SECAM - Système Électronique pour Couleur avec Mémoire. Developed in France. First used in 1967. A 625-line vertical, 50-line horizontal display.
PAL - Phase Alternating Line. Developed by German engineer Walter Bruch who patented his invention 1963 and the first commercial application of the PAL system was in August 1967. Also a 625/50-line display and alternative of NTSC. Proponents call it "Perfection At Last."
Television programs may be transmitted either “live” or from a recording. The principle means of recording television programs for future use is videotape recording. Videotape recording is similar to conventional tape recording .The sound is recorded along with the video signal on the same tape.
When a television program is broadcast, the varying electrical signals are then amplified and used to modulate a carrier wave the modulated carrier is usually fed to an antenna, where it is converted to electromagnetic waves and broadcast over a large region. The waves are sensed by antennas connected to television receivers.
The range of waves suitable for radio and television transmission is divided into channels, which are assigned to broadcast companies or services.
Most television viewers across the world no longer receive signals by using antennas; instead, they receive programming via cable television. Cable delivery of television started as a way to improve reception. A single, well-placed community antenna received the broadcast signals and distributed them over coaxial or fiber-optic cables to areas that otherwise would not be able to receive them. Today, cable television is popular because of the wide variety of programming it can deliver. Many systems now provide more than 100 channels of programming. Typically, a cable television company receives signals relayed from a communications satellite and sends those signals to its subscribers.
The first transatlantic television broadcast was accomplished by such a satellite, called Telstar, on July 10, 1962. Some television viewers use small satellite dishes to receive signals directly from satellites. Most satellite-delivered signals are scrambled and require a special decoder to receive them clearly.