kopia lustrzana https://github.com/proto17/dji_droneid
27 wiersze
1.1 KiB
Markdown
27 wiersze
1.1 KiB
Markdown
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# dji_droneid
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*THIS IS A WORK IN PROGRESS!!!*
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This project aims to demodulate DJI DroneID frames and eventually be able to craft arbitrary DroneID frames that can be sent with an SDR
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The `.m` files in this project *should* work with Octave 5.2.0 and MATLAB
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List of tasks:
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- Identify ZC sequence
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- Detect ZC sequence (done)
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- Coarse frequency offset detection/correction (in progress)
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- Fine frequency offset detection/correction
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- Phase correction
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- Symbol extraction (done)
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- Turbo Product Code removal
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- Descrambling
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- Deframing
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- Profit!
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## Identify ZC Sequence
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There are two Zadoff Chu sequences in each burst. It's unclear as to the correct parameters to generate these sequences. It's possible that they will have to be brute forced
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## Detect ZC Sequence
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This has been done by exploiting the fact that the first ZC sequence is symmetric in the time domain (the second might be too) and that a ZC sequence is a CAZAC (constant amplitude, zero autocorrelation).
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To find the sequence you just need to search through the signal one sample at a time takeing a window of `fft_size` samples, reversing the second half, and cross correlating.
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