FOSSCOMM 2018

»gr-satnogs: SatNOGS GNU Radio Out-Of-Tree Module«
2018-10-13, 16:15–16:45, Α1

gr-satnogs is an out-of-tree GNU Radio module that provides all the necessary tools for decoding signals from various sattelites.

SatNOGS provides a scalable and modular platform to communicate with satellites. Low Earth Orbit (LEO) satellites are our priority. Hundreds of interesting projects worth of tracking and listening are happening in LEO and SatNOGS provides a robust platform for doing so. In this talk, we present gr-satnogs, an out-of-tree GNU Radio module that provides all the necessary tools for decoding signals from various scientific and academic satellites. We have developed several decoders that operate in realtime during a LEO satellite pass. Combined with the SatNOGS rotator that tries to point as accurate as possible to the satellite trajectory, the decoder searches for transmitted frames. The successfully decoded frames are then uploaded automatically on the SatNOGS database for visualization and further analysis.

Currently, gr-satnogs modules incorporates decoders for many popular in LEO satellite missions transmission schemes such as AFSK1200, APRS1200, (G)FSK9600, APRS9600, APT, DUV, CW, LRPT using the GNU-Radio toolkit. In addition, decoders for APT and LRPT are producing on the fly the weather images transmitted by the corresponding meteorological satellites. For the most interesting of the available decoders, we present the design and the implementation details among with a live decoding demo from a IQ captured observation.

All of the available decoders are running in realtime on the RPi3 platform. To achieve this, several design decisions were made (RF performance vs realtime operation) and we discuss some of them.