IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
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출원번호 |
US-0909170
(2004-07-30)
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등록번호 |
US-7342538
(2008-03-11)
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발명자
/ 주소 |
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출원인 / 주소 |
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대리인 / 주소 |
Brinks, Hofer, Gilson & Lione
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인용정보 |
피인용 횟수 :
8 인용 특허 :
101 |
초록
▼
In a local positioning system, the land-based transmitters include free running oscillators or oscillators free of clock synchronization with any remote oscillator. A reference receiver receives the ranging signals from different transmitters and generates timing offset information, such as code pha
In a local positioning system, the land-based transmitters include free running oscillators or oscillators free of clock synchronization with any remote oscillator. A reference receiver receives the ranging signals from different transmitters and generates timing offset information, such as code phase measurements. The timing offset information is then communicated back to transmitters. The temporal offset information indicates relative timing or phasing of the different transmitted ranging signals to the reference receiver. The transmitters then transmit the temporal offset information with the ranging signals, such as modulating the transmitted code by the timing offset information. A mobile receiver is operable to receive the ranging signals and timing offset information in a same communications path, such as on a same carrier. Position is determined with the temporal offset information and the ranging signals. The temporal offset information for the various transmitters allows the mobile receiver to more accurately determine position than in an unsynchronized system.
대표청구항
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I claim: 1. A system for determining relative timing for a plurality of transmitters in a positioning system, the system comprising: first and second transmitters operable to transmit first and second ranging signals having first and second codes, respectively; and a reference receiver operable to
I claim: 1. A system for determining relative timing for a plurality of transmitters in a positioning system, the system comprising: first and second transmitters operable to transmit first and second ranging signals having first and second codes, respectively; and a reference receiver operable to receive the first and second ranging signals, the reference receiver operable to generate first and second timing off-set information, as a function of the first and second codes, for the first and second ranging signals, respectively; each of the first and second transmitters responsive to at least one of the first timing off-set information, second timing off-set information or combinations thereof; wherein the first and second transmitters comprise first and second land based transmitters, respectively. 2. The system of claim 1 wherein the first and second transmitters comprise first and second oscillators, respectively, the first oscillator being free of synchronization with the second oscillator. 3. The system of claim 1 wherein the first and second transmitters are operable to transmit the first and second ranging signals each with a modulation rate of a code being at least 30 MHz. 4. The system of claim 1 wherein the first and second transmitters comprise first and second oscillators, respectively, the first and second oscillators being free-running, the first and second ranging signals responsive to the first and second oscillators, respectively. 5. The system of claim 1 wherein the reference receiver is in a substantially fixed position relative to the first and second transmitters, the first and second timing off-set information representing clock timing of the first and second transmitters, respectively; further comprising: a mobile receiver operable to determine a position from the first and second ranging signals and the first and second timing off-set information. 6. The system of claim 5 wherein the mobile receiver is operable to determine the position as a function of the clock timing of the first and second transmitters. 7. The system of claim 5 wherein the reference receiver comprises a wireless communications transmitter operable to transmit the first timing off-set information, wherein the first transmitter comprises a wireless communications receiver operable to receive the first timing off-set information from the wireless communications transmitter, wherein the first ranging signal is modulated by the first timing off-set information and wherein the mobile receiver is free of communications with the first transmitter other than the first ranging signal. 8. The system of claim 1 further comprising: a mobile receiver operable to determine a position as a function of the first and second ranging signals and the first and second timing off-set information. 9. A system for determining relative timing for a plurality of transmitters in a positioning system, the system comprising: first and second transmitters operable to transmit first and second ranging signals having first and second codes, respectively; and a reference receiver operable to receive the first and second ranging signals, the reference receiver operable to generate first and second timing off-set information for the first and second ranging signals, respectively; each of the first and second transmitters responsive to at least one of the first timing off-set information, second timing off-set information or combinations thereof wherein the first and second transmitters are operable to transmit the first and second ranging signals each with a modulation rate of a code being at least 30 MHz; and wherein the modulation rate is at least about 60 MHz and less than about 250 MHz, the first and second ranging signals having first and second carrier waves in one of the bands of: X-band, ISM band and combinations thereof. 