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sdrangel/plugins/channelmimo/interferometer/interferometercorr.cpp

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///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2019-2020 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
// //
// 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 //
// (at your option) any later version. //
// //
// 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 <algorithm>
#include <functional>
#include "dsp/dspengine.h"
#include "dsp/fftfactory.h"
#include "dsp/fftengine.h"
#include "util/db.h"
#include "interferometercorr.h"
std::complex<float> s2c(const Sample& s)
{
return std::complex<float>{s.real() / SDR_RX_SCALEF, s.imag() / SDR_RX_SCALEF};
}
std::complex<float> s2cNorm(const Sample& s)
{
float x = s.real() / SDR_RX_SCALEF;
float y = s.imag() / SDR_RX_SCALEF;
float m = sqrt(x*x + y*y);
return std::complex<float>{x/m, y/m};
}
Sample sFirst(const Sample& a, const Sample& b) {
(void) b;
return a;
}
Sample sSecond(const Sample& a, const Sample& b) {
(void) a;
return b;
}
Sample sSecondInv(const Sample& a, const Sample& b) {
(void) a;
return Sample{-b.real(), -b.imag()};
}
Sample sAdd(const Sample& a, const Sample& b) { //!< Sample addition
return Sample{(a.real()+b.real())/2, (a.imag()+b.imag())/2};
}
Sample sAddInv(const Sample& a, const Sample& b) { //!< Sample addition
return Sample{(a.real()-b.real())/2, (a.imag()+b.imag())/2};
}
Sample sMulConj(const Sample& a, const Sample& b) { //!< Sample multiply with conjugate
Sample s;
// Integer processing
int64_t ax = a.real();
int64_t ay = a.imag();
int64_t bx = b.real();
int64_t by = b.imag();
int64_t x = ax*bx + ay*by;
int64_t y = ay*bx - ax*by;
s.setReal(x>>(SDR_RX_SAMP_SZ-1));
s.setImag(y>>(SDR_RX_SAMP_SZ-1));
// Floating point processing (in practice there is no significant performance difference)
// float ax = a.real() / SDR_RX_SCALEF;
// float ay = a.imag() / SDR_RX_SCALEF;
// float bx = b.real() / SDR_RX_SCALEF;
// float by = b.imag() / SDR_RX_SCALEF;
// float x = ax*bx + ay*by;
// float y = ay*bx - ax*by;
// s.setReal(x*SDR_RX_SCALEF);
// s.setImag(y*SDR_RX_SCALEF);
return s;
}
Sample sMulConjInv(const Sample& a, const Sample& b) { //!< Sample multiply with conjugate
Sample s;
// Integer processing
int64_t ax = a.real();
int64_t ay = a.imag();
int64_t bx = -b.real();
int64_t by = -b.imag();
int64_t x = ax*bx + ay*by;
int64_t y = ay*bx - ax*by;
s.setReal(x>>(SDR_RX_SAMP_SZ-1));
s.setImag(y>>(SDR_RX_SAMP_SZ-1));
return s;
}
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;
}
Sample invfft2star(const std::complex<float>& a) { //!< Complex float to Sample for 1 side time correlation
Sample s;
s.setReal(a.real()/2.82842712475f); // 2*sqrt(2)
s.setImag(a.imag()/2.82842712475f);
return s;
}
InterferometerCorrelator::InterferometerCorrelator(int fftSize) :
m_corrType(InterferometerSettings::CorrelationAdd),
m_fftSize(fftSize)
{
setPhase(0);
setGain(0);
FFTFactory *fftFactory = DSPEngine::instance()->getFFTFactory();
m_window.create(FFTWindow::Function::Hanning, fftSize);
m_data0w.resize(m_fftSize);
m_data1w.resize(m_fftSize);
for (int i = 0; i < 2; i++)
{
m_fftSequences[i] = fftFactory->getEngine(2*fftSize, false, &m_fft[i]); // internally twice the data FFT size
m_fft2Sequences[i] = fftFactory->getEngine(fftSize, false, &m_fft2[i]);
}
m_invFFTSequence = fftFactory->getEngine(2*fftSize, true, &m_invFFT);
m_invFFT2Sequence = fftFactory->getEngine(fftSize, true, &m_invFFT2);
m_dataj = new std::complex<float>[2*fftSize]; // receives actual FFT result hence twice the data FFT size
m_scorr.resize(fftSize);
m_tcorr.resize(fftSize);
m_scorrSize = fftSize;
m_tcorrSize = fftSize;
}
InterferometerCorrelator::~InterferometerCorrelator()
{
FFTFactory *fftFactory = DSPEngine::instance()->getFFTFactory();
