spectrumanalyser.java

用java 写的 Spectrum Analyser频谱分析

/*
 * @(#)SpectrumAnalyser.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.
 *
 */
package SpectrumAnalyser;
import java.awt.*;
import java.applet.Applet;

public class SpectrumAnalyser extends Applet {

    float[] signal;
    float[] spectrum;
    static float ampl = 1.0f;     // default amplitude = 1.0 V
    static float rate = 8000.0f;  // default sampling rate = 8000 samples/s
    int nSamples;
    GraphPlot plotSignal, plotSpectrum;
    Choice chWaveform, chSamples;
    TextField tfFreq, tfDCLevel, tfNoise;
    Checkbox cbAddDCLevel, cbAddNoise;
    Button btnSignal, btnSpectrum;
    //Label lblcopy = new Label("             华南理工大学电子信息学院");

    void buildConstraints(GridBagConstraints gbc, int gx, int gy,
                            int gw, int gh, int wx, int wy) {
        gbc.gridx = gx;
        gbc.gridy = gy;
        gbc.gridwidth = gw;
        gbc.gridheight = gh;
        gbc.weightx = wx;
        gbc.weighty = wy;
    }


   public void init() {

        GridBagLayout gb = new GridBagLayout();
        GridBagConstraints gbc = new GridBagConstraints();
        setLayout(gb);
        plotSignal = new GraphPlot();
        plotSpectrum = new GraphPlot();
        // Signal plot
        buildConstraints(gbc, 0, 0, 1, 1, 1, 45);
        gbc.fill = GridBagConstraints.BOTH;
        gb.setConstraints(plotSignal, gbc);
        add(plotSignal);

        // Spectrum plot
        buildConstraints(gbc, 0, 1, 1, 1, 0, 45);
        gbc.fill = GridBagConstraints.BOTH;
        gb.setConstraints(plotSpectrum, gbc);
        add(plotSpectrum);

        // Control panel
        buildConstraints(gbc, 0, 2, 1, 1, 0, 10);
        gbc.fill = GridBagConstraints.BOTH;
        Panel pnlControls = new Panel();
        gb.setConstraints(pnlControls, gbc);
        add(pnlControls);
        pnlControls.setLayout(new GridLayout(3, 2));

        // Waveform selection
        Panel pnlWaveform = new Panel();
        pnlWaveform.setLayout(new FlowLayout(FlowLayout.LEFT));
        Label lblWaveform = new Label("Waveform");
        chWaveform = new Choice();
	    chWaveform.addItem("Sine");
	    chWaveform.addItem("Cosine");
	    chWaveform.addItem("Square");
	    chWaveform.addItem("Triangular");
	    chWaveform.addItem("Sawtooth");
	    chWaveform.select("Sine");        // default waveform
        pnlWaveform.add(lblWaveform);
        pnlWaveform.add(chWaveform);
        pnlControls.add(pnlWaveform);

        // Added DC level setting
        Panel pnlAddDCLevel = new Panel();
        pnlAddDCLevel.setLayout(new FlowLayout(FlowLayout.LEFT));
        cbAddDCLevel = new Checkbox("Add DC level");
        tfDCLevel = new TextField("0", 5);
        Label lblDCLevelUnit = new Label("V");
        pnlAddDCLevel.add(cbAddDCLevel);
        pnlAddDCLevel.add(tfDCLevel);
        pnlAddDCLevel.add(lblDCLevelUnit);
        pnlControls.add(pnlAddDCLevel);

        // Signal frequency setting
        Panel pnlFrequency = new Panel();
        pnlFrequency.setLayout(new FlowLayout(FlowLayout.LEFT));
        Label lblFreq = new Label("Frequency");
        tfFreq = new TextField("1000", 8);
        Label lblFreqUnit = new Label("Hz");
        pnlFrequency.add(lblFreq);
        pnlFrequency.add(tfFreq);
        pnlFrequency.add(lblFreqUnit);
        pnlControls.add(pnlFrequency);

