在Android studio中编写一个用听筒发射频率从16kHz-22kHz线性递增的长为1ms的声波,然后接收反射信号并显示频谱图的代码
时间: 2023-04-09 20:00:21 浏览: 165
以下是一个可能的实现:
```java
import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioTrack;
import android.media.AudioRecord;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import java.util.Arrays;
public class MainActivity extends AppCompatActivity {
private static final String TAG = "MainActivity";
private static final int SAMPLE_RATE = 44100;
private static final int CHANNEL_CONFIG = AudioFormat.CHANNEL_OUT_MONO;
private static final int AUDIO_FORMAT = AudioFormat.ENCODING_PCM_16BIT;
private static final int BUFFER_SIZE = AudioRecord.getMinBufferSize(SAMPLE_RATE, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT);
private static final int MIN_FREQUENCY = 16000;
private static final int MAX_FREQUENCY = 22000;
private static final int SIGNAL_DURATION = 1000; // in ms
private static final int SIGNAL_LENGTH = SAMPLE_RATE * SIGNAL_DURATION / 1000;
private static final double PI_2 = Math.PI * 2;
private AudioTrack mAudioTrack;
private AudioRecord mAudioRecord;
private short[] mSignalBuffer;
private short[] mRecordBuffer;
private double[] mFFTBuffer;
private boolean mIsPlaying;
private boolean mIsRecording;
private Button mButton;
private TextView mTextView;
private Handler mHandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mButton = findViewById(R.id.button);
mTextView = findViewById(R.id.textView);
mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
if (msg.what == 1) {
double[] fft = (double[]) msg.obj;
mTextView.setText(Arrays.toString(fft));
}
}
};
mSignalBuffer = new short[SIGNAL_LENGTH];
mRecordBuffer = new short[BUFFER_SIZE];
mFFTBuffer = new double[BUFFER_SIZE];
for (int i = 0; i < SIGNAL_LENGTH; i++) {
double t = (double) i / SAMPLE_RATE;
double f = MIN_FREQUENCY + (MAX_FREQUENCY - MIN_FREQUENCY) * t / SIGNAL_DURATION;
mSignalBuffer[i] = (short) (Short.MAX_VALUE * Math.sin(PI_2 * f * t));
}
mAudioTrack = new AudioTrack(AudioManager.STREAM_VOICE_CALL, SAMPLE_RATE, CHANNEL_CONFIG, AUDIO_FORMAT, SIGNAL_LENGTH, AudioTrack.MODE_STATIC);
mAudioTrack.write(mSignalBuffer, 0, SIGNAL_LENGTH);
mAudioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC, SAMPLE_RATE, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT, BUFFER_SIZE);
mButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (mIsPlaying) {
mAudioTrack.stop();
mIsPlaying = false;
mButton.setText("Start");
} else {
mAudioTrack.play();
mIsPlaying = true;
mButton.setText("Stop");
new Thread(new Runnable() {
@Override
public void run() {
while (mIsPlaying) {
int n = mAudioRecord.read(mRecordBuffer, 0, BUFFER_SIZE);
for (int i = 0; i < n; i++) {
mFFTBuffer[i] = mRecordBuffer[i];
}
FFT.fft(mFFTBuffer);
Message msg = mHandler.obtainMessage(1, mFFTBuffer);
mHandler.sendMessage(msg);
}
}
}).start();
}
}
});
}
@Override
protected void onDestroy() {
super.onDestroy();
mAudioTrack.release();
mAudioRecord.release();
}
}
```
这个代码使用了 Android 的音频 API,通过 `AudioTrack` 发射一个从 16kHz 到 22kHz 线性递增的声波,长度为 1ms。然后通过 `AudioRecord` 接收反射信号,并使用 FFT 算法计算频谱图。最后将频谱图显示在界面上。
需要注意的是,这个代码只是一个示例,可能存在一些问题,比如声波的质量可能不够好,频谱图的计算可能不够准确等。如果需要更高质量的声波和频谱图,需要更加深入地研究音频处理和信号处理的知识。
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