title: Android Low pass filter and High pass filter
body: <p>I have  a very basic question.
  What is Low Pass filter and High Pass filter in case of Android Accelerometer? </p>
  
  <p>When I see the output from the Accelerometer Sensor, I see If I don't use any filter, (Case : I kept my cell phone idle on table) I get z Axis +ve value. Now If I think using basic physics, it gives me exact value(9.8approx) for small g i.e Acceleration due to gravity.</p>
  
  <p>To get the linear acceleration, If I add any force to phone it will change the Accelerometer value, but it will be <code>g + a</code> that I applied. So to get <code>a</code> why can't I just subtract directly from the value I am getting from Accelerometer? </p>
  
  <p>What is the use?<br>
  A basic definition I understand for low pass: To allow low value, High Pass : To allow high value.</p>