¿Cuándo anular el registro de BroadcastReceiver? En onPause(), onDestroy(), o onStop()?

¿Cuándo debo usar unregisterReceiver? En onPause(), onDestroy(), o onStop()?

Nota: Necesito que el servicio se ejecute en segundo plano.

Actualización:

1. Obtengo una excepción liberando receptores null.

2. La actividad se ha filtrado receptores de intención ¿te falta llamada a unregisterReceiver();

Por favor dime si hay algo mal, aquí está mi código:

private boolean processedObstacleReceiverStarted;
private boolean mainNotificationReceiverStarted;

protected void onResume() {

    super.onResume();
    try {
        registerReceivers();

    } catch (Exception e) {

        Log.e(MatabbatManager.TAG,
                "MAINActivity: could not register receiver for Matanbbat Action "
                        + e.getMessage());
    }
}

private void registerReceivers() {

    if (!mainNotificationReceiverStarted) {
        mainNotificationReceiver = new MainNotificationReceiver();

        IntentFilter notificationIntent = new IntentFilter();

        notificationIntent
                .addAction(MatabbatManager.MATABAT_LOCATION_ACTION);
        notificationIntent
                .addAction(MatabbatManager.MATABAT_New_DATA_RECEIVED);
        notificationIntent
                .addAction(MatabbatManager.STATUS_NOTIFCATION_ACTION);
        registerReceiver(mainNotificationReceiver, notificationIntent);

        mainNotificationReceiverStarted = true;

    }

    if (!processedObstacleReceiverStarted) {
        processedObstacleReceiver = new ProcessedObstacleReceiver();
        registerReceiver(processedObstacleReceiver, new IntentFilter(
                MatabbatManager.MATABAT_ALARM_LOCATION_ACTION));
        processedObstacleReceiverStarted = true;

    }

}

private void unRegisterReceivers() {

    if (mainNotificationReceiverStarted) {
        unregisterReceiver(mainNotificationReceiver);
        mainNotificationReceiverStarted = false;
    }
    if (processedObstacleReceiverStarted) {
        unregisterReceiver(processedObstacleReceiver);
        processedObstacleReceiverStarted = false;
    }

}


@Override
protected void onDestroy() {
    // TODO Auto-generated method stub
    super.onDestroy();

    try {

        unRegisterReceivers();
        mWakeLock.release();//keep screen on
    } catch (Exception e) {
        Log.e(MatabbatManager.TAG, getClass() + " Releasing receivers-" + e.getMessage());
    }

}