continuous updates for TDR/DFT with optional rate limit

Software/PC_Application/LibreVNA-GUI/Traces/Math/dft.cpp

@@ -7,6 +7,9 @@
 #include "ui_dftexplanationwidget.h"
 #include "appwindow.h"
 
+#include <chrono>
+#include <thread>
+
 #include <QDebug>
 
 using namespace std;
@@ -133,11 +136,6 @@ void Math::DFT::inputSamplesChanged(unsigned int begin, unsigned int end)
         warning("Not enough input samples");
         return;
     }
-    // DFT is computationally expensive, only update at the end of sweep -> check if this is the first changed data in the next sweep
-    if(begin != 0) {
-        // not the end, do nothing
-        return;
-    }
     // trigger calculation in thread
     semphr.release();
     success();
@@ -159,6 +157,8 @@ Math::DFTThread::DFTThread(Math::DFT &dft)
 void Math::DFTThread::run()
 {
     qDebug() << "DFT thread starting";
+    using namespace std::chrono;
+    auto lastCalc = system_clock::now();
     while(1) {
         dft.semphr.acquire();
         // clear possible additional semaphores
@@ -168,7 +168,13 @@ void Math::DFTThread::run()
             qDebug() << "DFT thread exiting";
             return;
         }
-        qDebug() << "DFT thread calculating";
+        // 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";
         double DC = dft.DCfreq;
         TDR *tdr = nullptr;
         if(dft.automaticDC) {

Software/PC_Application/LibreVNA-GUI/Traces/Math/tdr.cpp

@@ -6,6 +6,9 @@
 #include "Util/util.h"
 #include "appwindow.h"
 
+#include <chrono>
+#include <thread>
+
 #include <QVBoxLayout>
 #include <QLabel>
 #include <QDebug>
@@ -201,11 +204,6 @@ void TDR::inputSamplesChanged(unsigned int begin, unsigned int end)
 {
     Q_UNUSED(end);
     if(input->rData().size() >= 2) {
-        // TDR is computationally expensive, only update at the end of sweep -> check if this is the first changed data in the next sweep
-        if(begin != 0) {
-            // not the end, do nothing
-            return;
-        }
         // trigger calculation in thread
         semphr.release();
         success();
@@ -244,6 +242,8 @@ TDRThread::TDRThread(TDR &tdr)
 void TDRThread::run()
 {
     qDebug() << "TDR thread starting";
+    using namespace std::chrono;
+    auto lastCalc = system_clock::now();
     while(1) {
         tdr.semphr.acquire();
         // clear possible additional semaphores
@@ -253,7 +253,13 @@ void TDRThread::run()
             qDebug() << "TDR thread exiting";
             return;
         }
-        qDebug() << "TDR thread calculating";
+        // 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() << "TDR thread calculating";
         // perform calculation
         vector<complex<double>> frequencyDomain;
         auto stepSize = (tdr.input->rData().back().x - tdr.input->rData().front().x) / (tdr.input->rData().size() - 1);

Software/PC_Application/LibreVNA-GUI/preferences.cpp

@@ -210,6 +210,9 @@ PreferencesDialog::PreferencesDialog(Preferences *pref, QWidget *parent) :
            setInitialGUIState();
         }
     });
+    connect(ui->AcquisitionLimitTDRCheckbox, &QCheckBox::toggled, [=](bool enabled){
+        ui->AcquisitionDFTLimitValue->setEnabled(enabled);
+    });
 
     setInitialGUIState();
 }
@@ -257,6 +260,8 @@ void PreferencesDialog::setInitialGUIState()
     ui->AcquisitionFullSpanStart->setValue(p->Acquisition.fullSpanStart);
     ui->AcquisitionFullSpanStop->setValue(p->Acquisition.fullSpanStop);
     ui->AcquisitionFullSpanCalibrated->setChecked(p->Acquisition.fullSpanCalibratedRange);
+    ui->AcquisitionLimitTDRCheckbox->setChecked(p->Acquisition.limitDFT);
+    ui->AcquisitionDFTLimitValue->setValue(p->Acquisition.maxDFTrate);
 
