Method and device for chronologically synchronizing a location network

• US 20050001742A1
• Filed: 11/01/2002
• Published: 01/06/2005
• Est. Priority Date: 11/02/2001
• Status: Active Grant

• Current Assignee: Locata Corporation Pty Ltd
• Original Assignee: Locata Corporation Pty Ltd
• Inventors: Small, David
• Granted Patent: US 7,616,682 B2
• Time in Patent Office: Days
• US Class Current: 340/988
• CPC Class Codes: G01S 1/24 the synchronised signals being pulses or equivalent modulations on carrier waves and the transit times being compared by measuring the difference in arrival time of a significant part of the modulations , e.g. LORAN systems
• CPC Class Codes: G01S 19/10 providing dedicated supplementary positioning signals
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset
• CPC Class Codes: G01S 19/43 using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry
• CPC Class Codes: G01S 5/0081 Transmission between base stations
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0226 Transmitters
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: G01S 5/145 Using a supplementary range measurement, e.g. based on pseudo-range measurements
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 56/0065 using measurement of signal travel time

Abstract

A positioning system that includes a transceiver (hereafter termed a Positioning-Unit Device) that receives one or more reference positioning signals from other Positioning-Unit Devices and/or from other qualified reference positioning signal sources. Each of the received reference positioning signals preferably has a carrier component, a pseudo-random code component, and a data component. The Positioning-Unit Device generates, in response to the received reference positioning signals and their known locations, a unique positioning signal. The unique positioning signal has a carrier component chronologically synchronized to one or more of the carrier components of the received reference positioning signals, a pseudo-random code component chronologically synchronized to one or more of the pseudo-random code components of the received reference positioning signals, and a data component chronologically synchronized to one or more of the data components of the received reference positioning signals. Once a Positioning-Unit Device is chronologically synchronized to a reference transmitter other Positioning-Unit Devices entering the network can use its transmitted unique positioning signal as a reference positioning signal. The geographical distribution of these chronologically synchronized Positioning-Unit Devices creates a time-coherent network of positioning signals that propagate a reference timebase over a substantial geographical area. The positioning system also includes a roving position receiver. The roving position receiver can generate code-based single point position determinations by making range measurements for each of the received chronologically synchronized pseudorandom code and data components, and can generate carrier-based single point position determinations by making range measurements for each of the received chronologically synchronized carrier components. The formation of a chronologically synchronized positioning network allows a roving position receiver the ability to autonomously calculate both code and carrier-based single point position solutions without the requirement for differential correction or absolute time accuracy within the network.

Claims

1. A method of chronologically synchronizing a unique positioning signal generated by a positioning-unit device at a known location with at least one reference transmitter generating a reference positioning signal at a known location, the method comprising said positioning-unit device:

a) receiving and interpreting said reference positioning signal;

b) obtaining a reference positioning signal propagation delay between said reference transmitter and said positioning-unit device;

c) generating and transmitting a unique positioning signal;

d) receiving and interpreting the unique positioning signal transmitted in step (c);

e) comparing said received and interpreted reference positioning signal and said received and interpreted unique positioning signal of step (d) to deduce a transmission difference; and

f) adjusting continuously the generation of said unique positioning signal of step (c) by

i) said deduced transmission difference; and

ii) said reference positioning signal propagation delay such that said unique positioning signal is chronologically synchronized to said reference transmitter timebase.

2. The method of claim 1, wherein said adjusted and generated unique positioning signal of step (f) functions as a reference positioning signal for other positioning-unit devices.

3. The method of claim 1, wherein said deduced transmission difference includes comparison of integrated carrier phase measurements determined from carrier components of said reference positioning signal and said unique positioning signal to determine a carrier frequency difference.

4. The method of claim 1, wherein said deduced transmission difference includes comparison of navigation data components from said reference positioning signal and said unique positioning signal to determine a transmission time difference.

5. The method of claim 1, wherein said deduced transmission difference includes comparison of pseudorange measurements determined from pseudorandom code components of said reference positioning signal and said unique positioning signal to determine a pseudorandom code pseudorange difference.

