mirror of https://github.com/f4exb/sdrangel.git
287 lines
7.4 KiB
C++
287 lines
7.4 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2019 Edouard Griffiths, F4EXB //
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// //
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// This program 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 as version 3 of the License, or //
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// (at your option) any later version. //
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// //
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// This program 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 V3 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 program. If not, see <http://www.gnu.org/licenses/>. //
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///////////////////////////////////////////////////////////////////////////////////
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#include <QTime>
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#include <QDebug>
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#include <stdio.h>
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#include "dsp/dsptypes.h"
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#include "dsp/basebandsamplesink.h"
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#include "lorademodsink.h"
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const int LoRaDemodSink::DATA_BITS = 6;
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const int LoRaDemodSink::SAMPLEBITS = LoRaDemodSink::DATA_BITS + 2;
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const int LoRaDemodSink::SPREADFACTOR = (1 << LoRaDemodSink::SAMPLEBITS);
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const int LoRaDemodSink::LORA_SFFT_LEN = (LoRaDemodSink::SPREADFACTOR / 2);
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const int LoRaDemodSink::LORA_SQUELCH = 3;
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LoRaDemodSink::LoRaDemodSink() :
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m_spectrumSink(nullptr)
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{
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m_Bandwidth = LoRaDemodSettings::bandwidths[0];
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m_channelSampleRate = 96000;
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m_channelFrequencyOffset = 0;
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m_nco.setFreq(m_channelFrequencyOffset, m_channelSampleRate);
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m_interpolator.create(16, m_channelSampleRate, m_Bandwidth/1.9);
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m_sampleDistanceRemain = (Real) m_channelSampleRate / m_Bandwidth;
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m_chirp = 0;
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m_angle = 0;
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m_bin = 0;
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m_result = 0;
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m_count = 0;
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m_header = 0;
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m_time = 0;
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m_tune = 0;
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loraFilter = new sfft(LORA_SFFT_LEN);
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negaFilter = new sfft(LORA_SFFT_LEN);
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mov = new float[4*LORA_SFFT_LEN];
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history = new short[1024];
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finetune = new short[16];
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}
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LoRaDemodSink::~LoRaDemodSink()
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{
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delete loraFilter;
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delete negaFilter;
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delete [] mov;
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delete [] history;
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delete [] finetune;
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}
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void LoRaDemodSink::dumpRaw()
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{
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short bin, j, max;
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char text[256];
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max = m_time / 4 - 3;
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if (max > 140) {
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max = 140; // about 2 symbols to each char
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}
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for ( j=0; j < max; j++)
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{
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bin = (history[(j + 1) * 4] + m_tune ) & (LORA_SFFT_LEN - 1);
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text[j] = toGray(bin >> 1);
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}
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prng6(text, max);
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// First block is always 8 symbols
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interleave6(text, 6);
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interleave6(&text[8], max);
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hamming6(text, 6);
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hamming6(&text[8], max);
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for ( j=0; j < max / 2; j++)
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{
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text[j] = (text[j * 2 + 1] << 4) | (0xf & text[j * 2 + 0]);
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if ((text[j] < 32 )||( text[j] > 126)) {
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text[j] = 0x5f;
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}
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}
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text[3] = text[2];
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text[2] = text[1];
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text[1] = text[0];
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text[j] = 0;
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qDebug("LoRaDemodSink::dumpRaw: %s", &text[1]);
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}
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short LoRaDemodSink::synch(short bin)
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{
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short i, j;
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if (bin < 0)
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{
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if (m_time > 70) {
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dumpRaw();
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}
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m_time = 0;
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return -1;
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}
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history[m_time] = bin;
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if (m_time > 12)
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{
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if (bin == history[m_time - 6])
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{
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if (bin == history[m_time - 12])
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{
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m_tune = LORA_SFFT_LEN - bin;
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j = 0;
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for (i=0; i<12; i++) {
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j += finetune[15 & (m_time - i)];
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}
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if (j < 0) {
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m_tune += 1;
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}
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m_tune &= (LORA_SFFT_LEN - 1);
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m_time = 0;
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return -1;
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}
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}
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}
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m_time++;
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m_time &= 1023;
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if (m_time & 3) {
