kopia lustrzana https://github.com/rpp0/gr-lora
871 wiersze
36 KiB
C++
871 wiersze
36 KiB
C++
/* -*- c++ -*- */
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/*
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* Copyright 2016 Pieter Robyns.
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*
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* This is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3, or (at your option)
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* any later version.
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*
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* This software is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this software; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <gnuradio/io_signature.h>
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#include <gnuradio/expj.h>
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#include <liquid/liquid.h>
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#include <numeric>
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#include "decoder_impl.h"
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#include "tables.h"
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#include "utilities.h"
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//#define NO_TMP_WRITES 1 /// Debug output file write
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//#define CFO_CORRECT 1 /// Correct shift fft estimation
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#undef NDEBUG /// Debug printing
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namespace gr {
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namespace lora {
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decoder::sptr decoder::make(float samp_rate, int sf) {
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return gnuradio::get_initial_sptr
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(new decoder_impl(samp_rate, sf));
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}
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/**
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* The private constructor
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*/
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decoder_impl::decoder_impl(float samp_rate, uint8_t sf)
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: gr::sync_block("decoder",
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gr::io_signature::make(1, -1, sizeof(gr_complex)),
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gr::io_signature::make(0, 2, sizeof(float))) {
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this->d_state = gr::lora::DecoderState::DETECT;
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if (sf < 6 || sf > 13) {
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//throw std::invalid_argument("[LoRa Decoder] ERROR : Spreading factor should be between 6 and 12 (inclusive)!\n Other values are currently not supported.");
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std::cerr << "[LoRa Decoder] ERROR : Spreading factor should be between 6 and 12 (inclusive)!\n Other values are currently not supported." << std::endl;
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exit(1);
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}
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#ifndef NDEBUG
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this->d_debug_samples.open("/tmp/grlora_debug", std::ios::out | std::ios::binary);
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this->d_debug.open("/tmp/grlora_debug_txt", std::ios::out);
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#endif
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this->d_bw = 125000;
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this->d_cr = 4;
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this->d_samples_per_second = samp_rate;
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this->d_corr_decim_factor = 8; // samples_per_symbol / corr_decim_factor = correlation window. Also serves as preamble decimation factor
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this->d_payload_symbols = 0;
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this->d_cfo_estimation = 0.0f;
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this->d_dt = 1.0f / this->d_samples_per_second;
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this->d_sf = sf; // Only affects PHY send
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this->d_bits_per_second = (double)this->d_sf * (double)(1 + this->d_cr) / (1 << this->d_sf) * this->d_bw;
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this->d_symbols_per_second = (double)this->d_bw / (1 << this->d_sf);
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this->d_bits_per_symbol = (uint32_t)(this->d_bits_per_second / this->d_symbols_per_second);
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this->d_samples_per_symbol = (uint32_t)(this->d_samples_per_second / this->d_symbols_per_second);
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this->d_delay_after_sync = this->d_samples_per_symbol / 4;
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this->d_number_of_bins = (uint32_t)(1 << this->d_sf);
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this->d_number_of_bins_hdr = this->d_number_of_bins / 4;
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// Some preparations
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std::cout << "Bits per symbol: \t" << this->d_bits_per_symbol << std::endl;
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std::cout << "Bins per symbol: \t" << this->d_number_of_bins << std::endl;
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std::cout << "Header bins per symbol: " << this->d_number_of_bins_hdr << std::endl;
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std::cout << "Samples per symbol: \t" << this->d_samples_per_symbol << std::endl;
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std::cout << "Decimation: \t\t" << (this->d_samples_per_symbol / this->d_number_of_bins) << std::endl;
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this->build_ideal_chirps();
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this->set_output_multiple(2 * this->d_samples_per_symbol);
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this->d_fft.resize(this->d_number_of_bins);
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this->d_mult.resize(this->d_number_of_bins);
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this->d_q = fft_create_plan(this->d_number_of_bins, &this->d_mult[0], &this->d_fft[0], LIQUID_FFT_FORWARD, 0);
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// Decimation filter
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float g[DECIMATOR_FILTER_SIZE];
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liquid_firdes_rrcos(8, 1, 0.5f, 0.3f, g); // Filter for interpolating
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for (uint32_t i = 0; i < DECIMATOR_FILTER_SIZE; i++) // Reverse it to get decimation filter
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this->d_decim_h[i] = g[DECIMATOR_FILTER_SIZE - i - 1];
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this->d_decim_factor = this->d_samples_per_symbol / this->d_number_of_bins;
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this->d_decim = firdecim_crcf_create(this->d_decim_factor, this->d_decim_h, DECIMATOR_FILTER_SIZE);
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// Register gnuradio ports
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this->message_port_register_out(pmt::mp("frames"));
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this->message_port_register_out(pmt::mp("debug"));
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}
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/**
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* Our virtual destructor.
