I have made my own LilacSat-2 telemetry GNUradio receiver using the flowgraphs included in gr-lilacsat. The new features of this receiver are the following:
- All the decoders and the frontend are run on the same flowgraph. I find this more practical than having to run all the flowgraphs separately. Also, some blocks can be reused in this way.
- It uses gr-gpredict-doppler to compensate for Doppler. As I mentioned in a previous post, I prefer this to the Doppler correcting system included in
- It plots and outputs to a file the signal strength on 437.200MHz and 437.225MHz. This can be used for later analysis.
- It supports recording file input, or live SDR using an ALSA source (for the FUNCube Dongle Pro+, for instance). Another SDR supported by GNUradio can be easily used.
- It supports recording both the raw IQ data and the Doppler corrected IQ data. The raw IQ file can be then played back by simultaneously running Gpredict with the correct settings for the recorded pass. The Doppler corrected IQ file can be played back without running Gpredict.
This receiver can be downloaded from GitHub. The flowgraph is a bit crammed, but that’s what you get for having all the decoders in the same flowgraph. Several of the input/output blocks are disabled, so that you can choose which ones to use.