6. The method of claim 1, wherein said comparison of step (e) includes comparison of instantaneous carrier phase measurements determined from carrier components of said reference positioning signal and said unique positioning signal to determine an instantaneous carrier phase difference.

7. The method of claim 1, wherein said at least one reference transmitter includes positioning-unit devices, Wide Area Augmentation System satellites, Global Navigation Satellite System satellites, Pseudolites, or any other signals that incorporate timing information.

8. The method of claim 1, wherein said signal propagation delay of step (b) is obtained by interpreting said reference transmitter'"'"'s known location contained in said reference positioning signal, and said positioning-unit device'"'"'s known location contained in said unique positioning signal.

9. A positioning-unit device for chronologically synchronizing a unique positioning signal generated at a known location with at least one reference transmitter generating a reference positioning signal at a known location, the device comprising:

a) means for receiving and interpreting said reference positioning signal;

b) means to obtain a reference positioning signal propagation delay between said reference transmitter and said positioning-unit device;

c) means for generating and transmitting said unique positioning signal;

d) means for receiving and interpreting said unique positioning signal transmitted in step (c);

e) means for comparing said received reference positioning signal and said received unique positioning signal of step (d) to deduce a transmission difference; and

f) means for continuously adjusting the generation of said unique positioning signal of step (c) by

i) said deduced transmission difference; and

ii) said reference positioning signal propagation delay such that said unique positioning signal is chronologically synchronized to said reference transmitter timebase.

10. The device of claim 9, wherein said receiving and interpreting means of (a) above are further configured to receive unique positioning signals transmitted by other positioning unit devices and using said received unique positioning signals transmitted by other positioning unit devices as said reference positioning signal.

11. The device of claim 9, wherein said means for comparing includes means for comparison of integrated carrier phase measurements determined from carrier components of said reference positioning signal and said unique positioning signal to determine a carrier frequency difference.

12. The device of claim 9, wherein said means for comparing includes means for comparison of navigation data components from said reference positioning signal and said unique positioning signal to determine a transmission time difference.

13. The device of claim 9, wherein said means for comparing includes means for comparison of pseudorange measurements determined from pseudo-random code components of said reference positioning signal and said unique positioning signal to determine a pseudo-random code pseudorange difference.

14. The device of claim 9, wherein means for comparing includes means for comparison of instantaneous carrier phase measurements determined from carrier components of said reference positioning signal and said unique positioning signal to determine an instantaneous carrier phase difference.

15. The device of claim 9, wherein said at least one reference transmitter includes positioning-unit devices, Wide Area Augmentation System satellites, Global Navigation Satellite System satellites, Pseudolites, or any other signals that incorporate timing information.

16. The device of claim 9, wherein means for obtaining includes means to identify said reference transmitter'"'"'s known location contained in said reference positioning signal, and means to identify said positioning-unit device'"'"'s known location contained in said unique positioning signal, to calculate said signal propagation delay of step (b).

17. A system configured to determine the position of a roving position receiver, comprising:

a) at least one reference transmitter at a known location configured to generate and transmit reference positioning signals;

b) positioning-unit devices at known locations, each Positioning-unit device comprising;

i) means for receiving signals transmitted by both or either of said at least one reference transmitter and said positioning-unit devices;

ii) means for interpreting said received signals and in response generating a unique positioning signal that is synchronized with said reference transmitter; and

iii) means for transmitting said unique positioning signal;

c) said roving position receiver configured to receive said unique positioning signals, and subsequently calculate a single-point position solution.

18. The system of claim 17, wherein said unique positioning signals have frequency coherence with said received signals, and chronological coherence with said reference transmitter'"'"'s timebase.

19. The system of claim 17, wherein said at least one reference transmitter includes one or more of positioning-unit devices, Wide Area Augmentation System satellites, Global Navigation Satellite System satellites, Pseudolites, or any other signals that incorporate timing information.

