Mobile radio or mobiles refer to wireless communications systems and devices which are based on radio frequencies, and where the path of communications is movable on either end. There are a variety of views about what constitutes mobile equipment. For US licensing purposes, mobiles may include hand-carried, (sometimes called portable), equipment. A sales person or radio repair shop would understand the word mobile to mean vehicle-mounted: a transceiver used for radio communications from a vehicle. Mobile radios are mounted to a motor vehicle usually with the microphone and control panel in reach of the driver. Such a device is typically powered by the host vehicle's 12V DC electrical system. Some mobile radios are mounted in aircraft (aeronautical mobile), shipboard (maritime mobile), on motorcycles, or railroad locomotives. Power may vary with each platform. For example, a mobile radio installed in a locomotive would run off of 72V DC or 30V DC power. A large ship with 117V AC power might have a base station mounted on the ship's bridge.