Ranging system for determining ranging information of a spacecraft

• US 20040140930A1
• Filed: 09/29/2003
• Published: 07/22/2004
• Est. Priority Date: 03/29/2001
• Status: Active Grant

• Current Assignee: SES ASTRA SA (SES SA)
• Original Assignee: SES ASTRA SA (SES SA)
• Inventors: Harles, Guy
• Granted Patent: US 7,512,505 B2
• Time in Patent Office: Days
• US Class Current: 342/387
• CPC Class Codes: G01S 13/46 Indirect determination of position data
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 2013/466 by Trilateration, i.e. two antennas or two sensors determine separately the distance to a target, whereby with the knowledge of the baseline length, i.e. the distance between the antennas or sensors, the position data of the target is determined
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04B 7/18597 Arrangements for system physical machines management, i.e. for construction, operations control, administration, maintenance

Abstract

The invention refers to a ranging system for determining ranging information of a spacecraft carrying a component of a communication channel. In order to provide a ranging system for determining ranging information of a satellite carrying a transponder as well as to provide a method thereof which yield a sufficient accuracy without causing further costs when narrow spot beams by the transponder are used, a ranging system according to the invention comprises a plurality of receiving stations at different locations on earth, wherein each receiving station is arranged for receiving a reference signal from said component; synchronisation means for providing a synchronised time base between the plurality of receiving stations; calculation means for calculating said ranging information in accordance with the propagation time of each received reference signal and with the synchronised time base; wherein at least one receiving station comprises a correlation receiver for receiving the reference signal.

Claims

1. System for providing a common time base between different locations on earth, comprising:

a spacecraft carrying a component of a communication channel, wherein the position of said spacecraft is known,

a plurality of receiving stations at different locations on earth, wherein each receiving station is adapted to receive a reference signal from said component;

synchronisation means adapted to provide a synchronised time base between the plurality of receiving stations; and

correction means adapted to correct the synchronization error of the synchronized time base by the known position of the spacecraft and in accordance with the propagation time of each received reference signal.

2. System according to claim 1, wherein at least one receiving station comprises a correlation receiver yielding a correlation gain for receiving the reference signal.

3. System according to claim 2, wherein the correlation receiver is based on the correlation of a predetermined signal pattern contained in the reference signal.

4. System according to claim 2, wherein the correlation receiver is based on the spread spectrum demodulation of a spread spectrum signal.

5. System according to claim 4, wherein the spread spectrum demodulation yields a processing gain which corresponds to the correlation gain.

6. Method for providing a common time base between different locations on earth with the aid of a spacecraft carrying a component of a communication channel, wherein the position of said spacecraft is known, comprising the steps of:

receiving a reference signal from said component by a plurality of receiving stations at different locations on earth;

providing a synchronised time base between the plurality of receiving stations; and

correcting the synchronization error of the synchronized time base by the known position of the spacecraft and in accordance with the propagation time of each received reference signal.

7. Method according to claim 6, wherein for at least one receiving station a correlation method yielding a correlation gain for receiving the first reference signal and/or the second reference signal is applied.

8. Method according to claim 7, wherein the correlation method is based on the correlation of a predetermined signal pattern contained in the first reference signal and/or the second reference signal.

9. Method according to claim 7, wherein the correlation method is based on the spread spectrum demodulation of a spread spectrum signal.

10. Method according to claim 9, wherein the spread spectrum demodulation yields a processing gain which corresponds to the correlation gain.

11. Processing station for providing a common time base between different locations on earth with the aid of a spacecraft carrying a component of a communication channel, wherein the position of said spacecraft is known, comprising:

propagation time data receiving means adapted to receive propagation time data from a plurality of receiving stations at different locations on earth, wherein each receiving station is adapted to receive a reference signal from said component and wherein a synchronised time base is provided between the plurality of receiving stations, and

correction means adapted to correct the synchronization error of the synchronized time base by the known position of the spacecraft and in accordance with the propagation time of each received reference signal.

12. Processing method for providing a common time base between different locations on earth with the aid of a spacecraft carrying a component of a communication channel, wherein the position of said spacecraft is known, comprising the steps of:

receiving propagation time data from a plurality of receiving stations at different locations on earth, wherein each receiving station is adapted to receive a reference signal from said component and wherein a synchronised time base is provided between the plurality of receiving stations, and

correcting the synchronization error of the synchronized time base by the known position of the spacecraft and in accordance with the propagation time of each received reference signal.

13. Ranging system for determining ranging information of a first spacecraft (Sat 2A) with the aid of a second spacecraft (Sat 1A) whose ranging information is known, wherein the first spacecraft (Sat 2A) carries a first component of a communication channel and wherein the second spacecraft (Sat 1A) carries a second component of a communication channel, comprising:

a plurality of receiving stations at different locations on earth, wherein each receiving station is adapted to receive a first reference signal from the first component and a second reference signal from the second component;

synchronisation means adapted to provide a synchronised time base between the plurality of receiving stations;

calculation means adapted to calculate said ranging information in accordance with the propagation time of each first reference signal, wherein the synchronisation error of the synchronised time base is corrected by the known ranging information of the second spacecraft (Sat 1A) on the basis of each second reference signal.

