Show HN: Cyrinx (36kbps Acoustic Transport)
11 hours ago
- #OFDM-modem
- #acoustic-data-link
- #wireless-communication
- Cyrinx is a research modem that transmits data as sound, achieving up to 39.3 kbps goodput from a laptop speaker to a phone microphone without radio or network.
- Measured goodput varies by device and direction: 36.6 kbps from MacBook to Pixel 7a, 27.3 kbps reverse, and 36.57 kbps to iPhone 17 Pro Max.
- It uses OFDM with 2048-point FFT, channel estimation, pilot tracking, 16-QAM modulation, convolutional codes, and CRC-32 verification for reliable data transfer.
- The system degrades gracefully in poor acoustic conditions, employing techniques like two-microphone combining and non-coherent modes to maintain connectivity down to 138 bps.
- Cyrinx builds on prior art like minimodem and Quiet, adding rigorous measurement, documented limitations, and a portable C library for reproducible performance.