Switched video or switched digital video (SDV), sometimes referred to as switched broadcast (SWB), is a

telecommunications Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than tha ...

industry term for a

network Network, networking and networked may refer to: Science and technology * Network theory, the study of graphs as a representation of relations between discrete objects * Network science, an academic field that studies complex networks Mathematics ...

scheme for distributing digital video via a cable. Switched video sends the digital video more efficiently freeing bandwidth. The scheme applies to digital video distribution both on typical

cable TV Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with bro ...

systems using QAM channels, or on

IPTV Internet Protocol television (IPTV) is the delivery of television content over Internet Protocol (IP) networks. This is in contrast to delivery through traditional terrestrial, satellite, and cable television formats. Unlike downloaded med ...

systems.

Description

hybrid fibre-coaxial Hybrid fiber-coaxial (HFC) is a telecommunications industry term for a broadband network that combines optical fiber and coaxial cable. It has been commonly employed globally by cable television operators since the early 1990s. In a hybri ...

systems, a

fiber optic An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparency and translucency, transparent fiber made by Drawing (manufacturing), drawing glass (silica) or plastic to a diameter slightly thicker than that of a Hair ...

network extending from the operator's head end carries video channels out to a fiber optic node that services up to 2000 end points. Video is then sent via coaxial cable. Note that only a percentage of these homes are actively watching channels at a given time. Rarely are all channels being accessed by the homes in the service group. In a switched video system, the unwatched channels do not need to be sent. In US cable systems, equipment in the home sends a channel request signal back to the distribution hub. If a channel is requested, the distribution hub allocates a QAM channel and transmits the channel to the coaxial cable. For this to work, the home equipment must have two-way communication ability. Switched video uses the same mechanisms as

video on demand Video on demand (VOD) is a media distribution system that allows users to access videos without a traditional video playback device and the constraints of a typical static broadcasting schedule. In the 20th century, broadcasting in the form of ...

and may be viewed as non-ending video on demand that users share.

Technical

Two-way communication is handled differently between cable and IPTV schemes. IPTV uses Internet communication protocols but requires a different distribution infrastructure. US cable companies elected the less costly approach of upgrading existing infrastructure. In the upgrade approach, various proprietary schemes use specific frequencies for messaging the distribution hub. For switched video to work on cable systems, digital television users in a subscription group must have devices capable of communicating to the distribution hub in a compatible manner. Unlike other features dependent on two-way communication such as

, the requirement to upgrade all digital

set-top box A set-top box (STB), also colloquially known as a cable box and historically television decoder, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of si ...

es within a group makes conversion to switched video expensive.

CableLabs Cable Television Laboratories, Inc. (CableLabs) is a nonprofit corporation promoting innovation as a research and development lab founded in 1988 by American cable operators. System operators from around the world are eligible to be members. Th ...

proposed in the CableCARD 2.0 specification that two-way communication be supported with a scheme that required more powerful hardware capable of running

Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mo ...

software. Many cable companies indicated they would build lower cost devices that do not require this OCAP programming environment, so that upgrading to switched video would not be as costly. Consumer electronics companies also prefer a lighter weight solution, and so absent a standard, the conversion to switched video may require many years.

History

BigBand Networks BigBand Networks was a corporation headquartered in Redwood City, California, that opened in 1999 and specialized in selling multimedia technologies to cable television multi-system operators. It had its IPO on the Nasdaq in 2007, which wa ...

(acquired by Arris Group in 2011) was the switched video pioneer, and received the

Technology & Engineering Emmy Award The Technology and Engineering Emmy Awards, or Technology and Engineering Emmys, are one of two sets of Emmy Awards that are presented for outstanding achievement in engineering development in the television industry. The Technology and Enginee ...

in 2008 for innovation in the HFC market. Major vendors like Arris Group and

Cisco Cisco Systems, Inc., commonly known as Cisco, is an American-based multinational corporation, multinational digital communications technology conglomerate (company), conglomerate corporation headquartered in San Jose, California. Cisco develo ...

also provide SDV solutions for the cable operators. An emerging market supplies back office applications to analyze and control performance.

References

External links

Definition of switched video
- PC Magazine Overview
Switched Digital Video Architecture Guide
-

White Paper
How Switched Digital Video Works
- HowStuffWorks.com Outline
Using Bandwidth More Efficiently with Switched Digital Video
- Motorola

White Paper A white paper is a report or guide that informs readers concisely about a complex issue and presents the issuing body's philosophy on the matter. It is meant to help readers understand an issue, solve a problem, or make a decision. A white pape ...

(archived) {{DEFAULTSORT:Switched Video Broadband Cable television technology Streaming television

Description

Technical

History

See also

References

External links