SignalHop: the acoustic mesh networking stack that talks through sound

I wanted an answer to a boringly practical question: what if the network is gone, but the speakers and microphones still work?

SignalHop is an acoustic modem and mesh prototype that moves tiny messages over ultrasound instead of Wi‑Fi or Bluetooth.

What it actually does

The current build uses:

FSK tones at 18 kHz and 20 kHz
48 kHz sample rate
a 4 up-chirp sync preamble
frames with payloads up to 255 bytes
a WAV/audio runtime for encode/decode and round-trip testing

That makes it useful for emergency text, sensor payloads, and low-bandwidth status updates. Not glamorous. Very useful.

The measured part

From the current proof pack:

Metric	Value
Encode latency	16.634 ms mean
Decode latency	713.028 ms mean
Round-trip	true
Payload tested	77 bytes
Max payload	255 bytes

The decode path is slower because it scans the full signal with correlation. That is fine for v1. The important part is that the numbers are measured, not imagined.

The honest limitation

The core modem path is field-deployable today, but the full multi-node mesh still needs hardware validation across real devices. I’m keeping that line explicit on purpose.

That means this is a real protocol stack, not marketing fog.