How do I design a satellite modem for operation with a DVB-S2X waveform?

Designing a satellite modem for operation with a DVB-S2X waveform requires implementing the complete physical layer processing chain specified by the ETSI EN 302 307-2 standard, including: the modulator (mapping data bits to complex symbols for QPSK through 256APSK constellations, applying root-raised-cosine pulse shaping with roll-off factors of 5%, 10%, 15%, or 20%, and upconverting to the intermediate frequency or directly to RF), the LDPC/BCH encoder (encoding data frames with the concatenated BCH outer code and LDPC inner code at the selected code rate from 1/5 to 9/10; the LDPC encoder must support both 64,800-bit normal frames and 16,200-bit short frames), the demodulator (carrier and timing recovery to lock onto the received signal, soft-decision demodulation to generate log-likelihood ratios for each bit, and frame synchronization using the physical layer header), and the LDPC/BCH decoder (iterative LDPC decoding with 25-50 iterations for near-threshold performance, followed by BCH decoding for residual error correction). Key hardware considerations include: the ADC sampling rate (must be at least 2x the symbol rate; for a 500 Mbaud carrier: ADC rate > 1 GSPS with 8-10 bits resolution), the LDPC decoder throughput (the most computationally intensive block; modern ASIC implementations achieve 1-5 Gbps decoded throughput), and the DAC for the modulator (must support the full signal bandwidth with sufficient SFDR for high-order modulation: > 45 dBc for 256APSK).