Change from showing amplitudes to showing coefficient length in frequ…

…ency response and db scale (amplitude is for showing percentage of overall amplitude for a specific frequency to the whole signal). Added normalize option (on by default) for filter impulse response
hybridmachine · Jan 5, 2020 · ac399f4 · ac399f4
1 parent a61ad11
commit ac399f4
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Showing 11 changed files with 68 additions and 34 deletions.
diff --git a/SignalProcessor/Filters/WindowedSyncFilter.cs b/SignalProcessor/Filters/WindowedSyncFilter.cs
@@ -31,7 +31,7 @@ public WindowedSyncFilter()
         /// Note this filter kernel assumes samples are normalized by the caller
         /// </summary>
         /// <returns></returns>
-        public virtual List<double> ImpulseResponse()
+        public virtual List<double> ImpulseResponse(bool normalize = true)
         {
             List<double> impulseResponse;
             impulseResponse = new List<double>(FilterLength + 1);
@@ -54,10 +54,13 @@ public virtual List<double> ImpulseResponse()
                 normalizationFactor += impulseResponse[impulseResponse.Count - 1];
             }
 
-            // Normalize for unity gain at DC
-            for (int idx = 0; idx < impulseResponse.Count; idx++)
+            if (normalize)
             {
-                impulseResponse[idx] = impulseResponse[idx] / normalizationFactor;
+                // Normalize for unity gain at DC
+                for (int idx = 0; idx < impulseResponse.Count; idx++)
+                {
+                    impulseResponse[idx] = impulseResponse[idx] / normalizationFactor;
+                }
             }
 
             // Spectral inversion

diff --git a/SignalProcessor/IWindowedSyncFilter.cs b/SignalProcessor/IWindowedSyncFilter.cs
@@ -9,6 +9,6 @@ public interface IWindowedSyncFilter
         double CutoffFrequencySamplingFrequencyPercentage { get; set; }
         int FilterLength { get; set; }
 
-        List<double> ImpulseResponse();
+        List<double> ImpulseResponse(bool normalize = true);
     }
 }
diff --git a/SignalProcessor/SignalProcessor.csproj b/SignalProcessor/SignalProcessor.csproj
@@ -3,12 +3,12 @@
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
-    <AssemblyVersion>0.1.12.0</AssemblyVersion>
-    <FileVersion>0.1.12.0</FileVersion>
-    <PackageReleaseNotes>Stop cacheing impulse response, calculate every time ImpulseResponse is called, to avoid issues with changed parameters and stale impulse response. Callers should call and cache the value when performance is an issue</PackageReleaseNotes>
+    <AssemblyVersion>0.1.14.0</AssemblyVersion>
+    <FileVersion>0.1.14.0</FileVersion>
+    <PackageReleaseNotes>Add option to turn on / off normalization (default to on) for WindowedSyncFilter</PackageReleaseNotes>
     <Copyright>2020 Brian Tabone</Copyright>
     <Description>Digital Signal Processing (FFT and Correlation)</Description>
-    <Version>0.1.12</Version>
+    <Version>0.1.14</Version>
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>SignalProcessor.pfx</AssemblyOriginatorKeyFile>
@@ -17,7 +17,7 @@
     <RepositoryUrl>https://github.com/hybridmachine/DSP</RepositoryUrl>
     <RepositoryType>git</RepositoryType>
     <PackageProjectUrl>https://github.com/hybridmachine/DSP/projects/1</PackageProjectUrl>
-    <PackageTags>signal processing fft analysis</PackageTags>
+    <PackageTags>signal processing fft analysis windowedsync</PackageTags>
   </PropertyGroup>
 
   <ItemGroup>

diff --git a/Signals And Transforms/Models/WorkBook.cs b/Signals And Transforms/Models/WorkBook.cs
@@ -74,7 +74,7 @@ public List<double> ConvolvedFilterImpulseResponse()
         /// Band reject
         /// </summary>
         /// <returns></returns>
-        public List<double> SummedFilterImpulseResponse()
+        public List<double> SummedFilterImpulseResponse(bool normalize = true)
         {
             List<double> summedImpulseResponse = null;
             foreach (var filter in Filters.Values.Where(filt => filt.IsActive))
@@ -86,11 +86,11 @@ public List<double> SummedFilterImpulseResponse()
                 // Page 274 chapter 14 of "The Scientist and Engineer's Guide to Digital Signal Processing"
                 if (null == summedImpulseResponse)
                 {
-                    summedImpulseResponse = filter.ImpulseResponse();
+                    summedImpulseResponse = filter.ImpulseResponse(normalize);
                 }
                 else
                 {
-                    List<double> filterImpulseResponse = filter.ImpulseResponse();
+                    List<double> filterImpulseResponse = filter.ImpulseResponse(normalize);
 
