A TELEVISION SYSTEM FOR TERRAIN SURVEILLANCE

• US 3,668,308 A
• Filed: 07/20/1970
• Issued: 06/06/1972
• Est. Priority Date: 07/20/1970
• Status: Expired due to Term

• Current Assignee: Herman J. Hoffman, Warren T. Burt
• Original Assignee: Herman J. Hoffman, Warren T. Burt
• Inventors: Burt, Warren T., Hoffman, Herman J.
• Primary Examiner(s): Konick, Bernard
• Assistant Examiner(s): Pokotilow, Steven B.
• Application Number:
  US05/056,563
• Time in Patent Office: 687 Days
• Field of Search: 178/6.6R,6.6A,6.7R,6.7A,DIG.20 179/1.2T,1.2B
• US Class Current: 348/146
• CPC Class Codes: H04N 5/765 Interface circuits between an apparatus for recording and another apparatus
• CPC Class Codes: H04N 7/005 using at least one opto-electrical conversion device

Abstract

A system for terrain surveillance from an aircraft utilizing a scanning optical system, a TV monitor, and a modified video recorder. A rotating mirror scans a section of the terrain below the aircraft extending transversely to the aircraft flight path and directs the reflected light onto a photocell. The photocell signal forms the input to the video recorder and TV monitor. The TV display is unconventional in that each frame presented has one new scan added and the lower-most old scan is removed and thus the pilot sees on his monitor a terrain picture which advances as the aircraft moves along its flight path.

Claims

1. A system for terrain surveillance from an aircraft comprising:

means for scanning an area of terrain and projecting an image of the area;

means for controlling the scanning frequency of said scanning means in response to the ground speed of the aircraft;

photoelectric detector means, disposed so as to receive the projected image, for providing an electrical output signal in response to the image;

visual display means;

a video tape recorder connected between the detector means and the display means, said recorder including;

a. a stationary record head for recording information on the tape in response to the output of the detector;

b. a rotatably mounted disk;

c. a readout head means, mounted on the disk, for reading the information on the tape;

d. variable speed driving means for driving said tape past the record head and the readout head means; and

1 e. means for rotating the disk in the direction of tape movement at a speed which exceeds the speed of the tape by a predetermined amount; and

means for varying the speed of the tape driving means in response to the scanning frequency of the scanning means.

2. The system of claim 1 wherein the information is recorded on the tape as a series of individual lines, each line containing the information received from one scan of said scanning means, and the readout head means includes at least one readout head which is swept past sufficient lines to form one video frame for each complete revolution.

3. The system of claim 1 wherein the information is recorded on the tape as a series of individual lines, each line containing the information received from one scan of said scanning means, and the speed of the rotating disk exceeds the speed of the tape driving means by an amount which causes the readout head means to read one new line per frame of the picture on the display means.

4. The system of claim 3 wherein the display means is a TV monitor.

5. The system of claim 4 further including vertical sweep means for the TV monitor whereby each successive scan line will be added to the top of the video picture and one line dropped from the bottom to provide a continuous map of the aircraft flight path.

6. The system of claim 4 wherein the readout hEad means includes two readout heads mounted on the rotating disk, each head sweeping past 525 of the recorded lines per 180* of rotation of the disk.

7. The system of claim 6 wherein each head is swept past 525 of the recorded lines 15 times per second.

8. The system of claim 1 wherein the scanning mean uses a single line scan technique and includes:

a rotating mirror;

a gyro connected to the rotating mirror to stabilize it in pitch and roll;

an aperture to control the field of view of the rotating mirror, the aperture limiting the field to a single scan oriented transversely to the flight of the aircraft; and

an optical system to project an image from the mirror onto the detector.

9. The system of claim 8 wherein said aperture is variable, the size of the aperture being a function of the aircraft altitude.

10. The system of claim 8 wherein the rotating mirror is multisided, the number of reflective surfaces used being a function of the field of view required, and the desired speed of mirror rotation.

11. The system of claim 10 wherein the rotating mirror sweeps one line, perpendicular to the flight path, for each foot of forward motion of the aircraft with respect to the ground.

12. The system of claim 11 wherein the optical system is a reflective system of mirrors without the use of lenses.

13. The system of claim 12 wherein the detector means includes a photomultiplier cell.