One of the first decisions of the organization was the adoption of dvb as a basis for all development of digital compression standard MPEG-2. The second important decision taken dvb Project, – use of a common MPEG-2 multiplex in all media distribution and maximum unification of methods of error-correcting coding and modulation. In all cases, a Reed-Solomon code with a single block size, and in those cases where it is needed, a convolutional code with a single set of relative velocities. Processing of digital MPEG-2 stream for use in satellite broadcast detail is specified in en 300 421, adopted by etsi in 1998 6. 6, 6. 7. The sequence of processing steps is shown in Fig.

6. 4. Come on modulator input transport packets 188 bytes in length contain, as we know, sinhrobayt 0 47 and 187 bytes of data. To resolve neopredelennos T phase is formed, the inner loop of the modulator, which includes 8 packages: one with inverted start sinhrogruppoy 0hV8, the rest – with a non-inverted. Transport Stream enters the scrambler, where it is the summation from the pseudo dosluchaynoy sequence (PRS). Structural diagram adopted in the standard DVB-S scrambler / descrambler is shown in Fig. 6. 5 and consists of a shift register 15 flip-flops and le "XOR", summing modulo-2 signals Dov cells 14 and 15 and feeding the resultant signal to the input of cell 1. Symbol synch cells produced a clock speed of transport packets, cyclic syn chronization – inverted starting sinhrogruppami by which triggers the shift register are set to the initial state 1001 0101 0000 0000.