Technology; Modulation Standards; Dvb-S - Newtec AZ110 User Manual

Technology

7 TECHNOLOGY
This chapter describes the DVB-S and DVB-S2 modulation standards and the
processing modes of the AZ110 broadcast modulator.
7.1

Modulation Standards

7.1.1

DVB-S

DVB-S is the first generation of a standard for digital broadcasting via satellite.
DVB-S was designed to carry MPEG-2 transport streams over satellite. MPEG-2
transport streams typically carry one or several television or radio services
multiplexed into a synchronous bit stream. All service components are divided in
short packets of 188 bytes, each identified by a Program Identifier in the header of
the packet.
Generic data can also be carried in MPEG transport streams, provided that it is first
encapsulated in the transport stream packets. The most common way to
encapsulate IP data into MPEG streams is called Multi Protocol Encapsulation
(MPE) and is also specified by a DVB standard.
The total bit rate of the transport stream is constant but can typically be adjusted to
match the needs of the satellite link. If the desired transport stream rate is greater
than the sum of the carried components, null packets are added to the stream by
the multiplexer or the modulator. This operation is called rate adaptation.
DVB-S uses QPSK modulation and concatenated error protection based on a
convolutional Viterbi code and a shortened RS code.
Video, audio or IP data
Figure 38- DVB-S Used to Carry Video, Audio and Data in an MPEG Transport Stream
version 3.2
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User Manual for AZ110 Broadcast Satellite Modulator with ASI interface
PID 1
PID 2
PID 3
SHAPING THE FUTURE SATELLITE OF COMMUNICATIONS
DVB-S
TS
modulation