50 Chapter 10 – MPEG decoder
10911 V01.10
Chapter 10
MPEG decoder
An MPEG2/4 decoder is included in the delivery of this device. It functions as the Back-End of a DVB receiver. It
evaluates the Program Service Information (PSI) and decodes the digital audio and video data.
10.1 Program Service Information (PSI)
In digital television (DVB) technology, data is transmitted in byte-serial format via a transport stream (TS). The transport
stream usually contains several audio and video channels as well as data streams and additional program information,
all of which is transmitted in time-division multiplexing. Special tables transmitted in the transport stream provide
information about the channels and data services being sent. The receiver first needs to interpret these PSI tables in
order to give the user an overview in the form of channel lists. This process can take a few seconds (depending on the
number of programs they contain) and can be monitored in the MPEG window.
The MPEG window is seen at the bottom left of the screen. While this is being displayed, a new channel search is
running in a DVB-S transponder.
For a quick overview of the current transponder, the provider name and its orbital position are shown in the MPEG
window when the channel search is finished.
10.2 Network Information Table (NIT)
The NIT (Network Information Table) is a special table that contains information about other transponders and chan-
nels within the network (e.g. satellite, cable, DVB-T network). The information from the NIT can be used for navigation
(programme search).
The measuring receiver first needs to receive a digital channel.
MODE
> NIT starts the NIT search. If a NIT is found, the
decoder lists the entries of the NIT.
Summary of Contents for VAROS109
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