5 ms·

5bps/Hz is way overestimating their spectral efficiency.

• mlyle 4y ago
  64 QAM with FEC is specified as the original modulation in regulatory filings. This predicts 4.5-5.5 bits/Hz.
  • shaklee3 4y ago
    Yes, and dvbs-2 also supports very high modulation and code rates. but they're never used in practice since PSD limits don't allow you to transmit that much due to interference on other systems. starlink is not first in line for most of their spectrum, so they're abiding by direct spectral mask limits. I would guess they're at 16APSK at the highest.
    • mlyle 4y ago
      > so they're abiding by direct spectral mask limits Yes, obtained by channelization and OFDM, not by limiting modulation. Reverse engineering of the 10 to 12.7GHz band has shown a mixture of 16-QAM and 64-QAM frames. There's a bit of periodic 4-QAM too, which seems to be for acquisition and synchronization. Even 16-QAM can climb basically to 5 bits/Hz.
      • shaklee3 4y ago
        Please show a link where this was reverse-engineered. I'd be curious to see it.