CABLE-LESS TELEVISION SYSTEM

• US 3,674,925 A
• Filed: 12/03/1970
• Issued: 07/04/1972
• Est. Priority Date: 12/03/1970
• Status: Expired due to Term

• Current Assignee: Paul J. Heckman Jr
• Original Assignee: Paul J. Heckman Jr
• Inventors: Heckman, Paul J. Jr.
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Eckert, Jr., Richard K.
• Application Number:
  US05/094,659
• Time in Patent Office: 579 Days
• Field of Search: 250/199 178/DIG.1,29,DIG.8,DIG.38,6.8
• US Class Current: 348/143
• CPC Class Codes: H04N 7/005 using at least one opto-electrical conversion device
• CPC Class Codes: H04N 7/22 Adaptations for optical transmission

Abstract

This invention relates to apparatuses and methods for enabling surveillance of a distant target from a remote viewing point which does not require a cable or acoustic signals between the target and the viewing point. The apparatus at the target includes a light source, for example, a laser, for illuminating the target, and which may be modulated by any of various known techniques, at a frequency in the range of 3 kHz or more. A TV camera tube, which observes the target, generates a conventional composite video signal, including horisontal and vertical blanking pulses, the bandwidth of the video system being at least 50 kHz. A light source modulator connected between the light source and the TV camera tube, modulates the light source in accordance with the variation in amplitude of the composite video signal. The apparatus at the remote viewing point includes a lens for focusing the light from the target, remote light source, and any scattered light from the medium in which the target is located, and a photodetector for receiving the light focused by the lens. A frequency-compensating amplifier, connected to the photodetector, compensates for any drop in high-frequency response to the photodetector. A demodulator, connected to the output of the frequency-compensating amplifier, demodulates the modulated composite video signal, and, in effect, decodes the video information. A TV monitor, connected to the output of the pulse-time demodulator, permits observing the target at the viewing point remote from the target.

Claims

1. Apparatus for enabling surveillance of a target from a remote viewing point, not requiring a cable or acoustic signals between the target and the viewing point, the apparatus at the target comprising:

a light source, for illuminating the target area, whose intensity may be varied;

a TV camera tube, positioned to receive the light reflected from the target area, which generates a conventional composite video signal, including horizontal and vertical blanking pulses;

a light source modulator, connected between the light source and the TV camera tube, for modulating the intensity of the entire light source uniformly in accordance with the variation of amplitude of the composite video signal generated by the TV camera tube.

2. The surveillance apparatus according to claim 1, wherein the apparatus at the viewing point remote from the target comprises:

a lens for focusing the light from the distant target, the light source and any scattered light from the medium in which the target is located;

a photodetector for receiving the light focused by the lens;

a demodulator, connected to the output of the photodetector, for demodulating the modulated composite video signal; and

a TV monitor connected to the demodulator, for viewing the distant target.

3. The apparatus according to claim 2, wherein the light source is a laser source;

and the light source modulator and demodulator are pulse-time devices.

4. The apparatus according to claim 3, wherein the pulse-time modulator and demodulator comprise a pulse-duration modulator and demodulator.

5. The apparatus according to claim 3, wherein the pulse-time modulator and demodulator comprise a pulse-position moDulator and demodulator.

6. The apparatus according to claim 2, wherein the light source is a laser light source;

and the light source modulator and demodulator are amplitude-modulated devices, using a Kerr cell.

7. The surveillance apparatus according to claim 1, wherein the intensity of the light source may be varied at a frequency as high as 3 kHz or more;

and wherein the bandwidth of the video signal generated by the camera tube is at least 50 kHz.

8. The surveillance apparatus according to claim 2, further comprising:

a frequency-compensating amplifier, connected between the photodetector and the demodulator, for compensating for any drop in the high-frequency response of the photodetector.

9. Apparatus for enabling surveillance of a target from a remote viewing point, not requiring a cable or acoustic signals between the target and the viewing point, the apparatus at the target comprising:

an infrared (IR) radiation source, for illuminating the target area with IR radiation, whose intensity may be varied at a frequency as high as 3 kHz or more;

an IR scanning receiver tube, positioned to receive the light reflected from the target area, which generates a conventional composite video signal, including horizontal and vertical blanking pulses, the bandwidth of the video signal being at least 50 kHz;

an IR radiation source modulator, connected between the IR radiation source and the IR scanning tube, for modulating the intensity of the entire IR radiation source uniformly, for example, by pulse-time modulation, in accordance with the variation in amplitude of the composite video signal generated by the IR scanning receiver tube.

10. The surveillance apparatus according to claim 9, wherein the apparatus at the viewing point comprises:

a lens for focusing the IR radiation from the distant target, IR light source and any scattered IR radiation from the medium in which the target is located;

an IR photodetector for receiving the IR radiation focused by the lens;

a frequency-compensating amplifier, connected to the IR photodetector, for compensating for any drop in high-frequency response of the IR photodetector;

a demodulator, for example, a pulse-time demodulator, connected to the output of the frequency-compensating amplifier, for demodulating the modulated composite video signal; and

a TV monitor, connected to the demodulator, for observing the distant target.

11. A method for enabling surveillance of a target from a remote viewing point, not requiring a cable or acoustic signals between the target and the remote point, the method at the target comprising the steps of:

illuminating the target by a light source whose intensity may be varied at a frequency in the range of 3 kHz or more;

observing the target area by a TV camera tube, positioned to receive the light reflected from the target area, which generates a conventional composite video signal, including horizontal and vertical blanking pulses, the bandwidth of the video signal being at least 50 kHz; and

connecting a light source modulator between the light source and the camera tube, in order to uniformly modulate, for example, by pulse-time modulation, the entire light source in accordance with the variation in amplitude of the composite video signal generated by the TV camera tube.

12. The method according to claim 11, wherein the method at the remote viewing point comprises the steps of:

detecting the modulated variations in the intensity of the light source by means of a lens focusing the light variations upon a photodetector;

compensating for the frequency with a frequency-compensating amplifier, connected to the photodetector, which compensates for any drop in the high-frequency response of the photodetector;

demodulating, for example, by pulse-time demodulation, the compensated output of the frequency-compensating amplifier; and

viewing the distant target on a TV monitor connected to the output of the demodulator.