Selectable reference impedance

Software/PC_Application/Tools/impedancematchdialog.cpp

@@ -3,17 +3,18 @@
 #include "ui_impedancematchdialog.h"
 #include "Tools/eseries.h"
 #include "Util/util.h"
+#include "preferences.h"
 
 using namespace std;
 
-constexpr double ImpedanceMatchDialog::Z0;
-
 ImpedanceMatchDialog::ImpedanceMatchDialog(MarkerModel &model, Marker *marker, QWidget *parent) :
     QDialog(parent),
     ui(new Ui::ImpedanceMatchDialog)
 {
     ui->setupUi(this);
 
+    Z0 = Preferences::getInstance().Acquisition.refImp;
+
     // set SI units and prefixes
     ui->zReal->setUnit("Ohm");
     ui->zImag->setUnit("Ohm");

Software/PC_Application/Tools/impedancematchdialog.h

@@ -22,7 +22,7 @@ private slots:
     void calculateMatch();
 
 private:
-    static constexpr double Z0 = 50.0;
+    double Z0;
     Ui::ImpedanceMatchDialog *ui;
 };
 

Software/PC_Application/Traces/tracesmithchart.cpp

@@ -305,7 +305,7 @@ void TraceSmithChart::draw(QPainter &p) {
       p.drawLine(dataToPixel(complex<double>(edgeReflection,0)),dataToPixel(complex<double>(-edgeReflection,0)));
     constexpr std::array<double, 5> impedanceLines = {10, 25, 50, 100, 250};
     for(auto z : impedanceLines) {
-        z /= ReferenceImpedance;
+        z /= Preferences::getInstance().Acquisition.refImp;
         auto radius = 1.0/z;
         drawArc(SmithChartArc(QPointF(1.0, radius), radius, 0, 2*M_PI));
         drawArc(SmithChartArc(QPointF(1.0, -radius), radius, 0, 2*M_PI));
@@ -409,7 +409,7 @@ QString TraceSmithChart::mouseText(QPoint pos)
 {
     auto data = pixelToData(pos);
     if(abs(data) <= edgeReflection) {
-        data = 50.0 * (1.0 + data) / (1.0 - data);
+        data = Preferences::getInstance().Acquisition.refImp * (1.0 + data) / (1.0 - data);
         auto ret = Unit::ToString(data.real(), "", " ", 3);
         if(data.imag() >= 0) {
             ret += "+";
@@ -586,18 +586,19 @@ SmithChartConstantLine::SmithChartConstantLine()
 
 std::vector<SmithChartArc> SmithChartConstantLine::getArcs()
 {
+    double Z0 = Preferences::getInstance().Acquisition.refImp;
     std::vector<SmithChartArc> arcs;
     switch(type) {
     case Type::VSWR:
         arcs.push_back(SmithChartArc(QPointF(0.0, 0.0), (param - 1.0) / (param + 1.0)));
         break;
     case Type::Resistance: {
-        auto circleLeft = (param / 50.0 - 1.0) / (param / 50.0 + 1.0);
+        auto circleLeft = (param / Z0 - 1.0) / (param / Z0 + 1.0);
         arcs.push_back(SmithChartArc(QPointF((circleLeft + 1.0) / 2, 0.0), (1.0 - circleLeft) / 2.0));
     }
         break;
     case Type::Reactance: {
-        auto radius = 1.0/(param / 50.0);
+        auto radius = 1.0/(param / Z0);
         if(radius > 0) {
             arcs.push_back(SmithChartArc(QPointF(1.0, radius), radius));
         } else {

Software/PC_Application/Traces/tracesmithchart.h

@@ -115,7 +115,6 @@ public slots:
     void axisSetupDialog();
 
 protected:
-    static constexpr double ReferenceImpedance = 50.0;
     static constexpr double screenUsage = 0.9;
     static constexpr double smithCoordMax = 4096;
 

