What's the correct way to implement the BaseBand scrambler of DVBS2?

Question

I'm trying to implement a transmitter based on the DVBS2 standard. The guideline document shows a feedback shift registers for which the input does not depend on the message sent

DVBS2 base band scrambler

whereas MATLAB's comm.Scrambler object does mixes the message with the output to the register.

MATLAB's implementation in the comm library

What's the correct way and what's the difference between the two implementations with regards to the purpose of the scrambler?

Thanks in advance!

Answer 1

Both are the same and correct for DVBS2 BBFRAME scrambling. In the second case, if you fix m=15 and open p1 to p13 at all and close p14 and p15, you can do BBFRAME scrambling.

Note: In about 90 percent of DVBS2 signals the init registers state are (100101010000000). So you can calculate the side of the scrambler for the longest situation and for each signal with an arbitrary frame length fast. This sequence is found in this