iirfilterdesign.java

用java 写的IIR 滤波器设计

package IIRFilterDesign;

/*
 * @(#)IIRFilterDesign.java 1.0 06/04/21
 *
 * You can modify the template of this file in the
 * directory ..\JCreator\Templates\Template_2\Project_Name.java
 *
 * You can also create your own project template by making a new
 * folder in the directory ..\JCreator\Template\. Use the other
 * templates as examples.
 *
 */

import java.awt.*;
import java.applet.*;

public class IIRFilterDesign extends Applet {

  float rate = 8000.0f;   // fixed sampling rate
  int freqPoints = 250;   // number of points in FR plot
  int maxOrder = 16;      // maximum filter order
  int order;
  String filterType, prototype;
  float[] gain = new float[freqPoints+1];
  IIRFilter filter = new IIRFilter();
  GraphPlot frPlot = new GraphPlot();
  PoleZeroPlot pzPlot = new PoleZeroPlot();
  BorderLayout borderLayout1 = new BorderLayout();
  BorderLayout borderLayout2 = new BorderLayout();
  BorderLayout borderLayout3 = new BorderLayout();
  BorderLayout borderLayout4 = new BorderLayout();
  FlowLayout flowLayout1 = new FlowLayout(FlowLayout.LEFT);
  FlowLayout flowLayout2 = new FlowLayout(FlowLayout.LEFT);
  FlowLayout flowLayout3 = new FlowLayout(FlowLayout.LEFT);
  FlowLayout flowLayout4 = new FlowLayout(FlowLayout.LEFT);
  FlowLayout flowLayout5 = new FlowLayout(FlowLayout.LEFT);
  FlowLayout flowLayout6 = new FlowLayout(FlowLayout.LEFT);
  FlowLayout flowLayout7 = new FlowLayout(FlowLayout.LEFT);
  FlowLayout flowLayout8 = new FlowLayout(FlowLayout.LEFT);
  GridLayout gridLayout1 = new GridLayout(1, 2);
  GridLayout gridLayout2 = new GridLayout(4, 1);
  GridLayout gridLayout3 = new GridLayout(4, 1);
  CardLayout cardLayout1 = new CardLayout();
  Panel pnlControls = new Panel();
  Panel pnlLeftPanel = new Panel();
  Panel pnlRightPanel = new Panel();
  Panel pnlFilterType = new Panel();
  Panel pnlPrototype = new Panel();
  Panel pnlOrder = new Panel();
  Panel pnlPassband = new Panel();
  Panel pnlRipple = new Panel();
  Panel pnlButtons1 = new Panel();
  Panel pnlMinGain = new Panel();
  Panel pnlDisplay = new Panel();
  Panel pnlPZPlot = new Panel();
  Panel pnlFRPlot = new Panel();
  Panel pnlButtons2 = new Panel();
  Panel pnlCoeffs = new Panel();
  Label lblFilterType = new Label();
  Label lblPrototype = new Label();
  Label lblOrder = new Label();
  Label lblPassband = new Label();
  Label lblTo = new Label();
  Label lblHz = new Label();
  Label lblRipple = new Label();
  Label lblRippleUnit = new Label();
  Label lblMinGain = new Label();
  Label lblMinGainUnit = new Label();
  Label lblMaxOrder = new Label();
  CheckboxGroup cbgFilterType = new CheckboxGroup();
  Checkbox cbLowPass = new Checkbox();
  Checkbox cbBandPass = new Checkbox();
  Checkbox cbHighPass = new Checkbox();
  CheckboxGroup cbgPrototype = new CheckboxGroup();
  Checkbox cbButterworth = new Checkbox();
  Checkbox cbChebyshev = new Checkbox();
  TextField tfOrder = new TextField("1", 3);
  TextField tfFreq1 = new TextField("0", 5);
  TextField tfFreq2 = new TextField("1000", 5);
  TextField tfRipple = new TextField("1.0", 3);
  Button btnResponse = new Button();
  Button btnDesign = new Button();
  Button btnCoeffs = new Button();
  Button btnPoleZero = new Button();
  Choice chMinGain = new Choice();
  TextArea txtCoeffs = new TextArea();
  Label lblcopy = new Label("(c)华南理工大学电子信息学院",Label.CENTER);

