Communications system

• US 6,944,450 B2
• Filed: 04/10/2001
• Issued: 09/13/2005
• Est. Priority Date: 04/10/2000
• Status: Active Grant

• Current Assignee: Aerovironment
• Original Assignee: Aerovironment
• Inventors: Cox, Earl C.
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): RAMPURIA, SHARAD K
• Application Number:
  US09/832,328
• Publication Number:
  US 20010039189A1
• Time in Patent Office: 1,617 Days
• Field of Search: 455/427, 455429-431, 455/12.1, 455/13.3, 342355-356, 342/359, 342/367
• US Class Current: 455/431
• CPC Class Codes: H04B 7/18504 Aircraft used as relay or high altitude atmospheric platform
• CPC Class Codes: H04B 7/18508 with satellite system used as relay, i.e. aeronautical mobile satellite service

Abstract

This disclosure provides a communications system using a span-loaded flying wing, traveling at relatively slow speeds, that can remain airborne for long periods of time. The communications system uses the airplane as a long term high altitude platform that can serve at lest one of a number of potential functions. One function is to link to a ground station using radio wave signals and a satellite using optical signals. Another function is to serve as a relay station between ground communication nodes and individual end-users. Because the aircraft can tightly hold a station, the end-user'"'"'s antennas do not need to be continuously adjustable. For such a system, a large number of aircraft can be used, with the end-user antennas being configured for a narrow beamwidth so as to allow frequency reuse for different communication links.

Claims

1. A method of maintaining a communications link between a ground station and a suborbital platform, wherein the ground station communicates using an antenna that provides a communication signal of limited beamwidth, comprising:

positioning the suborbital platform and aiming the antenna such that the suborbital platform is within the beamwidth of the antenna'"'"'s signal;

maintaining the antenna'"'"'s aim in a fixed orientation; and

flying the suborbital platform in a pattern that maintains the suborbital platform within the beamwidth of the signal.

2. The method of claim 1, wherein the airplane is substantially maintained within a geostationary station delimited by a 4000-foot diameter circle and a 100-foot altitude range.

3. The method of claim 1, wherein the step of flying is continued for at least 200 hours.

4. The method of claim 1, wherein the step of flying is continued for at least 3000 hours.

5. The method of claim 1, wherein the suborbital platform is an airplane.

6. A communications system for communicating between a satellite and a ground station, comprising:

a downward-pointing communications antenna on the satellite, the downward-pointing antenna having a limited signal beam-width;

an upward-pointing communications antenna on the ground station, the upward-pointing antenna having a limited signal beam-width, wherein the downward-pointing antenna and the upward-pointing antenna are aimed such that they delimit a geostationary region of airspace that is within both signal beam-widths; and

a suborbital platform configured to fly a pattern entirely within the delimited region of airspace.

7. The communication system of claim 6, wherein the suborbital platform is substantially maintained within a geostationary station delimited by a 4000-foot diameter circle and a 100-foot altitude range.

8. A communication system, comprising:

a ground station;

a spacecraft in geosynchronous orbit, the ground station and the spacecraft having communications systems that are characterized by operating with given beamwidths; and

a suborbital platform maintained at a non-equatorial latitude that prevents the ground station from being within the beamwidth of communication signals transmitted by the spacecraft toward the suborbital platform, and that prevents the spacecraft from being within the beamwidth of communication signals transmitted by the ground station toward the suborbital platform;

wherein the ground station maintains both a direct communications signal and an indirect communications signal with the spacecraft, the indirect communications signal being directed to the suborbital platform which relays the signal to the spacecraft; and

wherein the direct and indirect communications signals from the ground station use the same wavelengths.

9. The communication system of claim 8, wherein the suborbital platform is configured to operate for at least 200 hours.

10. The communication system of claim 8, wherein the suborbital platform is configured to operate for at least 3000 hours.

11. The communication system of claim 8, wherein the suborbital platform is configured to maintain the airplane within a station delimited by a 4000-foot diameter circle and a 100-foot altitude range.

12. A communication apparatus for communicating data between a terrestrial gateway and a plurality of terrestrial terminals, comprising:

an airplane flying within a geostationary station; and

a network carried by the airplane, and having at least three downward-pointing communication devices, each communication device defining a beamwidth for communication, the communication devices'"'"' beamwidths delimiting distinct terrestrial communication cells that include the terminals when the airplane is aloft in a predetermined station;

wherein the network is configured to maintain a communications signal carrying the data with the gateway;

wherein the communications devices are configured to route the data carried by the communication signal between the network and the plurality of terminals; and

wherein each terminal has a terminal antenna configured for carrying the communication signal, the terminal antenna being configured such that the airplane'"'"'s entire flight station falls within the terminal antenna'"'"'s beamwidth without any adjustment of the terminal antenna'"'"'s aim.

13. The communications system of claim 12, wherein:

the network is configured to maintain additional communications signals carrying additional data with additional gateways; and

the communications devices are further configured to route the data carried by the additional communication signals between the network and the plurality of terminals.

14. The communications system of claim 12, wherein the communications device is carried by an airplane configured to stay aloft without refueling for at least 200 hours.

15. The communications system of claim 12, wherein the communications device is carried by an airplane configured to stay aloft without refueling for at least 3000 hours.

16. The communications system of claim 12, wherein the terminal antenna includes no active tracking mechanism.

17. A communication system for communicating data between one or more gateways and a plurality of terrestrial terminals, each terminal having an antenna characterized by an orientation and a beamwidth, comprising:

a plurality of airplanes including a first airplane and a second airplane, each airplane stationkeeping within a geostationary flight station; and

a plurality of networks, each airplane carrying a network, each network having at least three downward-pointing communication devices, each communication device defining a beamwidth for communication, the communication devices'"'"' beamwidths delimiting distinct terrestrial communication cells that include the terminals when the airplane is aloft in its respective flight station;

wherein the networks of the first airplane and the second airplane are configured to communicate with terminals in one or more of the same communication cells using the same wavelengths;

wherein each network is configured to maintain communications with the one or more gateways;

wherein each communications device is configured to route data carried by its respective network'"'"'s gateway communications between its respective network and one or more of the plurality of terminals; and

wherein each airplane'"'"'s respective station is outside of the oriented beamwidths of the terminal antennas that are in communication with other airplanes.

18. The communications system of claim 17, wherein each airplane is configured to stay aloft without refueling for at least 200 hours.

19. The communications system of claim 17, wherein each airplane is configured to stay aloft without refueling for at least 3000 hours.

20. The communications system of claim 17, wherein each terminal antenna is configured such that the entire station of the airplane, with which it is in communication, falls within the terminal antenna'"'"'s beamwidth without any adjustment of the terminal antenna'"'"'s orientation.

21. The communications system of claim 20, wherein the terminal antenna includes no active tracking mechanism.