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*/
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decoder_impl::~decoder_impl() {
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#ifndef NDEBUG
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if (this->d_debug_samples.is_open())
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this->d_debug_samples.close();
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if (this->d_debug.is_open())
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this->d_debug.close();
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#endif
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fft_destroy_plan(this->d_q);
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firdecim_crcf_destroy(this->d_decim);
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}
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void decoder_impl::build_ideal_chirps(void) {
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this->d_downchirp .resize(this->d_samples_per_symbol);
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this->d_upchirp .resize(this->d_samples_per_symbol);
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this->d_downchirp_ifreq .resize(this->d_samples_per_symbol);
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this->d_upchirp_ifreq .resize(this->d_samples_per_symbol);
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const double T = -0.5 * this->d_bw * this->d_symbols_per_second;
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const double f0 = (this->d_bw / 2.0f);
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const double pre_dir = 2.0f * M_PI;
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double t;
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gr_complex cmx = gr_complex(1.0f, 1.0f);
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for (uint32_t i = 0; i < this->d_samples_per_symbol; i++) {
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// Width in number of samples = samples_per_symbol
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// See https://en.wikipedia.org/wiki/Chirp#Linear
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t = this->d_dt * i;
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this->d_downchirp[i] = cmx * gr_expj(pre_dir * t * (f0 + T * t));
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this->d_upchirp[i] = cmx * gr_expj(pre_dir * t * (f0 + T * t) * -1.0f);
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}
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// Store instant. frequency
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instantaneous_frequency(&this->d_downchirp[0], &this->d_downchirp_ifreq[0], this->d_samples_per_symbol);
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instantaneous_frequency(&this->d_upchirp[0], &this->d_upchirp_ifreq[0], this->d_samples_per_symbol);
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samples_to_file("/tmp/downchirp", &this->d_downchirp[0], this->d_downchirp.size(), sizeof(gr_complex));
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samples_to_file("/tmp/upchirp", &this->d_upchirp[0], this->d_upchirp.size(), sizeof(gr_complex));
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}
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void decoder_impl::samples_to_file(const std::string path, const gr_complex *v, uint32_t length, uint32_t elem_size) {
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#ifndef NO_TMP_WRITES
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std::ofstream out_file;
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out_file.open(path.c_str(), std::ios::out | std::ios::binary);
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//for(std::vector<gr_complex>::const_iterator it = v.begin(); it != v.end(); ++it) {
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for (uint32_t i = 0; i < length; i++) {
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out_file.write(reinterpret_cast<const char *>(&v[i]), elem_size);
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}
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out_file.close();
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#else
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(void) path;
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(void) v;
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(void) length;
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(void) elem_size;
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#endif
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}
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void decoder_impl::samples_debug(const gr_complex *v, uint32_t length) {
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#ifndef NDEBUG
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gr_complex start_indicator(0.0f, 32.0f);
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this->d_debug_samples.write(reinterpret_cast<const char *>(&start_indicator), sizeof(gr_complex));
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for (uint32_t i = 1; i < length; i++) {
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this->d_debug_samples.write(reinterpret_cast<const char *>(&v[i]), sizeof(gr_complex));
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}
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#else
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(void) v;
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(void) length;
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#endif
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}
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bool decoder_impl::calc_energy_threshold(gr_complex *samples, int window_size, float threshold) {
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float result = 0.0f;
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for (int i = 0; i < window_size; i++) {
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float magn = abs(samples[i]);
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result += magn * magn;
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}
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result /= (float)window_size;
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#ifndef NDEBUG
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this->d_debug << "T: " << result << "\n";
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#endif
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return result > threshold;
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}
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void decoder_impl::instantaneous_frequency(const gr_complex *in_samples, float *out_ifreq, uint32_t window) {
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float iphase[window];
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if (window < 2) {
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// TODO: throw warning here
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std::cerr << "LoRa Decoder Warning: window size < 2 !" << std::endl;
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return;
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}
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this->instantaneous_phase(in_samples, iphase, window);
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// Instant freq
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for (uint32_t i = 1; i < window; i++) {
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out_ifreq[i - 1] = iphase[i] - iphase[i - 1];
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}
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// Make sure there is no strong gradient if this value is accessed by mistake
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out_ifreq[window - 1] = out_ifreq[window - 2];
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}
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inline void decoder_impl::instantaneous_phase(const gr_complex *in_samples, float *out_iphase, uint32_t window) {
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for (uint32_t i = 0; i < window; i++) {
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out_iphase[i] = arg(in_samples[i]);
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// = the same as atan2(imag(in_samples[i]),real(in_samples[i]));
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}
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liquid_unwrap_phase(out_iphase, window);
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}
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float decoder_impl::cross_correlate(const gr_complex *samples_1, const gr_complex *samples_2, int window) {
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float result = 0.0f;
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for (int i = 0; i < window; i++) {
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result += real(samples_1[i] * conj(samples_2[i]));
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}
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result /= (float)window;
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return result;
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}
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float decoder_impl::detect_downchirp(const gr_complex *samples, uint32_t window) {
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float samples_ifreq[window];
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instantaneous_frequency(samples, samples_ifreq, window);
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return norm_cross_correlate(samples_ifreq, &this->d_downchirp_ifreq[0], window);
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}
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/**
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* Calculate normalized cross correlation of real values.
