The CMS0044 J.83abc/DVB-C Cable FEC Encoder combines all of the channel coding and Forward Error Correction functions specified by DVB-C and by J83 Annexes A B and C. It is designed to interface to external modulators or advanced upconverting DACs such as the Analog Devices AD9789.
The CMS0044 includes functions for framing, scrambling, interleaving, Reed-Solomon coding, trellis coding, and QAM mapping.
The requirements of J83A J83C and DVB-C are virtually identical, but are quite different to the requirements for J83B. With the exception of the common interleaver block, two independent datapaths are required, as shown above.
The multi-channel encoder uses a common transmission mode, so symbol timing is common for all channels. The encoder may be built with individual interleave modes, as this does not impact data symbol timing. However, this requires more memory bandwidth.