High Altitude Balloon (HAB) Telemetry Library

This library contains software used to encode and decode telemetry used by the Project Horus High-Altitude Balloon (HAB) project (amongst other users). This software was originally developed as part of the codec2 project, but as of 2020 has been broken out into this separate project, to keep codec2 targeted at low-level voice-codec and modem development.

This library includes the following:

• The 'HorusBinary' demodulator, a high performance 4FSK modem used for low-rate positional telemetry from HABs. More information on this modem can be found here: https://github.com/projecthorus/horusbinary (This repository will eventually be re-worked to use this library)
• The 'Wenet' demodulator, used to downlink imagery from HAB payloads.

HorusDemodLib C Library

This contains the demodulator portions of horuslib, which are written in C.

Building

The library can be built and installed using:

$ git clone https://github.com/projecthorus/horusdemodlib.git
$ cd horusdemodlib && mkdir build && cd build
$ cmake ..
$ make
$ make install

Testing

Unit tests for the various demodulators can be run using:

$ cd build
$ ctest

API Reference

The main demodulator API is horus_api.h. An example of it in use in a C program is available in horus_demod.c

A Python wrapper is also available (via the horusdemodlib Python library which is also part of this repository). An example of its use is available here.

HorusDemodLib Python Library

The horusdemodlib Python library contains decoders for the different Project Horus telemetry formats, including:

• Horus Binary v1 (Legacy 22-byte Golay-encoded format)
• Horus Binary v2 (LDPC-Encoded 16 and 32-byte formats)

It also contains a wrapper around the C library (mentioned above), which contains the Horus modem demodulators.

The easiest way to install horusdemodlib is via pypi:

$ pip install horusdemodlib

If you want to install directly from this repository, you can run:

$ pip install -r requirements.txt
$ pip install -e .

Further Reading

Here are some links to projects and blog posts that use this code:

1. Horus Binary High Altitude Balloon (HAB) telemetry protocol, 3 second updates, works at 7dB lower SNR that RTTY.
2. Testing HAB Telemetry, Horus binary waveform
3. Wenet - high speed SSTV images from balloons at the edge of space
4. Wenet High speed SSTV images