Method and apparatus for providing an integrated communications, navigation and surveillance satellite system

• US 6,674,398 B2
• Filed: 10/05/2001
• Issued: 01/06/2004
• Est. Priority Date: 10/05/2001
• Status: Expired due to Fees

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Murphy, Timothy A.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US09/972,355
• Publication Number:
  US 20030067409A1
• Time in Patent Office: 823 Days
• Field of Search: 342/356, 342/357.01, 342/357.16, 342/456
• US Class Current: 342/357.21
• CPC Class Codes: G01S 19/00 Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
• CPC Class Codes: G01S 19/01 Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
• CPC Class Codes: G01S 19/02 Details of the space or ground control segments
• CPC Class Codes: G01S 19/071 DGPS corrections
• CPC Class Codes: G01S 19/072 Ionosphere corrections
• CPC Class Codes: G01S 19/38 Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
• CPC Class Codes: G01S 19/39 the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
• CPC Class Codes: H04B 7/18508 with satellite system used as relay, i.e. aeronautical mobile satellite service
• CPC Class Codes: H04B 7/18552 using a telephonic control signal and a second ranging satellite determining absolute distances from a plurality of spaced points of known location G01S5/14

Abstract

A system for providing integrated communications, navigation and surveillance capabilities. A space segment comprises a plurality of time synchronized satellites broadcasting navigation signals and have two-way communication capabilities. Each satellite also has communication switching capabilities and is part of a network. A terrestrial segment comprises processing apparatus that communicates the satellites through the network. A user segment comprises at least one mobile user device capable of two way communication with the plurality of satellites and of using the navigation signals to derive its position. The user device broadcasts surveillance signals which the processing apparatus uses to derive the position of the user device. The signals are also used by the system to measure and transmit the state of the ionosphere.

Claims

1. A system for providing integrated communications, navigation and surveillance information, the system comprising:

a space segment having a plurality of satellites with synchronized time, each satellite of the plurality of satellites broadcasting multiple navigation signals and each satellite of the plurality of satellites being capable of two way communication and of receiving and relaying surveillance signals, and each satellite of the plurality of satellites being part of a network, the network allowing each satellite of the plurality of satellites to communicate with any other satellite of the plurality of satellites;

a user segment having at least one mobile user device, the at least one user device being capable of direct two way communication with each satellite of the plurality of satellites that are within a line of sight of the least one user device and of two way communication with any satellite of the plurality of satellites through the network, the at least one user device being capable of receiving at least one of the navigation signals broadcast by the plurality of satellites and using the received navigation signal(s) to compute a position of the at least one user device, and the at least one user device being capable of broadcasting a surveillance signal to the plurality of satellites;

a terrestrial segment having a processing apparatus that is capable of two way communication with any satellite of the plurality of satellites through the network, the processing apparatus being capable of receiving surveillance signals relayed by the plurality of satellites and determining a position of the at least one user device that broadcast the surveillance signal,

wherein the surveillance signal broadcast by the at least one user device is a dual frequency surveillance signal, the processing apparatus uses the dual frequency surveillance signal to compute correction factors for ionospheric induced time delays in signals traveling through an ionosphere between each satellite of the plurality of satellites that received the dual frequency surveillance signal and the at least one user device and based on the correction factors computes a more accurate position for the at least one user device.

2. The system of claim 1, wherein:

each satellite of the plurality of satellites has communication switching capabilities so that each satellite of the plurality of satellites can route communication signals to a desired recipient.

3. The system of claim 1, wherein:

at least one satellite of the plurality of satellites is capable of measuring the time of arrival of surveillance signals received by the plurality of satellites and relaying the time of arrival measurements to the processing apparatus.

4. The system of claim 1, wherein:

the network is formed by each satellite of the plurality of satellites directly communicating with at least two other satellites of the plurality of satellites so that redundant communication paths exist and each satellite of the plurality of satellites is capable of communicating with any other satellite of the plurality of satellites either directly or through the network.

