Supported Operation Modes and Limitations

• The current implementation supports constant coding and modulation (CCM) only. It does not support adaptive or variable coding and modulation (ACM/VCM) yet.

  • The only block that supports ACM/VCM is the physical layer (PL) synchronization block implementing the low portion of the PL. However, the remaining blocks of the pipeline (e.g., BCH and LDPC FEC) still lack ACM/VCM support.

• CCM mode can operate with a single input stream (SIS) or multiple input streams (MIS).

• Only QPSK and 8PSK constellations are currently supported. 16APSK and 32APSK constellations are not supported yet.

• The SIMD-accelerated LDPC implementation supports the AVX2, SSE4.1, and NEON instruction sets. You can check whether these instruction sets are available in your machine by running:

  lscpu | grep -e avx2 -e sse4_1 -e neon
  

• SDR compatibility: | Application | USRP | bladeRF | ADALM-PLUTO (PlutoSDR) | RTL-SDR | | ———– | —————— | —————— | ———————- | —————— | | dvbs2-tx | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | | | dvbs2-rx | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |

Please feel free to get in touch if you would like to use another SDR device/board. Adding support should be straightforward if the device already has GNU Radio support. Pull requests are also welcome.

NOTE: The current implementations for the bladeRF and PlutoSDR are subject to experimental validation.

• The Tx application takes an MPEG transport stream on the input, and the RX application likewise outputs a transport stream. None of them offer any mechanism to process the MPEG transport stream itself. Processing of MPEG TS is beyond the scope of this project.

  • A handy tool to use in conjunction with this project’s transmitter/receiver is the tsp tool provided by the TSDuck toolkit. Refer to more info in the usage section.

• The current receiver implementation supports signal-to-noise ratios (SNRs) as low as 2 dB in pilot mode. Lower SNRs are yet to be supported.

  • The current performance bottleneck lies in the PL synchronization algorithms.
  • For example, the following configuration works (see the usage guide):

dvbs2-tx \
  --source file \
  --in-file data/example.ts \
  --in-repeat \
  --modcod qpsk1/4 \
  --pilots \
  --snr 2 \
  --freq-offset 1e5 | \
dvbs2-rx \
  --sink file \
  --out-file /dev/null \
  --modcod qpsk1/4 \
  --pilots on

• The PL synchronization block currently has limited support for PLFRAMES without pilot symbols. The full support for pilotless operation is still on the to-do list.

• Aside from simulation, the current implementation has been tested primarily with the Blockstream Satellite system. More specifically, it has been tested using the hardware recommended for Blockstream Satellite receivers and the system’s DVB-S2 configuration summarized below. Other hardware parts and DVB-S2 parameters are yet to be tested with live carriers.

  • SDR interface: RTL-SDR with a temperature-controlled crystal oscillator (TCXO) (see the recommendation).
  • Low-noise block downconverter (LNB): phase-locked loop (PLL) design with +-300 kHz local oscillator stability or better (see the recommendation).
  • DVB-S2 signal configured with:
    • QPSK3/5 MODCOD.
    • CCM/SIS mode.
    • Pilot symbols enabled.
    • 1 Mbaud.
    • 0.2 roll-off factor.

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