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WIP: TDR/DFT improvements

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This commit is contained in:
Jan Käberich 2024-12-16 22:21:33 +01:00
parent 4725942727
commit acb79fa3bc
6 changed files with 147 additions and 51 deletions
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104
Software/PC_Application/LibreVNA-GUI/Traces/Math/dft.cpp
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@ -17,6 +17,8 @@ using namespace std;
Math::DFT::DFT()
{
automaticDC = true;
removePaddingFromTDR = true;
revertWindowFromTDR = true;
DCfreq = 1000000000.0;
destructing = false;
@ -67,12 +69,23 @@ void Math::DFT::edit()
ui->windowBox->setLayout(new QVBoxLayout);
ui->windowBox->layout()->addWidget(window.createEditor());
connect(ui->DCautomatic, &QRadioButton::toggled, [=](bool automatic){
connect(ui->removePadding, &QCheckBox::toggled, this, [=](bool remove){
removePaddingFromTDR = remove;
});
connect(ui->revertWindow, &QCheckBox::toggled, this, [=](bool revert){
revertWindowFromTDR = revert;
});
connect(ui->DCautomatic, &QRadioButton::toggled, this, [=](bool automatic){
automaticDC = automatic;
ui->freq->setEnabled(!automatic);
updateDFT();
});
ui->removePadding->setChecked(removePaddingFromTDR);
ui->revertWindow->setChecked(revertWindowFromTDR);
if(automaticDC) {
ui->DCautomatic->setChecked(true);
} else {
@ -84,7 +97,7 @@ void Math::DFT::edit()
ui->freq->setPrefixes(" kMG");
ui->freq->setValue(DCfreq);
connect(ui->freq, &SIUnitEdit::valueChanged, [=](double newval){
connect(ui->freq, &SIUnitEdit::valueChanged, this, [=](double newval){
DCfreq = newval;
updateDFT();
});
@ -111,6 +124,8 @@ nlohmann::json Math::DFT::toJSON()
nlohmann::json j;
j["automatic_DC"] = automaticDC;
j["window"] = window.toJSON();
j["removePadding"] = removePaddingFromTDR;
j["revertWindow"] = revertWindowFromTDR;
if(!automaticDC) {
j["DC"] = DCfreq;
}
@ -124,6 +139,8 @@ void Math::DFT::fromJSON(nlohmann::json j)
if(j.contains("window")) {
window.fromJSON(j["window"]);
}
removePaddingFromTDR = j.value("removePadding", true);
revertWindowFromTDR = j.value("revertWindow", true);
}
void Math::DFT::inputSamplesChanged(unsigned int begin, unsigned int end)
@ -169,38 +186,33 @@ void Math::DFTThread::run()
qDebug() << "DFT thread exiting";
return;
}
// limit update rate if configured in preferences
auto &p = Preferences::getInstance();
if(p.Acquisition.limitDFT) {
std::this_thread::sleep_until(lastCalc + duration<double>(1.0 / p.Acquisition.maxDFTrate));
lastCalc = system_clock::now();
}
// qDebug() << "DFT thread calculating";
if(!dft.input) {
// not connected, skip calculation
continue;
}
double DC = dft.DCfreq;
TDR *tdr = nullptr;
if(dft.automaticDC) {
// find the last operation that transformed from the frequency domain to the time domain
auto in = dft.input;
while(in->getInput()->getDataType() != DFT::DataType::Frequency) {
in = dft.input->getInput();
}
switch(in->getType()) {
case DFT::Type::TDR: {
tdr = static_cast<TDR*>(in);
if(tdr->getMode() == TDR::Mode::Lowpass) {
DC = 0;
} else {
// bandpass mode, assume DC is in the middle of the frequency data
DC = tdr->getInput()->getSample(tdr->getInput()->numSamples()/2).x;
}
}
break;
default:
// unknown, assume DC is in the middle of the frequency data
DC = in->getInput()->getSample(in->getInput()->numSamples()/2).x;
// find the last TDR operation
auto in = dft.input;
while(in->getType() != DFT::Type::TDR) {
in = dft.input->getInput();
if(!in) {
break;
}
}
if(in) {
tdr = static_cast<TDR*>(in);
}
if(tdr && dft.automaticDC) {
if(tdr->getMode() == TDR::Mode::Lowpass) {
DC = 0;
} else {
// bandpass mode, assume DC is in the middle of the frequency data
DC = tdr->getInput()->getSample(tdr->getInput()->numSamples()/2).x;
}
}
auto samples = dft.input->rData().size();
auto timeSpacing = dft.input->rData()[1].x - dft.input->rData()[0].x;
vector<complex<double>> timeDomain(samples);
@ -208,14 +220,34 @@ void Math::DFTThread::run()
timeDomain.at(i) = dft.input->rData()[i].y;
}
Fft::shift(timeDomain, false);
dft.window.apply(timeDomain);
Fft::shift(timeDomain, true);
Fft::transform(timeDomain, false);
// shift DC bin into the middle
Fft::shift(timeDomain, false);
double binSpacing = 1.0 / (timeSpacing * timeDomain.size());
if(tdr) {
// split in padding and actual data sections
unsigned int padding = timeDomain.size() - tdr->getUnpaddedInputSize();
std::vector<std::complex<double>> pad_front(timeDomain.begin(), timeDomain.begin()+padding/2);
std::vector<std::complex<double>> data(timeDomain.begin()+padding/2, timeDomain.end()-padding/2);
std::vector<std::complex<double>> pad_back(timeDomain.end()-padding/2, timeDomain.end());
if(dft.revertWindowFromTDR) {
tdr->getWindow().reverse(data);
}
if(dft.removePaddingFromTDR) {
timeDomain = data;
} else {
// include padding
timeDomain = pad_front;
copy(data.begin(), data.end(), back_inserter(timeDomain));
copy(pad_back.begin(), pad_back.end(), back_inserter(timeDomain));
}
}
dft.data.clear();
int DCbin = timeDomain.size() / 2, startBin = 0;
if(DC > 0) {
@ -225,16 +257,18 @@ void Math::DFTThread::run()
dft.data.resize(timeDomain.size()/2, TraceMath::Data());
}
// reverse effect of frequency domain window function from TDR (if available)
if(tdr) {
tdr->getWindow().reverse(timeDomain);
}
for(int i = startBin;(unsigned int) i<timeDomain.size();i++) {
auto freq = (i - DCbin) * binSpacing + DC;
dft.data[i - startBin].x = round(freq);
dft.data[i - startBin].y = timeDomain.at(i);
}
emit dft.outputSamplesChanged(0, dft.data.size());
// limit update rate if configured in preferences
auto &p = Preferences::getInstance();
if(p.Acquisition.limitDFT) {
std::this_thread::sleep_until(lastCalc + duration<double>(1.0 / p.Acquisition.maxDFTrate));
lastCalc = system_clock::now();
}
}
}