A complete, open radiosonde (weather-balloon) telemetry system
flight-hardware firmware · long-range LoRa ground link · packaged desktop ground station

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PTHSonde flies a small ESP32-C3 payload that measures Pressure, Temperature, and Humidity (plus wind, GPS, and battery), streams it over 915 MHz LoRa to a ground receiver, and displays it in a one-click Windows app: live Skew-T, hodograph, time-series, a GFS-fed landing-prediction map, and a full SHARPpy SPC analysis panel. Altitude, ascent rate, and the sounding are derived from the barometric pressure sensor, so the profile keeps building past the GPS altitude ceiling — the flight record is complete all the way to burst.

_{The desktop ground station — live Skew-T, hodograph, wind and thermodynamic profiles, and link health.}

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System at a glance

   ┌──────────────────────── SONDE (in the air) ────────────────────────┐
   │  ESP32-C3-WROOM                                                     │
   │   • SHT41         temperature / relative humidity                   │
   │   • MS5611        barometric pressure  (drives altitude + ascent)   │
   │   • MCP3221 + NTC thermistor (primary air temperature)             │
   │   • INA219        battery voltage / current                         │
   │   • Quectel L86-M33 GPS   (Balloon mode — good to 80 km)            │
   │   • Ebyte E22-900T22S  LoRa @ 915 MHz, 22 dBm, 0.3 kbps (max range) │
   └───────────────────────────────┬────────────────────────────────────┘
                                    │  915 MHz LoRa
   ┌────────────────────────────────▼───────────────────────────────────┐
   │  GROUND RECEIVER — ESP32-C3 + E22, decodes packets, prints CSV      │
   └───────────────────────────────┬────────────────────────────────────┘
                                    │  USB serial
   ┌────────────────────────────────▼───────────────────────────────────┐
   │  PTHSonde DESKTOP APP  (Windows)                                    │
   │   • Python (Flask) owns the serial port + records the flight CSV    │
   │   • Native window (pywebview) renders the dashboard (single HTML)   │
   │   • SHARPpy renders the real SPC Skew-T/analysis panel on demand    │
   └────────────────────────────────────────────────────────────────────┘

Repository layout

Path	What it is
SondeTransmitter/	Flight firmware (Arduino/ESP32-C3). Reads the sensors + GPS and transmits telemetry over LoRa.
GroundReceiver/	Ground-station firmware (Arduino/ESP32-C3). Receives LoRa packets, prints them as CSV over USB.
Dashboard/	The ground-station UI — a single self-contained PTHSonde.html (+ logo).
processor/	The Python app: app.py (pywebview launcher), sonde_server.py (Flask + serial + flight recording), sharppy_render.py (headless SHARPpy), and the PyInstaller spec.
docs/	Hardware map, firmware build/flash guide, and dashboard guide.
pins.txt	Verified ESP32-C3 pin map for the sonde board.
Start PTHSonde.bat	One-click launcher (runs the app from source).

Quick start

Run the ground station (recommended): download the prebuilt Windows app from the Releases page, unzip, and run PTHSonde.exe. Connect the ground receiver over USB, select its COM port, and click Connect.

Run from source (needs Python 3.13):

pip install -r processor/requirements.txt      # flask, pyserial, pywebview, ...
# then, from the repo root:
Start PTHSonde.bat                              # or:  py -3.13 processor/app.py

Build the firmware: open SondeTransmitter/SondeTransmitter.ino and GroundReceiver/GroundReceiver.ino in the Arduino IDE (ESP32-C3 board support, USB CDC On Boot: Enabled) and flash each board. See docs/firmware.md.

Documentation

• docs/hardware.md — boards, sensors, pin map, LoRa RF plan, GPS balloon mode.
• docs/firmware.md — building & flashing both firmwares, the telemetry protocol, LED codes.
• docs/dashboard.md — using the app, recording a flight, the SHARPpy analysis, building the .exe.

Key features

• Complete soundings, every flight — a full SHARPpy SPC Skew-T, hodograph, and severe-weather index panel, rendered from your balloon's own data.
• Data all the way to burst — altitude, ascent rate, and the profile come from the onboard pressure sensor, so the sounding never stops at the GPS ceiling.
• Research-grade profiles — automatic thermal-soak correction removes surface heat bias from the lowest levels, so lifted-parcel indices reflect the true atmosphere.
• High-altitude tracking — verified GPS balloon mode follows the flight to 80 km, well past the 12 km limit of standard receivers.
• Long-range downlink — a 22 dBm LoRa link engineered for maximum range and margin.
• Reusable payload — a rugged, recoverable sonde with a swappable battery and a unique per-unit ID.

_{A full SHARPpy SPC analysis panel rendered from a flight's own data.}

_{A PTHSonde ascending under balloon and parachute shortly after launch.}

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PTHSonde — Tracer Lab.