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* See https://en.wikipedia.org/wiki/Cross-correlation#Normalized_cross-correlation.
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*/
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float decoder_impl::norm_cross_correlate(const float *samples_1, const float *samples_2, uint32_t window) {
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float result = 0.0f;
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float average_1 = std::accumulate(samples_1, samples_1 + window, 0.0f) / window;
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float average_2 = std::accumulate(samples_2, samples_2 + window, 0.0f) / window;
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float sd_1 = stddev(samples_1, window, average_1);
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float sd_2 = stddev(samples_2, window, average_2);
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for (uint32_t i = 0; i < window - 1; i++) {
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result += (samples_1[i] - average_1) * (samples_2[i] - average_2)
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/ (sd_1 * sd_2);
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}
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result /= (float)(window - 1);
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return result;
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}
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float decoder_impl::sliding_norm_cross_correlate(const float *samples_1, const float *samples_2, uint32_t window, uint32_t slide, int32_t *index) {
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float correlations[slide * 2];
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float samples_1_padded[window + slide * 2] = { 0.0f };
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double average_1 = std::accumulate(samples_1, samples_1 + window, 0.0) / window;
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double average_2 = std::accumulate(samples_2, samples_2 + window, 0.0) / window;
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double sd_1 = stddev(samples_1, window, average_1);
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double sd_2 = stddev(samples_2, window, average_2);
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uint32_t i, j;
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float result;
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// Create padding on both sides of the samples
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for (i = 0; i < window; i++) {
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samples_1_padded[i + slide - 1] = samples_1[i];
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}
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// Slide and correlate
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for (i = 0; i < 2 * slide; i++) {
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result = 0.0f;
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for (j = 0; j < window; j++) {
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result += (samples_1_padded[i + j] - average_1) * (samples_2[j] - average_2)
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/ (sd_1 * sd_2);
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}
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correlations[i] = result / (float)window;
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}
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// Determine best correlation
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uint32_t argmax = (std::max_element(correlations, correlations + slide * 2) - correlations);
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// Determine how much we have to slide before the best correlation is reached
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*index = argmax - slide;
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return correlations[argmax];
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}
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float decoder_impl::stddev(const float *values, uint32_t len, float mean) {
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float variance = 0.0f, temp;
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for (unsigned int i = 0; i < len; i++) {
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temp = values[i] - mean;
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variance += temp * temp;
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}
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variance /= (float)len;
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return std::sqrt(variance);
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}
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float decoder_impl::detect_upchirp(const gr_complex *samples, uint32_t window, uint32_t slide, int32_t *index) {
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float samples_ifreq[window];
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instantaneous_frequency(samples, samples_ifreq, window);
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return sliding_norm_cross_correlate(samples_ifreq, &this->d_upchirp_ifreq[0], window, slide, index);
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}
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unsigned int decoder_impl::get_shift_fft(gr_complex *samples) {
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float fft_mag[this->d_number_of_bins];
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gr_complex mult_hf[this->d_samples_per_symbol];
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#ifdef CFO_CORRECT
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determine_cfo(&samples[0]);
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#ifndef NDEBUG
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this->d_debug << "CFO: " << this->d_cfo_estimation << std::endl;
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#endif
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correct_cfo(&samples[0], this->d_samples_per_symbol);
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#endif
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samples_to_file("/tmp/data", &samples[0], this->d_samples_per_symbol, sizeof(gr_complex));
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// Multiply with ideal downchirp
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for (uint32_t i = 0; i < this->d_samples_per_symbol; i++) {
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mult_hf[i] = conj(samples[i] * this->d_downchirp[i]);