fftFactory->releaseEngine(2*m_fftSize, true, m_invFFTSequence);
fftFactory->releaseEngine(m_fftSize, true, m_invFFT2Sequence);
delete[] m_dataj;
for (int i = 0; i < 2; i++)
{
fftFactory->releaseEngine(2*m_fftSize, false, m_fftSequences[i]);
fftFactory->releaseEngine(m_fftSize, false, m_fft2Sequences[i]);
}
}
bool InterferometerCorrelator::performCorr(
const SampleVector& data0,
unsigned int size0,
const SampleVector& data1,
unsigned int size1
)
{
bool results = false;
const SampleVector *pdata1 = &data1;
if ((m_gain != 0) || (m_phase != 0))
{
if (size1 > m_data1p.size()) {
m_data1p.resize(size1);
}
pdata1 = &m_data1p;
if (m_phase == 0)
{
std::transform(
data1.begin(),
data1.begin() + size1,
m_data1p.begin(),
[this](const Sample& s) -> Sample
{
FixReal sx = s.real()*m_gain;
FixReal sy = s.imag()*m_gain;
return Sample{sx, sy};
}
);
}
else
{
std::transform(
data1.begin(),
data1.begin() + size1,
m_data1p.begin(),
[this](const Sample& s) -> Sample {
Sample t;
int64_t sx = s.real()*m_gain;
int64_t sy = s.imag()*m_gain;
int64_t x = sx*m_cos + sy*m_sin;
int64_t y = sy*m_cos - sx*m_sin;
t.setReal(x>>(SDR_RX_SAMP_SZ-1));
t.setImag(y>>(SDR_RX_SAMP_SZ-1));
return t;
}
);
}
}
switch (m_corrType)
{
case InterferometerSettings::Correlation0:
results = performOpCorr(data0, size0, pdata1, size1, sFirst);
break;
case InterferometerSettings::Correlation1:
results = performOpCorr(data0, size0, pdata1, size1, sSecond);
break;
case InterferometerSettings::CorrelationAdd:
results = performOpCorr(data0, size0, pdata1, size1, sAdd);
break;
case InterferometerSettings::CorrelationMultiply:
results = performOpCorr(data0, size0, pdata1, size1, sMulConj);
break;
case InterferometerSettings::CorrelationIFFT:
results = performIFFTCorr(data0, size0, pdata1, size1);
break;
case InterferometerSettings::CorrelationIFFTStar:
results = performIFFTCorr(data0, size0, pdata1, size1, true);
break;
case InterferometerSettings::CorrelationFFT:
results = performFFTProd(data0, size0, pdata1, size1);
break;
case InterferometerSettings::CorrelationIFFT2:
results = performIFFT2Corr(data0, size0, pdata1, size1);
break;
default:
break;
}
return results;
}
bool InterferometerCorrelator::performOpCorr(
const SampleVector& data0,
unsigned int size0,
const SampleVector* data1,
unsigned int size1,
Sample sampleOp(const Sample& a, const Sample& b)
)
{
unsigned int size = std::min(size0, size1);
adjustTCorrSize(size);
std::transform(
data0.begin(),
data0.begin() + size,
data1->begin(),
m_tcorr.begin(),
sampleOp
);
m_processed = size;
m_remaining[0] = size0 - size;
m_remaining[1] = size1 - size;
return true;
}
bool InterferometerCorrelator::performIFFTCorr(
const SampleVector& data0,
unsigned int size0,
const SampleVector* data1,
unsigned int size1,
bool star
)
{
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_fft[0]->in(),
s2c
);
m_window.apply(m_fft[0]->in());
std::fill(m_fft[0]->in() + m_fftSize, m_fft[0]->in() + 2*m_fftSize, std::complex<float>{0, 0});
m_fft[0]->transform();
// FFT[1]
std::transform(
begin1,
begin1 + m_fftSize,
m_fft[1]->in(),
s2c
);
m_window.apply(m_fft[1]->in());
std::fill(m_fft[1]->in() + m_fftSize, m_fft[1]->in() + 2*m_fftSize, std::complex<float>{0, 0});
m_fft[1]->transform();
// conjugate FFT[1]
std::transform(
m_fft[1]->out(),
m_fft[1]->out() + 2*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_fft[0]->out(),
m_fft[0]->out() + 2*m_fftSize,
m_dataj,
m_invFFT->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 and Hanning window
std::transform(
m_invFFT->in(),
m_invFFT->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_invFFT->transform();
if (star)
{
// sum first half with the reversed second half as one is the conjugate of the other this should yield constant phase
*m_tcorr.begin() = invfft2star(m_invFFT->out()[0]); // t = 0
std::reverse(m_invFFT->out() + m_fftSize, m_invFFT->out() + 2*m_fftSize);
