我已经实现了一段代码来计算磁场的特斯拉值。我最近对其进行了测试,我注意到当我在公共(public)汽车上时,该值是 24
,但当我在公共(public)汽车外时,该值约为 45
。我的意思是公共(public)汽车是金属的,所以里面的值(value)应该更高。对于这种奇怪的行为有什么解释吗?
感谢任何帮助。
代码:
public class MainActivity extends ActionBarActivity implements
SensorEventListener {
String telsaString;
private TextView magneticX;
private TextView magneticY;
private TextView magneticZ;
private TextView magneticT;
private SensorManager sensorManager = null;
private long lastUpdate = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
// Capture magnetic sensor related view elements
magneticX = (TextView) findViewById(R.id.valMag_X);
magneticY = (TextView) findViewById(R.id.valMag_Y);
magneticZ = (TextView) findViewById(R.id.valMag_Z);
magneticT = (TextView) findViewById(R.id.valMag_T);
// Register magnetic sensor
sensorManager.registerListener(this,
sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD),
SensorManager.SENSOR_DELAY_NORMAL);
}
@Override
protected void onPause() {
// Unregister the listener
sensorManager.unregisterListener(this);
super.onPause();
}
@Override
protected void onStop() {
// Unregister the listener
sensorManager.unregisterListener(this);
super.onStop();
}
@Override
protected void onResume() {
super.onResume();
// Register magnetic sensor
sensorManager.registerListener(this,
sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD),
SensorManager.SENSOR_DELAY_NORMAL);
}
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
public void onSensorChanged(SensorEvent sensorEvent) {
synchronized (this) {
float magX = sensorEvent.values[0];
float magY = sensorEvent.values[1];
float magZ = sensorEvent.values[2];
magneticX.setText(Float.toString(sensorEvent.values[0]));
magneticY.setText(Float.toString(sensorEvent.values[1]));
magneticZ.setText(Float.toString(sensorEvent.values[2]));
int teslaXYZ = (int)(Math.sqrt((magX * magX) + (magY * magY)
+ (magZ * magZ)));
String str = String.valueOf(teslaXYZ);
magneticT.setText(str);
long curTime = System.currentTimeMillis();
if ((curTime - lastUpdate) > 15000) {
lastUpdate = curTime;
try {
JSONObject tesla = new JSONObject();
tesla.put("tesla", teslaXYZ);
//tesla.put("tesla", teslaXYZ);
telsaString = tesla.toString();
new MyAsyncTask().execute(telsaString);
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
最佳答案
像公共(public)汽车这样的交通工具将包含许多金属部件,其中一些会被磁化并具有自己的磁场。您设备的磁力计会检测到地磁场和这些附加磁场的叠加,并会显示与您远离车辆时相比的错误方向和绝对值。
汽车的发动机和电力基础设施也会造成干扰(在测试时,我注意到启动汽车发动机时磁力计读数有明显差异)。
关于android - 车内磁场特斯拉值下降约20微特斯拉,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/30843960/