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}
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samples_to_file("/tmp/mult", &mult_hf[0], this->d_samples_per_symbol, sizeof(gr_complex));
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// Perform decimation
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for (uint32_t i = 0; i < this->d_number_of_bins; i++) {
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firdecim_crcf_execute(this->d_decim, &mult_hf[this->d_decim_factor * i], &d_mult[i]);
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}
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samples_to_file("/tmp/resampled", &this->d_mult[0], this->d_number_of_bins, sizeof(gr_complex));
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// Perform FFT
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fft_execute(this->d_q);
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// Get magnitude
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for (uint32_t i = 0; i < this->d_number_of_bins; i++) {
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fft_mag[i] = abs(this->d_fft[i]);
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}
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samples_to_file("/tmp/fft", &this->d_fft[0], this->d_number_of_bins, sizeof(gr_complex));
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// Return argmax here
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return (std::max_element(fft_mag, fft_mag + this->d_number_of_bins) - fft_mag);
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}
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unsigned int decoder_impl::max_frequency_gradient_idx(gr_complex *samples) {
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float instantaneous_phase[this->d_samples_per_symbol];
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float instantaneous_freq [this->d_samples_per_symbol];
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//float bins[this->d_number_of_bins];
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samples_to_file("/tmp/data", &samples[0], this->d_samples_per_symbol, sizeof(gr_complex));
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// Determine instant phase
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for (unsigned int i = 0; i < this->d_samples_per_symbol; i++) {
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instantaneous_phase[i] = arg(samples[i]);
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}
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liquid_unwrap_phase(instantaneous_phase, this->d_samples_per_symbol);
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float max_if_diff = 2000.0f;
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unsigned int max_if_diff_idx = 0;
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const double div = (double)this->d_samples_per_second / (2.0f * M_PI);
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for (unsigned int i = 1; i < this->d_samples_per_symbol; i++) {
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instantaneous_freq[i - 1] = (float)((instantaneous_phase[i] - instantaneous_phase[i - 1]) * div);
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}
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uint32_t osr = this->d_samples_per_symbol / this->d_number_of_bins;
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float last_avg = instantaneous_freq[0];
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for (unsigned int i = 0; i < this->d_number_of_bins; i++) {
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float avg = 0.0f;
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for (unsigned int j = 0; j < osr; j++) {
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avg += instantaneous_freq[(osr * i) + j];
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}
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avg /= (float)osr;
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float diff = abs(last_avg - avg);
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if (diff > max_if_diff) {
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max_if_diff = diff;
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max_if_diff_idx = i;
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}
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last_avg = avg;
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}
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//std::cout << "!!!" << max_if_diff << std::endl;
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return max_if_diff_idx;
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}
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bool decoder_impl::demodulate(gr_complex *samples, bool is_header) {
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unsigned int bin_idx = this->max_frequency_gradient_idx(samples);
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//unsigned int bin_idx = get_shift_fft(samples);
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//unsigned int bin_idx_test = get_shift_fft(samples);
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unsigned int bin_idx_test = 0;
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// Header has additional redundancy
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if (is_header) {
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bin_idx /= 4;
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bin_idx_test /= 4;
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}
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// Decode (actually gray encode) the bin to get the symbol value
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unsigned int word = gray_encode(bin_idx);
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#ifndef NDEBUG
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this->d_debug << gr::lora::to_bin(word, is_header ? this->d_sf - 2 : this->d_sf) << " " << bin_idx << std::endl;
|
|
#endif
|
|
this->d_words.push_back(word);
|
|
|
|
// Look for 4+cr symbols and stop
|
|
if (this->d_words.size() == (4u + this->d_cr)) {
|
|
// Deinterleave
|
|
this->deinterleave(is_header ? this->d_sf - 2 : this->d_sf);
|
|
|
|
return true; // Signal that a block is ready for decoding
|
|
}
|
|
|
|
return false; // We need more words in order to decode a block
|
|
}
|
|
|
|
void decoder_impl::deinterleave(uint32_t ppm) {
|
|
unsigned int bits_per_word = this->d_words.size();
|
|
|
|
if (bits_per_word > 8) {
|
|
// Not sure if this can ever occur. It would imply coding rate high than 4/8 e.g. 4/9.
