to at least two values of said magnetic heading, for producing a compensation factor that, when used to compensate said magnetic heading, adjusts said magnetic heading to correspond to said true heading; and said computing means including means for normalizing said two values of said magnetic heading.
Claim 2
Dependent Claim
87 words
A vehicle navigation system comprising: a GPS receiver; means for transforming outputs of said GPS receiver into a true heading; means for indicating as magnetic heading and for transmitting said magnetic heading to a computing means; said computing means, responsive to at least two values of said magnetic heading, for producing a compensation factor that, when used to compensate said magnetic heading, adjusts said magnetic heading to correspond to said true heading; and said computing means including means for normalizing said two values of said magnetic heading.
Claim 3
Dependent Claim
32 words
Apparatus according to claim 1, further comprising: said computing means including means for successively approximating a center of a normalized circle of magnetization; and means for calculating said compensation factor from center.
Claim 4
Dependent Claim
45 words
Apparatus according to claim 1, wherein said at least two values of said magnetic heading include first and second values obtained at first and second true heading angles that are at least a predetermined value apart; and said predetermined value is at least 20 degrees.
Claim 5
Dependent Claim
65 words
Apparatus according to claim 3, further comprising: said computing means including means for successively approximately a center of a normalized circle of magnetization, when said at least two values of said magnetic heading are less than said predetermined value apart; and said computing means employing said obtained first and second values when said obtained first and second values are at least said predetermined value apart.
References Cited (Backward Citations)
US4024382A
Cited
US4743913A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-08-15 | 1998-02-14 | 1998-08-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-08-15 | 2002-02-14 | 2002-08-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-08-15 | 2006-02-14 | 2006-08-16 | $7700.00 | Window Closed / Lapsed |