10. A system for determining relative timing for a plurality of transmitters in a positioning system, the system comprising: first and second transmitters operable to transmit first and second ranging signals having first and second codes, respectively; and a reference receiver operable to receive the first and second ranging signals, the reference receiver operable to generate first and second timing off-set information, as a function of the first and second codes, for the first and second ranging signals, respectively; each of the first and second transmitters responsive to at least one of the first timing off-set information, second timing off-set information or combinations thereof; wherein the first and second ranging signals are code division multiple access signals transmitted in time division multiple access time slots. 11. The system of claim 10 wherein the time slot is about as long as a code length. 12. The system of claim 10 wherein each time slot comprises a blank period. 13. The system of claim 10 wherein the time slot is about as long as a code length and every time slot is separated by a blank period, the blank period being about as long as the code length. 14. The system of claim 8 wherein the reference receiver is operable to transmit the first and second timing off-set information to one of the first transmitter, the second transmitter and combinations thereof and wherein the one is operable to transmit the first timing off-set information, second timing off-set information or combinations thereof to the mobile receiver in a substantially same carrier frequency band as the first or second ranging signals. 15. The system of claim 8 wherein the mobile receiver comprises a processor operable to determine a position as a function of the first and second ranging signals, the first and second ranging signals having a code phase accuracy to better than one meter. 16. A method for determining relative timing for a plurality of transmitters in a positioning system, the method comprising: (a) receiving first and second ranging signals from first and second locations, respectively, a first code phase for the first ranging signal being free of synchronization with a second code phase for the second ranging signal; (b) determining, as a function of the first and second code phases of the first and second ranging signals, a temporal off-set for the first code phase, the second code phase, or combinations thereof; (c) transmitting the temporal off-set to the first location wherein a subsequent first ranging signal transmitted from the first location is responsive to the temporal off-set; and (d) transmitting the first and second ranging signals from first and second land based transmitters at the first and second locations, respectively; wherein (a) comprises receiving at a land based receiver. 17. The method of claim 16 further comprising: (e) transmitting the first ranging signal from the first location; and (f) transmitting the second ranging signal from the second location different than the first location; wherein (a) comprises receiving the first and second ranging signals at a third location, the spatial relationship of the first, second and third locations being known. 18. The method of claim 17 further comprising: (e) determining a position of a mobile receiver as a function of the first and second ranging signals and the temporal off-set. 19. The method of claim 16 wherein (b) comprises determining a first temporal off-set for the first code phase from a clock of a reference receiver. 20. The method of claim 16 further comprising: (e) modulating a subsequent first ranging signal as a function of the temporal off-set. 21. The method of claim 20 wherein (e) comprises transmitting the temporal off-set as data with the first ranging signal. 22. The method of claim 16 wherein (a) comprises receiving the first and second ranging signals each with a modulation rate of a code being at least 30 MHz. 23. The method of claim 22 wherein (a) comprises receiving with the modulation rate being at least about 60 MHz and less than about 250 MHz, the first and second ranging signals having first and second carrier waves in one of the bands of: X-band, ISM band and combinations thereof. 24. The method of claim 16 wherein (a) comprises receiving the first and second ranging signals, the first and second ranging signals being responsive to first and second oscillators, respectively, the first and second oscillators being free-running. 25. The method of claim 16 wherein (a) comprises receiving with a reference receiver having a wireless communications transmitter operable to transmit the temporal off-set at a different frequency band than the first and second ranging signals; further comprising: (e) receiving the temporal off-set information at a transmitter, the transmitter operable to transmit the first ranging signal, wherein the first ranging signal is modulated by the temporal off-set; and (f) receiving the modulated first ranging signal at a mobile receiver free of communications with the transmitter other than the first ranging signal. 26. The method of claim 16 wherein (a) comprises receiving the first and second ranging signals as code division multiple access signals transmitted in time division multiple access time slots. 27. The system of claim 26 wherein the time slot is about as long as a code length. 28. The system of claim 26 wherein each time slot comprises a blank period. 29. The system of claim 26 wherein the time slot is about as long as a code length and time slots are separated by a blank period. 30. The method of claim 16 further comprising: (e) receiving the first and second ranging signals and the temporal off-set at a mobile receiver; and (f) determining a position of the mobile receiver as a function of the first and second ranging signals and the temporal off-set. 31. The method of claim 16 wherein (a) and (b) are performed at a reference receiver; further comprising: (e) transmitting the first ranging signal with a transmitter; wherein (c) comprises: (c1) transmitting the temporal off-set to the transmitter from the reference receiver; and (c2) transmitting the temporal off-set to a mobile receiver in a substantially same carrier frequency band as the first or second ranging signals. 