Software/PC_Application/Traces/tracexyplot.cpp

@@ -1247,7 +1247,7 @@ QString TraceXYPlot::AxisUnit(TraceXYPlot::YAxisType type)
         case TraceXYPlot::YAxisType::ImpulseReal: return "";
         case TraceXYPlot::YAxisType::ImpulseMag: return "dB";
         case TraceXYPlot::YAxisType::Step: return "";
-        case TraceXYPlot::YAxisType::Impedance: return "Ohm";
+        case TraceXYPlot::YAxisType::Impedance: return "Ω";
         case TraceXYPlot::YAxisType::GroupDelay: return "s";
         case TraceXYPlot::YAxisType::Disabled:
         case TraceXYPlot::YAxisType::Real:

Software/PC_Application/Util/util.cpp

@@ -1,5 +1,7 @@
 #include "util.h"
 
+#include "preferences.h"
+
 #include <QVector2D>
 
 void Util::unwrapPhase(std::vector<double> &phase, unsigned int start_index)
@@ -59,3 +61,7 @@ double Util::distanceToLine(QPointF point, QPointF l1, QPointF l2, QPointF *clos
     }
     return orthVect.length();
 }
+
+std::complex<double> Util::SparamToImpedance(std::complex<double> d) {
+    return Preferences::getInstance().Acquisition.refImp * (1.0 + d) / (1.0 - d);
+}

Software/PC_Application/Util/util.h

@@ -44,9 +44,7 @@ namespace Util {
     static inline double SparamToVSWR(std::complex<double> d) {
         return SparamToVSWR(abs(d));
     }
-    static inline std::complex<double> SparamToImpedance(std::complex<double> d) {
+    std::complex<double> SparamToImpedance(std::complex<double> d);
-        return 50.0 * (1.0 + d) / (1.0 - d);
-    }
     // all these conversions assume series connection of real and imag part
     static inline double SparamToResistance(std::complex<double> d) {
         return SparamToImpedance(d).real();

Software/PC_Application/VNA/Deembedding/matchingnetwork.cpp

@@ -32,7 +32,7 @@ void MatchingNetwork::transformDatapoint(Protocol::Datapoint &p)
                     complex<double>(p.real_S12, p.imag_S12),
                     complex<double>(p.real_S21, p.imag_S21),
                     complex<double>(p.real_S22, p.imag_S22));
-    auto measurement = ABCDparam(S, 50.0);
+    auto measurement = ABCDparam(S, Preferences::getInstance().Acquisition.refImp);
     if(matching.count(p.frequency) == 0) {
         // this point is not calculated yet
         MatchingPoint m;
@@ -56,7 +56,7 @@ void MatchingNetwork::transformDatapoint(Protocol::Datapoint &p)
     // at this point the map contains the matching network effect
     auto m = matching[p.frequency];
     auto corrected = m.p1 * measurement * m.p2;
-    S = Sparam(corrected, 50.0);
+    S = Sparam(corrected, Preferences::getInstance().Acquisition.refImp);
     p.real_S11 = real(S.m11);
     p.imag_S11 = imag(S.m11);
     p.real_S12 = real(S.m12);
@@ -541,7 +541,7 @@ ABCDparam MatchingComponent::parameters(double freq)
         } else {
             auto d = touchstone->interpolate(freq);
             auto S = Sparam(d.S[0], d.S[1], d.S[2], d.S[3]);
-            return ABCDparam(S, 50.0);
+            return ABCDparam(S, Preferences::getInstance().Acquisition.refImp);
         }
     default:
         return ABCDparam(1.0, 0.0, 0.0, 1.0);

Software/PC_Application/VNA/Deembedding/twothru.cpp

@@ -12,7 +12,7 @@ using namespace std;
 
 TwoThru::TwoThru()
 {
-    Z0 = 50.0;
+    Z0 = Preferences::getInstance().Acquisition.refImp;
 }
 
 void TwoThru::transformDatapoint(Protocol::Datapoint &p)

Software/PC_Application/preferences.cpp

@@ -88,6 +88,9 @@ PreferencesDialog::PreferencesDialog(Preferences *pref, QWidget *parent) :
     ui->StartupSARBW->setPrefixes(" k");
 
