Add Flattop to window functions

Author: Tony Kirke

qt_window/mainwindow.cpp

@@ -28,6 +28,7 @@ MainWindow::MainWindow(QWidget *parent) :
   Blackman_on = NULL;
   Bartlett_on = NULL;
   Chebyshev_on = NULL;
+  Flattop_on = NULL;
   Kaiser_on = NULL;
 
   graph_counter = 0;
@@ -44,6 +45,7 @@ MainWindow::MainWindow(QWidget *parent) :
   connect(ui->Blackman, SIGNAL(released()), this, SLOT(EChanged()));
   connect(ui->Bartlett, SIGNAL(released()), this, SLOT(FHChanged()));
   connect(ui->Chebyshev, SIGNAL(released()), this, SLOT(GChanged()));
+  connect(ui->Flattop, SIGNAL(released()), this, SLOT(FTChanged()));
   connect(ui->Kaiser, SIGNAL(released()), this, SLOT(CBChanged()));
 
   connect(ui->customPlot, SIGNAL(mousePress(QMouseEvent*)), 
@@ -57,7 +59,7 @@ MainWindow::MainWindow(QWidget *parent) :
 void MainWindow::BChanged() {
   if (Hanning_on==NULL) {
 	shape = "Hanning";
-	LPF.change_filter(spuce::Hamming);
+	LPF.change_filter(spuce::Hanning);
 	Hanning_on = ui->customPlot->addGraph();
 	plot2(ui->customPlot);
   } else {
@@ -114,6 +116,18 @@ void MainWindow::GChanged() {
 	ui->customPlot->replot();
   }
 }
+void MainWindow::FTChanged() {
+  if (Flattop_on==NULL) {
+	shape = "Flattop";
+	LPF.change_filter(spuce::Flattop);
+	Flattop_on = ui->customPlot->addGraph();
+	plot2(ui->customPlot);
+  } else {
+	ui->customPlot->removeGraph(Flattop_on);
+	Flattop_on = NULL;
+	ui->customPlot->replot();
+  }
+}
 void MainWindow::CBChanged() {
   if (Kaiser_on==NULL) {
 	shape = "Kaiser";
@@ -133,6 +147,7 @@ QCPGraph* MainWindow::GetPtr() {
   else if (shape=="Hanning")	return(Hanning_on);
   else if (shape=="Blackman") return(Blackman_on);
   else if (shape=="Chebyshev") return(Chebyshev_on);
+  else if (shape=="Flattop") return(Flattop_on);
   else if (shape=="Kaiser") return(Kaiser_on);
   else std::cout << "Invalid filter selection " << shape << "\n";
   return(Hanning_on);

qt_window/mainwindow.h

@@ -33,6 +33,7 @@ public slots:
   void GChanged(); 
   void EChanged(); 
   void FHChanged(); 
+  void FTChanged(); 
   void CBChanged(); 
   void graphPressEvent(QMouseEvent *event);
   void graphMoveEvent(QMouseEvent *event);
@@ -51,6 +52,7 @@ public slots:
   QCPGraph*  Blackman_on;
   QCPGraph*  Bartlett_on;
   QCPGraph*  Chebyshev_on;
+  QCPGraph*  Flattop_on;
   QCPGraph*  Kaiser_on;
   int graph_counter;
 

qt_window/make_filter.cpp

@@ -36,6 +36,7 @@ void make_filter::reset() {
   hamming_taps  =23;
   hanning_taps  =23;
   bartlett_taps =23;
+  flattop_taps =23;
   blackman_taps =23;
   kaiser_taps   =23;
   cheby_taps    =23;
@@ -63,6 +64,7 @@ void make_filter::vertical_swipe(int len) {
 	case Hamming:
 	case Blackman:
 	case Bartlett:
+	case Flattop:
 	case None:
       break;
   }
@@ -76,6 +78,7 @@ void make_filter::horiz_swipe(int len) {
   case Hanning:		hanning_taps = limit(hanning_taps + inc, MAX_FIR,MIN_FIR); break;
   case Hamming:		hamming_taps = limit(hamming_taps + inc, MAX_FIR,MIN_FIR); break;
   case Blackman:	blackman_taps = limit(blackman_taps + inc, MAX_FIR,MIN_FIR); break;
+  case Flattop:	  flattop_taps = limit(flattop_taps + inc, MAX_FIR,MIN_FIR); break;
   case Bartlett:	bartlett_taps = limit(bartlett_taps + inc, MAX_FIR,MIN_FIR); break;
   case Chebyshev:	cheby_taps = limit(cheby_taps + inc, MAX_FIR, MIN_FIR);		break;
   case Kaiser:	    kaiser_taps = limit(kaiser_taps + inc, MAX_FIR, MIN_FIR);	break;
@@ -91,8 +94,10 @@ double make_filter::update(double *w) {
   case Blackman:	       taps = design_window("blackman", blackman_taps); break;
   case Bartlett:	       taps = design_window("bartlett", bartlett_taps); break;
   case Kaiser:		       taps = design_window("kaiser", kaiser_taps, kaiser_beta); break;
+  case Flattop:		       taps = design_window("flattop", flattop_taps); break;
   case None:			for (int i = 0; i < pts; i++) w[i] = 1.0;			break;
   }
+
 	// Normalize for Frequency plots
 	float_type sum = 0;
 	for (size_t i=0;i<taps.size();i++) sum += taps[i];

