Support for SpaceTeamSat1 #783
Replies: 15 comments 6 replies
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Greetings! I'm sure you will get a reply to your inquiry. Meanwhile, do you have a specific launch date yet? Thanks and best of luck on the mission! -Scott, K4KDR |
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Thanks for the quick reply! The public information on this is "probably December" (after getting moved a bunch of times). if you have time for a quick chat I'd love to get some input regarding the groundstation side (my current flowgraph is working but decoding with weak signal has pretty bad success rate and I have some other issues). Us not really having enough time lead to the complete GS side getting neglected until now...) |
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Sorry - one other question, please. I see that you've been using GNU Radio to generate test signals, but do you have any I/Q (or audio) recordings from the spacecraft radio itself. Everyone likes to test their ground station w/ actual signals BEFORE launch when possible. Thanks! (just saw your reply - thank you! And yes, your RX flowgraph can be greatly simplified w/ the "standard" .YML file -based flowgraph that is common for those using gr-satellites in GNU Radio. Would you prefer that I email you an example) |
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I don't have an I/Q recording handy but I can definitely record one at the end of this week on the flatsat (currently a bit sick else I'd do it tomorrow ^^). |
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If possible, please use an SDR that does not add the dreaded 'DC Spike' to the recording. (Products such as AirSpy & HydraSDR-RFone do not add the center spike). Of course, if the only SDR hardware available DOES add the center spike, kindly offset your RX frequency so that the entirety of your signal is clear of the center spike. We can adjust our playback offset as needed. Any reasonable sample rate is fine. Since I/Q files can get large, it's helpful to keep the sample fairly short with a modest sample rate. For testing, a good clean signal is preferable. So, no need to artificially inject attenuation, noise, etc. Just specify the type of file & sample rate when shared. Thanks! |
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Will do thanks, I don't think I have a SDR without a DC spike so an offset will have to do. |
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Here is an example (UN-tested) of a basic satellite telemetry decoder using gr-satellites, configured for SpaceTeamSat1. You can adjust the sample rate and specify file names for I/Q or Audio input files. Or, input 'live' audio from an SDR. Note that audio is only useful up to certain baud rates! The outputs are self-explanatory. It's common for each ground station to make adjustments to suit their own experience & preferences, so please do the same. (you can also include a SOURCE block in the flowgraph for your SDR hardware if preferred, including doppler compensation!) What is lacking in this example (other than input files) is the .YML file that I'll leave to others to assist with. That will define all of your stated downlink modes & baud rates; that way, decodes are possible even from multiple modes/bauds in the same session! The URL is --> https://www.dropbox.com/scl/fi/wjhhs7nng1fgvxtsiftz4/SpaceTeamSat1_YML_decoder.grc?rlkey=s3n8xvvo6g6kv15mnxvyxg4a7&dl=0
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All of this is already supported in gr-satellites, so a suitable SatYAML file should work. Once you share an IQ file I can validate that the SatYAML file works and add it. Documentation and/or code for a I will move this issue to a discussion, since we have a specific discussions section for support to satellite teams. |
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Good evening, up front all the best with your mission. When the IQ is available I will also put some effort in creating a yaml file. Jan | PE0SAT |
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Sorry for the long silence. I'll work on the telemetry parser definition next. |
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Thank you for the sample files! Can you confirm if those are 9600 baud signals (as mentioned in your original post). And by chance was there any decimation applied to the SDR doing the recording... when I replay your files, at 8M sample rate they don't appear as I would expect. Thanks! |
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Good evening, after some testing and the hint given by @K4KDR I got a working solution.
Files can found at the following location. Jan | PE0SAT |
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That's great, Jan!! And I've just finished testing a flowgraph from I/Q, audio WAV, and 'live' audio from GQRX if anyone would like a starting point in GNU Radio to adjust to their preferences. The GRC file is at: https://www.dropbox.com/scl/fi/ybqu2swl9yynaemojpic4/sdr_trx_cosmos_2026-01-28_k4kdr-shared.grc?rlkey=4u74bfcezb9w5k9sthpoii25m&dl=0 ... and the 48k audio file created from the Team's I/Q recording is at: https://www.dropbox.com/scl/fi/me04uf7vlnddq675s5ljm/FM-demod_SpaceTeamSat-1_sample_48k_AUDIO.wav?rlkey=kuzac5r8m39e4mk62owyp0w6e&dl=0
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Wasn't this supposed to be GMSK? If so, the deviation would be 9600/4 = 2400 Hz. |
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Hi!
Our cubesat (https://db.satnogs.org/satellite/GCRL-7329-1908-5510-3384) will launch soon.
Protocol wise it is relatively standard CCSDS and I'd ask you to support it gr-satellites.
It is an amateur mission, see https://spaceteam.at/en/sts1-en/ for detailed mission description.
We intend to publish all data regarding the satellite (most of it can already be found on GitHub and Zenodo, including hardware designs and the firmware running on the cubesat).
Modulation and channel coding is GMSK with 9600 Baud, dual-basis RS223/255, CCSDS scrambling and unpunctured convolutional coding.
Baud rate can be increased for non-beacon data up to 115200.
The Flowgraph (based on gr-satellite blocks) we are currently using can be found here: https://github.com/SpaceTeam/STS1_Channel_Coding_Tests/blob/master/sdr_trx_cosmos.grc (feel free to give input in case there are obvious improvements that could be made. One thing we noticed that seems odd is that the decode success rate is strongly dependant on the sample rate and decimation and more often isn't better).
Sorry for the late coordination :/
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