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  2. Videotelephony - Wikipedia

    en.wikipedia.org/wiki/Videotelephony

    The movie was released shortly before AT&T began its efforts to commercialize its Picturephone Mod II service in several cities and depicts a video call to Earth using an advanced AT&T videophone—which it predicts will cost $1.70 for a two-minute call in 2001 (a fraction of the company's real rates on Earth in 1968).

  3. Optical communication - Wikipedia

    en.wikipedia.org/wiki/Optical_communication

    A replica of a Chappe telegraph tower (18th century). A 'semaphore telegraph', also called a 'semaphore line', 'optical telegraph', 'shutter telegraph chain', 'Chappe telegraph', or 'Napoleonic semaphore', is a system used for conveying information by means of visual signals, using towers with pivoting arms or shutters, also known as blades or paddles.

  4. Rules for traffic lights - Wikipedia

    en.wikipedia.org/wiki/Rules_for_traffic_lights

    Traffic light in Chelyabinsk, Russia showing a green light with a digital countdown (in the centre aspect) of the time left until the signal switches to amber. Red light running occurs when a motorist enters a junction any time after the signal light turns red unless a legal turn on red manoeuvre is completed. [3]

  5. Signal lights - Wikipedia

    en.wikipedia.org/wiki/Signal_lights

    Signal lights may refer to: Traffic light, signal lights controlling automotive & pedestrian traffic flow; Turn signals, signal lights indicating automotive change of direction; Railway signalling, use of signal lights to control train traffic flow; Signal lamp, a device for communicating between ships with flashing lights.

  6. Video modulation - Wikipedia

    en.wikipedia.org/wiki/Video_modulation

    Video signals are usually encoded into binary digit (0, 1) or seven digit pulse-code modulation (PCM), which is a method used to digitally represent original video signal. . The video signal converted to binary digit PCM at the point of origin can be then transmitted over existing telephone cable or wire directly to the destination

  7. 'Turn off the lights!': Donald Trump leads unusual chant ...

    www.aol.com/article/2016/02/21/turn-off-the...

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  8. Line signaling - Wikipedia

    en.wikipedia.org/wiki/Line_signaling

    Line signaling is responsible for off-hook, ringing signal, answer, ground start, on-hook unidirectional supervision messaging in each direction from calling party to called party and vice versa. After an off-hook, line signaling initiates register signaling to accomplish the exchange of telephone numbers of called party and in more modern line ...

  9. Supervision (telephony) - Wikipedia

    en.wikipedia.org/wiki/Supervision_(telephony)

    The signal may be implemented by removal of battery on the circuit (open switching interval) or by polarity reversal of the tip and ring conductors of the telephone line. An analogue telephone line may also send tones, such as a busy signal , reorder tone , or dial tone , to indicate a call has ended.