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return -1;
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}
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return (bin + m_tune) & (LORA_SFFT_LEN - 1);
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}
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int LoRaDemodSink::detect(Complex c, Complex a)
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{
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int p, q;
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short i, result, negresult, movpoint;
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float peak, negpeak, tfloat;
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float mag[LORA_SFFT_LEN];
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float rev[LORA_SFFT_LEN];
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loraFilter->run(c * a);
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negaFilter->run(c * conj(a));
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// process spectrum twice in FFTLEN
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if (++m_count & ((1 << DATA_BITS) - 1)) {
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return m_result;
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}
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movpoint = 3 & (m_count >> DATA_BITS);
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loraFilter->fetch(mag);
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negaFilter->fetch(rev);
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peak = negpeak = 0.0f;
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result = negresult = 0;
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for (i = 0; i < LORA_SFFT_LEN; i++)
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{
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if (rev[i] > negpeak)
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{
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negpeak = rev[i];
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negresult = i;
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}
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tfloat = mov[i] + mov[LORA_SFFT_LEN + i] +mov[2 * LORA_SFFT_LEN + i]
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+ mov[3 * LORA_SFFT_LEN + i] + mag[i];
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if (tfloat > peak)
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{
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peak = tfloat;
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result = i;
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}
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mov[movpoint * LORA_SFFT_LEN + i] = mag[i];
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}
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p = (result - 1 + LORA_SFFT_LEN) & (LORA_SFFT_LEN -1);
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q = (result + 1) & (LORA_SFFT_LEN -1);
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finetune[15 & m_time] = (mag[p] > mag[q]) ? -1 : 1;
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if (peak < negpeak * LORA_SQUELCH)
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{
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result = -1;
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}
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result = synch(result);
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if (result >= 0) {
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m_result = result;
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}
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return m_result;
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}
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void LoRaDemodSink::feed(const SampleVector::const_iterator& begin, const SampleVector::const_iterator& end)
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{
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int newangle;
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Complex ci;
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m_sampleBuffer.clear();
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for (SampleVector::const_iterator it = begin; it < end; ++it)
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{
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Complex c(it->real() / SDR_RX_SCALEF, it->imag() / SDR_RX_SCALEF);
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c *= m_nco.nextIQ();
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if (m_interpolator.decimate(&m_sampleDistanceRemain, c, &ci))
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{
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m_chirp = (m_chirp + 1) & (SPREADFACTOR - 1);
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m_angle = (m_angle + m_chirp) & (SPREADFACTOR - 1);
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Complex cangle(cos(M_PI*2*m_angle/SPREADFACTOR),-sin(M_PI*2*m_angle/SPREADFACTOR));
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newangle = detect(ci, cangle);
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m_bin = (m_bin + newangle) & (LORA_SFFT_LEN - 1);
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Complex nangle(cos(M_PI*2*m_bin/LORA_SFFT_LEN),sin(M_PI*2*m_bin/LORA_SFFT_LEN));
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m_sampleBuffer.push_back(Sample(nangle.real() * 100, nangle.imag() * 100));
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m_sampleDistanceRemain += (Real) m_channelSampleRate / m_Bandwidth;
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}
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}
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if (m_spectrumSink) {
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m_spectrumSink->feed(m_sampleBuffer.begin(), m_sampleBuffer.end(), false);
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}
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}
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void LoRaDemodSink::applyChannelSettings(int channelSampleRate, int bandwidth, int channelFrequencyOffset, bool force)
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{
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qDebug() << "LoRaDemodSink::applyChannelSettings:"
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<< " channelSampleRate: " << channelSampleRate
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<< " channelFrequencyOffset: " << channelFrequencyOffset;
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if((channelFrequencyOffset != m_channelFrequencyOffset) ||
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(channelSampleRate != m_channelSampleRate) || force)
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{
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m_nco.setFreq(-channelFrequencyOffset, channelSampleRate);
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}
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if ((channelSampleRate != m_channelSampleRate) || force)
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{
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qDebug() << "LoRaDemodSink::applyChannelSettings: m_interpolator.create";
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m_interpolator.create(16, channelSampleRate, bandwidth / 1.9f);
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m_sampleDistanceRemain = (Real) channelSampleRate / bandwidth;
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}
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m_channelSampleRate = channelSampleRate;
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m_Bandwidth = bandwidth;
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m_channelFrequencyOffset = channelFrequencyOffset;
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}
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void LoRaDemodSink::applySettings(const LoRaDemodSettings& settings, bool force)
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{
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qDebug() << "LoRaDemodSink::applySettings:"
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<< " m_centerFrequency: " << settings.m_centerFrequency
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<< " m_bandwidthIndex: " << settings.m_bandwidthIndex
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<< " m_spread: " << settings.m_spread
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<< " m_rgbColor: " << settings.m_rgbColor
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<< " m_title: " << settings.m_title
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<< " force: " << force;
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m_settings = settings;
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}
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