|
|
std::cerr << "More than 8 bits per word. uint8_t will not be sufficient! Bytes need to be stored in intermediate array and then packed into words_deinterleaved!" << std::endl;
|
|
}
|
|
|
|
std::deque<uint8_t> words_deinterleaved;
|
|
unsigned int offset_start = ppm - 1, offset_diag, i;
|
|
uint8_t d;
|
|
|
|
for (i = 0; i < ppm; i++) {
|
|
d = 0;
|
|
offset_diag = offset_start;
|
|
|
|
for (unsigned int j = 0; j < bits_per_word; j++) {
|
|
uint8_t power = 1 << j;
|
|
unsigned int power_check = 1 << offset_diag;
|
|
|
|
if (this->d_words[j] & power_check) { // Mask triggers
|
|
d += power;
|
|
}
|
|
|
|
if (offset_diag) offset_diag--;
|
|
else offset_diag = ppm - 1;
|
|
}
|
|
|
|
offset_start--;
|
|
words_deinterleaved.push_front(d);
|
|
}
|
|
|
|
#ifndef NDEBUG
|
|
std::vector<uint8_t> wd(words_deinterleaved.begin(), words_deinterleaved.begin() + ppm-1);
|
|
print_vector(this->d_debug, wd, "D", sizeof(uint8_t) * 8);
|
|
#endif
|
|
|
|
// Add to demodulated data
|
|
this->d_demodulated.insert(this->d_demodulated.end(), words_deinterleaved.begin(), words_deinterleaved.end());
|
|
|
|
// Cleanup
|
|
this->d_words.clear();
|
|
}
|
|
|
|
int decoder_impl::decode(uint8_t *out_data, bool is_header) {
|
|
const uint8_t *prng = NULL;
|
|
const uint8_t shuffle_pattern[] = {7, 6, 3, 4, 2, 1, 0, 5};
|
|
|
|
if (is_header) {
|
|
prng = gr::lora::prng_header;
|
|
} else {
|
|
switch(this->d_sf) {
|
|
case 7: prng = gr::lora::prng_payload_sf7; break;
|
|
case 8: prng = gr::lora::prng_payload_sf8; break;
|
|
case 9: prng = gr::lora::prng_payload_sf9; break;
|
|
case 10: prng = gr::lora::prng_payload_sf10; break;
|
|
case 11: prng = gr::lora::prng_payload_sf11; break;
|
|
case 12: prng = gr::lora::prng_payload_sf12; break;
|
|
default: prng = gr::lora::prng_payload_sf7; break;
|
|
}
|
|
}
|
|
|
|
this->deshuffle(shuffle_pattern, is_header);
|
|
this->dewhiten(prng);
|
|
this->hamming_decode(out_data);
|
|
|
|
// Nibbles are reversed TODO why is this?
|
|
this->nibble_reverse(out_data, this->d_payload_length);
|
|
|
|
// Print result
|
|
std::stringstream result;
|
|
|
|
for (uint32_t i = 0; i < this->d_payload_length; i++) {
|
|
result << " " << std::hex << std::setw(2) << std::setfill('0') << (int)out_data[i];
|
|
}
|
|
|
|
if (!is_header) {
|
|
this->d_data.insert(this->d_data.end(), out_data, out_data + this->d_payload_length);
|
|
std::cout << result.str() << std::endl;
|
|
|
|
pmt::pmt_t payload_blob = pmt::make_blob(&this->d_data[0],
|
|
sizeof(uint8_t) * (this->d_payload_length + 3));
|
|
this->message_port_pub(pmt::mp("frames"), payload_blob);
|
|
} else {
|
|
this->d_data.insert(this->d_data.end(), out_data, out_data + 3);
|
|
std::cout << result.str();
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
void decoder_impl::deshuffle(const uint8_t *shuffle_pattern, bool is_header) {
|
|
const uint32_t to_decode = is_header ? 5 : this->d_demodulated.size();
|
|
const uint32_t len = sizeof(shuffle_pattern) / sizeof(uint8_t);
|
|
uint8_t original, result;
|
|
|
|
for (uint32_t i = 0; i < to_decode; i++) {
|
|
original = this->d_demodulated[i];
|
|
result = 0;
|
|
|
|
for (uint32_t j = 0; j < len; j++) {
|
|
if (original & (1 << shuffle_pattern[j])) {
|
|
result |= 1 << j;
|
|
}
|
|
}
|
|
|
|
float sum = 0.0f;
|
|
for(int i = 0; i < d_samples_per_symbol-1; i++) {
|
|
sum += instantaneous_freq[i];
|
|
#ifndef NDEBUG
|
|
//print_vector(d_debug, d_words_deshuffled, "S", sizeof(uint8_t)*8);
|
|
print_vector_raw(this->d_debug, this->d_words_deshuffled, sizeof(uint8_t) * 8);
