TV

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What Is TV?

Television (TV) is a broadcast medium that captures, transmits, and displays moving images with synchronized audio, allowing content to reach audiences across distances ranging from a few kilometers to the entire globe. The technology integrates optics, radio-frequency transmission, signal processing, and display engineering into a single system. From its early experimental demonstrations in the 1920s to the high-resolution streaming services of today, television has continuously absorbed advances from neighboring engineering disciplines.

TV technology draws its roots from electromechanical scanning systems pioneered by researchers such as John Logie Baird, followed by the fully electronic systems developed by Philo Farnsworth and Vladimir Zworykin. The shift from mechanical to electronic scanning in the 1930s established the core architecture, a camera that converts light to electrical signals, a transmission chain, and a receiver that reconstructs the image, that persists in updated form across all subsequent generations of the medium.

Analog and Color Television

Early broadcast television used analog signals in which picture information was encoded as continuous voltage variations. The National Television System Committee (NTSC) standard, adopted in the United States in 1941 and extended to color in 1953, encoded color as a subcarrier phase and amplitude modulation added to the existing luminance signal. PAL and SECAM served similar roles in Europe. Color compatibility was engineered so that black-and-white receivers could still display the luminance component of a color broadcast, a constraint that shaped the encoding mathematics of all three analog systems.

Digital Television and HDTV

Digital television replaces the continuous analog waveform with compressed binary data. The transition brought higher picture quality, more efficient use of spectrum, and the ability to multiplex several programs within a single broadcast channel. High-definition television (HDTV) operates at resolutions of 1280x720 or 1920x1080 pixels with a 16:9 aspect ratio, a substantial increase over the 480-line standard-definition systems it replaced. The ATSC standards developed by the Advanced Television Systems Committee define the encoding, transmission, and receiver specifications used in North America. Video compression relies on the MPEG-2 and later H.264 and H.265 codecs, which exploit spatial and temporal redundancy to achieve the data rates compatible with broadcast and cable delivery.

Over-the-Air and Cable Delivery

Over-the-air (OTA) broadcasting transmits signals from a tower to receiving antennas using allocated spectrum in the VHF and UHF bands. The FCC's digital television transition, completed in the United States in June 2009, repurposed analog spectrum for broadband wireless use while moving broadcasters to digital-only transmission. Cable television distributes the same content, and much additional programming, through coaxial and fiber-optic plant. Cable systems modulate multiple channels onto a shared medium using frequency-division multiplexing and, since the adoption of DOCSIS standards, carry two-way data traffic alongside video.

Streaming Video

Streaming video delivers television content over IP networks rather than dedicated broadcast or cable infrastructure. A content delivery network caches encoded video segments close to viewers, and adaptive bitrate algorithms select the appropriate quality tier based on available bandwidth. The MPEG-DASH standard and Apple's HTTP Live Streaming (HLS) protocol are the two dominant delivery formats. Unlike broadcast, streaming is unicast: each viewer receives a separate data stream, which shifts capacity demands from the transmission infrastructure to server and network provisioning. Platform providers increasingly use machine learning for encoding optimization, recommendation, and content-based indexing.