SW Version 2.04 30-January-2009 Page 46 of 128
Figure 32 - GBIO_SCS / DDM-SCR scrambler architecture
Figure 33 - New ASIO based scrambler architecture
The SCS module is the master of the scrambling system. It is aware of the ECMG and
the scrambler module. Upon configuration the SCS card generates a CW, sends it to
the ECMG, which returns the ECM. The SCS then sends the CW to the selected
scrambler and transfers the ECM to the correct output card for play out.
Before it is possible to define an output stream with the scrambling properties it is
necessary to define the ECM generator, as the SCS needs to know where to contact
the encryption system. Next step is to define an ECM. The ECM definition associates a
CW id and access criteria. The output can now be defined and scrambled. When
configuring the output to be scrambled the ECM selection list implicitly represents the
CW and access criteria while the scrambler indicates which scrambler card to use, for
the new platform the scrambler must match the card which provides the ECM.
4.4.3.2 DDM-Scrambler Card Configuration
The DDM-scrambler runs on a dedicated card which supports the CSA and the AES
scrambling algorithm. The algorithm is implemented in separate FPGA images which
are loaded during boot. Consequently the card cannot support both algorithms
simultaneously. The algorithm to use is defined by the card options which are
described by an option file.
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