Medium earth orbit augmentation of a global positioning system for global navigation

• US 6,182,927 B1
• Filed: 09/24/1998
• Issued: 02/06/2001
• Est. Priority Date: 09/24/1998
• Status: Expired due to Term

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Galvin, Dennis M.
• Primary Examiner(s): ELDRED, JOHN W
• Application Number:
  US09/159,740
• Time in Patent Office: 866 Days
• Field of Search: 244/158.R, 455/12.1, 455/13.1, 455/13.2, 342/352, 342/357
• US Class Current: 244/158.4
• CPC Class Codes: B64G 1/1014 Navigation satellites
• CPC Class Codes: B64G 1/1085 Swarms and constellations
• CPC Class Codes: G01S 19/073 involving a network of fixed stations
• CPC Class Codes: G01S 19/10 providing dedicated supplementary positioning signals
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]

Abstract

A satellite navigation system and method for improving overall navigation accuracy when used in conjunction with the existing Global Positioning System. At least twelve satellites reside in a plurality of medium earth orbits, each orbit having a period of at least three sidereal hours and less than one sidereal day, and an inclination angle between 35 and 75 degrees or between 105 and 145 degrees. The satellites are positioned within their orbits such that the vertical navigation accuracy provided by the system is at least 7.6 meters with at least 99.9% availability.

Claims

1. A satellite navigation system for improving overall navigation accuracythe system designed for use with a global positioning system having 24 satellites in six orbital planes at 55 degrees inclination, 12 sidereal hour periods, and right ascension of the ascending nodes offset from each other by 60 degrees, the satellite navigation system comprising:

at least 12 satellites residing in a plurality of medium earth orbits, each of the plurality of orbits having a period of at least 3 sidereal hours and less than one sidereal day, and an inclination angle selected from the group consisting of angles between 35 and 75 degrees and angles between 105 and 145 degrees, each of the at least 12 satellites positioned within the plurality of orbits at sufficient elevation angles to a user such that a vertical navigation accuracy provided by the system is at least approximately 7.6 meters with at least approximately 99.9% availability; and

means for transmitting a navigation signal to the user carried by each of the at least 12 satellites.

2. The system of claim 1 wherein all of the periods are identical and are selected from the group consisting of 16, 12, 8, 6, 4, and 3 sidereal hours.

3. The system of claim 2 further designed for use with a ground based monitoring system including a plurality of reference stations for monitoring the navigation signals of all of the satellites, a monitor station for processing the navigation signals relayed from the reference stations to generate correction data, and a ground uplink station for transmitting the correction data to the at least 12 satellites, the satellite navigation system further comprising:

a receiver for receiving the correction data substantially continuously from the ground based monitoring system carried by each of the at least 12 satellites, and

means for transmitting the correction data substantially continuously to the user carried by each of the at least 12 satellites.

4. The system of claim 3 wherein a first, a second, a third and a fourth of the at least 12 satellites reside in a first of the plurality of orbits having a right ascension of ascending node of approximately 47 degrees, a fifth, a sixth, a seventh and an eighth of the at least 12 satellites reside in a second of the plurality of orbits having a right ascension of ascending node of approximately 167 degrees, and a ninth, a tenth, an eleventh and a twelfth of the at least 12 satellites reside in a third of the plurality of orbits having a right ascension of ascending node of approximately 287 degrees, all of the plurality of orbits having a period of 12 sidereal hours, an inclination angle of 55 degrees, and an eccentricity of zero.

5. The system of claim 4 wherein the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh and twelfth of the at least 12 satellites have a mean anomaly of approximately 44, 76, 217, 310, 14, 154, 207, 306, 9, 75, 159 and 260 degrees respectively as measured at a time zero of an 863^rd week of existence of the global positioning system.

6. The system of claim 3 wherein all of the inclination angles are identical and are selected from the group consisting of 63.4 and 116.6 degrees, all of the plurality of orbits have an identical eccentricity of less than 0.5, and all of the plurality of orbits reach an apogee over global positions selected to provide the vertical accuracy in a geographical region of interest.

