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Stripped down normalized cross correlator 

This new version is much more of an estimate of the cross correlation, but it's a *lot* faster.  Still need to do more real world testing of it
gr-droneid-update
David Protzman 2022-06-20 13:07:31 -04:00
rodzic 2e33165cbe
commit 4b46d30248
1 zmienionych plików z 4 dodań i 21 usunięć
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gnuradio/gr-droneid/lib/normalized_xcorr.cc
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@ -54,35 +54,18 @@ namespace gr {
return 0;
}
auto running_sum = std::accumulate(samples, samples + window_size_ - 1, complex_t{0, 0});
complex_t last_val = {0, 0};
const auto max_correlations = sample_count - window_size_;
if (scores_.size() < max_correlations) {
scores_.resize(max_correlations);
}
for (auto offset = decltype(max_correlations){0}; offset < max_correlations; offset++) {
std::copy(samples + offset, samples + offset + window_size_, temp_.begin());
running_sum += samples[offset + window_size_ - 1] - last_val;
last_val = samples[offset];
const auto mean = running_sum / static_cast<sample_t>(window_size_);
std::for_each(temp_.begin(), temp_.end(), [&mean](complex_t & sample){
sample -= mean;
});
complex_t sum;
volk_32fc_x2_dot_prod_32fc(&sum, &temp_[0], &taps_[0], window_size_);
sum /= static_cast<sample_t>(window_size_);
scores_[offset] = sum / static_cast<sample_t>(std::sqrt(taps_var_ * misc_utils::var_no_mean(temp_)));
volk_32fc_x2_dot_prod_32fc(&scores_[offset], samples + offset, &taps_[0], window_size_);
}
volk_32fc_magnitude_squared_32f(output_samples, &scores_[0], scores_.size());
const complex_t scalar = {1 / static_cast<sample_t>(sqrt(taps_var_) * window_size_), 0};
volk_32fc_s32fc_multiply_32fc(&scores_[0], &scores_[0], scalar, max_correlations);
volk_32fc_magnitude_squared_32f(output_samples, &scores_[0], max_correlations);
return max_correlations;
}