android – 使用Goertzel算法处理音频信号的结果

概述我做了一个小信号处理应用程序.它使用Goerztel算法处理特定频率的音频信号(莫尔斯码).应用程序将临时文件保存到文件系统,记录完成后,开始检测信号.现在我得到了一堆数量的结果. 我真的不知道从那些量级中读到什么.如何从这些量级解码摩尔斯电码？我怎么读它们？试图找到参考,但没有解释什么是结果以及如何阅读它. 编辑： 我的摩尔斯电码应用程序是用Delphi编写的,并使用Windows Beep函数 我做了一个小信号处理应用程序.它使用Goerztel算法处理特定频率的音频信号(莫尔斯码).应用程序将临时文件保存到文件系统,记录完成后,开始检测信号.现在我得到了一堆数量的结果.

我真的不知道从那些量级中读到什么.如何从这些量级解码摩尔斯电码？我怎么读它们？试图找到参考,但没有解释什么是结果以及如何阅读它.

编辑：

我的摩尔斯电码应用程序是用Delphi编写的,并使用Windows Beep函数以特定频率发送信号.我使用1200赫兹的信号.信号和单词之间也会暂停,莫尔斯的哔哔声就像维基百科所描述的那样.一切都准确.

Goertzel.java：

public class Goertzel {        private float samplingRate;        private float targetFrequency;        private int n;        private double coeff,Q1,Q2;        private double sine,cosine;        public Goertzel(float samplingRate,float targetFrequency,int inN) {            this.samplingRate = samplingRate;            this.targetFrequency = targetFrequency;            n = inN;            sine = Math.sin(2 * Math.PI * (targetFrequency / samplingRate));            cosine = Math.cos(2 * Math.PI * (targetFrequency / samplingRate));            coeff = 2 * cosine;        }        public voID resetGoertzel() {            Q1 = 0;            Q2 = 0;        }        public voID initGoertzel() {            int k;            float floatN;            double omega;            floatN = (float) n;            k = (int) (0.5 + ((floatN * targetFrequency) / samplingRate));            omega = (2.0 * Math.PI * k) / floatN;            sine = Math.sin(omega);            cosine = Math.cos(omega);            coeff = 2.0 * cosine;            resetGoertzel();        }        public voID processSample(double sample) {            double Q0;            Q0 = coeff * Q1 - Q2 + sample;            Q2 = Q1;            Q1 = Q0;        }        public double[] getRealimag(double[] parts) {            parts[0] = (Q1 - Q2 * cosine);            parts[1] = (Q2 * sine);            return parts;        }        public double getMagnitudeSquared() {            return (Q1 * Q1 + Q2 * Q2 - Q1 * Q2 * coeff);        }    }

SoundCompareActivity.java

import java.io.file;import java.io.fileNotFoundException;import java.io.fileOutputStream;import java.io.IOException;import androID.app.Activity;import androID.media.AudioFormat;import androID.media.AudioRecord;import androID.media.MediaRecorder;import androID.os.Bundle;import androID.util.Log;import androID.vIEw.VIEw;import androID.vIEw.VIEw.OnClickListener;import androID.Widget.button;    public class SoundCompareActivity extends Activity {        private static final int RECORDER_SAMPLE_RATE = 8000; // at least 2 times                                                                // higher than sound                                                                // frequency,private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_CONfigURATION_MONO;        private static final int RECORDER_AUdio_ENCoding = AudioFormat.ENCoding_PCM_16BIT;        private AudioRecord recorder = null;        private int bufferSize = 0;        private Thread recordingThread = null;        private boolean isRecording = false;        private button startRecBtn;        private button stopRecBtn;        /** Called when the activity is first created. */        @OverrIDe        public voID onCreate(Bundle savedInstanceState) {            super.onCreate(savedInstanceState);            setContentVIEw(R.layout.main);            startRecBtn = (button) findVIEwByID(R.ID.button1);            stopRecBtn = (button) findVIEwByID(R.ID.button2);            startRecBtn.setEnabled(true);            stopRecBtn.setEnabled(false);            bufferSize = AudioRecord.getMinBufferSize(RECORDER_SAMPLE_RATE,RECORDER_CHANNELS,RECORDER_AUdio_ENCoding);            startRecBtn.setonClickListener(new OnClickListener() {                @OverrIDe                public voID onClick(VIEw v) {                    Log.d("SOUNDCOMPARE","Start Recording");                    startRecBtn.setEnabled(false);                    stopRecBtn.setEnabled(true);                    stopRecBtn.requestFocus();                    startRecording();                }            });            stopRecBtn.setonClickListener(new OnClickListener() {                @OverrIDe                public voID onClick(VIEw v) {                    Log.d("SOUNDCOMPARE","Stop recording");                    startRecBtn.setEnabled(true);                    stopRecBtn.setEnabled(false);                    startRecBtn.requestFocus();                    stopRecording();                }            });        }        private voID startRecording() {            recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,RECORDER_SAMPLE_RATE,RECORDER_AUdio_ENCoding,bufferSize);            recorder.startRecording();            isRecording = true;            recordingThread = new Thread(new Runnable() {                @OverrIDe                public voID run() {                    writeAudioDataToTempfile();                }            },"AudioRecorder Thread");            recordingThread.start();        }        private String getTempfilename() {            file file = new file(getfilesDir(),"tempaudio");            if (!file.exists()) {                file.mkdirs();            }            file tempfile = new file(getfilesDir(),"signal.raw");            if (tempfile.exists())                tempfile.delete();            return (file.getabsolutePath() + "/" + "signal.raw");        }        private voID writeAudioDataToTempfile() {            byte data[] = new byte[bufferSize];            String filename = getTempfilename();            fileOutputStream os = null;            try {                os = new fileOutputStream(filename);            } catch (fileNotFoundException e) {                e.printstacktrace();            }            int read = 0;            if (os != null) {                while (isRecording) {                    read = recorder.read(data,bufferSize);                    if (read != AudioRecord.ERROR_INVALID_OPERATION) {                        try {                            os.write(data);                        } catch (IOException e) {                            e.printstacktrace();                        }                    }                }                try {                    os.close();                } catch (IOException e) {                    e.printstacktrace();                }            }        }        private voID deleteTempfile() {            file file = new file(getTempfilename());            file.delete();        }        private voID stopRecording() {            if (recorder != null) {                isRecording = false;                recorder.stop();                recorder.release();                recorder = null;                recordingThread = null;            }            new MorseDecoder().execute(new file(getTempfilename()));            }    }