14. Ranging system according to claim 13, wherein at least one receiving station comprises a correlation receiver yielding a correlation gain for receiving the first reference signal and/or the second reference signal.

15. Ranging system according to claim 14, wherein the correlation receiver is based on the correlation of a predetermined signal pattern contained in the first reference signal and/or the second reference signal.

16. Ranging system according to claim 14, wherein the correlation receiver is based on the spread spectrum demodulation of a spread spectrum signal.

17. Ranging system according to claim 16, wherein the spread spectrum demodulation yields a processing gain which corresponds to the correlation gain.

18. Ranging method for determining ranging information of a first spacecraft (Sat 2A) with the aid of a second spacecraft (Sat 1A) whose ranging information is known, wherein the first spacecraft (Sat 2A) carries a first component of a communication channel and wherein the second spacecraft (Sat 1A) carries a second component of a communication channel, comprising the steps of:

receiving a first reference signal from said first component and a second reference signal from said second component independently by a plurality of receiving stations at different locations on earth;

providing a synchronised time base between the plurality of receiving stations;

calculating said ranging information in accordance with the propagation time of each first reference signal, wherein the synchronisation error of the synchronised time base is corrected by the known ranging information of the second spacecraft (Sat 1A) on the basis of each second reference signal.

19. Method according to claim 18, wherein for at least one receiving station a correlation method yielding a correlation gain for receiving the first reference signal and/or the second reference signal is applied.

20. Method according to claim 19, wherein the correlation method is based on the correlation of a predetermined signal pattern contained in the first reference signal and/or the second reference signal.

21. Method according to claim 19, wherein the correlation method is based on the spread spectrum demodulation of a spread spectrum signal.

22. Method according to claim 21, wherein the spread spectrum demodulation yields a processing gain which corresponds to the correlation gain.

23. Receiving station for providing ranging information of a first spacecraft (Sat 2A) with the aid of a second spacecraft (Sat 1A) whose ranging information is known, wherein the first spacecraft (Sat 2A) carries a first component of a communication channel and wherein the second spacecraft (Sat 1A) carries a second component of a communication channel, comprising:

an antenna adapted to receive a first reference signal from said first component and a second reference signal from said second component;

synchronisation means adapted to provide a synchronised time base between said receiving station and a reference point on earth, wherein the synchronisation error of the synchronised time base is corrected by the known ranging information of the second spacecraft (Sat 1A) on the basis of the second reference signal; and

measurement means adapted to measure the propagation time of the first reference signal in accordance with the corrected synchronized time base.

24. Method for operating a receiving station for providing ranging information of a first spacecraft (Sat 2A) with the aid of a second spacecraft (Sat 1A) whose ranging information is known, wherein the first spacecraft (Sat 2A) carries a first component of a communication channel and wherein the second spacecraft (Sat 1A) carries a second component of a communication channel, comprising the steps of:

receiving a first reference signal from said first component and a second reference signal from said second component;

providing a synchronised time base between said receiving station and a reference point on earth, wherein the synchronisation error of the synchronised time base is corrected by the known ranging information of the second spacecraft (Sat 1A) on the basis of the second reference signal; and

measuring the propagation time of the first reference signal in accordance with the corrected synchronised time base.

25. Processing station for processing ranging information of a first spacecraft (Sat 2A) with the aid of a second spacecraft (Sat 1A) whose ranging information is known, wherein the first spacecraft (Sat 2A) carries a first component of a communication channel and wherein the second spacecraft (Sat 1A) carries a second component of a communication channel, comprising:

propagation time data receiving means adapted to receive propagation time data from a plurality of receiving stations at different locations on earth;

wherein each receiving station is adapted to receive a first reference signal from the first component and a second reference signal from the second component, wherein a synchronised time base is provided between the plurality of receiving stations, and wherein the synchronisation error of the synchronised time base is corrected by the known ranging information of the second spacecraft (Sat 1A) on the basis of each second reference signal.

26. Processing method for processing ranging information of a first spacecraft (Sat 2A) with the aid of a second spacecraft (Sat 1A) whose ranging information is known, wherein the first spacecraft (Sat 2A) carries a first component of a communication channel and wherein the second spacecraft (Sat 1A) carries a second component of a communication channel, comprising the steps of:

receiving propagation time data from a plurality of receiving stations at different locations on earth;

wherein each receiving station is adapted to receive a first reference signal from the first component and a second reference signal from the second component, wherein a synchronised time base is provided between the plurality of receiving stations, and wherein the synchronisation error of the synchronised time base is corrected by the known ranging information of the second spacecraft (Sat 1A) on the basis of each second reference signal.