        // Added random noise setting
        Panel pnlAddNoise = new Panel();
        pnlAddNoise.setLayout(new FlowLayout(FlowLayout.LEFT));
        cbAddNoise = new Checkbox("Add random noise");
        tfNoise = new TextField("0", 5);
        Label lblNoiseUnit = new Label("V");
        pnlAddNoise.add(cbAddNoise);
        pnlAddNoise.add(tfNoise);
        pnlAddNoise.add(lblNoiseUnit);
        pnlControls.add(pnlAddNoise);

        // Number of samples
        Panel pnlSamples = new Panel();
        pnlSamples.setLayout(new FlowLayout(FlowLayout.LEFT));
        Label lblSamples = new Label("Number of samples");
        chSamples = new Choice();
        chSamples.addItem("32");
        chSamples.addItem("64");
        chSamples.addItem("128");
        chSamples.addItem("256");
        chSamples.addItem("512");
        chSamples.select("256");
        pnlSamples.add(lblSamples);
        pnlSamples.add(chSamples);
        pnlControls.add(pnlSamples);

        Panel pnlButtons = new Panel();
        btnSignal = new Button("Plot signal");
        btnSpectrum = new Button("Spectrum");
        btnSpectrum.disable();  // can't show spectrum until signal generated
        pnlButtons.setLayout(new FlowLayout(FlowLayout.LEFT));
        pnlButtons.add(btnSignal);
        pnlButtons.add(btnSpectrum);
        pnlControls.add(pnlButtons);
    }
/*
    public void init() {

        GridBagLayout gb = new GridBagLayout();
        GridBagConstraints gbc = new GridBagConstraints();
        setLayout(gb);
        plotSignal = new GraphPlot();
        plotSpectrum = new GraphPlot();
        // Signal plot
        buildConstraints(gbc, 0, 0, 1, 1, 1, 45);
        gbc.fill = GridBagConstraints.BOTH;
        gb.setConstraints(plotSignal, gbc);
        add(plotSignal);

        // Spectrum plot
        buildConstraints(gbc, 0, 1, 1, 1, 0, 45);
        gbc.fill = GridBagConstraints.BOTH;
        gb.setConstraints(plotSpectrum, gbc);
        add(plotSpectrum);

        // Control panel
        buildConstraints(gbc, 0, 2, 1, 1, 0, 10);
        gbc.fill = GridBagConstraints.BOTH;
        Panel pnlControls = new Panel();
        gb.setConstraints(pnlControls, gbc);
        add(pnlControls);
        pnlControls.setLayout(new GridLayout(3, 2));

        // Waveform selection
        Panel pnlWaveform = new Panel();
        pnlWaveform.setLayout(new FlowLayout(FlowLayout.LEFT));
        Label lblWaveform = new Label("波形");
        chWaveform = new Choice();
	    chWaveform.addItem("正弦");
	    chWaveform.addItem("余弦");
	    chWaveform.addItem("方波");
	    chWaveform.addItem("三角波");
	    chWaveform.addItem("锯齿波");
	    chWaveform.select("正弦");        // default waveform
        pnlWaveform.add(lblWaveform);
        pnlWaveform.add(chWaveform);
        pnlControls.add(pnlWaveform);

        // Added DC level setting
        Panel pnlAddDCLevel = new Panel();
        pnlAddDCLevel.setLayout(new FlowLayout(FlowLayout.LEFT));
        cbAddDCLevel = new Checkbox("加入直流电平");
        tfDCLevel = new TextField("0", 5);
        Label lblDCLevelUnit = new Label("V");
        pnlAddDCLevel.add(cbAddDCLevel);
        pnlAddDCLevel.add(tfDCLevel);
        pnlAddDCLevel.add(lblDCLevelUnit);
        pnlControls.add(pnlAddDCLevel);

