GUST — Generic Universal Shortwave Telemetry

A terse HF broadcast protocol inspired by Olivia, optimized for sub-5-second transmissions.

GUST is an open amateur radio digital protocol for robust one-way transmission of telemetry data and short messages on shortwave (HF). It serves as an HF backbone between local data sources (weather stations, LoRa/Meshtastic meshes, sensors) and remote receive-only stations — independent of internet infrastructure.

Developed by OE3GAS (Vienna, Austria) · License: CC BY-SA 4.0

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Protocol at a Glance

Parameter	Value
Modulation	MFSK-8 (8 tones, orthogonal)
Symbol rate	31.25 Baud
Channel bandwidth	250 Hz
Channels	10 (NF 400–2900 Hz, fits standard SSB passband)
Frame duration	4.1–5.4 s (typ. 4.9 s for weather)
FEC	Reed-Solomon RS(255,223), shortened for short frames
CRC	CRC-16/CCITT-FALSE
Dial frequency	14.110 MHz USB (20 m, all stations identical)
Channel assignment	SHA-256(callsign) % 10 — deterministic, no coordination

Frame Types

Code	Type	Payload
0x01	Weather telemetry	Temp, humidity, pressure, wind, rain, UV
0x02	Position	Lat/Lon/Alt/Speed/Heading (APRS-compatible fields)
0x03	Station telemetry	Voltage, current, temp, CPU, uptime
0x20	Emergency beacon	Position + persons + injury + resources + priority
0x40	Free text / QSO fragment	Destination callsign + UTF-8 text
0x41	CQ / call	Callsign broadcast

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Quickstart

Requirements: Python 3.9+, a PC soundcard connected to an SSB transceiver (or HackRF for lab tests).

git clone https://github.com/OE3GAS/gust.git
cd gust
pip install -r requirements.txt

# Copy and edit the config
cp gateway.json.example gateway.json

# List audio devices
python gust.py devices

# Monitor mode (RX only)
python gust.py rx --device <audio_device_index>

# Send a weather frame (simulation)
python gust.py tx weather --dry-run

# Full gateway daemon (TX + RX + Web UI)
python gust.py daemon

Web interface available at http://localhost:8080 after starting daemon.

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Test Frequencies

Planned test operation with selected partner stations on the following HF digital sub-bands (IARU Region 1):

Band	Segment (kHz)
630 m	475–479
160 m	1838–1840
80 m	3570–3600
40 m	7040–7050
30 m	10130–10150
20 m	14110–14125 ← active
17 m	18105–18109
15 m	21090–21110
10 m	28120–28150

Additional tests on VHF/UHF: 144.900 MHz (2 m), 432.200 MHz (70 cm).

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File Structure

gust.py               — CLI entry point (tx / rx / daemon / info / devices)
gust_frame.py         — Frame layer: encoding, CRC, RS-FEC, channel assignment
gust_modulator.py     — MFSK-8 modulator / demodulator (FFT-based)
gust_audio.py         — Audio I/O, PTT control (GPIO / hamlib / null)
gust_hackrf.py        — HackRF One TX path (SoapySDR)
gust_rx.py            — Continuous RX loop (asyncio, ring buffer, dedup cache)
gust_decode.py        — Standalone decoder helper
gust_eventbus.py      — asyncio fan-out event bus
gust_web.py           — aiohttp web server, REST API, WebSocket, web UI
gateway.json.example  — Configuration template
requirements.txt      — Python dependencies
gust_spec.md          — Full protocol specification

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Configuration

Copy gateway.json.example to gateway.json and adapt:

{
  "callsign": "OE3GAS",
  "audio": {
    "device": 9,
    "ptt_backend": "hamlib",
    "level": 30,
    "hamlib_host": "localhost",
    "hamlib_port": 4532
  },
  "web": {
    "host": "0.0.0.0",
    "port": 8080,
    "api_key": ""
  }
}

ptt_backend options: hamlib · gpio · null (dry-run / lab)

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Dependencies

numpy          — Signal processing
scipy          — FFT, WAV I/O
reedsolo       — Reed-Solomon FEC
sounddevice    — Audio I/O
aiohttp        — Web server (daemon mode)

Optional (Raspberry Pi gateway):

RPi.GPIO       — PTT via GPIO
smbus2         — BME280 weather sensor
meshtastic     — Meshtastic/MeshCom integration
paho-mqtt      — MQTT input from WiFi sources

Install: pip install -r requirements.txt

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Status

Phase	Description	Status
1	Modulator / Demodulator	✅ Complete
2	Frame layer	✅ Complete
3	Hardware integration	✅ Complete
4	Source integration	✅ Complete
5	Web interface & event bus	✅ Complete
6	MQTT bridge	🔲 Optional / deferred
7	On-air tests & decoder robustness	✅ Largely complete
8	Publication	🚧 In progress

Decoder performance (HackRF → IC-7610 loopback): decode threshold ≤ 10 dB SNR, 100% frame recovery rate (20/20 simplex test, May 2026).

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License

© 2025–2026 OE3GAS
Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)

You are free to share and adapt this work, provided you give appropriate credit and distribute any derivative works under the same license.

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Contributing / Contact

This is a personal amateur radio research project. Feedback, reports of successful reception, and suggestions are welcome via GitHub Issues.

73 de OE3GAS