|
|
this->d_debug << std::endl;
|
|
#endif
|
|
|
|
// We're done with these words
|
|
if (is_header){
|
|
this->d_demodulated.erase(this->d_demodulated.begin(), this->d_demodulated.begin() + 5);
|
|
this->d_demodulated.clear();
|
|
}
|
|
}
|
|
|
|
void decoder_impl::dewhiten(const uint8_t *prng) {
|
|
uint32_t i, len = this->d_words_deshuffled.size();
|
|
|
|
/*d_cfo_estimation = (*std::max_element(instantaneous_freq, instantaneous_freq+d_samples_per_symbol-1) + *std::min_element(instantaneous_freq, instantaneous_freq+d_samples_per_symbol-1)) / 2;*/
|
|
}
|
|
|
|
void decoder_impl::correct_cfo(gr_complex* samples, int num_samples) {
|
|
for(uint32_t i = 0; i < num_samples; i++) {
|
|
samples[i] = samples[i] * gr_expj(2.0f * M_PI * -d_cfo_estimation * (d_dt * i));
|
|
this->d_words_deshuffled.clear();
|
|
}
|
|
|
|
void decoder_impl::hamming_decode(uint8_t *out_data) {
|
|
uint8_t data_indices[4] = {1, 2, 3, 5};
|
|
|
|
switch(this->d_cr) {
|
|
case 4: case 3:
|
|
gr::lora::hamming_decode_soft(&this->d_words_dewhitened[0], this->d_words_dewhitened.size(), out_data);
|
|
break;
|
|
case 2: case 1: // TODO: Report parity error to the user
|
|
gr::lora::fec_extract_data_only(&this->d_words_dewhitened[0], this->d_words_dewhitened.size(), data_indices, 4, out_data);
|
|
break;
|
|
}
|
|
|
|
this->d_words_dewhitened.clear();
|
|
|
|
/*
|
|
fec_scheme fs = LIQUID_FEC_HAMMING84;
|
|
unsigned int n = ceil(this->d_words_dewhitened.size() * 4.0f / (4.0f + d_cr));
|
|
|
|
unsigned int k = fec_get_enc_msg_length(fs, n);
|
|
fec hamming = fec_create(fs, NULL);
|
|
|
|
fec_decode(hamming, n, &d_words_dewhitened[0], out_data);
|
|
|
|
d_words_dewhitened.clear();
|
|
fec_destroy(hamming);*/
|
|
}
|
|
|
|
void decoder_impl::nibble_reverse(uint8_t *out_data, int len) {
|
|
for (int i = 0; i < len; i++) {
|
|
out_data[i] = ((out_data[i] & 0x0f) << 4) | ((out_data[i] & 0xf0) >> 4);
|
|
}
|
|
}
|
|
|
|
void decoder_impl::determine_cfo(const gr_complex *samples) {
|
|
float instantaneous_phase[this->d_samples_per_symbol];
|
|
// float instantaneous_freq [this->d_samples_per_symbol];
|
|
double div = (double) this->d_samples_per_second / (2.0f * M_PI);
|
|
|
|
// Determine instant phase
|
|
for (unsigned int i = 0; i < this->d_samples_per_symbol; i++) {
|
|
instantaneous_phase[i] = arg(samples[i]);
|
|
}
|
|
|
|
liquid_unwrap_phase(instantaneous_phase, this->d_samples_per_symbol);
|
|
|
|
// Determine instant freq
|
|
// for (unsigned int i = 1; i < this->d_samples_per_symbol; i++) {
|
|
// instantaneous_freq[i - 1] = (float)((instantaneous_phase[i] - instantaneous_phase[i - 1]) * div);
|
|
// }
|
|
|
|
float sum = 0.0f;
|
|
|
|
for (uint32_t i = 1; i < this->d_samples_per_symbol; i++) {
|
|
sum += (float)((instantaneous_phase[i] - instantaneous_phase[i - 1]) * div);
|
|
}
|
|
|
|
this->d_cfo_estimation = sum / (float)(this->d_samples_per_symbol - 1);
|
|
|
|
/*d_cfo_estimation = (*std::max_element(instantaneous_freq, instantaneous_freq+d_samples_per_symbol-1) + *std::min_element(instantaneous_freq, instantaneous_freq+d_samples_per_symbol-1)) / 2;*/
|
|
}
|
|
|
|
void decoder_impl::correct_cfo(gr_complex *samples, uint32_t num_samples) {
|
|
const float mul = 2.0f * M_PI * -this->d_cfo_estimation * this->d_dt;
|
|
|
|
for (uint32_t i = 0; i < num_samples; i++) {
|
|
samples[i] *= gr_expj(mul * i);
|
|
}
|
|
}
|
|
|
|
int decoder_impl::find_preamble_start(gr_complex *samples) {
|
|
for (uint32_t i = 0; i < this->d_samples_per_symbol; i++) {
|
|
if (!this->get_shift_fft(&samples[i]))
