Radio broadcasting is wireless transmission by radio waves of a signal intended to reach a wide audience, without provision for any return signal. This transmit-only_by_one_(or synchronously by several)/receive-only_by_many topology is sometimes referred to as "unidirectional" as opposed to "bidirectional", but this usage should not be confused with the common usage of "unidirectional" as a synonym of "directional" and as opposed to "omnidirectional", which refers literally to the direction or directions in which the signal is propagated. Stations can be linked in radio networks to broadcast a common radio format, either in broadcast syndication or simulcast or both. Audio broadcasting also can be done via cable radio, local wire television networks, satellite radio, and internet radio via streaming media on the Internet. The signal types can be either analog audio or digital audio.
Internet radio technology
Internet radio services are usually accessible from anywhere in the world with a suitable internet connection available; one could, for example, listen to an Australian station from Europe and America. This has made internet radio particularly suited to and popular among expatriate listeners. Nevertheless, some major networks like CBS Radio, Pandora Radio, iHeartRadio and Citadel Broadcasting (except for news/talk and sports stations) in the United States, and Chrysalis in the United Kingdom, restrict listening to in-country due to music licensing and advertising issues.
Internet radio is also suited to listeners with special interests that are often not adequately served by local radio stations
Internet radio is typically listened to on a standard home PC or similar device, through an embedded player program located on the respective station's website. In recent years, dedicated devices that resemble and offer the listener a similar experience to a traditional radio receiver have arrived on the market.
Streaming technology is used to distribute Internet radio, typically using a lossy audio codec. Streaming audio formats include MP3, Ogg Vorbis, Windows Media Audio, RealAudio, and HE-AAC (or aacPlus). Audio data is continuously transmitted serially (streamed) over the local network or internet in TCP or UDP packets, then reassembled at the receiver and played a second or two later. The delay is called lag, and is introduced at several stages of digital audio broadcasting.
A local tuner simulation program includes all the online radios that can also be heard in the air in the city.