5. The system of claim 1, wherein:

the terrestrial segment has a plurality of ground stations that are capable of direct two way communication with each satellite of the plurality of satellites that are within a line of sight of the plurality of ground stations, and each ground station of the plurality of ground stations being capable two way communication using ground based telecommunication networks; and

the network is formed by the plurality of ground stations and the plurality of satellites.

6. The system of claim 1, wherein:

the processing apparatus communicates the correction factors to the at least one user device; and

the at least one user device uses the correction factors along with the navigation signals to compute a more accurate position of the at least one user device.

7. The system of claim 1, wherein:

the at least one user device is one of a plurality of user devices and the surveillance signal broadcast by each user device the plurality of user devices is a dual frequency surveillance signal;

the processing apparatus uses the dual frequency surveillance signals broadcast by the plurality of user devices to compute a model which describes variation of a delay through the ionosphere as a function of geographic location; and

the processing apparatus broadcasts through the network the model along with the correction factors so that any device capable of receiving and processing the broadcast model can use the correction factors along with the navigation signals to compute a more accurate position.

8. The system of claim 1, wherein the at least one user device communicates the position of the at least one user device computed by the at least one user device to the plurality of satellites along with a surveillance signal and the processing apparatus computes the position of the at least one user device based on the surveillance signal and compares the two computed positions.

9. The system of claim 8, wherein the processing apparatus performs a system integrity check if the two computed positions differ by more than a predetermined amount.

10. The system of claim 8, wherein the processing apparatus communicates to the at least one user device via the network the position of the at least one user device computed by the processing apparatus if the two computed positions differ by more than a predetermined amount.

11. The system of claim 1, wherein the terrestrial segment further comprises:

at least one monitoring station having a known position and being capable of receiving the navigation signals broadcast by the plurality of satellites and of direct two way communication with each satellite within a line of site of the at least one monitoring station and of two way communication with each satellite of the plurality of satellites through the network, the at least one monitoring station computing a position of the at least one monitoring station based on the received navigation signals and communicating the computed position to the processing apparatus so that integrity of the system can be checked.

12. The system of claim 11, wherein:

the at least one monitoring station is one of a plurality of monitoring stations and each monitoring station of the plurality of monitoring stations broadcasts a dual frequency surveillance signal to the plurality of satellites;

the processing apparatus uses the dual frequency surveillance signals broadcast by the plurality of monitoring stations to compute a model which describes variation of a delay through the ionosphere as a function of geographic location; and

the processing apparatus broadcasts through the network the model along with correction factors so that any device capable of receiving and processing the broadcast model can use the model and the correction factors along with the navigation signals to compute a more accurate position.

13. The system of claim 1, wherein the at least one user device informs the plurality of satellites that the at least one user device is not receiving the at least one navigation signal the at least one user device is capable of receiving whenever the at least one user device is not receiving the at least one navigation signal broadcast by the plurality of satellites.

14. The system of claim 13, wherein the processing apparatus computes the probable location of an interference source that is preventing the at least one user device from receiving the at least one navigation signal.

15. The system of claim 1, wherein:

at least one satellite of the plurality of satellites directly communicates with at least three other satellites of the plurality of satellites and the at least one satellite of the plurality of satellites is capable of transmitting navigation signals to the at least three other satellites of the plurality of satellites; and

the processing apparatus is capable of using the transmitted navigation signals to compute the ephemeris of the at least one satellite of the plurality of satellites.

16. The system of claim 15, wherein the processing apparatus compares the computed ephemeris of the at least one satellite of the plurality of satellites with the navigation signals being broadcast by the at least one satellite of the plurality of satellites and autonomously corrects the navigation signals being broadcast by the at least one satellite of the plurality of satellites if the navigation signals being broadcast by the at least one satellite of the plurality of satellites does not match the computed ephemeris.