20. The system of claim 17, wherein said unique positioning signals include a carrier component, a pseudorandom code component and a data component, and wherein said roving position receiver determines pseudorandom code single point position determinations for each of the received pseudorandom code components and data components.

21. The system of claim 17, wherein said unique positioning signals include a carrier component, a pseudorandom code component and a data component, and wherein said roving position receiver determines carrier single point position determinations for each of the received carrier components.

22. For location, a method of generating frequency coherence between a received reference positioning signal and a generated and transmitted unique positioning signal, the method comprising:

a) deploying a positioning-unit device comprising;

i) means to receive said reference positioning signal;

ii) means to generate said unique positioning signal;

iii) means to adjust said unique positioning signal with a frequency steerable clock;

iv) means to supply a common oscillator signal to said receive means and said frequency steerable clock; and

v) means to transmit said unique positioning signal;

b) receiving said reference positioning signal and measuring its frequency offset relative to said common oscillator;

c) generating said unique positioning signal;

d) adjusting said unique positioning signal by applying said measured frequency offset to said frequency steerable clock, said steerable clocked referenced to said common oscillator;

e) transmitting said unique positioning signal,

such that the frequency of the transmitted unique positioning signal is aligned with the frequency of the reference positioning signal.

23. A method as claimed in claim 22, wherein said frequency steerable clock is adjusted by an additional frequency offset for a predetermined time period to chronologically slew said unique positioning signal.

24. A positioning-unit device for generating frequency coherence between a received reference positioning signal and a generated and transmitted unique positioning signal, the device comprising:

a) means configured to receive said reference positioning signal and measure its frequency offset relative to an oscillator;

b) means configured to generate said unique positioning signal;

c) means configured to adjust said unique positioning signal with a frequency steerable clock, referenced to said oscillator, and responsive to said frequency offset;

d) means to transmit said unique positioning signal.

25. A device as claimed in claim 24, wherein said frequency steerable clock is further configured to be responsive to an additional frequency offset applied for a predetermined time period to chronologically slew said unique positioning signal.

26. In a roving position receiver, a method for determining and correcting for a difference in the timebase of adjacent autonomous positioning networks, each network comprising a plurality of positioning unit devices in known positions synchronized to a local reference timebase, the method comprising:

a) positioning unit devices of a first autonomous positioning network receive signals from positioning unit devices of an adjacent second autonomous positioning network, measure the timebase difference with respect to the first autonomous positioning network'"'"'s timebase, and in response calculate a clock correction;

b) positioning unit devices from said first autonomous positioning network subsequently transmit said calculated clock correction within the network data portion of their transmitted first autonomous positioning networks unique positioning signals;

c) a roving position receiver that is located in an area wherein it receives signals from positioning unit devices within both networks applies said calculated clock corrections to said signals from positioning unit devices of an adjacent second autonomous positioning network before calculating a single point position solution,

such that signals from networks synchronized to different local reference timebases can be used for a position solution.

27. For location, a system for creating single point wide-lane ambiguity resolution solutions, the system comprising:

a) at least one reference transmitter at a known location configured to generate and transmit a plurality of positioning signals at a plurality of frequencies;

b) positioning unit devices at known locations, each positioning unit device comprising;

i) means for receiving signals transmitted by both or either of said at least one reference transmitter and said positioning unit devices;

ii) means for interpreting said received signals and in response generating corresponding unique positioning signals on a plurality of frequencies which are synchronized to said received signals; and

iii) means for transmitting said generated corresponding unique positioning signals;

c) a roving position receiver configured to resolve wide-lane carrier phase ambiguity and subsequently calculate a single point position solution.

28. A system as in claim 27, wherein said at least one reference transmitter at a known location is configured to generate and transmit a plurality of non-coherent positioning signals at a plurality of frequencies.

29. A system as in claim 27, wherein further means are configured to calculate a propagation delay offset between said at least one reference transmitter and said positioning unit devices and subsequently adjust said generated corresponding unique positioning signals by said calculated propagation delay offset.