Receives and decodes telemetry from meteorological radiosondes — weather balloons that transmit GPS position, temperature, humidity, and other atmospheric data as they ascend.
UI Overview
Settings
- Frequency: The frequency to monitor. Default is 402.7 MHz, which is the primary international radiosonde downlink band. Adjustable via the encoder knob or on-screen numpad.
- RF Amp (0 or 1): Enables/disables the internal RF amplifier.
- LNA gain (0–40): Low-noise amplifier gain. See Receive Quality Issues.
- VGA gain (0–62): Variable-gain amplifier gain. See Receive Quality Issues.
- RSSI: Signal strength indicator.
- Volume: Audio output volume.
Decoded Fields
The app displays a common set of fields for all sonde types. Fields that are not available for a given sonde type are shown as .... Vertical speed is calculated by the app from successive GPS altitude readings and packet timestamps.
| Field | Meteomodem M10 | Meteomodem M20 | Meteomodem M2K2 | Vaisala RS41-SG |
|---|---|---|---|---|
| Type | ✓ | ✓ | ✓ | ✓ |
| ID / Serial | ✓ | ✓ | — | ✓ |
| DateTime | ✓ | ✓ | ✓ | ✓ |
| Battery voltage | ✓ | ✓ | ✓ | ✓ |
| Frame number | — | ✓ | — | ✓ |
| Temperature | ✓ | ✓ | — | ✓ |
| Humidity | ✓ | ✓ | — | ✓ |
| Pressure | — | ✓ | — | — |
| GPS (Lat / Lon / Alt) | ✓ | ✓ | ✓ | ✓ |
| Vertical speed | ✓ | ✓ | ✓ | ✓ |
Checkboxes
- Log: Logs received packets to the SD card. A new timestamped file is created each time the app is opened:
LOGS/SONDE_YYYYMMDD_HHMMSS.TXT. The log contains raw packet bit data and a reception timestamp. - CRC: Enables CRC checking. When active, packets that fail their checksum are discarded rather than displayed. CRC is supported for M10, M20, and RS41-SG; M2K2 does not have a CRC implementation.
Beep on Packet
The app emits an RSSI-level-dependent audio beep when a packet is received. The beep pitch corresponds to signal strength. This behaviour is controlled by the global Beep on packets setting in Settings → Radio, not by a per-app checkbox.
Map Buttons
- See QR: Generates a
geo:latitude,longitudeQR code for the last received GPS fix. Scanning the code on a smartphone opens its map application at those coordinates. - See on map: Opens the built-in world map view centred on the last received GPS fix. Requires
world_map.binto be present in the/ADSB/folder on the SD card.
Settings Persistence
The Log and CRC checkbox states are saved to rx_sonde.ini on the SD card when App Settings is enabled in the global Settings menu.