Optical communication system using a high altitude tethered balloon

• US 7,046,934 B2
• Filed: 07/03/2002
• Issued: 05/16/2006
• Est. Priority Date: 01/10/2000
• Status: Expired due to Fees

• Current Assignee: Johns Hopkins University
• Original Assignee: Johns Hopkins University
• Inventors: Goldfinger, Andrew D., Jerardi, Thomas W., Badesha, Surjit S.
• Primary Examiner(s): Vanderpuye, Kenneth
• Assistant Examiner(s): TRAN, DZUNG D
• Application Number:
  US10/188,631
• Publication Number:
  US 20020167702A1
• Time in Patent Office: 1,413 Days
• Field of Search: 398/121, 398/122, 398/125, 398/129, 398/131, 398/128, 342 53- 54, 342/159, 342/367
• US Class Current: 398/121
• CPC Class Codes: B64B 1/50 Captive balloons
• CPC Class Codes: B64B 1/60 Gas-bags surrounded by separate containers of inert gas
• CPC Class Codes: B64G 1/1007 Communications satellites
• CPC Class Codes: B64G 1/66 Arrangements or adaptations of apparatus or instruments, not otherwise provided for
• CPC Class Codes: B64G 5/00 Ground equipment for vehicles, e.g. starting towers, fuelling arrangements B64G3/00 takes precedence
• CPC Class Codes: H04B 10/118 specially adapted for satellite communication
• CPC Class Codes: H04B 7/18504 Aircraft used as relay or high altitude atmospheric platform

Abstract

An optical communication system using a high altitude tethered balloon 10 that operates above most clouds and atmospheric turbulence. An optical communication system includes a balloon 10 with an optical communication payload 30, a fiber optic cable attached to the tether 12, an automated winch system 14, and a ground station 28. The balloon 10 is designed for sustained flight at, and recovery from, high altitude using the automated winch system 14. An acquisition, tracking and pointing (ATP) system 22 enables a balloon-based optical transceiver 24 to maintain line-of-sight optical communications with an overhead satellite 34. The optical link between the satellite 34 and the balloon 10 is an open channel. Data is transmitted to the ground station 28 from the balloon 10 through the secure fiber optic closed channel attached to the tether 12.

Claims

1. An optical communication system for achieving a clear optical path between earth and a spacecraft with minimal atmospheric disturbances, comprising:

a ground station;

a high altitude balloon system, said balloon system including;

a balloon;

an automated winch near said ground station and operatively connected to said balloon for launching and recovering said balloon; and

a tether extending from said winch to said balloon;

a transceiver attached to said balloon for transmitting or receiving optical data to and from the spacecraft;

an acquisition, tracking and pointing system attached to said balloon for locating the spacecraft, said acquisition, tracking and pointing system including;

a telescope;

coarse pointing means, including a differential GPS system for determining a coarse attitude of said balloon relative to earth fixed coordinates, for determining based on said coarse attitude a coarse line of sight from said balloon to the satellite;

a gimbal, operatively connected to said telescope and to said means for determining said coarse line of sight, for aligning said telescope with said coarse line of sight from said balloon to the satellite; and

fine pointing means, using “

blob coloring”

of an optical signal received from the spacecraft through the coarsely aligned telescope, for further aligning said telescope with said spacecraft so as to center a field-of-view of said transceiver with the spacecraft, thereby enabling open channel optical communication between said balloon and the spacecraft; and

a fiber optic cable attached to said tether and extending from said balloon to said ground station, enabling closed channel optical communication between said balloon and said ground station.

2. An optical communication system as recited in claim 1, wherein said fiber optic cable is embedded in said tether.

3. An optical communication system as recited in claim 1, wherein said tether is tapered between said balloon and said winch.

4. An optical communication system as recited in claim 1, wherein said balloon is spherical in shape.

5. An optical communication system as recited in claim 1, wherein said balloon is operated at an altitude between 12 and 21 km.

6. An optical communication system as recited in claim 1, wherein said high altitude balloon system further comprises:

a ballonet; and

a pressurization system operatively connected to said ballonet for filling and exhausting said ballonet.

7. An optical communication system as recited in claim 1, wherein the spacecraft is a satellite.

8. The system of claim 1, wherein said fine pointing means further includes:

a focal plane array for imaging the optical signal received through the telescope as a collection of intensity “

blobs”

; and

means, using said blob coloring of said intensity blobs, for centering the optical signal in the transceiver field-of-view.

9. The system of claim 1, wherein the coarse pointing means further includes:

a GPS navigation receiver for determining a position of said balloon,

wherein said coarse pointing means includes means for determining said coarse line of sight from said balloon to the satellite based on both said balloon coarse attitude from said DGPS and said balloon position from said GPS navigation receiver.

10. An optical communication system for achieving a clear optical path between earth and a spacecraft with minimal atmospheric disturbances, comprising:

a ground station;

a high altitude balloon system, said balloon system including;

a balloon;

an automated winch near said ground station and operatively connected to said balloon for launching and recovering said balloon; and

a tether extending from said winch to said balloon;

a transceiver attached to said balloon for transmitting or receiving optical data to and from the spacecraft;

an acquisition, tracking and pointing system attached to said balloon for locating the spacecraft, said acquisition, tracking and pointing system including;

a telescope;

coarse pointing means, including a differential GPS system for determining a coarse attitude of said balloon relative to earth fixed coordinates, for determining based on said coarse attitude a coarse line of sight from said balloon to the satellite;

a gimbal, operatively connected to said telescope and to said means for determining said coarse line of sight, for aligning said telescope with said coarse line of sight from said balloon to the satellite, thereby positioning an optical signal from the spacecraft within a field-of-view of said telescope; and

fine pointing means, operatively coupled to said gimbal, using “

blob coloring”

for further aligning said telescope with the spacecraft so as to center the spacecraft optical signal within a FOV of said transceiver that is narrower than and within said telescope FOV, thereby enabling open channel optical communication between said balloon and the spacecraft; and

a fiber optic cable attached to said tether and extending from said balloon to said ground station, enabling closed channel optical communication between said balloon and said ground station.