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Analog television
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<p>Analog television is the original <a href="/facts/Television/X4YG5nT1">television</a> technology that uses <a href="/facts/Analog_signal/xDbb4uB5">analog signals</a> to transmit <a href="/facts/Video/F1AV8ben">video</a> and audio. In an analog television broadcast, the brightness, colors and sound are represented by <a href="/facts/Amplitude/aEckuXJM">amplitude</a>, <a href="/facts/Instantaneous_phase_and_frequency/fJ17zuan">phase and frequency</a> of an analog signal. </p><p>Analog signals vary over a continuous range of possible values which means that <a href="/facts/Electronic_noise/Izbv38Rr">electronic noise</a> and interference may be introduced. Thus with analog, a moderately weak signal becomes <a href="/facts/Noise_(video)/DEqPzu8m">snowy</a> and subject to interference. In contrast, picture quality from a <a href="/facts/Digital_television/KQCyILQa">digital television</a> (DTV) signal remains good until the signal level drops below <a href="/facts/Digital_cliff/Jo0XUcG9">a threshold</a> where reception is no longer possible or becomes intermittent. </p><p>Analog television may be wireless (<a href="/facts/Terrestrial_television/3nTUr9cY">terrestrial television</a> and <a href="/facts/Satellite_television/UxytxnPW">satellite television</a>) or can be distributed over a cable network as <a href="/facts/Cable_television/GzXa4pbW">cable television</a>. </p><p>All <a href="/facts/Broadcast_television_system/BT0FfFcy">broadcast television systems</a> used analog signals before the arrival of DTV. Motivated by the lower bandwidth requirements of <a href="/facts/Compressed_video/gMFuY4FT">compressed digital signals</a>, beginning just after the year 2000, a <a href="/facts/Digital_television_transition/egLLIUlR">digital television transition</a> is proceeding in most countries of the world, with different deadlines for the cessation of analog broadcasts. Several countries have made the switch already, with the remaining countries still in progress mostly in Africa, Asia, and South America. </p>