                     // Ignore any filters that don't have the same filter length
                     if (filterImpulseResponse.Count == summedImpulseResponse.Count)

diff --git a/Signals And Transforms/Properties/Resources.Designer.cs b/Signals And Transforms/Properties/Resources.Designer.cs
diff --git a/Signals And Transforms/Properties/Resources.resx b/Signals And Transforms/Properties/Resources.resx
@@ -147,6 +147,9 @@
   <data name="FILTER_CUTOFF_PERCENTAGE" xml:space="preserve">
     <value>Sampling Frequency Cutoff %</value>
   </data>
+  <data name="FILTER_DECIBEL_RESPONSE_TITLE" xml:space="preserve">
+    <value>Frequency Response (db)</value>
+  </data>
   <data name="FILTER_FREQUENCY_RESPONSE_TITLE" xml:space="preserve">
     <value>Frequency Response</value>
   </data>
@@ -159,6 +162,9 @@
   <data name="FILTER_NAME" xml:space="preserve">
     <value>Filter Name</value>
   </data>
+  <data name="FILTER_STEP_RESPONSE_TITLE" xml:space="preserve">
+    <value>Step Response</value>
+  </data>
   <data name="FILTER_TYPE_HIGH" xml:space="preserve">
     <value>High</value>
   </data>
@@ -214,9 +220,6 @@
   <data name="SIGNAL_PLOT_TITLE" xml:space="preserve">
     <value>Signal</value>
   </data>
-  <data name="STEP_RESPONSE_TITLE" xml:space="preserve">
-    <value>Step Response</value>
-  </data>
   <data name="WORKBOOK_FILE_EXTENSION" xml:space="preserve">
     <value>.stw</value>
   </data>

diff --git a/Signals And Transforms/SignalsAndTransforms.csproj b/Signals And Transforms/SignalsAndTransforms.csproj
@@ -83,8 +83,8 @@
       <HintPath>..\packages\OxyPlot.Wpf.2.0.0\lib\net45\OxyPlot.Wpf.dll</HintPath>
     </Reference>
     <Reference Include="ReachFramework" />
-    <Reference Include="SignalProcessor, Version=0.1.12.0, Culture=neutral, PublicKeyToken=9353e2f223b6035d, processorArchitecture=MSIL">
-      <HintPath>packages\SignalProcessor.0.1.12\lib\netstandard2.0\SignalProcessor.dll</HintPath>
+    <Reference Include="SignalProcessor, Version=0.1.14.0, Culture=neutral, PublicKeyToken=9353e2f223b6035d, processorArchitecture=MSIL">
+      <HintPath>packages\SignalProcessor.0.1.14\lib\netstandard2.0\SignalProcessor.dll</HintPath>
     </Reference>
     <Reference Include="SQLitePCLRaw.batteries_v2, Version=2.0.2.669, Culture=neutral, PublicKeyToken=8226ea5df37bcae9, processorArchitecture=MSIL">
       <HintPath>packages\SQLitePCLRaw.bundle_e_sqlite3.2.0.2\lib\net461\SQLitePCLRaw.batteries_v2.dll</HintPath>

diff --git a/Signals And Transforms/View Models/FilterViewModel.cs b/Signals And Transforms/View Models/FilterViewModel.cs
@@ -9,6 +9,7 @@
 using System.Collections.ObjectModel;
 using System.ComponentModel;
 using System.Linq;
+using System.Numerics;
 using System.Text;
 using System.Threading.Tasks;
 
@@ -31,6 +32,8 @@ public FilterViewModel()
 
         public IList<DataPoint> FrequencyResponsePoints { get; private set; }
 
+        public IList<DataPoint> DecibelResponsePoints { get; private set; }
+
         public IList<DataPoint> StepResponsePoints { get; private set; }
 
         public event PropertyChangedEventHandler PropertyChanged;
@@ -50,7 +53,7 @@ public void AddFilter(Filter newFilter)
         private List<double> GetStepData(int len)
         {
             List<double> stepData = new List<double>();
-            int pointsOn = len / 3; // point at which signal switches from 0 to 1
+            int pointsOn = len / 2; // point at which signal switches from 0 to 1
 
             for (int idx = 0; idx < len; idx++)
             {
@@ -61,7 +64,7 @@ private List<double> GetStepData(int len)
 
         private void LoadFilterData()
         {
-            List<double> summedFilterData = manager.ActiveWorkBook().SummedFilterImpulseResponse();
+            List<double> summedFilterData = manager.ActiveWorkBook().SummedFilterImpulseResponse(true);
             if (summedFilterData == null || summedFilterData.Count == 0)
             {
                 return;
@@ -82,12 +85,17 @@ private void LoadFilterData()
             Convolution convolver = new Convolution();
             List<double> stepResponse = convolver.Convolve(summedFilterData, GetStepData(summedFilterData.Count + 16), ConvolutionType.INPUTSIDE);
             FrequencyResponsePoints = new List<DataPoint>(frequencyDomain.FrequencyAmplitudes.Count);
+            DecibelResponsePoints = new List<DataPoint>(FrequencyResponsePoints.Count);
 