  //Construct the applet
  public IIRFilterDesign() {
  }

  //Initialize the applet
  public void init() {
    this.setLayout(borderLayout1);
    pnlDisplay.setLayout(cardLayout1);
    this.add("Center", pnlDisplay);
    pnlDisplay.add("PZPlot", pnlPZPlot);
    pnlDisplay.add("FRPlot", pnlFRPlot);
    pnlDisplay.add("Coeffs", pnlCoeffs);
    pnlCoeffs.setLayout(borderLayout4);
    pnlButtons2.setLayout(flowLayout8);
    pnlFRPlot.setLayout(borderLayout3);
    frPlot.setPlotStyle(GraphPlot.SPECTRUM);
    frPlot.setTracePlot(true);
    frPlot.setLogScale(true);
    frPlot.setBgColor(Color.lightGray);
    frPlot.setPlotColor(Color.blue);
    frPlot.setAxisColor(Color.darkGray);
    frPlot.setGridColor(Color.darkGray);
    pnlPZPlot.setLayout(borderLayout2);
    pnlPZPlot.add("Center", pzPlot);
    pnlFRPlot.add("Center", frPlot);
    pnlCoeffs.add("Center", txtCoeffs);
    this.add("North", pnlControls);
    this.add("South", lblcopy);
    Font f  = new Font("Dialog", 0, 11);
    lblFilterType.setFont(f);
    lblFilterType.setText("滤波器类型:");
    cbLowPass.setFont(f);
    cbLowPass.setLabel("低通");
    cbLowPass.setCheckboxGroup(cbgFilterType);
    cbBandPass.setFont(f);
    cbBandPass.setLabel("带通");
    cbBandPass.setCheckboxGroup(cbgFilterType);
    cbHighPass.setFont(f);
    cbHighPass.setLabel("高通");
    cbHighPass.setCheckboxGroup(cbgFilterType);
    cbLowPass.setState(true);
    lblPrototype.setFont(f);
    lblPrototype.setText("原型:");
    cbButterworth.setFont(f);
    cbButterworth.setLabel("巴特沃兹");
    cbButterworth.setCheckboxGroup(cbgPrototype);
    cbChebyshev.setFont(f);
    cbChebyshev.setLabel("切比雪夫");
    cbChebyshev.setCheckboxGroup(cbgPrototype);
    cbButterworth.setState(true);
    lblOrder.setFont(f);
    lblOrder.setText("滤波器阶数:");
    tfOrder.setFont(f);
    lblMaxOrder.setFont(new Font("Dialog", 2, 11));
    lblMaxOrder.setText("(max " + String.valueOf(maxOrder) + ")" );
    txtCoeffs.setText("滤波器系数\n\n");
    btnCoeffs.disable();
    btnCoeffs.setFont(f);
    btnCoeffs.setLabel("系数");
    lblPassband.setFont(f);
    lblPassband.setText("通带:");
    tfFreq1.setEditable(false);
    tfFreq1.setFont(f);
    lblTo.setFont(f);
    lblTo.setText("to");
    tfFreq2.setFont(f);
    lblHz.setFont(f);
    lblHz.setText("Hz");
    lblRipple.disable();
    lblRipple.setFont(f);
    lblRipple.setText("通带波纹:");
    tfRipple.disable();
    tfRipple.setFont(f);
    lblRippleUnit.disable();
    lblRippleUnit.setFont(f);
    lblRippleUnit.setText("dB");
    btnResponse.disable();
    btnResponse.setFont(f);
    btnResponse.setLabel("频率响应");
    btnDesign.setFont(f);
    btnDesign.setLabel("设计");
    lblMinGain.disable();
    lblMinGain.setFont(f);
    lblMinGain.setText("最小显示增益:");
    lblMinGainUnit.disable();
    lblMinGainUnit.setFont(f);
    lblMinGainUnit.setText("dB");
    btnPoleZero.setLabel("极点/零点");
    btnPoleZero.disable();
    btnPoleZero.setFont(f);
    chMinGain.addItem("-10");
    chMinGain.addItem("-50");
    chMinGain.addItem("-100");
    chMinGain.addItem("-200");
    chMinGain.select("-100");
    chMinGain.disable();
    chMinGain.setFont(f);
    pnlButtons1.setLayout(flowLayout7);
    pnlMinGain.setLayout(flowLayout6);
    pnlRipple.setLayout(flowLayout5);
    pnlPassband.setLayout(flowLayout4);
    pnlOrder.setLayout(flowLayout3);
    pnlPrototype.setLayout(flowLayout2);
    pnlFilterType.setLayout(flowLayout1);
    pnlRightPanel.setLayout(gridLayout3);
    pnlLeftPanel.setLayout(gridLayout2);
    pnlControls.setLayout(gridLayout1);
    pnlControls.add(pnlLeftPanel);
    pnlLeftPanel.add(pnlFilterType);
    pnlFilterType.add(lblFilterType);
    pnlFilterType.add(cbLowPass);
    pnlFilterType.add(cbBandPass);
    pnlFilterType.add(cbHighPass);
    pnlLeftPanel.add(pnlPrototype);
    pnlPrototype.add(lblPrototype);
    pnlPrototype.add(cbButterworth);
    pnlPrototype.add(cbChebyshev);
    pnlLeftPanel.add(pnlOrder);
    pnlOrder.add(lblOrder);
    pnlOrder.add(tfOrder);
    pnlOrder.add(lblMaxOrder);
    pnlLeftPanel.add(pnlPassband);
    pnlPassband.add(lblPassband);
    pnlPassband.add(tfFreq1);
    pnlPassband.add(lblTo);
    pnlPassband.add(tfFreq2);
    pnlPassband.add(lblHz);
    pnlControls.add(pnlRightPanel);
    pnlRightPanel.add(pnlRipple);
    pnlRipple.add(lblRipple);
    pnlRipple.add(tfRipple);
    pnlRipple.add(lblRippleUnit);
    pnlRightPanel.add(pnlMinGain);
    pnlMinGain.add(lblMinGain);
    pnlMinGain.add(chMinGain);
    pnlMinGain.add(lblMinGainUnit);
    pnlRightPanel.add(pnlButtons1);
    pnlButtons1.add(btnDesign);
    pnlButtons1.add(btnPoleZero);
    pnlRightPanel.add(pnlButtons2);
    pnlButtons2.add(btnResponse);
    pnlButtons2.add(btnCoeffs);
  }

