[DRAFT] Amateur Balloon Telemetry Format

This page describes the telemetry format that is uploaded to the SondeHub ElasticSearch Database.

Each telemetry datapoint is uploaded as a JSON object, with the fields described in the tables below. Multiple telemetry datapoints can be uploaded in one request.

Mandatory Fields

These fields represent the bare minimum amount of data that must be included in an upload.

Field	Type	Description	Allowed Values	Notes
software_name	string	Name of the decoding software		e.g. 'horusdemodlib', 'Horus-GUI'
software_version	string	Version of the decoding software		e.g. '0.3.0'
uploader_callsign	string	Callsign of the uploader		Arbitrary string. Uploader position information and other metadata will be handled separately, but will need to match this callsign to enable calculation of listener statistics.
time_received	string	The time the telemetry packet was received. UTC time in YYYY-MM-DDTHH:MM:SS.SSSSSSZ format.
payload_callsign	string	Callsign of the payload being launched
datetime	string	Date/Time from the sonde's GPS, provided in YYYY-MM-DDTHH:MM:SS.SSSSSSZ format		Note - as many amateur payloads only send time, not date, the date must be added on by the listener. Refer here for an example function to do this.
lat	float	Latitude (decimal degrees)
lon	float	Longitude (decimal degrees)
alt	float	Altitude (metres)

Optional Telemetry Fields

These fields should only be included in the uploaded JSON object if they are available, and considered to be reliable. Additional fields will be accepted however they may not be able to be queried from certain APIs.

Field	Type	Description	Notes
frame	int	Frame Number, ideally unique over the entire flight.
temp	float	Measured Temperature (deg C, generally assumed to be an internal temperature sensor)
ext_temperature	float	External Temperature (deg C)
ext_humidity	float	Measured Relative Humidity (%)
ext_pressure	float	Measured Pressure (hPa)
vel_h	float	Horizontal Velocity (assumed to be in m/s)
speed	float	Horizontal Velocity (assumed to be in kph) (apologies for the two entries here...)
ascent_rate OR vel_v	float	Vertical Velocity (m/s) (The Horus binary decoders use the field name 'ascent_rate')
heading	float	Heading (degrees True)
sats	int	Number of SVs used in position solution
batt	float	Battery Voltage (volts)
tx_frequency	float	Transmit frequency of the radiosonde in MHz, as determined by information provided in the payload telemetry.
raw	string	Raw payload packet, as ascii text starting with $$ for RTTY packets, or hexadecimal for binary packets.

Optional Metadata Fields

These fields provide additional information about how and where the payload telemetry was received. These are all optional, though we recommend sending modulation and frequency to inform other tracker users where and how the payload is transmitting.

Field	Type	Description	Notes
modulation	str	Modulation of the signal, will be shown on the sidebar on the tracker.	Example values: 'APRS', 'Horus Binary', 'RTTY', 'LoRa', 'WSPR'
baud_rate	int	Baud rate of the modulation, not applicable to all modes. Rounded to the nearest Hz.	Examples: 50, 100
snr	float	Signal-to-Noise ratio of the received signal, in dB
frequency	float	Transmit frequency of the radiosonde in MHz, as estimated by the receiver software (e.g. FSK frequency estimation).
rssi	float	Received-Signal-Strength-Indication of the payload signal, nominally in dBm
uploader_position	list	Station position, as a list [lat, lon, alt]
uploader_antenna	string	Station antenna information, free-text string.
uploader_radio	string	Station radio information, free-text string.