Implementing an accurate compass with Android

Question

It's been like 2 weeks trying different ways to calculate the azimuth of the phone, but I've found basically two problems:

My problems

1. A 360º turn is not always 360º. If I do my turn quickly, I get done my 360º before the end of the turn, if I go slowly, I get done my 360º after the end of the turn.
2. The azimuth gets moved randomly when I put it laying on the table. Or even holding in the same position, for any tick, I get a +- 3 degrees, so if I stay with 200º and I wait, I could be 197º. And then if I keep waiting, it could reach 194º, but I'm staying.

What am I looking for?

For the problem 1.-, I'm looking for a precise movement on the X axis (azimuth). A good example can be found in the HelloPanoramaGL project sample. It moves smoothly and you can get the sensation you're moving a real panorama.

For the problem 2.-, This project based in a Panorama for iOS does both 1.- and 2.-. When you do a turn, it gets the same position.

What I've tried

Well, after 2 weeks I dare to say I've done everything I found on Internet, for example:

• Trying to set the Sensor.TYPE_ORIENTATION which is deprecated, but it's the one that has provided me best results.
• Trying a combination of Sensor.TYPE_ACCELEROMETER and Sensor.TYPE_MAGNETIC_FIELD. Also adding a Low Pass Filter to the Sensors.
• Using the rest of the sensors like Sensor.TYPE_ROTATION_VECTOR to wait for any hope to make it work.

But I got my problems not solved.

This is my current code now:

Declaring all sensors:

    private SensorManager sensorManager;
    private Sensor magnetic_field;
    private Sensor accelerometer;
    private Sensor orientation;

initializing onCreate():

    sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
    orientation = sensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION);
    accelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
    magnetic_field = sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);

registering the listener onResume():

    sensorManager.registerListener(this, magnetic_field, SensorManager.SENSOR_DELAY_FASTEST);
    sensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_FASTEST);
    sensorManager.registerListener(this, orientation, SensorManager.SENSOR_DELAY_FASTEST);
    // tried with SENSOR_DELAY_FASTEST, SENSOR_DELAY_UI and SENSOR_DELAY_GAME

and getting the results:

@Override
public void onSensorChanged(SensorEvent event) {
    if (event.sensor.getType() == Sensor.TYPE_ORIENTATION) {
        float azimuth1 = event.values[0];
        return;
    }

    if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER)
        mGravity = event.values;
    if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD)
        mGeomagnetic = event.values;
    if (mGravity != null && mGeomagnetic != null) {
        float R_[] = new float[9];
        float I_[] = new float[9];
        boolean success = SensorManager.getRotationMatrix(R_, I_, mGravity, mGeomagnetic);
        if (success) {
            float orientation[] = new float[3];
            SensorManager.getOrientation(R_, orientation);
            azimut = orientation[0]; // orientation contains: azimut, pitch and roll
        }
    }
}

If you could help me with that it would be great.

Thank you very much.

Regards.

Rafael.