qt_window/make_filter.h

@@ -11,6 +11,7 @@ enum fil_enum {
   Bartlett,
   Blackman,
   Kaiser,
+	Flattop,
   Chebyshev
 };
 
@@ -26,6 +27,7 @@ class make_filter {
   int hamming_taps;
   int hanning_taps;
   int bartlett_taps;
+  int flattop_taps;
   int blackman_taps;
   int kaiser_taps;
 

qt_window/ui_mainwindow.h

@@ -34,6 +34,7 @@ class Ui_MainWindow
     QPushButton *Kaiser;
     QPushButton *Bartlett;
     QPushButton *Chebyshev;
+    QPushButton *Flattop;
     QPushButton *Hanning;
     QStatusBar *statusBar;
 
@@ -85,6 +86,10 @@ class Ui_MainWindow
         Chebyshev->setObjectName(QStringLiteral("Chebyshev"));
         Chebyshev->setGeometry(QRect(10, 190, 181, 27));
         Chebyshev->setCheckable(true);
+        Flattop = new QPushButton(centralWidget);
+        Flattop->setObjectName(QStringLiteral("Flattop"));
+        Flattop->setGeometry(QRect(10, 220, 181, 27));
+        Flattop->setCheckable(true);
         Hanning = new QPushButton(centralWidget);
         Hanning->setObjectName(QStringLiteral("Hanning"));
         Hanning->setGeometry(QRect(10, 40, 181, 27));
@@ -108,6 +113,7 @@ class Ui_MainWindow
         Kaiser->setText(QApplication::translate("MainWindow", "Kaiser", 0));
         Bartlett->setText(QApplication::translate("MainWindow", "Bartlett", 0));
         Chebyshev->setText(QApplication::translate("MainWindow", "Chebyshev", 0));
+        Flattop->setText(QApplication::translate("MainWindow", "Flattop", 0));
         Hanning->setText(QApplication::translate("MainWindow", "Hanning", 0));
     } // retranslateUi
 

spuce/filters/design_window.h

@@ -23,6 +23,8 @@ std::vector<float_type> design_window(const std::string& fir_type, int order, fl
 		win = bartlett(order);
 	} else if (fir_type == "chebyshev") {
 		win = cheby(order, beta);
+	} else if (fir_type == "flattop") {
+		win = flattop(order);
 	} else {
 		win = rectangular(order);
 	}

spuce/filters/window.cpp

@@ -76,6 +76,18 @@ std::vector<float_type> rectangular(long nf) {
     for (int i = 0; i < nf; i++) w[i] = 1.0;
     return (w);
 }
+std::vector<float_type> flattop(long nf)
+{
+	static const double a0 = 1.0, a1 = 1.93, a2 = 1.29, a3 = 0.388, a4=0.028;
+	std::vector<float_type> w(nf);
+	for (int i = 0; i < nf; i++) {
+		w[i] = a0	-a1*std::cos((2.0*M_PI*i)/(nf-1))
+			+a2*std::cos((4.0*M_PI*i)/(nf-1))
+			-a3*std::cos((6.0*M_PI*i)/(nf-1))
+			+a4*std::cos((8.0*M_PI*i)/(nf-1));
+	}
+	return w;
+}
 //!  \ingroup fir
 //! \brief hamming window \f$ w(n) = 0.54 - 0.46*cos( 2*\pi*n/(nf-1) )\f$
 std::vector<float_type> hamming(long nf) {

spuce/filters/window.h

@@ -9,6 +9,8 @@ namespace spuce {
 //! \brief rectangular window \f$ w(n) = 1;\f$
 //!  \ingroup functions fir
 std::vector<float_type> rectangular(long nf);
+//!  \ingroup functions fir
+std::vector<float_type> flattop(long nf);
 //! \brief hamming window \f$ w(n) = 0.54 - 0.46*cos( 2*\pi*n/(nf-1) )\f$
 //!  \ingroup functions fir
 std::vector<float_type> hamming(long nf);