             // Load the frequency response graph data
-            List<double> values = new List<double>(frequencyDomain.FrequencyAmplitudes.Values);
-            for (int idx = 0; idx < frequencyDomain.FrequencyAmplitudes.Count; idx++)
+            // Only scan the first half of the coefficients (up to the Nyquist frequency)
+            int coefficientMax = (frequencyDomain.FourierCoefficients.Count / 2);
+            for (int idx = 0; idx < coefficientMax; idx++)
             {
-                FrequencyResponsePoints.Add(new DataPoint((((double)idx + 1.0) / summedFilterData.Count), values[idx]));
+                double coeffLen = Complex.Abs(frequencyDomain.FourierCoefficients[idx]);
+                double cuttoffFrequencyPercent = (((double)idx + 1.0) / summedFilterData.Count);
+                FrequencyResponsePoints.Add(new DataPoint(cuttoffFrequencyPercent, coeffLen));
+                DecibelResponsePoints.Add(new DataPoint(cuttoffFrequencyPercent, 20 * Math.Log10(coeffLen)));
             }
 
             int startingOffset = (summedFilterData.Count / 2);
@@ -111,6 +119,7 @@ private void LoadFilterData()
 
             NotifyPropertyChanged(nameof(ImpulseResponsePoints));
             NotifyPropertyChanged(nameof(FrequencyResponsePoints));
+            NotifyPropertyChanged(nameof(DecibelResponsePoints));
             NotifyPropertyChanged(nameof(StepResponsePoints));
             NotifyPropertyChanged(nameof(Filters));
         }

diff --git a/Signals And Transforms/Views/FilterView.xaml b/Signals And Transforms/Views/FilterView.xaml
@@ -78,14 +78,22 @@
                                     MarkerType="Square"/>
                 </oxy:Plot.Series>
             </oxy:Plot>
-            <oxy:Plot x:Name="StepResponsePlot" Grid.Column="0" Grid.Row="1" Margin="5" Title="{x:Static res:Resources.STEP_RESPONSE_TITLE}">
+            <oxy:Plot x:Name="StepResponsePlot" Grid.Column="0" Grid.Row="1" Margin="5" Title="{x:Static res:Resources.FILTER_STEP_RESPONSE_TITLE}">
                 <oxy:Plot.Series>
                     <oxy:LineSeries ItemsSource="{Binding StepResponsePoints}"
                                     Color="Cyan" 
                                     MarkerFill="SteelBlue" 
                                     MarkerType="Square"/>
                 </oxy:Plot.Series>
             </oxy:Plot>
+            <oxy:Plot x:Name="DecibelResponsePlot" Grid.Column="1" Grid.Row="1" Margin="5" Title="{x:Static res:Resources.FILTER_DECIBEL_RESPONSE_TITLE}">
+                <oxy:Plot.Series>
+                    <oxy:LineSeries ItemsSource="{Binding DecibelResponsePoints}"
+                                    Color="Cyan" 
+                                    MarkerFill="SteelBlue" 
+                                    MarkerType="Square"/>
+                </oxy:Plot.Series>
+            </oxy:Plot>
         </Grid>
     </Grid>
 </UserControl>
diff --git a/Signals And Transforms/packages.config b/Signals And Transforms/packages.config
@@ -10,7 +10,7 @@
   <package id="Microsoft.NetFramework.Analyzers" version="2.9.8" targetFramework="net472" developmentDependency="true" />
   <package id="OxyPlot.Core" version="2.0.0" targetFramework="net472" />
   <package id="OxyPlot.Wpf" version="2.0.0" targetFramework="net472" />
-  <package id="SignalProcessor" version="0.1.12" targetFramework="net472" />
+  <package id="SignalProcessor" version="0.1.14" targetFramework="net472" />
   <package id="SQLitePCLRaw.bundle_e_sqlite3" version="2.0.2" targetFramework="net472" />
   <package id="SQLitePCLRaw.core" version="2.0.2" targetFramework="net472" />
   <package id="SQLitePCLRaw.lib.e_sqlite3" version="2.0.2" targetFramework="net472" />

diff --git a/UnitTests/WindowedSyncFilterTest.cs b/UnitTests/WindowedSyncFilterTest.cs
@@ -26,6 +26,7 @@ public void LowPassWindowedSyncTest()
 
             List<double> impulseResponse = filter.ImpulseResponse();
             List<double> secondImpulseResponseTest = filter.ImpulseResponse();
+            List<double> non_normalizedResponseTest = filter.ImpulseResponse(false);
 
             // Make sure back to back calls return the same data for the same parameters
             for (int idx = 0; idx < impulseResponse.Count; idx++)
@@ -37,6 +38,7 @@ public void LowPassWindowedSyncTest()
 
             Assert.IsNotNull(impulseResponse);
             Assert.IsNotNull(highImpulseResponse);
+            Assert.IsNotNull(non_normalizedResponseTest);
 
             Assert.IsTrue(impulseResponse.Count == filter.FilterLength + 1);
         }