  //Get Applet information
  public String getAppletInfo() {
    return "华南理工大学电子信息学院";
  }

  //Get parameter info
  public String[][] getParameterInfo() {
    return null;
  }

  private void setRippleState(boolean b) {
    if (b) {
      lblRipple.enable();
      tfRipple.enable();
      lblRippleUnit.enable();
    }
    else {
      lblRipple.disable();
      tfRipple.disable();
      lblRippleUnit.disable();
    }
  }

  private void setMinGainState(boolean b) {
    if (b) {
      lblMinGain.enable();
      chMinGain.enable();
      lblMinGainUnit.enable();
    }
    else {
      lblMinGain.disable();
      chMinGain.disable();
      lblMinGainUnit.disable();
    }
  }

  void designFilter() {
    order = Integer.parseInt(tfOrder.getText());
    if (order > maxOrder) {
      showStatus("滤波器阶数过高 (max. "
                   + String.valueOf(maxOrder) + ")");
    }
    else {
      filterType = cbgFilterType.getCurrent().getLabel();
      if ((filterType.equals("带通")) && ((order % 2) != 0)) {
        showStatus("对于带通滤波器，阶数必须为偶数");
      }
      else {
        filter.setFilterType(filterType);
        prototype = cbgPrototype.getCurrent().getLabel();
        filter.setPrototype(prototype);
        filter.setRate(rate);
        filter.setOrder(order);
        filter.setFreq1(Float.valueOf(tfFreq1.getText()).floatValue());
        filter.setFreq2(Float.valueOf(tfFreq2.getText()).floatValue());
        if (cbChebyshev.getState())
          filter.setRipple(Float.valueOf(tfRipple.getText()).floatValue());
        filter.design();
        btnResponse.enable();
        btnPoleZero.enable();
      }
    }
  }

