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Kod Zgłoszenia Packages Projekty Wydania Wiki Aktywność

Better Sliding Cross Correlation 

+ Re-added sliding cross correlation, but now starts from the
index found by the falling edge detector, which enables
very fast cross correlation and yields much more
accurate results
~ Changed index_correction correlation percentage threshold
from 0.8 to 0.9 for accuracy improvements
pull/27/head
Wosser1sProductions 2017-04-19 21:43:06 +02:00
rodzic 8194dfaf46
commit d814ea01f3
1 zmienionych plików z 22 dodań i 23 usunięć
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45
lib/decoder_impl.cc
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@ -1,6 +1,6 @@
/* -*- c++ -*- */
/*
* Copyright 2016 Pieter Robyns.
* Copyright 2017 Pieter Robyns, William Thenaers.
*
* This is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@ -315,9 +315,13 @@ namespace gr {
float decoder_impl::sliding_norm_cross_correlate_upchirp(const float *samples, uint32_t window, uint32_t slide, int32_t *index) {
(void) slide;
bool found_change = false;
uint32_t max = 0u, min;
const uint32_t coeff = 16u;
bool found_change = false;
uint32_t max = 0u, min;
const uint32_t coeff = (this->d_sf + this->d_sf + this->d_sf >> 1u);
const uint32_t len = window / 2u;
float max_correlation = 0.0f;
for (uint32_t i = 0u; i < window - coeff - 1u; i += coeff / 2u) {
if (samples[i] - samples[i + coeff] > 0.2f) { // Goes down
@ -331,23 +335,20 @@ namespace gr {
return 0.0f;
}
max = std::max_element(samples + gr::lora::clamp((int)(max - coeff), 0, (int)window),
samples + gr::lora::clamp(max + coeff, 0u, window)) - samples;
min = std::min_element(samples + gr::lora::clamp(max + 1u, 0u, window),
samples + gr::lora::clamp(max + 2u * coeff, 0u, window)) - samples;
max = std::max_element(samples + gr::lora::clamp((int)(max - 2u * coeff), 0, (int)window),
samples + gr::lora::clamp(max + coeff, 0u, window)) - samples;
min = std::min_element(samples + gr::lora::clamp(max + 1u, 0u, window),
samples + gr::lora::clamp(max + 3u * coeff, 0u, window)) - samples;
max += (min - max) / 2;
*index = max;
// Extra to allow falling edge on 99% of sample == Practically synced
// Should improve detection by not discarding almost synced samples, but doesn't..
// if ((max - coeff / 2) > (window * 0.98f)) {
//// printf("ALREADY SYNCED\n");
// *index = 0;
// return 0.99f;
// }
return this->cross_correlate_ifreq(samples, this->d_upchirp_ifreq, max, window);
for (int32_t i = max; i < min; i++) {
const float max_corr = this->cross_correlate_ifreq(samples + i, this->d_upchirp_ifreq, 0u, len);
if (max_corr > max_correlation) {
*index = i;
max_correlation = max_corr;
}
}
return max_correlation;
}
/**
@ -437,8 +438,6 @@ namespace gr {
unsigned int decoder_impl::max_frequency_gradient_idx(gr_complex *samples) {
float instantaneous_freq [this->d_samples_per_symbol];
float max_if_diff = 0.0f; //2000.0f;
unsigned int max_if_diff_idx = 0u;
samples_to_file("/tmp/data", &samples[0], this->d_samples_per_symbol, sizeof(gr_complex));
@ -770,7 +769,7 @@ namespace gr {
this->d_samples_per_symbol / this->d_corr_decim_factor,
&index_correction);
if (c > 0.8f) {
if (c > 0.9f) {
#ifndef NDEBUG
this->d_debug << "Cu: " << c << std::endl;
#endif