7. The system of claim 6 wherein the at least 12 satellites reside in at least 12 orbits, all of the at least 12 orbits having an inclination angle of 63.4 degrees, a period of 8 sidereal hours, and reaching an apogee over approximately 63 degrees North latitude and approximately 20 degrees East longitude, approximately 63 degrees North latitude and approximately 140 East longitude, and approximately 63 degrees North latitude and approximately 100 degrees West longitude.

8. The system of claim 6 wherein the at least 12 satellites reside in at least 12 orbits, all of the at least 12 orbits having an inclination angle of 63.4 degrees, a period of 16 sidereal hours, and reaching an apogee over approximately 63 degrees North latitude and approximately 20 degrees East longitude, approximately 63 degrees North latitude and approximately 140 East longitude, and approximately 63 degrees North latitude and approximately 100 degrees West longitude.

9. A method for improving overall satellite navigation accuracy, the method being designed for use with a global positioning system having 24 satellites in six orbital planes at 55 degrees inclination, 12 sidereal hour periods, and right ascension of ascending nodes offset from each other by 60 degrees the method comprising:

placing at least 12 satellites into a plurality of medium earth orbits, each of the plurality of orbits having a period of at least 3 sidereal hours and less than one sidereal day, and an inclination angle selected from the group consisting of angles between 35 and 75 degrees and angles between 105 and 145 degrees, each of the at least 12 satellites positioned within the plurality of orbits at sufficient elevation angles to a user such that a vertical navigation accuracy provided by the system is at least approximately 7.6 meters with at least approximately 99.9% availability; and

transmitting a navigation signal from each of the at least 12 satellites to the user.

10. The method of claim 9 wherein all of the periods are identical and are selected from the group consisting of 16, 12, 8, 6, 4, and 3 sidereal hours.

11. The method of claim 10 further designed for use with a ground based monitoring system including a plurality of reference stations for monitoring the navigation signals of all of the satellites, a monitor station for processing the navigation signals relayed from the reference stations to generate correction data, and a ground uplink station for transmitting the correction data to the at least 12 satellites, the satellite navigation system further comprising:

receiving the correction data substantially continuously from the ground based monitoring system at each of the at least 12 satellites; and

transmitting the correction data substantially continuously from each of the at least 12 satellites to the user.

12. The method of claim 11 wherein a first, a second, a third and a fourth of the at least 12 satellites are placed in a first of the plurality of orbits having a right ascension of ascending node of approximately 47 degrees, a fifth, a sixth, a seventh and an eighth of the at least 12 satellites are placed in a second of the plurality of orbits having a right ascension of ascending node of approximately 167 degrees, and a ninth, a tenth, an eleventh and a twelfth of the at least 12 satellites are placed in a third of the plurality of orbits having a right ascension of ascending node of approximately 287 degrees, all of the plurality of orbits having a period of 12 sidereal hours, an inclination angle of 55 degrees, and an eccentricity of zero.

13. The method of claim 12 wherein the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh and twelfth of the at least 12 satellites have a mean anomaly of approximately 44, 76, 217, 310. 14, 154, 207. 306, 9, 75, 159 and 260 degrees respectively as measured at a time zero of an 863^rd week of existence of the global positioning system.

14. The method as in claim 11, wherein all of the inclination angles are identical and are selected from the group consisting of 63.4 and 116.6 degrees, all of the plurality of orbits have an identical eccentricity of less than 0.5, and all of the plurality of orbits reach an apogee over global positions selected to provide the vertical accuracy in a geographical region of interest.

15. The method as in claim 14 wherein the at least 12 satellites are placed in at least 12 orbits, all of the at least 12 orbits having an inclination angle of 63.4 degrees, a period of 8 sidereal hours, and reaching an apogee over approximately 63 degrees North latitude and approximately 20 degrees East longitude, approximately 63 degrees North latitude and approximately 140 East longitude, and approximately 63 degrees North latitude and approximately 100 degrees West longitude.

16. The method as in claim 14 wherein the at least 12 satellites are placed in at least 12 orbits, all of the at least 12 orbits having an inclination angle of 63.4 degrees, a period of 16 sidereal hours, and reaching an apogee over approximately 63 degrees North latitude and approximately 20 degrees East longitude, approximately 63 degrees North latitude and approximately 140 East longitude, and approximately 63 degrees North latitude and approximately 100 degrees West longitude.