        // Signal frequency setting
        Panel pnlFrequency = new Panel();
        pnlFrequency.setLayout(new FlowLayout(FlowLayout.LEFT));
        Label lblFreq = new Label("频率");
        tfFreq = new TextField("1000", 8);
        Label lblFreqUnit = new Label("Hz");
        pnlFrequency.add(lblFreq);
        pnlFrequency.add(tfFreq);
        pnlFrequency.add(lblFreqUnit);
        pnlControls.add(pnlFrequency);

        // Added random noise setting
        Panel pnlAddNoise = new Panel();
        pnlAddNoise.setLayout(new FlowLayout(FlowLayout.LEFT));
        cbAddNoise = new Checkbox("加入随机噪声");
        tfNoise = new TextField("0", 5);
        Label lblNoiseUnit = new Label("V");
        pnlAddNoise.add(cbAddNoise);
        pnlAddNoise.add(tfNoise);
        pnlAddNoise.add(lblNoiseUnit);
        pnlControls.add(pnlAddNoise);

        // Number of samples
        Panel pnlSamples = new Panel();
        pnlSamples.setLayout(new FlowLayout(FlowLayout.LEFT));
        Label lblSamples = new Label("样本数");
        chSamples = new Choice();
        chSamples.addItem("32");
        chSamples.addItem("64");
        chSamples.addItem("128");
        chSamples.addItem("256");
        chSamples.addItem("512");
        chSamples.select("256");
        pnlSamples.add(lblSamples);
        pnlSamples.add(chSamples);
        pnlControls.add(pnlSamples);

        Panel pnlButtons = new Panel();
        btnSignal = new Button("显示信号");
        btnSpectrum = new Button("频谱");
        btnSpectrum.disable();  // can't show spectrum until signal generated
        pnlButtons.setLayout(new FlowLayout(FlowLayout.LEFT));
        pnlButtons.add(btnSignal);
        pnlButtons.add(btnSpectrum);
        pnlControls.add(pnlButtons);
        //pnlControls.add(lblcopy);
    }
*/
    public boolean action(Event evt, Object obj) {
        if (evt.target == btnSignal) {
            nSamples = Integer.parseInt(chSamples.getSelectedItem());
            signal = new float[nSamples];
            SignalGenerator sg = new SignalGenerator();
            sg.setWaveform(chWaveform.getSelectedItem());
            sg.setAmplitude(ampl);
            sg.setSamplingRate(rate);
            sg.setFrequency(Float.valueOf(tfFreq.getText()).floatValue());
            sg.setSamples(nSamples);
            boolean addDC = cbAddDCLevel.getState();
            sg.setDCLevelState(addDC);
            if (addDC) sg.setDCLevel(Float.valueOf(tfDCLevel.getText()).floatValue());
            boolean addNoise = cbAddNoise.getState();
            sg.setNoiseState(addNoise);
            if (addNoise) sg.setNoise(Float.valueOf(tfNoise.getText()).floatValue());
            signal = sg.generate();
            float maxValue = 0.0f;
            for (int i = 0; i < nSamples; i++)
                maxValue = Math.max(maxValue, Math.abs(signal[i]));
            plotSignal.setYmax(maxValue);
            plotSignal.setPlotValues(signal);
            btnSpectrum.enable();
            repaint();
            return true;
        }
        else
        if (evt.target == btnSpectrum) {
            spectrum = new float [nSamples / 2];
            FastFourierTransform fft = new FastFourierTransform();
            spectrum = fft.fftMag(signal);
            plotSpectrum.setPlotStyle(GraphPlot.SPECTRUM);
            plotSpectrum.setTracePlot(false);
            float maxValue = 0.0f;
            for (int i = 0; i < nSamples/2; i++)
                maxValue = Math.max(maxValue, Math.abs(spectrum[i]));
            plotSpectrum.setYmax(maxValue);
            plotSpectrum.setPlotValues(spectrum);
            btnSpectrum.disable();
            repaint();
            return true;
        }
        else
            return false;
    }

}