Video communication system and phase or frequency modulator included therein
First Claim
Patent Images
1. A video communication system for transmitting still pictures of a scene during periodic intervals each of a predetermined duration, comprising:
- a T.V. camera producing video analog signals of the scene to be transmitted;
an analog-to-digital converter converting the video analog signals to pixel digital signals representing the gray level of each pixel in the scene;
a memory for storing said pixel gray levels for the predetermined duration;
generator means for generating a carrier wave;
and a modulator for modulating said carrier wave by said pixel gray levels from said memory;
said modulator being a phase modulator which shifts the cross-over point of the carrier wave no more than 180°
according to the gray level of the respective pixel in said picture.
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Abstract
A video communication system for transmitting still pictures of a scene during periodic intervals comprises a T.V. camera producing video analog signals of the scene to be transmitted, an analog-to-digital converter converting the video analog signals to pixel digital signals representing the gray level of each pixel in the scene, a memory for storing the pixel gray levels, and a phase modulator for modulating a carrier wave by the pixel gray levels from the memory.
90 Citations
19 Claims
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1. A video communication system for transmitting still pictures of a scene during periodic intervals each of a predetermined duration, comprising:
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a T.V. camera producing video analog signals of the scene to be transmitted; an analog-to-digital converter converting the video analog signals to pixel digital signals representing the gray level of each pixel in the scene; a memory for storing said pixel gray levels for the predetermined duration; generator means for generating a carrier wave; and a modulator for modulating said carrier wave by said pixel gray levels from said memory; said modulator being a phase modulator which shifts the cross-over point of the carrier wave no more than 180°
according to the gray level of the respective pixel in said picture. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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2. A video communication system for transmitting still pictures of a scene during periodic intervals each of a predetermined duration, comprising:
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a T.V. camera producing video analog signals of the scene to be transmitted; an analog-to-digital converter converting the video analog signals to pixel digital signals representing the gray level of each pixel in the scene; a memory for storing said pixel gray levels for the predetermined duration; generator means for generating a carrier wave; and a modulator for modulating said carrier wave by said pixel gray levels from said memory; said modulator comprising;
a converter converting said stored pixel gray levels to a series of signal pulses each having a duration corresponding to the instantaneous value of the stored pixel gray level;
said modulator changing the cross-over point of the carrier wave according to the duration of said signal pulses, to thereby modulate the carrier wave according to the instantaneous value of the stored pixel gray level. - View Dependent Claims (3, 4, 5, 6)
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13. A phase modulator for modulating a carrier wave by video analog signals derived from a picture and converted to pixel digital signals representing the gray levels of the picture elements in the picture, said modulator comprising:
- generator means generating a carrier wave;
a converter converting said pixel digital signals to a series of signal pulses each having a duration corresponding to the instantaneous value of the video analog signals; and
modulator means changing the cross-over point of the carrier wave no more than 180°
according to the duration of said signal pulses, to thereby modulate the carrier wave according to the instantaneous value of the video analog signal. - View Dependent Claims (14, 15, 16, 17, 18, 19)
- generator means generating a carrier wave;
Specification