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https://github.com/f4exb/sdrangel.git
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332 lines
7.2 KiB
C++
332 lines
7.2 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2012 maintech GmbH, Otto-Hahn-Str. 15, 97204 Hoechberg, Germany //
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// written by Christian Daniel //
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// (c) 2015 John Greb
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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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// //
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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 "lorademod.h"
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#include "dsp/channelizer.h"
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#include "lorabits.h"
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MESSAGE_CLASS_DEFINITION(LoRaDemod::MsgConfigureLoRaDemod, Message)
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LoRaDemod::LoRaDemod(SampleSink* sampleSink) :
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m_sampleSink(sampleSink),
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m_settingsMutex(QMutex::Recursive)
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{
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setObjectName("LoRaDemod");
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m_Bandwidth = 7813;
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m_sampleRate = 96000;
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m_frequency = 0;
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m_nco.setFreq(m_frequency, m_sampleRate);
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m_interpolator.create(16, m_sampleRate, m_Bandwidth/1.9);
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m_sampleDistanceRemain = (Real)m_sampleRate / 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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LoRaDemod::~LoRaDemod()
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{
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if (loraFilter)
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delete loraFilter;
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if (negaFilter)
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delete negaFilter;
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if (mov)
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delete [] mov;
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if (history)
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delete [] history;
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if (finetune)
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delete [] finetune;
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}
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void LoRaDemod::configure(MessageQueue* messageQueue, Real Bandwidth)
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{
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Message* cmd = MsgConfigureLoRaDemod::create(Bandwidth);
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messageQueue->push(cmd);
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}
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void LoRaDemod::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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{
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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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{
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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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printf("%s\n", &text[1]);
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}
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short LoRaDemod::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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{
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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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{
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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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{
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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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{
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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 LoRaDemod::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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{
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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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{
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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 LoRaDemod::feed(const SampleVector::const_iterator& begin, const SampleVector::const_iterator& end, bool pO)
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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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m_settingsMutex.lock();
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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() / 32768.0, it->imag() / 32768.0);
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c *= m_nco.nextIQ();
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if(m_interpolator.interpolate(&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_sampleRate / m_Bandwidth;
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}
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}
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if(m_sampleSink != 0)
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{
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m_sampleSink->feed(m_sampleBuffer.begin(), m_sampleBuffer.end(), false);
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}
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m_settingsMutex.unlock();
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}
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void LoRaDemod::start()
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{
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}
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void LoRaDemod::stop()
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{
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}
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bool LoRaDemod::handleMessage(const Message& cmd)
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{
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qDebug() << "LoRaDemod::handleMessage";
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if (Channelizer::MsgChannelizerNotification::match(cmd))
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{
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Channelizer::MsgChannelizerNotification& notif = (Channelizer::MsgChannelizerNotification&) cmd;
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m_settingsMutex.lock();
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m_sampleRate = notif.getSampleRate();
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m_nco.setFreq(-notif.getFrequencyOffset(), m_sampleRate);
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m_interpolator.create(16, m_sampleRate, m_Bandwidth/1.9);
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m_sampleDistanceRemain = m_sampleRate / m_Bandwidth;
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m_settingsMutex.unlock();
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qDebug() << "LoRaDemod::handleMessage: MsgChannelizerNotification: m_sampleRate: " << m_sampleRate
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<< " frequencyOffset: " << notif.getFrequencyOffset();
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return true;
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}
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else if (MsgConfigureLoRaDemod::match(cmd))
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{
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MsgConfigureLoRaDemod& cfg = (MsgConfigureLoRaDemod&) cmd;
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m_settingsMutex.lock();
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m_Bandwidth = cfg.getBandwidth();
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m_interpolator.create(16, m_sampleRate, m_Bandwidth/1.9);
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m_settingsMutex.unlock();
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qDebug() << " MsgConfigureLoRaDemod: m_Bandwidth: " << m_Bandwidth;
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return true;
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}
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else
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{
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if(m_sampleSink != 0)
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{
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return m_sampleSink->handleMessage(cmd);
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}
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else
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{
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return false;
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}
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}
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}
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