Analog TV was the original television technology that transmitted video and audio using analog signals, which are continuous electrical waves varying in amplitude, phase, and frequency to represent brightness, colors, and sound
. In an analog TV broadcast, images were created by scanning lines across the screen rapidly enough that the human eye perceived a moving picture, with synchronization signals ensuring proper timing for image reconstruction
. The technology evolved from early mechanical systems with spinning disks to all-electronic systems using cathode-ray tubes (CRT), where an electron beam swept across a phosphor-coated screen to produce images by varying beam intensity
. Analog TV signals were broadcast over radio frequencies (VHF and UHF) using amplitude modulation for video and frequency modulation for audio
. Because analog signals vary continuously, they were susceptible to interference and noise, which could degrade picture quality, causing effects like snow or ghosting as the signal weakened
. Analog TV required manual tuning to select channels, each assigned a specific frequency
. Analog television was the dominant system worldwide until the transition to digital television began in the early 2000s, motivated by digital's better bandwidth efficiency and superior image quality
. Digital TV eventually replaced analog broadcasts in most countries, although some regions still completed the transition more recently. In summary, analog TV was a continuous signal-based system for broadcasting television content, using CRT displays and radio frequency transmission, characterized by susceptibility to signal degradation and lower resolution compared to modern digital TV
