tvsignals

TV signals are the electrical or optical representations of audiovisual content that televisions decode and reproduce. They can be analog or digital and may carry video, audio, and data such as subtitles, program guides, and metadata. In traditional contexts, TV signals traverse multiple stages from capture to display, including encoding, modulation, transmission, reception, and decoding.

Analog television signals historically used separate carriers for video and audio with a scanning process that produced interlaced frames. Common regional standards included NTSC, PAL, and SECAM, each with characteristic frame rates, resolutions, and color encoding schemes. Analog systems are sensitive to noise and signal degradation, and their picture quality tends to improve only as signal power is increased.

Digital television signals transmit compressed video and audio as discrete bits, enabling higher efficiency, improved robustness, and new services. Established digital terrestrial standards include DVB-T/T2, ATSC, ISDB-T, and DTMB, with regional variations. Digital signals commonly multiplex multiple channels and data streams into a single transport stream, using formats such as MPEG and, more recently, H.265/HEVC. Ancillary data like electronic program guides and subtitles are often carried alongside the main streams.

TV signals are delivered through terrestrial broadcast, cable or fiber networks, satellite, and increasingly IP-based delivery to televisions and set-top boxes. Key components in the chain include encoders, multiplexers, modulators, transmitters, receivers, decoders, and displays. Regulatory bodies and standardization groups, such as the ITU and DVB or ATSC, coordinate spectrum use and technical specifications to ensure compatibility and interoperability.