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CCIR System A was the 405 line analog broadcast television system broadcast in the UK and Ireland. It was discontinued in 1985. == Specifications == (詳細はAmplitude Modulation. But a portion of the upper side band is suppressed. This technique is known as vestigial side band modulation (AC3). The polarity of modulation is positive, meaning that an increase in the instantaneous brightness of the video signal results in an increase in RF power and vice versa. Specifically, the sync pulses (being "blacker than black") result in minimum power (possibly zero power) from the vision transmitter. The audio signal was modulated by Amplitude modulation. The separation between the audio AM carrier and the video carrier is -3.5 MHz. The total RF bandwidth of System A was 4.26 MHz, allowing System A to be transmitted in the 5.0 MHz wide channels specified for television in the British VHF bands with an ample 740 kHz guard zone between channels. In specs, sometimes, other parameters such as vestigial sideband characteristics and gamma of display device are also given. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「CCIR System A」の詳細全文を読む スポンサード リンク
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