US4445118A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Navigation system and method
Assignee: National Aeronautics and Space Administration
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Filing: 1981-05-22
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Granted: 1984-04-24
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Expires: 2001-05-22
Abstract
Abstract In a global positioning system (GPS), such as the NAVSTAR/GPS system, wherein the position coordinates of user terminals (14) are obtained by processing multiple signals transmitted by a constellation of orbiting satellites (16), an acquisition-aiding signal generated by an earth-based control station (12) is relayed to user terminals via a geostationary satellite (10) to simplify user equipment. The aiding signal is FSK modulated on a reference channel slightly offset from the standard GPS channel. The aiding signal identifies satellites in view having best geometry and includes Doppler prediction data as well as GPS satellite coordinates and identification data associated with user terminals within an area being served by the control station (12) and relay satellite (10). The aiding signal significantly reduces user equipment by simplifying spread spectrum signal demodulation and reducing data processing functions previously carried out at the user terminals (14).
Inventors
- 👤 Ralph E. Taylor
- 👤 James W. Sennott
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 02:10
CPC Classifications
G; G01; G01S; G01S19/00; G01S19/01; G01S19/03; G01S19/05; G01S5/00; G01S5/0009; G01S5/0018; G01S5/0027; G01S5/0036
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
116 words
A system for determining the position of a user terminal comprising: means remote from said user terminal for transmitting a signal containing information indicative of the location of the signal transmitting means, almanac data, timing and synchronization data (epoch) and clock correction data; and means remote from said signal transmitting means and said user terminal for receiving said transmitted signal and converting said transmitted signal to an aiding signal containing information which identifies said signal transmitting means as well as the spatial coordinate data and predicted Doppler data for said signal transmitting means, said receiving means transmitting said aiding signal to said user terminal; said signal transmitting means also transmitting said signal to said user terminal.
Claim 2
Independent Claim
116 words
A system for determining the position of a user terminal comprising: means remote from said user terminal for transmitting a signal containing information indicative of the location of the signal transmitting means, almanac data, timing and synchronization data (epoch) and clock correction data; and means remote from said signal transmitting means and said user terminal for receiving said transmitted signal and converting said transmitted signal to an aiding signal containing information which identifies said signal transmitting means as well as the spatial coordinate data and predicted Doppler data for said signal transmitting means, said receiving means transmitting said aiding signal to said user terminal; said signal transmitting means also transmitting said signal to said user terminal.
Claim 3
Dependent Claim
22 words
The system of claim 1 wherein said signal transmitting means includes a plurality of signal sources which are displaced from each other.
Claim 4
Dependent Claim
16 words
The system of claim 2 wherein said plurality of signal sources are a constellation of satellites.
Claim 5
Dependent Claim
17 words
The system of claim 1 wherein said aiding signal is transmitted with frequency shift key (FSK) modulation.
Claim 6
Dependent Claim
19 words
The system of claim 1 wherein said aiding signal is transmitted to said user terminal via a relay tower.
Claim 7
Dependent Claim
19 words
The system of claim 1 wherein said aiding signal is transmitted to said user terminal via a relay satellite.
Claim 8
Dependent Claim
16 words
The system of claim 1 wherein said aiding signal includes a stepped pseudo-random (PRN) code reference.
Claim 9
Dependent Claim
18 words
The system of claim 1 wherein said user terminal includes a receiver with a pseudo-random (PRN) code generator.
Claim 10
Independent Claim
103 words
A method for determining the position of a user terminal comprising: transmitting a signal containing information indicative of the location of the signal source, almanac data, timing and synchronization data (epoch) and clock correction data; receiving said signal at said user terminal; receiving said signal at a location remote from said signal source which is also remote from said user terminal; converting said signal at said remote location to an aiding signal containing information which identifies said signal source as well as the predicted Doppler data and the spatial coordinate data for said signal source; transmitting said aiding signal to said user terminal.