MorseDecoder.java：

import java.io.file;import java.io.fileinputStream;import java.io.fileNotFoundException;import java.io.IOException;import java.nio.ByteBuffer;import java.nio.ByteOrder;import java.nio.ShortBuffer;import androID.media.AudioFormat;import androID.media.AudioRecord;import androID.os.AsyncTask;import androID.util.Log;public class MorseDecoder extends AsyncTask<file,VoID,VoID> {    private fileinputStream is = null;    @OverrIDe    protected VoID doInBackground(file... files) {        int index;        //double magnitudeSquared;         double magnitude;         int bufferSize = AudioRecord.getMinBufferSize(8000,AudioFormat.CHANNEL_CONfigURATION_MONO,AudioFormat.ENCoding_PCM_16BIT);        Goertzel g = new Goertzel(8000,1200,bufferSize);        g.initGoertzel();        for (int i = 0; i < files.length; i++) {            byte[] data = new byte[bufferSize];            try {                is = new fileinputStream(files[i]);                while(is.read(data) != -1) {                    ShortBuffer sbuf = ByteBuffer.wrap(data).order(ByteOrder.liTTLE_ENDIAN).asShortBuffer();                    short[] audioShorts = new short[sbuf.capacity()];                    sbuf.get(audioShorts);                    float[] audiofloats = new float[audioShorts.length];                    for (int j = 0; j < audioShorts.length; j++) {                        audiofloats[j] = ((float)audioShorts[j]) / 0x8000;                    }                    for (index = 0; index < audiofloats.length; index++) {                         g.processSample(data[index]);                     }                    magnitude = Math.sqrt(g.getMagnitudeSquared());                    Log.d("SoundCompare","relative magnitude = " + magnitude);                    g.resetGoertzel();                }                is.close();            } catch (fileNotFoundException e) {                e.printstacktrace();            } catch (IOException e) {                e.printstacktrace();            }        }        return null;    }}

EDIT2：

注意处理样本中的一些错误.在while循环中更改了代码.

while(is.read(data) != -1) {                    ShortBuffer sbuf = ByteBuffer.wrap(data).order(ByteOrder.liTTLE_ENDIAN).asShortBuffer();                    short[] audioShorts = new short[sbuf.capacity()];                    sbuf.get(audioShorts);                    float[] audiofloats = new float[audioShorts.length];                    for (int j = 0; j < audioShorts.length; j++) {                        audiofloats[j] = ((float)audioShorts[j]) / 0x8000;                    }                    for (index = 0; index < audiofloats.length; index++) {                         g.processSample(audiofloats[index]);                         magnitude = Math.sqrt(g.getMagnitudeSquared());                        Log.d("SoundCompare","relative magnitude = " + magnitude);                    }                    //magnitude = Math.sqrt(g.getMagnitudeSquared());                    //Log.d("SoundCompare","relative magnitude = " + magnitude);                    g.resetGoertzel();                }

问候,
恶者

解决方法 当存在通带内的音调时,Goertzel filter的输出将增加,然后在移除音调时减小.为了检测音调的脉冲,例如,莫尔斯码,你需要在滤波器的输出上使用某种阈值检测器,它将逐个样本地给出“音调存在”/“音调不存在”的布尔值.尝试绘制输出值,一旦你以图形形式看到它就应该很明显. 总结

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