|
|
return i;
|
|
}
|
|
|
|
return -1;
|
|
}
|
|
|
|
int decoder_impl::find_preamble_start_fast(gr_complex *samples, uint32_t len) {
|
|
(void) len;
|
|
|
|
const uint32_t decimation = this->d_corr_decim_factor;
|
|
const uint32_t decim_size = this->d_samples_per_symbol / decimation;
|
|
|
|
const float mul = (float)this->d_samples_per_second / (2.0f * M_PI);
|
|
uint32_t rising = 0;
|
|
static const uint32_t rising_required = 2;
|
|
|
|
void decoder_impl::msg_lora_frame(const uint8_t *frame_bytes, uint32_t frame_len) {
|
|
|
|
}
|
|
|
|
int decoder_impl::work(int noutput_items,
|
|
gr_vector_const_void_star &input_items,
|
|
gr_vector_void_star &output_items) {
|
|
gr_complex* input = (gr_complex*) input_items[0];
|
|
gr_complex* raw_input = (gr_complex*) input_items[1];
|
|
float *out = (float*)output_items[0];
|
|
|
|
switch(d_state) {
|
|
case DETECT: {
|
|
int i = find_preamble_start_fast(&input[0], 2*d_samples_per_symbol);
|
|
if(i != -1) {
|
|
uint32_t c_window = std::min(2*d_samples_per_symbol - i, d_samples_per_symbol);
|
|
int32_t index_correction = 0;
|
|
float c = detect_upchirp(&input[i], c_window, d_samples_per_symbol / d_corr_decim_factor, &index_correction);
|
|
if(c > 0.8f) {
|
|
d_debug << "Cu: " << c << std::endl;
|
|
samples_to_file("/tmp/detectb", &input[i], d_samples_per_symbol, sizeof(gr_complex));
|
|
samples_to_file("/tmp/detect", &input[i+index_correction], d_samples_per_symbol, sizeof(gr_complex));
|
|
d_corr_fails = 0;
|
|
d_state = SYNC;
|
|
consume_each(i+index_correction);
|
|
break;
|
|
void decoder_impl::msg_raw_chirp_debug(const gr_complex *raw_samples, uint32_t num_samples) {
|
|
pmt::pmt_t chirp_blob = pmt::make_blob(raw_samples, sizeof(gr_complex) * num_samples);
|
|
message_port_pub(pmt::mp("debug"), chirp_blob);
|
|
}
|
|
|
|
void decoder_impl::msg_lora_frame(const uint8_t *frame_bytes, uint32_t frame_len) {
|
|
// ?? No implementation
|
|
}
|
|
|
|
int decoder_impl::work(int noutput_items,
|
|
gr_vector_const_void_star& input_items,
|
|
gr_vector_void_star& output_items) {
|
|
(void) noutput_items;
|
|
(void) output_items;
|
|
|
|
gr_complex *input = (gr_complex *) input_items[0];
|
|
gr_complex *raw_input = (gr_complex *) input_items[1];
|
|
// float *out = (float *)output_items[0];
|
|
|
|
switch (this->d_state) {
|
|
case gr::lora::DecoderState::DETECT: {
|
|
int i = this->find_preamble_start_fast(&input[0], 2 * this->d_samples_per_symbol);
|
|
|
|
if (i != -1) {
|
|
uint32_t c_window = std::min(2 * this->d_samples_per_symbol - i,
|
|
this->d_samples_per_symbol);
|
|
int32_t index_correction = 0;
|
|
float c = this->detect_upchirp(&input[i],
|
|
c_window,
|
|
this->d_samples_per_symbol / this->d_corr_decim_factor,
|
|
&index_correction);
|
|
|
|
if (c > 0.8f) {
|
|
#ifndef NDEBUG
|
|
this->d_debug << "Cu: " << c << std::endl;
|
|
#endif
|
|
this->samples_to_file("/tmp/detectb", &input[i], this->d_samples_per_symbol, sizeof(gr_complex));
|
|
this->samples_to_file("/tmp/detect", &input[i + index_correction], this->d_samples_per_symbol, sizeof(gr_complex));
|
|
this->d_corr_fails = 0;
|
|
this->d_state = gr::lora::DecoderState::SYNC;
|
|
this->consume_each(i + index_correction);
|
|
break;
|
|
}
|
|
}
|
|
|
|
this->consume_each(2 * this->d_samples_per_symbol);
|
|
break;
|
|
}
|
|
|
|
case gr::lora::DecoderState::SYNC: {
|
|
double c = this->detect_downchirp(&input[0], this->d_samples_per_symbol);
|
|
#ifndef NDEBUG
|
|
this->d_debug << "Cd: " << c << std::endl;
|
|
#endif
|
|
|
|
if (c > 0.98f) {
|
|
#ifndef NDEBUG
