digital television

digital television
EnEdC EnEdC · Public domain · source
Name	Digital television
Introduced	1990s
Predecessors	Analog television
Standards	ATSC, DVB, ISDB, DTMB

digital television is the transmission of television signals using digital signal processing and data compression techniques rather than analogue modulation. It replaced many aspects of analog television systems by encoding audio, video, and metadata into binary streams suitable for terrestrial, satellite, cable, and internet distribution. The shift enabled higher picture quality, efficient spectrum use, and new services that transformed broadcasters such as BBC, NAB, NHK, RTL Group, and CBS.

History

The origins trace to experimental work by researchers at institutions like Bell Labs, RCA Corporation, and Nippon Telegraph and Telephone during the mid-20th century, culminating in digital video concepts from the MPEG committee and standards bodies. The 1980s and 1990s saw prototyping by companies including Sony, Panasonic, Thomson SA, and Philips alongside academic labs at MIT, Stanford University, and University of Tokyo. Regulatory and industry milestones include the formation of Advanced Television Systems Committee (ATSC) and the Digital Video Broadcasting Project (DVB), with early deployments such as DirecTV, Sky UK, and Japan’s NHK BS Digital. The analogue switch-off campaigns in nations influenced decisions at forums like the ITU and regional unions such as the European Union and ASEAN.

Technology and Standards

Digital television relies on standards for encoding, modulation, and multiplexing developed by bodies including ISO, IEC, ITU-R, ETSI, and ARIB. Core compression standards—part of the MPEG family and H.264/MPEG-4 AVC—work with container and metadata formats from ISO/IEC JTC 1. Regional transmission standards include ATSC, DVB-T2, ISDB-T, and DTMB, each specifying modulation schemes like OFDM, 8VSB, and error correction using Reed–Solomon and LDPC codes. Middleware and interactive systems such as HbbTV, MHEG-5, and ARIB BML enable hybrid broadcast-broadband services, while conditional access is governed by systems from Nagravision, Conax, and Irdeto.

Transmission and Reception

Terrestrial broadcasting uses transmitter networks operated by entities such as TDF (company), Arqiva, and Nippon Telegraph and Telephone subsidiaries; satellite distribution is dominated by operators like SES S.A., Intelsat, and Eutelsat; cable networks run by Comcast, Virgin Media, and NTT Communications often use DVB-C or DOCSIS-linked systems. Reception devices include set-top boxes from Samsung Electronics, LG Electronics, Humax, and integrated television sets complying with certification from groups like CTA and EICTA. Antenna design, link budgets, multipath mitigation, and return path provisioning for interactive services combine radio engineering practices established by IEEE standards and field measurement campaigns linked to broadcasters such as PBS and ZDF.

Broadcasting Formats and Services

Digital systems support formats from standard definition (SD) to high definition (HD), ultra-high-definition (UHD/4K/8K) promoted by NHK and manufacturers like Sharp. Multichannel audio formats include Dolby Digital, DTS, and DTS:X. Service types expanded to include multicast channels, electronic programme guides (EPGs), subtitles and closed captioning standards used by BBC and ABC, video-on-demand platforms pioneered by Netflix and Hulu, and targeted advertising technologies deployed by media conglomerates such as WarnerMedia and Disney–ABC Television Group. Advanced codecs like HEVC and emerging AV1 support efficient UHD delivery for broadcasters and over-the-top services coordinated through consortia including the Alliance for Open Media.

Adoption and Global Transition

Countries organized digital switchover (DSO) timetables led by agencies such as Ofcom, FCC, ANATEL, and MIC (Japan) with varied timelines: early adopters like United States, United Kingdom, and Japan completed transitions in the 2000s–2010s while others followed under ITU guidance. Market players such as Philips, RCA, and Sony Corporation drove consumer device availability; subsidies and converter voucher programs were implemented by governments including Australia and Brazil to aid households. Spectrum reallocation from broadcasting to mobile broadband involved auctions and policies influenced by telecom operators like Verizon and China Mobile.

Impact on Content and Industry

Digitalization restructured production workflows at studios such as BBC Studios, Paramount Pictures, and NHK Science & Technical Research Laboratories by enabling file-based editing, non-linear workflows, and digital archiving strategies advocated by institutions like the Library of Congress. Advertising and audience measurement evolved with analytics and addressable ad systems operated by firms like Comscore and Nielsen Media Research. The rise of multicast and narrowcast services created new distribution models exploited by broadcasters including MGM Television and telecom integrators such as Deutsche Telekom.

Regulation and Policy

Policy frameworks governing spectrum, content quotas, and technical interoperability involve regulators like the Federal Communications Commission, European Audiovisual Observatory, and national ministries of communications. Intellectual property issues prompted patent licensing frameworks negotiated among corporations such as MPEG LA and standards organizations like ITU and ISO. Public service obligations and accessibility mandates are enforced through statutes and codes overseen by entities including Ofcom and ACMA.

Category:Broadcasting