DMB - Digital Multimedia Broadcast
Short for Digital Multimedia Broadcast, DMB is a technique of multicasting multimedia content over the Internet, or satellite, to be tuned in by multimedia receivers, or players, capable of playing back the multimedia program. Digital broadcasters not only deliver video and voice, but may also include data files and entire applications.
Technical Features of DMB
Digital multimedia broadcasting is based on the Eureka 147 DAB standard. Digital
television uses the T-DMB which is made for transmissions on frequency bands III
(VHF) and L (SHF). T-DMB is an ETSI standard (TS 102 427 and TS 102 428).
As for satellite radio, there were a few matter to be resolved by the main satellite radio broadcasters. In order to receive the transmission, the satellite radio receiver needs to be in the line of sight of the satellite – and there is the problem of having different landscaping objects block the direct transmission. Land based devices were installed in order to eliminate the lack of direct satellite transmission. Since the wider spectrum of broadcasts has to be covered, digital multimedia broadcasting uses OFDM-4DPSK modulation and a chip of T-DMB receiver is also provided by MPEG-2 Transport Stream De-multiplexer. This helps reduce the negative effects of shadowing and fading, present in many digital transmissions.
The most popular application of DMB is mobile television. DMB can also transmit movies, video clips, music, RSS feeds, and text messages. Most existing and proposed DMB services operate on a fee-based subscription basis, although advertising has been suggested as a revenue source. A free state-operated DMB service is available in South Korea.
Some common examples of multimedia broadcast content include:
One of the advantages of multimedia broadcasting over traditional video broadcasting is that through a process called multicast, a single broadcast can send programming to thousands of receivers, which can play back the content individualized to the location.
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