Transmitting Digital Television Signals by Satellite - DVB-S/S2 - Digital Video and Audio Broadcasting Technology - page 261

14.7 DVBS2

DVB-S was adopted in 1994, using QPSK as a modulation method and a
concatenated error protection system of Reed-Solomon FEC and convolu-
tion coding. In 1997, the DVB DSNG standard [ETS301210] was laid
down which was created for reporting purposes (DSNG = Digital Satellite
News Gathering). Live signals are transmitted by satellite, e.g. from out-
side broadcast vans at big public events to the studios. DVB DSNG al-
ready uses 8PSK and 16QAM. In 2003, new methods, both for direct
broadcasting and for professional applications, were defined as "DVB-S2"
(s. Fig. 14.25.) in ETSI document [ETS302307] .

QPSK,
8PSK,
16APSK,
32APSK,
Hierarch. mod.

Opt.
DVBS
FEC

MPEG 2
TS

BCH,
LDPC,
bit interl.

Single
or
multiple
input
streams
(MPEG2 TS
or generic)

Input
inter
face

Mode
adaptation

Stream
adaptation

FEC
encoding

Mapper

CRC8 encoding,
baseband signalling
merging

Padding,
baseband
scrambling

Code rate

Up
conversion,
amplification,
uplink

Physical layer
signalling,
pilot insertion,
scrambling

Physical
layer
framing

Rolloff
filter

IQ
modulator

0.20, 0.25,
0.35

Fig. 14.25. Block diagram of a DVB-S2 modulator

Both QPSK, 8PSK (uniform and non-uniform) and 16APSK (16 ampli-
tude phase shift keying) were provided as modulation methods, the latter
only being used in the professional field (DSNG). The error protection
used is completely new, e.g. LDPC (low density parity check). The stan-
dard is quite open for broadcasting, interactive services and DSNG. Data
streams not conforming to the MPEG-2 stream can also be transmitted and
it is possible to transmit either one or a number of transport streams. This
also applies to generic data streams which can also be divided into packets.
Fig. 14.25. shows the block diagram of a DVB-S2 modulator. At the input
interface, the data stream or streams appear in the form of an MPEG-2