SVP UDT-4K, Руководство пользователя

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UDT-4K UHD HEVC Digital Camera Transmitter
MANUAL V0
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C.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.
C.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 C.4: 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.
Figure C.5: DVB-S2 FEC