This repository is presented as a companion to the article "Deep space reception of Tianwen-1 by AMSAT-DL using GNU Radio" presented in the Proceedings of the GNU Radio Conference in 2021. It contains flowgraphs to decode the telemetry signals of Tianwen-1.
The contents of the repository are the following:
tianwen1.grc. Decoder for the low rate residual carrier telemetry.tianwen1_hsd.grc. Decoder for the QPSK suppressed carrier telemetry.tianwen1_hsd_shortframes.grc. Decoder for the QPSK suppressed carrier telemetry with short frames.tianwen1_qpsk_lowrate.grc. Decoder for the QPSK suppressed carrier low rate telemetry. This mode is only used very briefly when switching to and from high speed data and is not treated in the paper.
The bochum folder contains these decoders organized as hierarchical flowgraphs,
which is the approach that was used in the Bochum to interface to the USRP receiver.
The recording_test.grc is the top level flowgraph, and the remaining flowgraphs
are hierarchical flowgraphs that contain each of the decoders.