Recommended Modulation Use
For all payload rates at 2560 bps and below, Popoto recommends BPSK.
BPSK offers:
- Lower SNR requirement than QPSK, typically a 2-3 dB advantage
- Greater robustness under multipath and platform motion
- Wider operational envelope in low-SNR coastal environments
The QPSK modes at 2560 bps and below are retained for backward compatibility only. They remain supported for legacy systems but are not recommended for new applications unless required for interoperability.
Payload Mode Summary
| Mode | Mod | Rate (bps) | FEC | Repetition | Recommended | Notes |
|---|---|---|---|---|---|---|
FH_80bps | FH-FSK | 80 | inherent | n/a | Yes | Extreme low-SNR |
BPSK_640bps | BPSK | 640 | 1/2 | 4x | Yes | Most robust coherent |
BPSK_960bps | BPSK | 960 | 1/2 | 2.67x | Yes | Long-range, low-SNR |
BPSK_1280bps | BPSK | 1280 | 1/2 | 2x | Yes | Medium/long range |
BPSK_2560bps | BPSK | 2560 | 1/2 | 1x | Yes | Baseline BPSK |
QPSK_1280bps | QPSK | 1280 | 1/2 | 4x | No | Backward compatible |
QPSK_1920bps | QPSK | 1920 | 1/2 | 2.67x | No | Backward compatible |
QPSK_2560bps | QPSK | 2560 | 1/2 | 2x | No | Backward compatible |
QPSK_5120bps | QPSK | 5120 | 1/2 | 1x | Yes | High-rate coded mode |
QPSK_10240bps | QPSK | 10240 | None | None | Conditional | Requires external FEC |