32. A system for determining relative timing for positioning, the system comprising: a first land-based transmitter operable to transmit first ranging signals and first differential timing off-set information for the first ranging signals; and a mobile receiver operable to receive the first ranging signals and the first differential timing off-set information in a single first communications path, the mobile receiver operable to determine a position as a function of a correlation of code of the first ranging signal with a replica code and the first differential timing off-set information. 33. The system of claim 32 further comprising: a second transmitter operable to transmit second ranging signals in a second communications path with the mobile receiver; wherein one of the second and first transmitters is operable to transmit second timing off-set information in one of the first and second communications paths, the first differential timing off-set information indicating a relationship of the first ranging signal to a common clock and the second timing off-set information indicating a relationship of the second ranging signal to the common clock; and wherein the mobile receiver is operable to determine the position as a function of the second ranging signals. 34. The system of claim 32 further comprising: a reference receiver operable to receive the first ranging signals on a second communications path, operable to generate the first differential timing off-set information, and operable to transmit the first differential timing off-set information to the first transmitter on a third communications path different than the second communications path. 35. The system of claim 34 wherein the first and second communications paths comprise signals in a X-band and wherein the third communications path comprises signals in a band other than the X-band. 36. The system of claim 34 wherein the first and second communications paths comprise signals in a ISM-band and wherein the third communications path comprises signals in a band other than the same ISM-band. 37. The system of claim 32 wherein the first transmitter is operable to transmit the first ranging signals with a modulation rate of a code being at least 30 MHz. 38. The system of claim 37 wherein the modulation rate is at least about 60 MHz and less than about 250 MHz, and wherein the single first communications path is at one of the bands of: X-band, ISM band and combinations thereof. 39. The system of claim 32 wherein the first transmitter comprises a land based transmitter. 40. The system of claim 32 wherein the mobile receiver is free of communications with the first transmitter other than the first ranging signal modulated by the first differential timing off-set information. 41. The system of claim 32 wherein the second transmitter is a satellite. 42. A method for determining relative timing for positioning, the method comprising: (a) transmitting from a land-based transmitter first ranging signals and a first differential timing off-set information for the first ranging signals, the first ranging signal having a code and modulated by the first differential timing off-set information; (b) receiving the first ranging signals and the first differential timing off-set information in a single first communications path at a mobile receiver; and (c) determining a position of the mobile receiver as a function of the first ranging signal and the first differential timing off-set information. 43. The method of claim 42 further comprising: (d) transmitting second ranging signals in a second communications path with the mobile receiver; and (e) transmitting second timing off-set information in one of the first and second communications paths, the first differential timing off-set information indicating a relationship of the first ranging signal to a common clock and the second timing off-set information indicating a relationship of the second ranging signal to the common clock; wherein (c) comprises determining the position as a function of the first and second ranging signals and the first and second timing off-set information. 44. The method of claim 42 wherein (a) comprises transmitting from a first transmitter; further comprising: (d) receiving the first ranging signals from the first transmitter on a second communications path with a reference receiver; (e) generating the first differential timing off-set information with the reference receiver; and (f) transmitting the first differential timing off-set information to the first transmitter on a third communications path different than the second communications path. 45. The method of claim 44 wherein the first and second communications paths comprise signals in a X-band and wherein the third communications path comprises signals in a band other than the X-band. 46. The method of claim 44 wherein the first and second communications paths comprise signals in a ISM band and wherein the third communications path comprises signals in a band other than the same ISM band. 47. The method of claim 42 wherein (a) comprises transmitting the first ranging signals with a modulation rate of a code being at least 30 MHz. 48. The method of claim 47 wherein (a) comprises transmitting with the modulation rate being at least about 60 MHz and less than about 250 MHz, and wherein the single first communications path is at one of the bands of: X-band, ISM band and combinations thereof. 49. The method of claim 42 wherein (a) comprises transmitting with a first transmitter, the mobile receiver being free of communications with the first transmitter other than the first ranging signal modulated by the first differential timing off-set information.
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