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sdrangel/plugins/channel/lora/lorademod.cpp

332 lines
7.2 KiB
C++

///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2012 maintech GmbH, Otto-Hahn-Str. 15, 97204 Hoechberg, Germany //
// written by Christian Daniel //
// (c) 2015 John Greb
// //
// This program is free software; you can redistribute it and/or modify //
// it under the terms of the GNU General Public License as published by //
// the Free Software Foundation as version 3 of the License, or //
// //
// This program is distributed in the hope that it will be useful, //
// but WITHOUT ANY WARRANTY; without even the implied warranty of //
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
// GNU General Public License V3 for more details. //
// //
// You should have received a copy of the GNU General Public License //
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
///////////////////////////////////////////////////////////////////////////////////
#include <QTime>
#include <QDebug>
#include <stdio.h>
#include "lorademod.h"
#include "dsp/channelizer.h"
#include "lorabits.h"
MESSAGE_CLASS_DEFINITION(LoRaDemod::MsgConfigureLoRaDemod, Message)
LoRaDemod::LoRaDemod(SampleSink* sampleSink) :
m_sampleSink(sampleSink),
m_settingsMutex(QMutex::Recursive)
{
setObjectName("LoRaDemod");
m_Bandwidth = 7813;
m_sampleRate = 96000;
m_frequency = 0;
m_nco.setFreq(m_frequency, m_sampleRate);
m_interpolator.create(16, m_sampleRate, m_Bandwidth/1.9);
m_sampleDistanceRemain = (Real)m_sampleRate / m_Bandwidth;
m_chirp = 0;
m_angle = 0;
m_bin = 0;
m_result = 0;
m_count = 0;
m_header = 0;
m_time = 0;
m_tune = 0;
loraFilter = new sfft(LORA_SFFT_LEN);
negaFilter = new sfft(LORA_SFFT_LEN);
mov = new float[4*LORA_SFFT_LEN];
history = new short[1024];
finetune = new short[16];
}
LoRaDemod::~LoRaDemod()
{
if (loraFilter)
delete loraFilter;
if (negaFilter)
delete negaFilter;
if (mov)
delete [] mov;
if (history)
delete [] history;
if (finetune)
delete [] finetune;
}
void LoRaDemod::configure(MessageQueue* messageQueue, Real Bandwidth)
{
Message* cmd = MsgConfigureLoRaDemod::create(Bandwidth);
messageQueue->push(cmd);
}
void LoRaDemod::dumpRaw()
{
short bin, j, max;
char text[256];
max = m_time / 4 - 3;
if (max > 140)
{
max = 140; // about 2 symbols to each char
}
for ( j=0; j < max; j++)
{
bin = (history[(j + 1) * 4] + m_tune ) & (LORA_SFFT_LEN - 1);
text[j] = toGray(bin >> 1);
}
prng6(text, max);
// First block is always 8 symbols
interleave6(text, 6);
interleave6(&text[8], max);
hamming6(text, 6);
hamming6(&text[8], max);
for ( j=0; j < max / 2; j++)
{
text[j] = (text[j * 2 + 1] << 4) | (0xf & text[j * 2 + 0]);
if ((text[j] < 32 )||( text[j] > 126))
{
text[j] = 0x5f;
}
}
text[3] = text[2];
text[2] = text[1];
text[1] = text[0];
text[j] = 0;
printf("%s\n", &text[1]);
}
short LoRaDemod::synch(short bin)
{
short i, j;
if (bin < 0)
{
if (m_time > 70)
{
dumpRaw();
}
m_time = 0;
return -1;
}
history[m_time] = bin;
if (m_time > 12)
{
if (bin == history[m_time - 6])
{
if (bin == history[m_time - 12])
{
m_tune = LORA_SFFT_LEN - bin;
j = 0;
for (i=0; i<12; i++)
{
j += finetune[15 & (m_time - i)];
}
if (j < 0)
{
m_tune += 1;
}
m_tune &= (LORA_SFFT_LEN - 1);
m_time = 0;
return -1;
}
}
}
m_time++;
m_time &= 1023;
if (m_time & 3)