|
|
this->d_debug << "SYNC: " << c << std::endl;
|
|
#endif
|
|
// Debug stuff
|
|
this->samples_to_file("/tmp/sync", &input[0], this->d_samples_per_symbol, sizeof(gr_complex));
|
|
|
|
this->d_state = gr::lora::DecoderState::PAUSE;
|
|
} else {
|
|
this->d_corr_fails++;
|
|
|
|
if (this->d_corr_fails > 32) {
|
|
this->d_state = gr::lora::DecoderState::DETECT;
|
|
#ifndef NDEBUG
|
|
this->d_debug << "Lost sync" << std::endl;
|
|
#endif
|
|
}
|
|
}
|
|
|
|
this->consume_each(this->d_samples_per_symbol);
|
|
break;
|
|
}
|
|
|
|
case gr::lora::DecoderState::PAUSE: {
|
|
this->d_state = gr::lora::DecoderState::DECODE_HEADER;
|
|
|
|
//samples_debug(input, d_samples_per_symbol + d_delay_after_sync);
|
|
this->consume_each(this->d_samples_per_symbol + this->d_delay_after_sync);
|
|
break;
|
|
}
|
|
|
|
case gr::lora::DecoderState::DECODE_HEADER: {
|
|
this->d_cr = 4;
|
|
|
|
if (this->demodulate(input, true)) {
|
|
uint8_t decoded[3];
|
|
// TODO: A bit messy. I think it's better to make an internal decoded std::vector
|
|
this->d_payload_length = 3;
|
|
|
|
this->decode(decoded, true);
|
|
|
|
this->nibble_reverse(decoded, 1); // TODO: Why? Endianess?
|
|
this->d_payload_length = decoded[0];
|
|
this->d_cr = this->lookup_cr(decoded[1]);
|
|
|
|
int symbols_per_block = this->d_cr + 4;
|
|
int bits_needed = this->d_payload_length * 8 + 16;
|
|
float symbols_needed = float(bits_needed) * (symbols_per_block / 4.0f) / float(this->d_sf);
|
|
int blocks_needed = ceil(symbols_needed / symbols_per_block);
|
|
this->d_payload_symbols = blocks_needed * symbols_per_block;
|
|
|
|
#ifndef NDEBUG
|
|
this->d_debug << "LEN: " << this->d_payload_length << " (" << this->d_payload_symbols << " symbols)" << std::endl;
|
|
#endif
|
|
|
|
this->d_state = gr::lora::DecoderState::DECODE_PAYLOAD;
|
|
}
|
|
|
|
this->msg_raw_chirp_debug(raw_input, this->d_samples_per_symbol);
|
|
//samples_debug(input, d_samples_per_symbol);
|
|
this->consume_each(this->d_samples_per_symbol);
|
|
break;
|
|
}
|
|
|
|
case gr::lora::DecoderState::DECODE_PAYLOAD: {
|
|
if (this->demodulate(input, false)) {
|
|
this->d_payload_symbols -= (4 + this->d_cr);
|
|
|
|
if (this->d_payload_symbols <= 0) {
|
|
uint8_t decoded[this->d_payload_length] = { 0 };
|
|
|
|
this->decode(decoded, false);
|
|
|
|
this->d_state = gr::lora::DecoderState::DETECT;
|
|
this->d_data.clear();
|
|
}
|
|
}
|
|
|
|
this->msg_raw_chirp_debug(raw_input, this->d_samples_per_symbol);
|
|
//samples_debug(input, d_samples_per_symbol);
|
|
this->consume_each(this->d_samples_per_symbol);
|
|
break;
|
|
}
|
|
|
|
case gr::lora::DecoderState::STOP: {
|
|
this->consume_each(this->d_samples_per_symbol);
|
|
break;
|
|
}
|
|
|
|
default: {
|
|
std::cerr << "LoRa Decoder: No state! Shouldn't happen\n";
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Tell runtime system how many output items we produced.
|
|
return 0;
|
|
}
|
|
|
|
void decoder_impl::set_sf(uint8_t sf) {
|
|
(void) sf;
|
|
std::cerr << "[LoRa Decoder] WARNING : Setting the spreading factor during execution is currently not supported." << std::endl
|
|
<< "Nothing set, kept SF of " << this->d_sf << "." << std::endl;
|
|
}
|
|
|
|
void decoder_impl::set_samp_rate(float samp_rate) {
|
|
(void) samp_rate;
|
|
std::cerr << "[LoRa Decoder] WARNING : Setting the sample rate during execution is currently not supported." << std::endl
|
|
<< "Nothing set, kept SR of " << this->d_samples_per_second << "." << std::endl;
|
|
}
|
|
|
|
} /* namespace lora */
|
|
} /* namespace gr */
|