title: Sensor.TYPE_LINEAR_ACCELERATION returns null on Android 4+
body: <p>I would like to use the accelerometer data in my application. </p>
  
  <p>I am able to access the <code>TYPE_ACCELEROMETER</code> without any problems, but many suggest to use the <code>TYPE_LINEAR_ACCELERATION</code> which is already filtered from the earth gravity. It looks like I do not have access to that sensor though, as in the code below the log will return null. 
  From what I understand <code>TYPE_LINEAR_ACCELERATION</code> is available as a "software sensor" on Android API greater then 8...I am using 14 as my minimum on a Samsung Galaxy Tab 2. </p>
  
  <p>Any idea why I get null? Is it because this model does not have a gyroscope?</p>
  
  <p>Code:</p>
  
  <pre><code>mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
  
  mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
  
  mLinearAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_LINEAR_ACCELERATION);
  
  Log.i("TYPE_LINEAR_ACCELERATION", String.valueOf(mLinearAccelerometer));
  </code></pre>
  
  <p>Thanks</p>
  
  <p>Edit: added missing "=" sign</p>