We check telemetry from all clients submitting data to SondeHub. Sometimes these checks cause false positives (usually when reception is poor, GPS signal is poor or there is multiple radiosondes on the same frequency). If error messages are occurring often then there is no reason to worry.

z-check

Frames are compared to each other and we will mark outlier frames as bad using a basic z-score check. This check will fail if the radiosonde travels too far compared to other frames. This check generates a lot of false positives so it's fine to ignore in most cases. We often see this check failing when decoding DFM, RS92 radiosondes or when GPS jammers are used or when two radiosondes are on the same frequency.

Lat/Lng = 0.0

If the lat and lng are exactly 0 we assume a decoder issue has occurred and the location is invalid

Altitude = 0

If the altitude is exactly 0 then we assume something bad has happened in the decoder. This is only triggered if the altitude is exactly 0. Slight above and below won't trigger this.

Humidity < 0, Pressure < 0

If the pressure or humidity are below 0 the frame is invalid

Sats < 4

If the sats are less 4 then we can assume that the radiosonde doesn't have a 3D fix and shouldn't be trusted.

Datetime

We only accept telemetry that has been seen within 48 hours

Serial number

We confirm that the serial number is valid for the type of radiosonde.

API Error response

The API error response looks like this

{
    "message": "some or all payloads could not be processed",
    "errors": [
        {
            "error_message": "z-check failed - payload GPS may not be valid for M3423108.",
            "payload": {
                "software_name": "radiosonde_auto_rx",
                "software_version": "1.5.3",
                "uploader_antenna": "discone+preamp",
                "time_received": "2021-08-23T11:03:47.133237Z",
                "datetime": "2021-08-23T11:04:03.240000Z",
                "manufacturer": "Vaisala",
                "type": "RS92",
                "serial": "M3423108",
                "subtype": "RS92-SGP",
                "frame": 5714,
                "lat": 67.35274,
                "lon": 26.63484,
                "alt": 24442.69628,
                "temp": -48.5,
                "humidity": 0.0,
                "pressure": 30.99,
                "vel_v": 5.326,
                "vel_h": 4.826,
                "heading": 358.34311,
                "frequency": 401.999,
                "snr": 12.7,
                "lon_outliers": true,
                "alt_outliers": true
            }
        }
    ]
}