Electro-optical tracking computer utilizing television camera

• US 3,988,534 A
• Filed: 07/28/1969
• Issued: 10/26/1976
• Est. Priority Date: 07/28/1969
• Status: Expired due to Term

• Current Assignee: Northrop Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Corporation (Northrop Grumman Corporation)
• Inventors: Sacks, Jacob M.
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US04/848,401
• Time in Patent Office: 2,647 Days
• Field of Search: 178/6.8, 178/DIG. 21
• US Class Current: 348/171
• CPC Class Codes: G01S 3/7864 T.V. type tracking systems

Abstract

A television camera is trained on a target to produce a video image thereof. The video signals are converted to unipolar form such that black to white and white to black contrast produces the same polarity video signals and these signals appropriately filtered so that only the desired target signals remain. A tracking gate is generated which automatically accommodates to the size of the selected target and forms an optical window which surrounds the target on a viewing screen. In an acquisition mode of operation, the operator brings the target so that it lies within the window at which time he initiates a "track" mode of operation whereupon error signals are generated as the target moves out of the window, these error signals being utilized in a servo system to slew the camera such as to maintain "lock-on".

Claims

1. In combination:

a television camera for generating bipolar video signals representing targets within its field of view, said camera including a video monitor,

means for full wave rectifying said signals to convert them to unipolar form,

means for generating a tracking gate,

means for automatically controlling the dimensions of said gate in accordance with the dimensions of one of said video signals representing a selected target,

means for eliminating video signals of less than a predetermined width,

means for comparing said gate and said signals representing a selected target for time coincidence, and generating error signals whenever they tend to drift out of coincidence, and

tracking servo means responsive to said error signals for slewing said camera so as to minimize said error signals.

2. The combination of claim 1 and further including means for eliminating video signals not in time coincidence with said gate.

3. The combination of claim 1 wherein said means for generating error signals includes a horizontal error detector for comparing horizontal video signals for time coincidence with a horizontal gate and a vertical error detector for comparing vertical signals for time coincidence with a vertical gate.

4. The combination of claim 1 and further including means responsive to said gate for generating a window signal for display on said monitor.

5. The combination of claim 4 wherein said means for generating a window signal is adapted to generate a square window in accordance with the greatest of the horizontal and vertical dimensions of said selected target.

6. The combination of claim 4 and further including means for switching to a caged mode of operation wherein said window signal is fixed in size and position on said monitor.

7. In a tracking computer,

a television camera for generating bipolar video signals in accordance with targets within its field of view, said camera including an optical monitor,

means for full wave rectifying said video signals to convert them to unipolar form,

means for eliminating signals of less than a critical pulse width from said unipolar video signals, leaving only signals representing the major portion of a selected target,

means responsive to said signals representing the major portion of said target for automatically generating window control signals in accordance with the dimensions of said major portions of said target,

means responsive to said window control signals for generating window signals for display on said monitor,

means responsive to said window control signals for eliminating video signals not in time coincidence therewith, said time coincident signals representing the major portion of said target,

means for generating a threshold reference signal in accordance with the peak of said time coincidence signals which is scaled in response to a signal in accordance with the size of said window signals,

threshold detector means receiving said video signals and said threshold level signal for positive and negative limiting said video signals in accordance with said threshold reference signal, and

means for generating error signals whenever said window signals and said signals representing the major portion of said target to drift out of time coincidence with each other.

8. The tracking computer of claim 7 wherein said means for generating window control signals includes means for generating equal horizontal and vertical window control signals in accordance with the greatest of these two dimensions of the major portion of said target.

9. The computer of claim 7 and further including means for switching said computer to a caged mode of operation wherein said window control signals are fixed in size and position.

10. The computer of claim 7 and further including dynamic acquisition means for automatically switching from caged operation to tracking operation whenever the video signals having time coincidence with said window signal exceed a predetermined level.

11. In a tracking computer,

a television camera for generating video signals in accordance with targets within its field of view, said camera including a video monitor, said camera being adapted to be trained onto a target,

means for generating an optical window, said window being displayed on said monitor,

mode control means for alternatively caging said window on said monitor in a fixed position and size or permitting said window to function as a tracking gate,

video processor and target selector means for full wave rectifying said video signals to convert them to unipolar form and for eliminating signals not arriving in time coincidence with said window,

target width discriminator means receiving the output of said video processor and target selector means for eliminating video signals of less than a predetermined pulse width leaving only signals representing the major portion of the target,

window size control means responsive to said signals representing the major portion of the target for automatically controlling the dimensions of said window to accommodate the major portion of the target,

error detector means for comparing said signals representing the major portion of the target with said window and for generating error signals whenever they tend to drift out of time coincidence with each other, and

tracking servo means responsive to said error signals for slewing said camera to minimize said error signals.

12. The computer of claim 11 wherein said window size control means comprises means for generating equal horizontal and vertical window portions in accordance with the greatest of these two dimensions of the major portion of the target.

13. The computer of claim 11 and further including dynamic acquisition means for automatically switching from caged operation to tracking operation whenever video signals falling within the window exceed a predetermined level.

14. The computer of claim 11 wherein said size control means includes means for generating signals in accordance with the horizontal and vertical dimensions of the major portion of the target respectively and means for generating a composite window control signal in accordance with the greater of these two dimensions.

15. The computer of claim 14 wherein said error detector means comprises separate horizontal and vertical error detectors for generating horizontal and vertical error signals respectively.

16. The computer of claim 15 and further including dynamic response control means for controlling the gain of said horizontal error detector means in inverse relationship to the height of the major portion of the target.