The AHA4709L LLR Demapper core is compliant with section 5.4* (see Note 1) of the Digital Video Broadcast S2-Extention (DVB-S2X) standard. By default, this core uses re-labeled constellation points to implement the re-ordering of interleaved columns in section 5.3.3 of the DVB-S2X standard as required by the AHA4709D Decoder core. The core takes in digital I/Q symbol data and outputs soft metric symbol values or LLRs at a resolution depth of 6 bits per LLR value. The core allows code and modulation changes on a block-by-block basis to fully support both Adaptive Coding Modulation (ACM) and Variable Coding Modulation (VCM).
The AHA4709L core extends the functionality of the AHA4702L DVB-S2 core by supporting new lower-order (BPSK) and higher-order (64, 128, 256 APSK) modulations.
Note 1: De-Spreading of “Spread Factor 2” VL-SNR BPSK codes must be done before the input to this core. PI/2 BPSK symbols also must already be converted to BPSK i.e. In=Qn=(1/sqrt(2)(1-2Yn) for n=1 to N, where N is # of symbols in frame.