DAB
DAB (Digital Audio Broadcasting), also
known as Eureka 147, is a technology for broadcasting
of audio using digital radio transmission.
Traditionally radio programmes
were broadcast on different frequencies via FM
and AM, and the radio had to be tuned into each
frequency. This used up a comparatively large
amount of spectrum for a relatively small number
of stations, limiting listening choice. DAB is
a digital radio broadcasting system that through
the application of multiplexing and compression
combines multiple audio streams onto a single
broadcast frequency called a DAB ensemble.
DVB-T
DVB (Digital Video Broadcasting) is an
internationally accepted open standard for digital
television made by ETSI (European Telecommunications
Standard Institutes).
DVB systems distribute
data through a number of approaches, including
by satellite (DVB-S, DVB-S2 and DVB-SH; also DVB-SMATV
for distribution via SMATV); cable (DVB-C); terrestrial
television (DVB-T) and terrestrial television
for handhelds (DVB-H); and via microwave using
DTT (DVB-MT), the MMDS (DVB-MC), and/or MVDS standards
(DVB-MS).
These standards define
the physical layer and data link layer of the
distribution system. Devices interact with the
physical layer via a synchronous parallel interface
(SPI), synchronous serial interface (SSI), or
asynchronous serial interface (ASI). All data
is transmitted in MPEG-2 transport streams with
some additional constraints (DVB-MPEG). A standard
for temporally compressed distribution to mobile
devices (DVB-H) was published in November 2004. |