Теперь ComboBox показывает все существующие элементы из коллекции, а при выборе элемента отображается настройка элементов DataGrid. Плюс сверху накинул много рефактора для большей гибкости при добавлении новых классов сигналов.

Signal Generator/AddSignalWindow.xaml

@@ -18,11 +18,13 @@
         </Grid.ColumnDefinitions>
 
         <TextBlock x:Name="signalType_TextBlock" Margin="0,0,10,5" Grid.Row="0" Grid.Column="0">Тип сигнала:</TextBlock>
-        <ComboBox x:Name="signalType_ComboBox" Margin="0,0,0,5" HorizontalAlignment="Stretch"  Grid.Row="0" Grid.Column="1"/>
-        <DataGrid x:Name="signalProps_DataGrid" Margin="0,0,0,5" HorizontalAlignment="Stretch" Grid.Row="1" Grid.ColumnSpan="2">
+        <ComboBox x:Name="signalType_ComboBox" Margin="0,0,0,5" HorizontalAlignment="Stretch"  Grid.Row="0" Grid.Column="1"
+                  ItemsSource="{Binding}" DisplayMemberPath="typeToString" SelectionChanged="signalType_ComboBox_SelectionChanged"/>
+        <DataGrid x:Name="signalProps_DataGrid" Margin="0,0,0,5" HorizontalAlignment="Stretch" Grid.Row="1" Grid.ColumnSpan="2"
+                  ItemsSource="{Binding}" AutoGenerateColumns="False">
             <DataGrid.Columns>
-                <DataGridTextColumn Header="Название" Width="*" IsReadOnly="True"/>
-                <DataGridTextColumn Header="Параметр" />
+                <DataGridTextColumn Header="Название параметра" Width="*" IsReadOnly="True" Binding="{Binding Path=name}"/>
+                <DataGridTextColumn Header="Значение параметра"  Binding="{Binding Path=value}"/>
             </DataGrid.Columns>
         </DataGrid>
         <Button x:Name="createItem_Button" Height="20" Width="120" Content="Создать элемент" Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="2"/>

Signal Generator/AddSignalWindow.xaml.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
@@ -19,9 +20,19 @@ namespace Signal_Generator
     /// </summary>
     public partial class AddSignalWindow : Window
     {
+        ObservableCollection<Parameter> signalProps = new ObservableCollection<Parameter>();
         public AddSignalWindow()
         {
             InitializeComponent();
+            signalProps_DataGrid.ItemsSource = signalProps;
+        }
+
+        private void signalType_ComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
+        {
+            signalProps.Clear();
+            var dict = ((IAnalogSignal)signalType_ComboBox.SelectedItem).paramsCollection as Collection<Parameter>;
+            foreach (Parameter p in dict)
+                signalProps.Add(p);
         }
     }
 }

Signal Generator/AnalogSignalMethods.cs

@@ -0,0 +1,20 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Signal_Generator
+{
+    class AnalogSignalMethods
+    {
+        internal string paramsToString(Collection<Parameter> paramsCollection)
+        {
+            string result = "";
+            foreach (Parameter p in paramsCollection)
+                result += " / " + p.name + " " + p.value;
+            return result;
+        }
+    }
+}

Signal Generator/FmSignal.cs

@@ -1,45 +1,38 @@
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 
 namespace Signal_Generator
 {
-    class FmSignal : IAnalogSignal
+    class FmSignal : AnalogSignalMethods, IAnalogSignal
     {
-        public Dictionary<string, double> paramsDict { get; set; }
+        public Collection<Parameter> paramsCollection { get; set; }
 
         public string typeToString
         {
-            get
-            {
-                return "FM сигнал";
-            }
+            get { return "FM сигнал"; }
         }
 
-        public string paramsToString
+        public new string paramsToString
         {
-            get
-            {
-                string result = "";
-                foreach (KeyValuePair<string, double> pair in paramsDict)
-                    result += " / " + pair.Key + " " + pair.Value;
-                return result;
-            }
+            get { return paramsToString(paramsCollection); }
         }
 
         public FmSignal(double ampl, double freq, double ampl2)
         {
-            paramsDict = new Dictionary<string, double>();
-            paramsDict.Add("Амплитуда несущей", ampl);
-            paramsDict.Add("Частота несущей", freq);
-            paramsDict.Add("Амплитуда", ampl);
+            paramsCollection = new Collection<Parameter>();
+            paramsCollection.Add(new Parameter("Амплитуда несущей", ampl));
+            paramsCollection.Add(new Parameter("Частота несущей", freq));
+            paramsCollection.Add(new Parameter("Амплитуда", ampl2));
         }
         
         public double currentAmplitude(double t)
         {
-            return paramsDict.ElementAt(0).Value * Math.Sin(2 * Math.PI * paramsDict.ElementAt(1).Value * t + paramsDict.ElementAt(1).Value * Math.Sin(t));
+            var c = paramsCollection.ToArray<Parameter>();
+            return c[0].value * Math.Sin(2 * Math.PI * c[1].value* t + c[2].value * Math.Sin(t));
         }
     }
 }

