An HV-ECU acquires electric power information from an electricity transmission line by using a modem. By making a transmission zero of the first-level unit be located at a second harmonic frequency point of the second-level unit, the filtering apparatus can have high suppression on a second harmonic, thereby obtaining relatively desirable far-end suppression performance. The base stations are connected to a zone control station, which controls communications with the mobile station within the zone. The quantity of light integrated by the pixel depends on how many elements are switched on, that is to say project light onto the film, while the film passes through the projection area of the modulator. The filling layer is then removed.