About the DVB options
R&S
®
SMW-K52/-K116
12
User Manual 1175.6778.02 ─ 19
Figure 2-2: Components of the transmission system DVB-S2/S2X
FEC = Forward error correction
BCH = Bose-Chaudhuri-Hocquenghem multiple error correction binary block codes
LDPC = Low-density parity check
The main improvements of the second-generation DVB system for satellites (DVB-S2)
compared to DVB-S are:
●
Input stream adapter, suitable for operation with single and multiple input streams
and different formats (packetized or continuous)
●
FEC system based on LDPC codes concatenated with BCH codes
●
Range of code rates (from 1/4 up to 9/10);
Four constellations with different spectrum efficiency and optimized for operation
over non-linear transponders
●
Three predefined spectrum shapes with rolloff factors 0.35, 0.25 and 0.20
●
Adaptive coding and modulation (ACM) functionality for optimized channel coding
and modulation on a frame-by-frame basis.
The DVB-S2X is an extension to the DVB-S2 standard. The DVB-S2X reuses the DVB-
S2 system architecture and improves it with the following:
●
Adds finer MODCOD steps, higher-order modulations and complex constellations
●
Three new sharper spectrum shapes
●
Defines the VL-SNR (low signal to noise ratio) mode for example for mobile appli-
cations
●
Optional periodic pilots and physical layer scrambles for easy synchronization
●
GSE-Lite compliant signaling and streaming
●
Adds a high-efficiency mode (GSE-HEM) intended to transport GSE and GSE-Lite
packets
About DVB-S2/S2X