Signal Generator/IAnalogSignal.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
@@ -11,6 +12,6 @@ namespace Signal_Generator
         string typeToString { get; }
         string paramsToString { get; }
         double currentAmplitude(double t);
-        Dictionary<String, Double> paramsDict { get; set; }
+        Collection<Parameter> paramsCollection { get; set; }
     }
 }

Signal Generator/MainWindow.xaml.cs

@@ -24,10 +24,16 @@ namespace Signal_Generator
         AddSignalWindow addSignalWindow_Instance = new AddSignalWindow();
         TaskWindow taskWindow_Instance = new TaskWindow();
         ObservableCollection<IAnalogSignal> s;
+        ObservableCollection<IAnalogSignal> typesOfSignal = new ObservableCollection<IAnalogSignal>();
 
         public MainWindow()
         {
             InitializeComponent();
+
+            typesOfSignal.Add(new SinusoidalSignal(0, 0));
+            typesOfSignal.Add(new FmSignal(0, 0, 0));
+            addSignalWindow_Instance.signalType_ComboBox.ItemsSource = typesOfSignal;
+
             s = new ObservableCollection<IAnalogSignal>();
             signals_ListBox.Items.Clear();
             signals_ListBox.ItemsSource = s;
@@ -42,7 +48,6 @@ namespace Signal_Generator
         {
             SinusoidalSignal s1 = new SinusoidalSignal(1, 50);
             s.Add(s1);
-            signals_ListBox.UpdateLayout();
         }
   
 

Signal Generator/MultiSignal.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
@@ -16,7 +17,9 @@ namespace Signal_Generator
 
         string IAnalogSignal.paramsToString => throw new NotImplementedException();
 
-        Dictionary<string, double> IAnalogSignal.paramsDict { get => throw new NotImplementedException(); set => throw new NotImplementedException(); }
+        string IAnalogSignal.typeToString => throw new NotImplementedException();
+
+        Collection<Parameter> IAnalogSignal.paramsCollection { get => throw new NotImplementedException(); set => throw new NotImplementedException(); }
 
         public MultiSignal()
         {
@@ -42,5 +45,10 @@ namespace Signal_Generator
             }
             return summaryAmplitude;
         }
+
+        double IAnalogSignal.currentAmplitude(double t)
+        {
+            throw new NotImplementedException();
+        }
     }
 }

Signal Generator/Parameter.cs

@@ -0,0 +1,20 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Signal_Generator
+{
+    class Parameter
+    {
+        public string name { get; set; }
+        public double value { get; set; }
+
+        public Parameter (string name, double value)
+        {
+            this.name = name;
+            this.value = value;
+        }
+    }
+}

Signal Generator/Signal Generator.csproj

@@ -58,8 +58,10 @@
     <Compile Include="AddSignalWindow.xaml.cs">
       <DependentUpon>AddSignalWindow.xaml</DependentUpon>
     </Compile>
+    <Compile Include="AnalogSignalMethods.cs" />
     <Compile Include="FmSignal.cs" />
     <Compile Include="Settings.cs" />
+    <Compile Include="Parameter.cs" />
     <Compile Include="SinusoidalSignal.cs" />
     <Compile Include="TaskWindow.xaml.cs">
       <DependentUpon>TaskWindow.xaml</DependentUpon>

Signal Generator/SinusoidalSignal.cs

@@ -1,50 +1,38 @@
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 
 namespace Signal_Generator
 {
-    class SinusoidalSignal : IAnalogSignal
+    class SinusoidalSignal : AnalogSignalMethods, IAnalogSignal
     {
         public string typeToString
         {
-            get
-            {
-                return "SIN сигнал";
-            }
+            get { return "SIN сигнал"; }
         }
 
-        public string paramsToString
+        public new string paramsToString
         {
-            get
-            {
-                string result = "";
-                foreach (KeyValuePair<string, double> pair in paramsDict)
-                    result += " / " + pair.Key + " " + pair.Value;
-                return result;
-            }
+            get { return paramsToString(paramsCollection); }
         }
 
-        public Dictionary<String, Double> paramsDict { get; set; }
-
-        public override string ToString()
-        {
-            return "SIN signal";
-        }
+        public Collection<Parameter> paramsCollection { get; set; }
 
         public SinusoidalSignal(double ampl, double freq, double phase = 0)
         {
-            paramsDict = new Dictionary<string, double>();
-            paramsDict.Add("Амплитуда", ampl);
-            paramsDict.Add("Частота", freq);
-            paramsDict.Add("Фаза", phase);
+            paramsCollection = new Collection<Parameter>();
+            paramsCollection.Add(new Parameter("Амплитуда", ampl));
+            paramsCollection.Add(new Parameter("Частота", freq));
+            paramsCollection.Add(new Parameter("Фаза", phase));
         }
 
         public double currentAmplitude(double t)
         {
-            return paramsDict.ElementAt(0).Value * Math.Sin(2 * Math.PI * paramsDict.ElementAt(1).Value * t + paramsDict.ElementAt(2).Value);
+            var c = paramsCollection.ToArray<Parameter>();
+            return c[0].value * Math.Sin(2 * Math.PI * c[1].value * t + c[2].value);
         }
     }
 }