{
return -1;
}
return (bin + m_tune) & (LORA_SFFT_LEN - 1);
}
int LoRaDemod::detect(Complex c, Complex a)
{
int p, q;
short i, result, negresult, movpoint;
float peak, negpeak, tfloat;
float mag[LORA_SFFT_LEN];
float rev[LORA_SFFT_LEN];
loraFilter->run(c * a);
negaFilter->run(c * conj(a));
// process spectrum twice in FFTLEN
if (++m_count & ((1 << DATA_BITS) - 1))
{
return m_result;
}
movpoint = 3 & (m_count >> DATA_BITS);
loraFilter->fetch(mag);
negaFilter->fetch(rev);
peak = negpeak = 0.0f;
result = negresult = 0;
for (i = 0; i < LORA_SFFT_LEN; i++)
{
if (rev[i] > negpeak)
{
negpeak = rev[i];
negresult = i;
}
tfloat = mov[i] + mov[LORA_SFFT_LEN + i] +mov[2 * LORA_SFFT_LEN + i]
+ mov[3 * LORA_SFFT_LEN + i] + mag[i];
if (tfloat > peak)
{
peak = tfloat;
result = i;
}
mov[movpoint * LORA_SFFT_LEN + i] = mag[i];
}
p = (result - 1 + LORA_SFFT_LEN) & (LORA_SFFT_LEN -1);
q = (result + 1) & (LORA_SFFT_LEN -1);
finetune[15 & m_time] = (mag[p] > mag[q]) ? -1 : 1;
if (peak < negpeak * LORA_SQUELCH)
{
result = -1;
}
result = synch(result);
if (result >= 0)
{
m_result = result;
}
return m_result;
}
void LoRaDemod::feed(const SampleVector::const_iterator& begin, const SampleVector::const_iterator& end, bool pO)
{
int newangle;
Complex ci;
m_sampleBuffer.clear();
m_settingsMutex.lock();
for(SampleVector::const_iterator it = begin; it < end; ++it)
{
Complex c(it->real() / 32768.0, it->imag() / 32768.0);
c *= m_nco.nextIQ();
if(m_interpolator.interpolate(&m_sampleDistanceRemain, c, &ci))
{
m_chirp = (m_chirp + 1) & (SPREADFACTOR - 1);
m_angle = (m_angle + m_chirp) & (SPREADFACTOR - 1);
Complex cangle(cos(M_PI*2*m_angle/SPREADFACTOR),-sin(M_PI*2*m_angle/SPREADFACTOR));
newangle = detect(ci, cangle);
m_bin = (m_bin + newangle) & (LORA_SFFT_LEN - 1);
Complex nangle(cos(M_PI*2*m_bin/LORA_SFFT_LEN),sin(M_PI*2*m_bin/LORA_SFFT_LEN));
m_sampleBuffer.push_back(Sample(nangle.real() * 100, nangle.imag() * 100));
m_sampleDistanceRemain += (Real)m_sampleRate / m_Bandwidth;
}
}
if(m_sampleSink != 0)
{
m_sampleSink->feed(m_sampleBuffer.begin(), m_sampleBuffer.end(), false);
}
m_settingsMutex.unlock();
}
void LoRaDemod::start()
{
}
void LoRaDemod::stop()
{
}
bool LoRaDemod::handleMessage(const Message& cmd)
{
qDebug() << "LoRaDemod::handleMessage";
if (Channelizer::MsgChannelizerNotification::match(cmd))
{
Channelizer::MsgChannelizerNotification& notif = (Channelizer::MsgChannelizerNotification&) cmd;
m_settingsMutex.lock();
m_sampleRate = notif.getSampleRate();
m_nco.setFreq(-notif.getFrequencyOffset(), m_sampleRate);
m_interpolator.create(16, m_sampleRate, m_Bandwidth/1.9);
m_sampleDistanceRemain = m_sampleRate / m_Bandwidth;
m_settingsMutex.unlock();
qDebug() << "LoRaDemod::handleMessage: MsgChannelizerNotification: m_sampleRate: " << m_sampleRate
<< " frequencyOffset: " << notif.getFrequencyOffset();
return true;
}
else if (MsgConfigureLoRaDemod::match(cmd))
{
MsgConfigureLoRaDemod& cfg = (MsgConfigureLoRaDemod&) cmd;
m_settingsMutex.lock();
m_Bandwidth = cfg.getBandwidth();
m_interpolator.create(16, m_sampleRate, m_Bandwidth/1.9);
m_settingsMutex.unlock();
qDebug() << " MsgConfigureLoRaDemod: m_Bandwidth: " << m_Bandwidth;
return true;
}
else
{
if(m_sampleSink != 0)
{
return m_sampleSink->handleMessage(cmd);
}
else
{
return false;
}
}
}