     // Acquisition page
+    ui->AcquisitionReferenceImpedance->setUnit("Ω");
+    ui->AcquisitionReferenceImpedance->setPrefixes(" ");
+    ui->AcquisitionReferenceImpedance->setPrecision(3);
     ui->AcquisitionDFTlimitRBW->setUnit("Hz");
     ui->AcquisitionDFTlimitRBW->setPrefixes(" k");
     connect(ui->AcquisitionUseDFT, &QCheckBox::toggled, [=](bool enabled) {
@@ -234,6 +237,7 @@ void PreferencesDialog::setInitialGUIState()
     ui->AcquisitionAdjustPowerLevel->setChecked(p->Acquisition.adjustPowerLevel);
     ui->AcquisitionUseHarmonic->setChecked(p->Acquisition.harmonicMixing);
     ui->AcquisitionAllowSegmentedSweep->setChecked(p->Acquisition.allowSegmentedSweep);
+    ui->AcquisitionReferenceImpedance->setValue(p->Acquisition.refImp);
     ui->AcquisitionUseDFT->setChecked(p->Acquisition.useDFTinSAmode);
     ui->AcquisitionDFTlimitRBW->setValue(p->Acquisition.RBWLimitForDFT);
     ui->AcquisitionAveragingMode->setCurrentIndex(p->Acquisition.useMedianAveraging ? 1 : 0);
@@ -294,6 +298,7 @@ void PreferencesDialog::updateFromGUI()
     p->Acquisition.adjustPowerLevel = ui->AcquisitionAdjustPowerLevel->isChecked();
     p->Acquisition.harmonicMixing = ui->AcquisitionUseHarmonic->isChecked();
     p->Acquisition.allowSegmentedSweep = ui->AcquisitionAllowSegmentedSweep->isChecked();
+    p->Acquisition.refImp = ui->AcquisitionReferenceImpedance->value();
     p->Acquisition.useDFTinSAmode = ui->AcquisitionUseDFT->isChecked();
     p->Acquisition.RBWLimitForDFT = ui->AcquisitionDFTlimitRBW->value();
     p->Acquisition.useMedianAveraging = ui->AcquisitionAveragingMode->currentIndex() == 1;

Software/PC_Application/preferences.h

@@ -73,6 +73,7 @@ public:
         bool useDFTinSAmode;
         double RBWLimitForDFT;
         bool useMedianAveraging;
+        double refImp; // reference impedance
 
         // advanced, hardware specific settings
         double IF1;
@@ -152,6 +153,7 @@ private:
         {&Acquisition.useDFTinSAmode, "Acquisition.useDFTinSAmode", true},
         {&Acquisition.RBWLimitForDFT, "Acquisition.RBWLimitForDFT", 3000.0},
         {&Acquisition.useMedianAveraging, "Acquisition.useMedianAveraging", false},
+        {&Acquisition.refImp, "Acquisition.referenceImpedance", 50.0},
         {&Acquisition.IF1, "Acquisition.IF1", 62000000},
         {&Acquisition.ADCprescaler, "Acquisition.ADCprescaler", 128},
         {&Acquisition.DFTPhaseInc, "Acquisition.DFTPhaseInc", 1280},

Software/PC_Application/preferencesdialog.ui

@@ -745,6 +745,24 @@
               </property>
              </widget>
             </item>
+            <item>
+             <layout class="QFormLayout" name="formLayout_11">
+              <item row="0" column="0">
+               <widget class="QLabel" name="label_39">
+                <property name="text">
+                 <string>Reference impedance:</string>
+                </property>
+               </widget>
+              </item>
+              <item row="0" column="1">
+               <widget class="SIUnitEdit" name="AcquisitionReferenceImpedance">
+                <property name="toolTip">
+                 <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;Frequency of the first IF&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+                </property>
+               </widget>
+              </item>
+             </layout>
+            </item>
            </layout>
           </widget>
          </item>