17. The system of claim 1, wherein:

at least one satellite of the plurality of satellites broadcasts a navigation signal at a first frequency and sends a communication signal at the first frequency and the navigation signal acts as a pilot tone for the system.

18. A method of providing improved accuracy in determining a position of an object by monitoring ionospheric delay experienced by a signal traveling through an ionosphere and correcting for the ionospheric delay, the method comprising the steps of:

providing a plurality of time synchronized satellites with each satellite of the plurality of satellites broadcasting multiple navigation signals and being capable of two-way communication with other devices;

providing a network so that each satellite of the plurality of satellites is capable of communicating with any other satellite of the plurality of satellites;

providing at least one user device capable of two-way communication with any satellite of the plurality of satellites that are within a line of sight of the at least one user device and of two way communication with any satellite of the plurality of satellites via the network;

broadcasting a dual frequency surveillance signal from the at least one user device;

receiving the dual frequency surveillance signal on each satellite of the plurality of satellites within the line of sight of the at least one user device;

calculating a correction factor for each satellite of the plurality of satellites that received the dual frequency surveillance signal by using the received dual frequency surveillance signal to correct for ionospheric induced time delays caused by the ionosphere in signals traveling between the at least one user device and each satellite of the plurality of satellites that received the surveillance signal;

transmitting from at least one satellite of the plurality of satellites to the at least one user device the correction factor for each satellite of the plurality of satellites that received the surveillance signal;

receiving the correction factors by the at least one user device so that the at least one user device can correct for the time delays in navigation signals broadcast from each satellite of the plurality of satellites for which a correction factor was calculated;

correcting each navigation signal received by the at least one user device for which a correction factor was received; and

determining a position of the at least one user device based on the navigation signals received by the at least one user device and the corrections made to the navigation signals.

19. The method of claim 18, wherein the step of broadcasting a dual frequency surveillance signal comprises broadcasting a surveillance signal on two different frequencies that are generally phase coherent and chip synchronous at a phase center of a transmit antenna on the at least one user device.

20. The method of claim 18, wherein the step of calculating a correction factor for each satellite of the plurality of satellites that received the dual frequency surveillance signal further comprises the steps of:

using the dual frequency surveillance signals broadcast by the at least one user device to compute a model which describes variation of ionospheric induced time delays as a function of geographic location;

calculating correction factors for the model based upon the ionospheric induced delays calculated for each satellite of the plurality of satellites that received the surveillance signal;

the step of transmitting the correction factors further comprising transmitting the model along with the correction factors; and

the step of correcting each navigation signal received by the at least one user device further comprises correcting each navigation signal received by the at least one user device based on the model, the correction factors, and a specific line of sight projection between the at least one user device and each satellite of the plurality of satellites for which a correction factor was received.

21. The method of claim 20, wherein the step of transmitting the model along with the correction factors further comprises broadcasting the model along with the correction factors so that any device capable of receiving and using the broadcast can use the model and the correction factors to determine a more accurate position of said any device.

22. The method of claim 21, wherein:

the step of providing at least one user device comprises providing a plurality of user devices; and

the step of broadcasting a dual frequency surveillance signal further comprises broadcasting a dual frequency surveillance signal from each user device of the plurality of user devices.

23. The method of claim 22, wherein the step of broadcasting a dual frequency surveillance signal is performed on a predetermined interval so that the calculation of the ionospheric delay can be updated on the predetermined interval.

