![]() ![]() Instead of hanging out of a locomotive cab and grabbing train orders while rolling past a station, voice communications with rolling trains became possible. Railroads used medium frequency range ( MF) communications (similar to the AM broadcast band) to improve safety. These systems used one-way broadcasting instead of two-way conversations. Certain modern two-way radio systems may have full-duplex telephone capability.Įarly users of mobile radio equipment included transportation and government. These systems run on push-to-talk-based infrastructure such as Nextel's iDEN, Specialized Mobile Radio (SMR), MPT-1327, Enhanced Specialized Mobile Radio (ESMR) or conventional two-way systems. ![]() Two-way radio is primarily a dispatch tool intended to communicate in simplex or half-duplex modes using push-to-talk, and primarily intended to communicate with other radios rather than telephones. They run on telephony-based infrastructure such as AMPS or GSM. The connection is taken down when the end button is pressed. The connection sets up based on the user dialing. Radiotelephones are full-duplex (simultaneous talk and listen), circuit switched, and primarily communicate with telephones connected to the public switched telephone network. A parallel to this concept is the convergence of computing and telephones. The backbone or infrastructure supporting the system defines which category or taxonomy applies. The distinction between radiotelephones and two-way radio is becoming blurred as the two technologies merge. A large ship with 117 V AC power might have a base station mounted on the ship's bridge.Īccording to article 1.67 of the ITU, a mobile radio is "A station in the mobile service intended to be used while in motion or during halts at unspecified points." Nomenclature: Two-way versus telephone ![]() For example, a mobile radio installed in a locomotive would run off of 72 or 30 Volt DC power. Some mobile radios are mounted in aircraft (aeronautical mobile), shipboard (maritime mobile), on motorcycles, or railroad locomotives. In the US, such a device is typically powered by the host vehicle's 12 Volt electrical system. Mobile radios are mounted to a motor vehicle usually with the microphone and control panel in reach of the driver. Ī sales person or radio repair shop would understand the word mobile to mean vehicle-mounted: a transmitter-receiver (transceiver) used for radio communications from a vehicle. For US licensing purposes, mobiles may include hand-carried, (sometimes called portable), equipment. There are a variety of views about what constitutes mobile equipment. Mobile radio or mobiles refer to wireless communications systems and devices which are based on radio frequencies (using commonly UHF or VHF frequencies), and where the path of communications is movable on either end. National Guard operating a mobile radio station (1922) Mobile radio on board of Zeppelin For mobile radios used in amateur radio, see amateur radio mobile operation. This article is about professional equipment. ![]()
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