     ui->GraphsDefaultTransmission->setCurrentText(p->Graphs.defaultGraphs.transmission);
     ui->GraphsDefaultReflection->setCurrentText(p->Graphs.defaultGraphs.reflection);
@@ -354,6 +359,8 @@ void PreferencesDialog::updateFromGUI()
     p->Acquisition.fullSpanStart = ui->AcquisitionFullSpanStart->value();
     p->Acquisition.fullSpanStop = ui->AcquisitionFullSpanStop->value();
     p->Acquisition.fullSpanCalibratedRange = ui->AcquisitionFullSpanCalibrated->isChecked();
+    p->Acquisition.limitDFT = ui->AcquisitionLimitTDRCheckbox->isChecked();
+    p->Acquisition.maxDFTrate = ui->AcquisitionDFTLimitValue->value();
 
     p->Graphs.defaultGraphs.transmission = ui->GraphsDefaultTransmission->currentText();
     p->Graphs.defaultGraphs.reflection = ui->GraphsDefaultReflection->currentText();

Software/PC_Application/LibreVNA-GUI/preferences.h

@@ -104,6 +104,10 @@ public:
         double fullSpanStart;
         double fullSpanStop;
         bool fullSpanCalibratedRange;
+
+        // Math settings
+        bool limitDFT;
+        double maxDFTrate;
     } Acquisition;
     struct {
         bool showUnits;
@@ -208,6 +212,8 @@ private:
         {&Acquisition.fullSpanStart, "Acquisition.fullSpanStart", 0.0},
         {&Acquisition.fullSpanStop, "Acquisition.fullSpanStop", 6000000000.0},
         {&Acquisition.fullSpanCalibratedRange, "Acquisition.fullSpanCalibratedRange", false},
+        {&Acquisition.limitDFT, "Acquisition.limitDFT", true},
+        {&Acquisition.maxDFTrate, "Acquisition.maxDFTrate", 1.0},
         {&Graphs.showUnits, "Graphs.showUnits", true},
         {&Graphs.Color.background, "Graphs.Color.background", QColor(Qt::black)},
         {&Graphs.Color.axis, "Graphs.Color.axis", QColor(Qt::white)},

Software/PC_Application/LibreVNA-GUI/preferencesdialog.ui

@@ -93,7 +93,7 @@
        </size>
       </property>
       <property name="currentIndex">
-       <number>2</number>
+       <number>1</number>
       </property>
       <widget class="QWidget" name="Startup">
        <layout class="QHBoxLayout" name="horizontalLayout_4">
@@ -824,6 +824,55 @@
               </layout>
              </widget>
             </item>
+            <item>
+             <widget class="QGroupBox" name="groupBox_15">
+              <property name="title">
+               <string>Math operations</string>
+              </property>
+              <layout class="QHBoxLayout" name="horizontalLayout_6">
+               <item>
+                <widget class="QCheckBox" name="AcquisitionLimitTDRCheckbox">
+                 <property name="text">
+                  <string>Limit TDR/DFT to </string>
+                 </property>
+                </widget>
+               </item>
+               <item>
+                <widget class="QDoubleSpinBox" name="AcquisitionDFTLimitValue">
+                 <property name="enabled">
+                  <bool>false</bool>
+                 </property>
+                 <property name="minimum">
+                  <double>0.100000000000000</double>
+                 </property>
+                 <property name="maximum">
+                  <double>100.000000000000000</double>
+                 </property>
+                </widget>
+               </item>
+               <item>
+                <widget class="QLabel" name="label_30">
+                 <property name="text">
+                  <string>updates per second</string>
+                 </property>
+                </widget>
+               </item>
+               <item>
+                <spacer name="horizontalSpacer_8">
+                 <property name="orientation">
+                  <enum>Qt::Horizontal</enum>
+                 </property>
+                 <property name="sizeHint" stdset="0">
+                  <size>
+                   <width>40</width>
+                   <height>20</height>
+                  </size>
+                 </property>
+                </spacer>
+               </item>
+              </layout>
+             </widget>
+            </item>
             <item>
              <spacer name="verticalSpacer_2">
               <property name="orientation">
@@ -1688,8 +1737,8 @@
             <rect>
              <x>0</x>
              <y>0</y>
-             <width>168</width>
+             <width>697</width>
-             <height>127</height>
+             <height>563</height>
             </rect>
            </property>
            <layout class="QHBoxLayout" name="horizontalLayout_12">
@@ -1778,8 +1827,8 @@
             <rect>
              <x>0</x>
              <y>0</y>
-             <width>215</width>
+             <width>697</width>
-             <height>168</height>
+             <height>563</height>
             </rect>
            </property>
            <layout class="QHBoxLayout" name="horizontalLayout_19">