24. A method of determining a position of an object, the method comprising the steps of:

providing a plurality of time synchronized satellites with each satellite of the plurality of satellites broadcasting multiple navigation signals and being capable of two-way communication with other devices;

providing a network so that each satellite of the plurality of satellites is capable of communicating with any other satellite of the plurality of satellites;

providing at least one user device capable of direct two-way communication with any satellite of the plurality of satellites that are within a line of sight of the at least one user device and of two way communication with any satellite of the plurality of satellites through the network;

receiving at least one of the navigation signals broadcast from each satellite of the plurality of satellites that are within the line of sight of the at least one user device by the at least one user device;

calculating a position of the at least one user device based on the received navigation signal(s);

broadcasting from the at least one user device the calculated position of the at least one user device along with broadcasting a surveillance signal;

receiving the broadcast position of the at least one user device and the surveillance signal by at least three satellites of the plurality of satellites;

calculating the position of the at least one user device based on the surveillance signals received by the at least three satellites of the plurality of satellites;

comparing the two calculated positions of the at least one user device; and

transmitting to the at least one user device the position of the at least one user device calculated based upon the received surveillance signals if the two calculated positions differ by more than a predetermined amount.

25. The method of claim 24, further comprising the step of performing an integrity check of the plurality of satellites if the two calculated positions differ by more than a predetermined amount.

26. A method of determining the position of an object when navigation signals being broadcast from a plurality of satellites are not being received, the method comprising the steps of:

providing a plurality of time synchronized satellites with each satellite of the plurality of satellites broadcasting multiple navigation signals and being capable of two-way communication with other devices;

providing a network so that each satellite of the plurality of satellites is capable of communicating with any other satellite of the plurality of satellites;

providing at least one user device capable of direct two-way communication with each satellite of the plurality of satellites within a line of sight of the at least one user device and of two way communication with any satellite of the plurality of satellites through the network;

broadcasting from the at least one user device a surveillance signal along with a message signal indicating that the at least one user device is not receiving the broadcast navigation signals when the at least one user device is not receiving at least one of the broadcast navigation signals;

receiving the surveillance signal along with the message signal by each satellite of the plurality of satellites within the line of sight of the at least one user device;

calculating a position of the at least one user device based on the received surveillance signals; and

broadcasting from at least one satellite of the plurality of satellites to the at least one user device the calculated position of the at least one user device.

27. The method of claim 26, further comprising the steps of:

Verifying the broadcasting of navigation signals by each satellite of the plurality of satellites when the message signal is received;

calculating a likely location of an interference source that is blocking reception of the navigation signals by the at least one user device based on the calculated position of the at least one user device if each satellite of the plurality of satellites is verified to be broadcasting navigation signals; and

transmitting to a desired party the likely location of the interference source.

28. A system for providing integrated communications, navigation and surveillance information, the system comprising:

a space segment having a plurality of satellites with synchronized time, each satellite of the plurality of satellites broadcasting multiple navigation signals and each satellite of the plurality of satellites being capable of two way communication and of receiving and relaying surveillance signals, and each satellite of the plurality of satellites being part of a network, the network allowing each satellite of the plurality of satellites to communicate with any other satellite of the plurality of satellites;

a user segment having at least one mobile user device, the at least one user device being capable of direct two way communication with each satellite of the plurality of satellites that are within a line of sight of the least one user device and of two way communication with any satellite of the plurality of satellites through the network, the at least one user device being capable of receiving at least one of the navigation signals broadcast by the plurality of satellites and using the received navigation signal(s) to compute a position of the at least one user device, and the at least one user device being capable of broadcasting a surveillance signal to the plurality of satellites;

a terrestrial segment having a processing apparatus that is capable of two way communication with any satellite of the plurality of satellites through the network, the processing apparatus being capable of receiving surveillance signals relayed by the plurality of satellites and determining a position of the at least one user device that broadcast the surveillance signal; and

wherein the at least one user device communicates the position of the at least one user device computed by the at least one user device to the plurality of satellites along with a surveillance signal, the processing apparatus computes the position of the at least one user device based on the surveillance signal and compares the two computed positions, and the processing apparatus performs a system integrity check if the two computed positions differ by more than a predetermined amount.

