SVP UDR-70, Руководство пользователя

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UDR-70 H.265 Portable Receiver
USER’S MANUAL V1.0
D.4. DVB-S2
DVB-S2 is a digital satellite system developed by the DVB
Project. It makes use of the latest modulation and coding
techniques to deliver performance that approaches the
theoretical limit for such systems.
D.4.1. How Does It Work
The original DVB-S system, on which DVB-S2 is based, specifies the
use of QPSK modulation along with various tools for channel coding
and error correction. Further additions were made with the
emergence of DVB-DNSG (Digital Satellite News Gathering), for
example allowing the use of 8PSK and 16QAM modulation. DVB-S2
delivers excellent performance, coming close to Shannon limit, the
theoretical maximum information transfer rate in a channel for a
given noise level. It can operate at carrier-to-noise ratios from -2dB
(i.e., below the noise floor) with QPSK, through to +16dB using
32APSK. DVB-S2 benefits from more recent developments and has
the following key technical characteristics:
New modulation schemes
There are four modulation modes available, with QPSK and 8PSK
intended for broadcast applications in non-linear satellite
transponders driven close to saturation. 16APSK and 32APSK,
requiring a higher level of C/N, are mainly targeted at professional
applications such as news gathering and interactive services.
Figure 113: New DVB-S2 modulation schemes
Forward Error Correction
DVB-S2 uses a very powerful Forward error Correction scheme (FEC),
a key factor in allowing achievement of excellent performance in the
presence of high levels of noise and interference. The FEC system is
based on concatenation of BCH (Bose, Chaudhuri – Hocquengham)
with LDPC (Low density Parity Check) inner coding.