std::transform(
m_invFFT->out() + 1,
m_invFFT->out() + m_fftSize,
m_invFFT->out() + m_fftSize,
m_tcorr.begin() + nfft*m_fftSize,
[](const std::complex<float>& a, const std::complex<float>& b) -> Sample {
Sample s;
std::complex<float> sum = a + b;
s.setReal(sum.real()/12.0f);
s.setImag(sum.imag()/12.0f);
return s;
}
);
}
else
{
std::transform(
m_invFFT->out(),
m_invFFT->out() + m_fftSize,
m_tcorr.begin() + nfft*m_fftSize,
[](const std::complex<float>& a) -> Sample {
Sample s;
s.setReal(a.real()/6.0f);
s.setImag(a.imag()/6.0f);
return s;
}
);
}
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;
}
bool InterferometerCorrelator::performIFFT2Corr(
const SampleVector& data0,
unsigned int size0,
const SampleVector* data1,
unsigned 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(),
s2c
);
m_window.apply(m_fft2[0]->in());
m_fft2[0]->transform();
// FFT[1]
std::transform(
begin1,
begin1 + m_fftSize,
m_fft2[1]->in(),
s2c
);
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,
m_invFFT2->out() + m_fftSize,
m_tcorr.begin() + nfft*m_fftSize,
[](const std::complex<float>& a) -> Sample {
Sample s;
s.setReal(a.real()/3.0f);
s.setImag(a.imag()/3.0f);
return s;
}
);
std::transform(
m_invFFT2->out(),
m_invFFT2->out() + m_fftSize/2,
m_tcorr.begin() + nfft*m_fftSize + m_fftSize/2,
[](const std::complex<float>& a) -> Sample {
Sample s;
s.setReal(a.real()/3.0f);
s.setImag(a.imag()/3.0f);
return s;
}
);
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;
}
bool InterferometerCorrelator::performFFTProd(
const SampleVector& data0,
unsigned int size0,
const SampleVector* data1,
unsigned 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(),
s2cNorm
);
m_window.apply(m_fft2[0]->in());
m_fft2[0]->transform();
// FFT[1]
std::transform(
begin1,
begin1 + m_fftSize,
m_fft2[1]->in(),
s2cNorm
);
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 both results
std::transform(
m_fft2[0]->out(),
m_fft2[0]->out() + m_fftSize,
m_dataj,
m_invFFT2->in(),
[this](std::complex<float>& a, const std::complex<float>& b) -> std::complex<float> {
return (a*b);
}
);
// copy product to time domain - re-order, convert and scale to FFT size
std::transform(
m_invFFT2->in(),
m_invFFT2->in() + m_fftSize/2,
m_tcorr.begin() + nfft*m_fftSize + m_fftSize/2,
[](const std::complex<float>& a) -> Sample {
Sample s;
s.setReal(a.real()/2.0f);
s.setImag(a.imag()/2.0f);
return s;
}
);
std::transform(
m_invFFT2->in() + m_fftSize/2,
m_invFFT2->in() + m_fftSize,
m_tcorr.begin() + nfft*m_fftSize,
[](const std::complex<float>& a) -> Sample {
Sample s;
s.setReal(a.real()/2.0f);
s.setImag(a.imag()/2.0f);
return s;
}
);
// feed spectrum with the sum
std::transform(
begin0,
begin0 + m_fftSize,
begin1,
m_scorr.begin() + nfft*m_fftSize,
sAdd
);
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;
if (nFFTSize > m_scorrSize)
{
m_scorr.resize(nFFTSize);
m_scorrSize = nFFTSize;
}
}
void InterferometerCorrelator::adjustTCorrSize(int size)
{
int nFFTSize = (size/m_fftSize)*m_fftSize;
if (nFFTSize > m_tcorrSize)
{
m_tcorr.resize(nFFTSize);
m_tcorrSize = nFFTSize;
}
}
void InterferometerCorrelator::setPhase(int phase)
{
m_phase = phase;
if (phase == 0)
{
m_sin = 0;
m_cos = 1<<(SDR_RX_SAMP_SZ-1);
}
else if (phase == 90)
{
m_sin = 1<<(SDR_RX_SAMP_SZ-1);
m_cos = 0;
}
else if (phase == -90)
{
m_sin = -(1<<(SDR_RX_SAMP_SZ-1));
m_cos = 0;
}
else if ((phase == -180) || (phase == 180))
{
m_sin = 0;
m_cos = -(1<<(SDR_RX_SAMP_SZ-1));
}
else
{
m_phase = phase % 180;
double d_sin = sin(M_PI*(m_phase/180.0)) * (1<<(SDR_RX_SAMP_SZ-1));
double d_cos = cos(M_PI*(m_phase/180.0)) * (1<<(SDR_RX_SAMP_SZ-1));
m_sin = d_sin;
m_cos = d_cos;
}
}
void InterferometerCorrelator::setGain(int gainCB)
{
double db = gainCB / 10.0;
m_gainCB = gainCB;
m_gain = CalcDb::powerFromdB(db);
}
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