29. A system for providing integrated communications, navigation and surveillance information, the system comprising:

a space segment having a plurality of satellites with synchronized time, each satellite of the plurality of satellites broadcasting multiple navigation signals and each satellite of the plurality of satellites being capable of two way communication and of receiving and relaying surveillance signals, and each satellite of the plurality of satellites being part of a network, the network allowing each satellite of the plurality of satellites to communicate with any other satellite of the plurality of satellites;

a user segment having at least one mobile user device, the at least one user device being capable of direct two way communication with each satellite of the plurality of satellites that are within a line of sight of the least one user device and of two way communication with any satellite of the plurality of satellites through the network, the at least one user device being capable of receiving at least one of the navigation signals broadcast by the plurality of satellites and using the received navigation signal(s) to compute a position of the at least one user device, and the at least one user device being capable of broadcasting a surveillance signal to the plurality of satellites;

a terrestrial segment having a processing apparatus that is capable of two way communication with any satellite of the plurality of satellites through the network, the processing apparatus being capable of receiving surveillance signals relayed by the plurality of satellites and determining a position of the at least one user device that broadcast the surveillance signal; and

wherein the at least one user device communicates the position of the at least one user device computed by the at least one user device to the plurality of satellites along with a surveillance signal, the processing apparatus computes the position of the at least one user device based on the surveillance signal and compares the two computed positions, and the processing apparatus communicates to the at least one user device via the network the position of the at least one user device computed by the processing apparatus if the two computed positions differ by more than a predetermined amount.

30. A system for providing integrated communications, navigation and surveillance information, the system comprising:

a space segment having a plurality of satellites with synchronized time, each satellite of the plurality of satellites broadcasting multiple navigation signals and each satellite of the plurality of satellites being capable of two way communication and of receiving and relaying surveillance signals, and each satellite of the plurality of satellites being part of a network, the network allowing each satellite of the plurality of satellites to communicate with any other satellite of the plurality of satellites;

a user segment having at least one mobile user device, the at least one user device being capable of direct two way communication with each satellite of the plurality of satellites that are within a line of sight of the least one user device and of two way communication with any satellite of the plurality of satellites through the network, the at least one user device being capable of receiving at least one of the navigation signals broadcast by the plurality of satellites and using the received navigation signal(s) to compute a position of the at least one user device, and the at least one user device being capable of broadcasting a surveillance signal to the plurality of satellites;

a terrestrial segment having a processing apparatus that is capable of two way communication with any satellite of the plurality of satellites through the network, the processing apparatus being capable of receiving surveillance signals relayed by the plurality of satellites and determining a position of the at least one user device that broadcast the surveillance signal; and

wherein the at least one user device informs the plurality of satellites that the at least one user device is not receiving the at least one navigation signal the at least one user device is capable of receiving whenever the at least one user device is not receiving the at least one navigation signal broadcast by the plurality of satellites and the processing apparatus computes the probable location of an interference source that is preventing the at least one user device from receiving the at least one navigation signal.

31. A method of determining a position of an object, the method comprising the steps of:

providing a plurality of time synchronized satellites with each satellite of the plurality of satellites broadcasting multiple navigation signals and being capable of two-way communication with other devices;

providing a network so that each satellite of the plurality of satellites is capable of communicating with any other satellite of the plurality of satellites;

providing at least one user device capable of direct two-way communication with any satellite of the plurality of satellites that are within a line of sight of the at least one user device and of two way communication with any satellite of the plurality of satellites through the network;

receiving at least one of the navigation signals broadcast from each satellite of the plurality of satellites that are within the line of sight of the at least one user device by the at least one user device;

calculating a position of the at least one user device based on the received navigation signal(s);

broadcasting from the at least one user device the calculated position of the at least one user device along with broadcasting a surveillance signal;

receiving the broadcast position of the at least one user device and the surveillance signal by at least three satellites of the plurality of satellites;

calculating the position of the at least one user device based on the surveillance signals received by the at least three satellites of the plurality of satellites;

comparing the two calculated positions of the at least one user device; and

performing an integrity check of the plurality of satellites if the two calculated positions differ by more than a predetermined amount.