Claim 11
Independent Claim
103 words
A method for determining the position of a user terminal comprising: transmitting a signal containing information indicative of the location of the signal source, almanac data, timing and synchronization data (epoch) and clock correction data; receiving said signal at said user terminal; receiving said signal at a location remote from said signal source which is also remote from said user terminal; converting said signal at said remote location to an aiding signal containing information which identifies said signal source as well as the predicted Doppler data and the spatial coordinate data for said signal source; transmitting said aiding signal to said user terminal.
Claim 12
Dependent Claim
19 words
The method of claim 9 wherein said transmitted signal consists of a plurality of signals originating from displaced sources.
Claim 13
Dependent Claim
14 words
The method of claim 10 wherein said displaced sources are a constellation of satellites.
Claim 14
Dependent Claim
17 words
The method of claim 9 wherein said aiding signal is transmitted with frequency shift key (FSK) modulation.
Claim 15
Dependent Claim
19 words
The method of claim 9 wherein said aiding signal is transmitted to said user terminal via a relay tower.
Claim 16
Dependent Claim
19 words
The method of claim 9 wherein said aiding signal is transmitted to said user terminal via a relay satellite.
Claim 17
Dependent Claim
16 words
The method of claim 9 wherein said aiding signal includes a stepped pseudo-random (PRN) code reference.
Claim 18
Dependent Claim
18 words
The method of claim 9 wherein said user terminal includes a receiver with a pseudo-random (PRN) code generator.
Claim 19
Dependent Claim
137 words
In a system for determining the position of a user terminal including: (1) means remote from said user terminal for transmitting a signal containing information indicative of the location of the signal transmitting means, almanac data, timing and synchronization data (epoch) and clock correction data; and (2) receiving means at said user terminal for receiving said transmitted signal: the improvement in said system comprising: (1) means remote from said signal transmitting means and said user terminal for receiving said transmitted signal and converting said transmitted signal to an aiding signal containing information which identifies said signal transmitting means as well as the predicted Doppler data and the spatial coordinate data for said signal transmitting means; and (2) means for transmitting said aiding signal to said user terminal; whereby the complexity of said receiving means may be relaxed.
Claim 20
Dependent Claim
137 words
In a system for determining the position of a user terminal including: (1) means remote from said user terminal for transmitting a signal containing information indicative of the location of the signal transmitting means, almanac data, timing and synchronization data (epoch) and clock correction data; and (2) receiving means at said user terminal for receiving said transmitted signal: the improvement in said system comprising: (1) means remote from said signal transmitting means and said user terminal for receiving said transmitted signal and converting said transmitted signal to an aiding signal containing information which identifies said signal transmitting means as well as the predicted Doppler data and the spatial coordinate data for said signal transmitting means; and (2) means for transmitting said aiding signal to said user terminal; whereby the complexity of said receiving means may be relaxed.
Claim 21
Dependent Claim
22 words
The system of claim 17 wherein said signal transmitting means includes a plurality of signal sources which are displaced from each other.
Claim 22
Dependent Claim
16 words
The system of claim 18 wherein said plurality of signal sources are a constellation of satellites.
Claim 23
Dependent Claim
17 words
The system of claim 17 wherein said aiding signal is transmitted with frequency shift key (FSK) modulation.
Claim 24
Dependent Claim
19 words
The system of claim 17 wherein said aiding signal is transmitted to said user terminal via a relay tower.
Claim 25
Dependent Claim
19 words
The system of claim 17 wherein said aiding signal is transmitted to said user terminal via a relay satellite.
Claim 26
Dependent Claim
16 words
The system of claim 17 wherein said aiding signal includes a stepped pseudo-random (PRN) code reference.
Claim 27
Dependent Claim
18 words
The system of claim 17 wherein said user terminal includes a receiver with a pseudo-random (PRN) code generator.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-04-24 | 1987-10-24 | 1988-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-04-24 | 1991-10-24 | 1992-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-04-24 | 1995-10-24 | 1996-04-24 | $7700.00 | Window Closed / Lapsed |