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Start detecting.

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This commit is contained in:
John Greb 2015-01-12 19:59:45 +00:00
parent dde49f8650
commit 1e77911e9c
3 changed files with 32 additions and 5 deletions
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33
plugins/channel/lora/lorademod.cpp
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@ -35,6 +35,7 @@ LoRaDemod::LoRaDemod(SampleSink* sampleSink) :
m_chirp = 0; m_chirp = 0;
m_angle = 0; m_angle = 0;
m_bin = 0;
loraFilter = new sfft(LORA_SFFT_LEN); loraFilter = new sfft(LORA_SFFT_LEN);
} }
@ -51,10 +52,32 @@ void LoRaDemod::configure(MessageQueue* messageQueue, Real Bandwidth)
cmd->submit(messageQueue, this); cmd->submit(messageQueue, this);
} }
int LoRaDemod::detect(Complex c)
{
int i, result;
Real peak, mag;
cmplx bins[LORA_SFFT_LEN];
// TODO: don`t need per-sample sliding FFT time resolution
loraFilter->run(c, bins);
peak = mag = 0;
result = 0;
for (i = 0; i < LORA_SFFT_LEN; i++) {
mag = bins[i].real() * bins[i].real()
+ bins[i].imag() * bins[i].imag();
if (mag > peak) {
peak = mag;
result = i;
}
}
return result;
}
void LoRaDemod::feed(SampleVector::const_iterator begin, SampleVector::const_iterator end, bool pO) void LoRaDemod::feed(SampleVector::const_iterator begin, SampleVector::const_iterator end, bool pO)
{ {
int newangle;
Complex ci; Complex ci;
cmplx bins[LORA_SFFT_LEN];
m_sampleBuffer.clear(); m_sampleBuffer.clear();
for(SampleVector::const_iterator it = begin; it < end; ++it) { for(SampleVector::const_iterator it = begin; it < end; ++it) {
Complex c(it->real() / 32768.0, it->imag() / 32768.0); Complex c(it->real() / 32768.0, it->imag() / 32768.0);
@ -64,9 +87,11 @@ void LoRaDemod::feed(SampleVector::const_iterator begin, SampleVector::const_ite
m_chirp = (m_chirp + 1) & (SPREADFACTOR - 1); m_chirp = (m_chirp + 1) & (SPREADFACTOR - 1);
m_angle = (m_angle + m_chirp) & (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)); Complex cangle(cos(M_PI*2*m_angle/SPREADFACTOR),-sin(M_PI*2*m_angle/SPREADFACTOR));
ci *= cangle; newangle = detect(ci * cangle);
loraFilter->run(ci, bins);
m_sampleBuffer.push_back(Sample(ci.real() * 32000, ci.imag() * 32000)); 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() * 1000, nangle.imag() * 1000));
m_sampleDistanceRemain += (Real)m_sampleRate / m_Bandwidth; m_sampleDistanceRemain += (Real)m_sampleRate / m_Bandwidth;
} }
} }

2
plugins/channel/lora/lorademod.h
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@ -38,6 +38,7 @@ public:
void configure(MessageQueue* messageQueue, Real Bandwidth); void configure(MessageQueue* messageQueue, Real Bandwidth);
void feed(SampleVector::const_iterator begin, SampleVector::const_iterator end, bool pO); void feed(SampleVector::const_iterator begin, SampleVector::const_iterator end, bool pO);
int detect(Complex c);
void start(); void start();
void stop(); void stop();
bool handleMessage(Message* cmd); bool handleMessage(Message* cmd);
@ -69,6 +70,7 @@ private:
int m_frequency; int m_frequency;
int m_chirp; int m_chirp;
int m_angle; int m_angle;
int m_bin;
sfft* loraFilter; sfft* loraFilter;

2
sdrbase/dsp/fftfilt.cxx
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@ -240,6 +240,6 @@ void sfft::run(const cmplx& input, cmplx *result)
*end = vrot_bins + last ; *end = vrot_bins + last ;
itr != end ; itr != end ;
++itr, result++ ) { ++itr, result++ ) {
*result = itr->bins = itr->bins * itr->vrot + z * itr->vrot; *result = itr->bins = (itr->bins + z) * itr->vrot;
} }
} }