def to_JSON(self):
        """Dumps object fields into a JSON formatted string

        :returns:  the JSON string

        """
        return json.dumps({"reference_time": self._reference_time,
                           "location": json.loads(self._location.to_JSON()),
                           "value": self._value,
                           "reception_time": self._reception_time,
                           })
Dumps object fields into a JSON formatted string

        :returns:  the JSON string