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Interferometer: implemented 2 side FFT time correlation

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This commit is contained in:
f4exb 2019-10-08 08:01:04 +02:00
parent afc5b97863
commit 95fccf290c
4 changed files with 145 additions and 5 deletions
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130
plugins/channelmimo/interferometer/interferometercorr.cpp
View File

@ -78,13 +78,20 @@ Sample sMulConjInv(const Sample& a, const Sample& b) { //!< Sample multiply with
return s;
}
Sample invfft2s(const std::complex<float>& a) { //!< Complex float to Sample
Sample invfft2s(const std::complex<float>& a) { //!< Complex float to Sample for 1 side time correlation
Sample s;
s.setReal(a.real()/2.0f);
s.setImag(a.imag()/2.0f);
return s;
}
Sample invfft2s2(const std::complex<float>& a) { //!< Complex float to Sample for 2 sides time correlation
Sample s;
s.setReal(a.real());
s.setImag(a.imag());
return s;
}
InterferometerCorrelator::InterferometerCorrelator(int fftSize) :
m_corrType(InterferometerSettings::CorrelationAdd),
m_fftSize(fftSize)
@ -98,10 +105,14 @@ InterferometerCorrelator::InterferometerCorrelator(int fftSize) :
{
m_fft[i] = FFTEngine::create();
m_fft[i]->configure(2*fftSize, false); // internally twice the data FFT size
m_fft2[i] = FFTEngine::create();
m_fft2[i]->configure(fftSize, false);
}
m_invFFT = FFTEngine::create();
m_invFFT->configure(2*fftSize, true);
m_invFFT2 = FFTEngine::create();
m_invFFT2->configure(fftSize, true);
m_dataj = new std::complex<float>[2*fftSize]; // receives actual FFT result hence twice the data FFT size
m_scorr.resize(fftSize);
@ -114,9 +125,12 @@ InterferometerCorrelator::~InterferometerCorrelator()
{
delete[] m_dataj;
delete m_invFFT;
delete m_invFFT2;
for (int i = 0; i < 2; i++) {
for (int i = 0; i < 2; i++)
{
delete m_fft[i];
delete m_fft2[i];
}
}
@ -148,6 +162,9 @@ bool InterferometerCorrelator::performCorr(
case InterferometerSettings::CorrelationFFT:
results = performFFTCorr(data0, size0, data1, size1);
break;
case InterferometerSettings::CorrelationFFT2:
results = performFFT2Corr(data0, size0, data1, size1);
break;
default:
break;
}
@ -171,6 +188,9 @@ bool InterferometerCorrelator::performCorr(
case InterferometerSettings::CorrelationFFT:
results = performFFTCorr(data0, size0, m_data1p, size1);
break;
case InterferometerSettings::CorrelationFFT2:
results = performFFT2Corr(data0, size0, m_data1p, size1);
break;
default:
break;
}
@ -214,6 +234,9 @@ bool InterferometerCorrelator::performCorr(
case InterferometerSettings::CorrelationFFT:
results = performFFTCorr(data0, size0, m_data1p, size1);
break;
case InterferometerSettings::CorrelationFFT2:
results = performFFT2Corr(data0, size0, m_data1p, size1);
break;
default:
break;
}
@ -346,6 +369,109 @@ bool InterferometerCorrelator::performFFTCorr(
return nfft > 0;
}
bool InterferometerCorrelator::performFFT2Corr(
const SampleVector& data0,
int size0,
const SampleVector& data1,
int size1
)
{
unsigned int size = std::min(size0, size1);
int nfft = 0;
SampleVector::const_iterator begin0 = data0.begin();
SampleVector::const_iterator begin1 = data1.begin();
adjustSCorrSize(size);
adjustTCorrSize(size);
while (size >= m_fftSize)
{
// FFT[0]
std::transform(
begin0,
begin0 + m_fftSize,
m_fft2[0]->in(),
[](const Sample& s) -> std::complex<float> {
return std::complex<float>{s.real() / SDR_RX_SCALEF, s.imag() / SDR_RX_SCALEF};
}
);
m_window.apply(m_fft2[0]->in());
m_fft2[0]->transform();
// FFT[1]
std::transform(
begin1,
begin1 + m_fftSize,
m_fft2[1]->in(),
[](const Sample& s) -> std::complex<float> {
return std::complex<float>{s.real() / SDR_RX_SCALEF, s.imag() / SDR_RX_SCALEF};
}
);
m_window.apply(m_fft2[1]->in());
m_fft2[1]->transform();
// conjugate FFT[1]
std::transform(
m_fft2[1]->out(),
m_fft2[1]->out() + m_fftSize,
m_dataj,
[](const std::complex<float>& c) -> std::complex<float> {
return std::conj(c);
}
);
// product of FFT[1]* with FFT[0] and store in inverse FFT input
std::transform(
m_fft2[0]->out(),
m_fft2[0]->out() + m_fftSize,
m_dataj,
m_invFFT2->in(),
[](std::complex<float>& a, const std::complex<float>& b) -> std::complex<float> {
return (a*b);
}
);
// copy product to correlation spectrum - convert and scale to FFT size
std::transform(
m_invFFT2->in(),
m_invFFT2->in() + m_fftSize,
m_scorr.begin() + nfft*m_fftSize,
[this](const std::complex<float>& a) -> Sample {
Sample s;
s.setReal(a.real()*(SDR_RX_SCALEF/m_fftSize));
s.setImag(a.imag()*(SDR_RX_SCALEF/m_fftSize));
return s;
}
);
// do the inverse FFT to get time correlation
m_invFFT2->transform();
std::transform(
m_invFFT2->out() + m_fftSize/2 + 1,
m_invFFT2->out() + m_fftSize,
m_tcorr.begin() + nfft*m_fftSize,
invfft2s2
);
std::transform(
m_invFFT2->out(),
m_invFFT2->out() + m_fftSize/2,
m_tcorr.begin() + nfft*m_fftSize + m_fftSize/2,
invfft2s2
);
size -= m_fftSize;
begin0 += m_fftSize;
begin1 += m_fftSize;
nfft++;
}
// update the samples counters
m_processed = nfft*m_fftSize;
m_remaining[0] = size0 - nfft*m_fftSize;
m_remaining[1] = size1 - nfft*m_fftSize;
return nfft > 0;
}
void InterferometerCorrelator::adjustSCorrSize(int size)
{
int nFFTSize = (size/m_fftSize)*m_fftSize;