  void plotResponse() {
    filter.setFreqPoints(freqPoints);
    gain = filter.filterGain();
    frPlot.setYmax(minPlotGain());
    frPlot.setPlotValues(gain);
    repaint();
    cardLayout1.show(pnlDisplay, "FRPlot");
  }

  void plotPolesAndZeros() {
    // pole and zero locations
    // NB poles and zeros have indices 1 .. order
    float[] pReal = new float[order + 1];
    float[] pImag = new float[order + 1];
    float[] z     = new float[order + 1];
    for (int i = 1; i <= order; i++) {
      pReal[i] = filter.getPReal(i);
      pImag[i] = filter.getPImag(i);
      z[i]     = filter.getZero(i);
    }
    pzPlot.setPolesAndZeros(pReal, pImag, z);
    repaint();
    cardLayout1.show(pnlDisplay, "PZPlot");
  }

  private float minPlotGain() {
    return Math.abs(Float.valueOf(chMinGain.getSelectedItem()).floatValue());
  }

  void listCoeffs() {
    txtCoeffs.setText(prototype + " IIR滤波器\n\n");
    txtCoeffs.appendText("滤波器类型: " + filterType + "\n");
    txtCoeffs.appendText("通带: " + tfFreq1.getText() + " - "
                                  + tfFreq2.getText() + " Hz\n");
    if (cbChebyshev.getState())
      txtCoeffs.appendText("通带波纹: " + tfRipple.getText() + " dB\n");
    txtCoeffs.appendText("阶数: " + String.valueOf(order) + "\n\n");
    txtCoeffs.appendText("系数\n\n");
    for (int i = 0; i <= order; i++)
      txtCoeffs.appendText("a[" + String.valueOf(i) + "] = "
                         + String.valueOf(filter.getACoeff(i))
                         + "     \tb[" + String.valueOf(i) + "] = "
                         + String.valueOf(filter.getBCoeff(i)) + "\n");
    cardLayout1.show(pnlDisplay, "Coeffs");
  }

  public boolean action(Event evt, Object arg) {
    if (evt.target instanceof Checkbox) {
      if (cbLowPass.getState()) {
        tfFreq1.setText("0");
        tfFreq1.setEditable(false);
        tfFreq2.setEditable(true);
        btnCoeffs.disable();
      }
      if (cbBandPass.getState()) {
        tfFreq1.setText("");
        tfFreq2.setText("");
        tfFreq1.setEditable(true);
        tfFreq2.setEditable(true);
        btnCoeffs.disable();
      }
      if (cbHighPass.getState()) {
        tfFreq1.setText("");
        tfFreq2.setText(String.valueOf(rate/2).toString());
        tfFreq1.setEditable(true);
        tfFreq2.setEditable(false);
        btnCoeffs.disable();
      }
      setRippleState(cbChebyshev.getState());
      btnResponse.disable();
      btnPoleZero.disable();
      return true;
    }

    if (evt.target == btnDesign) {
      designFilter();
      return true;
    }

    if (evt.target == btnPoleZero) {
      setMinGainState(false);
      plotPolesAndZeros();
      return true;
    }

    if (evt.target == btnResponse) {
      setMinGainState(true);
      plotResponse();
      btnCoeffs.enable();
      return true;
    }

    if (evt.target == btnCoeffs) {
      listCoeffs();
      return true;
    }

    if (evt.target == chMinGain) {
      if (btnResponse.isEnabled()) {
        plotResponse();
      }
      return true;
    }

    return false;
  }

  public boolean keyDown(Event evt, int key) {
    btnResponse.disable();
    btnPoleZero.disable();
    btnCoeffs.disable();
    return false;
  }

}