WIP - experiments

src/dsp/filter/design/FilterViewer.java

@@ -1,6 +1,7 @@
 package dsp.filter.design;
 
 import dsp.filter.FilterFactory;
+import dsp.filter.Window;
 import dsp.filter.fir.FIRFilterSpecification;
 import dsp.filter.fir.remez.PolyphaseChannelizerFilterFactory;
 import dsp.filter.fir.remez.RemezFIRFilterDesigner;
@@ -25,11 +26,20 @@ public class FilterViewer extends Application
     @Override
     public void start(Stage primaryStage) throws Exception
     {
-        Scene scene = new Scene(new FilterView(getFilter()));
+        float[] taps = getFilter();
 
-        primaryStage.setTitle("Filter Viewer");
-        primaryStage.setScene(scene);
-        primaryStage.show();
+        if(taps != null)
+        {
+            Scene scene = new Scene(new FilterView(taps));
+
+            primaryStage.setTitle("Filter Viewer");
+            primaryStage.setScene(scene);
+            primaryStage.show();
+        }
+        else
+        {
+            throw new Exception("Couldn't start application - filter error");
+        }
     }
 
     public static void main(String[] args)
@@ -93,7 +103,10 @@ public class FilterViewer extends Application
 //            mLog.error("Filter design error", fde);
 //        }
 
-        taps = PolyphaseChannelizerFilterFactory.getFilter(10000000, 312500, 0.21);
+//        taps = PolyphaseChannelizerFilterFactory.getFilter(2000000, 12500, 0.3);
+
+        taps = FilterFactory.getSinc(10000000, 12500, 450, Window.WindowType.HANNING);
+
         return taps;
     }
 }

src/dsp/filter/fir/remez/PolyphaseChannelizerFilterFactory.java

@@ -30,10 +30,10 @@ public class PolyphaseChannelizerFilterFactory
 
     public static float[] getFilter(int sampleRate, int channelBandwidth, double alpha)
     {
-        FIRLinearPhaseFilterType type = FIRLinearPhaseFilterType.TYPE_1_ODD_LENGTH_EVEN_ORDER_SYMMETRICAL;
+        FIRLinearPhaseFilterType type = FIRLinearPhaseFilterType.TYPE_2_EVEN_LENGTH_ODD_ORDER_SYMMETRICAL;
 
         int passBandStart = 0;
-        int gridDensity = 50;
+        int gridDensity = 60;
 
         int rolloffFrequency = (int)(alpha * (double)channelBandwidth);
 
@@ -43,13 +43,16 @@ public class PolyphaseChannelizerFilterFactory
         int stopBandStart = channelBandwidth + rolloffFrequency;
 
         double passRipple = 0.01d;
+        double transitionRipple = 0.02d;
         double stopRipple = 0.001d; //Approximately 90 dB of attenuation
 
         int order = FIRFilterSpecification.estimateFilterOrder( sampleRate, passBandStop, stopBandStart,
             passRipple, stopRipple );
 
-        // Ensure even order since we're designing a Type 1 filter
-        if(order % 2 == 1)
+//        order = 1001;
+
+        // Ensure odd order since we're designing a Type 2 filter
+        if(order % 2 == 0)
         {
             order++;
         }
@@ -62,10 +65,10 @@ public class PolyphaseChannelizerFilterFactory
             passBandStop, 1.0, passRipple, 1.0);
 
         //Use the filter order as the weighting for the pass band edge frequency
-        double weight = order;
+//        double weight = order;
 
         FIRFilterSpecification.FrequencyBand transitionBand = new FIRFilterSpecification.FrequencyBand(sampleRate,
-            channelBandwidth, channelBandwidth, OBJECTIVE_BAND_EDGE_COEFFICIENT_AMPLITUDE, passRipple, weight);
+            channelBandwidth, channelBandwidth, OBJECTIVE_BAND_EDGE_COEFFICIENT_AMPLITUDE, transitionRipple, 5.0);
 
         FIRFilterSpecification.FrequencyBand stopBand = new FIRFilterSpecification.FrequencyBand(sampleRate,
             stopBandStart, (int)(sampleRate / 2), 0.0, stopRipple);
@@ -91,13 +94,4 @@ public class PolyphaseChannelizerFilterFactory
 
         return filter;
     }
-
-    public static void main(String[] args)
-    {
-        mLog.debug("Starting ...");
-
-        float[] filter = getFilter(200000, 12500, 0.21);
-
-        mLog.debug("Finished ...");
-    }
 }