Android : Displaying the averaged values of the speedometer android

I have written a code for a speedometer in eclipse. It is working fine. I am trying to display the averaged values of the speed that the speedometer is measuring and while i try to do that i am failing because i am not finding the right approach on how to do it.

Here is my code:

LocationManager lm = (LocationManager) this
                .getSystemService(Context.LOCATION_SERVICE);
        lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);

        this.onLocationChanged(null);

    }

    @Override
    public void onLocationChanged(Location location) {
        TextView tv = (TextView) findViewById(R.id.textView1);


        if (location == null) {

            tv.setText("0.0");
        } else {

            float nCurrentSpeed = location.getSpeed();
            tv.setText(nCurrentSpeed + "");


        }

    }

How can i do it? Thanks in advance.