12
plugins/channelmimo/interferometer/interferometercorr.h
View File

@ -68,13 +68,21 @@ private:
const SampleVector& data1,
int size1
);
bool performFFT2Corr( //!< Returns true if results were produced
const SampleVector& data0,
int size0,
const SampleVector& data1,
int size1
);
void adjustSCorrSize(int size);
void adjustTCorrSize(int size);
InterferometerSettings::CorrelationType m_corrType;
int m_fftSize; //!< FFT length
FFTEngine *m_fft[2]; //!< FFT engines
FFTEngine *m_invFFT; //!< Inverse FFT engine
FFTEngine *m_fft[2]; //!< FFT engines (double FFT)
FFTEngine *m_invFFT; //!< Inverse FFT engine (double FFT)
FFTEngine *m_fft2[2]; //!< FFT engines
FFTEngine *m_invFFT2; //!< Inverse FFT enginw
FFTWindow m_window; //!< FFT window
std::complex<float> *m_dataj; //!< conjuate of FFT transform
SampleVector m_data0w; //!< windowed data 0

5
plugins/channelmimo/interferometer/interferometergui.ui
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@ -194,6 +194,11 @@
<string>FFT</string>
</property>
</item>
<item>
<property name="text">
<string>FFT2</string>
</property>
</item>
</widget>
</item>
<item>

3
plugins/channelmimo/interferometer/interferometersettings.h
View File

@ -31,7 +31,8 @@ struct InterferometerSettings
Correlation1,
CorrelationAdd,
CorrelationMultiply,
CorrelationFFT
CorrelationFFT,
CorrelationFFT2
};
CorrelationType m_correlationType;