kopia lustrzana https://github.com/proto17/dji_droneid
Added comments about the different OFDM symbol counts
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@ -35,7 +35,11 @@ function [bursts] = extract_bursts_from_file(input_path, sample_rate, frequency_
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% Find all instances of the first ZC sequence
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indices = find_zc_indices_by_file(input_path, sample_rate, frequency_offset, correlation_threshold, chunk_size);
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% Number of samples that need to be extracted. There are 9 OFDM symbols, 2 long and 7 short cyclic prefixes
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% In the DJI Mini 2 there are 9 OFDM symbols: 2 long cyclic prefixes, 7 short. This isn't the case on all drones.
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% For some drones there are just 8 OFDM symbols. It looks like those drones just don't send the first OFDM symbol
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% that's present on the Mini 2. That symbol XOR's out to all zeros anyway, so it's not important. So, to keep
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% things consistent, the logic below will always extract out 9 OFDM symbols worth of samples. In later steps the
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% first OFDM symbol isn't used for anything.
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burst_sample_count = (padding * 2) + (long_cp_len * 2) + (short_cp_len * 7) + (fft_size * 9);
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freq_offset_vec = reshape(exp(freq_offset_constant * [1:burst_sample_count]), 1, []);
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