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Receiving High Altitude Balloon Telemetry

Mark Jessop edited this page Jul 9, 2023 · 11 revisions

SondeHub-Amateur can display telemetry from a variety of different high-altitude balloon payloads. In most cases, you can determine what kind of telemetry the payload in question is using by looking at the 'Modulation' field, shown in the payload detail area. In some cases the frequency of the signal (as estimated by the receiver) is shown.

Information on how to receive some of the more common modulation types is provided below.

Horus Binary (v1/v2)

'Horus Binary' is a modulation format developed by Project Horus as an open-source and highly-robust alternative to RTTY and LoRa. In most cases, Horus Binary payloads transmit on the 70cm amateur radio band, or the 434 MHz ISM band.

The signal can be received using either a Single-Sideband (SSB) capable receiver, or a Software-Defined Radio (RTLSDR, Airspy, etc...). As the telemetry is very robust, only a fairly modest antenna setup is required, and the telemetry can often be received using as little as a 1/4-wave antenna.

The telemetry can be demodulated using Horus-GUI on Windows, OSX and Linux, or using the command-line horusdemodlib decoder on Linux systems (e.g. Raspberry Pi).

RTTY (UKHAS-format Telemetry)

Like Horus Binary payloads, RTTY payloads are usually found in the 70cm band, or 434 MHz ISM band, and require a SSB receiver. Currently support for RTTY telemetry in SondeHub-Amateur is extremely limited, as there is currently no UKHAS-compliant string parser in the telemetry processing pipeline.

Limited support for receiving and uploading RTTY is available through the use of Horus-GUI, which will decode some RTTY transmissions.

Dave Akerman's HAB Base software can also interface with fldigi to receive RTTY telemetry and upload it to SondeHub-Amateur.

LoRa (UKHAS-format Telemetry)

LoRa payloads using UKHAS-format ASCII telemetry (not to be confused with LoRaWAN payloads) are often found in Europe, in particular the UK, with the popular 'FlexTrak' and 'Pi-in-the-Sky' trackers. These are most often found in the 70cm ISM band, around (~434 MHz) - check the SondeHub-Amateur tracker for the exact frequency in use.

These can be decoded using a LoRa receiver IC, and Dave Akerman's HAB Base, PADD, Explora and LoRa gateway software. You can find information about Dave's software here.

Amateur Packet Reporting Service (APRS)

The modulation type of 'APRS' on amateur.sondehub.org indicates that the telemetry was imported from the APRS Internet Service system. This means that the payload itself may be:

  • Transmitting APRS-format telemetry via radio, on the relevant local APRS frequency (usually on the 2m band), received by 'digipeaters' and 'iGates', and uploaded into APRS-IS.
  • Transmitting some other modulation (e.g. WSPR, JT9, others) which has been received and uploaded into the APRS-IS network by the payload owner.

Unfortunately it can be difficult to tell these apart, but as a general rule flights which are 'floaters' are usually transmitting WSPR, and 'regular' flights (flights that ascend to ~30km before bursting and landing) use 2m APRS.

You can assist with receiving regular 2m APRS launches by setting up an APRS iGate. This can be done using as little as a RTLSDR and a Raspberry Pi.

WSPR

Currently WSPR flights are ingested into the SondeHub-Amateur database via APRS-IS.

LoRaWAN (TTN v3 / Helium)

Telemetry from flights using LoRaWAN can only be extracted from the various LoRaWAN networks (e.g. TheThingsNetwork) by the payload owner, using software like ttn-sondehub-bridge.