How far can a radio station broadcast?
33094374#23
The other meaning of the term "channel" in telecommunications is seen in the phrase communications channel, which is a subdivision of a transmission medium so that it can be used to send multiple streams of information simultaneously. For example, one radio station can broadcast radio waves into free space at frequencies in the neighborhood of 94.5 MHz (megahertz) while another radio station can simultaneously broadcast radio waves at frequencies in the neighborhood of 96.1 MHz. Each radio station would transmit radio waves over a frequency bandwidth of about 180 kHz (kilohertz), centered at frequencies such as the above, which are called the "carrier frequencies". Each station in this example is separated from its adjacent stations by 200 kHz, and the difference between 200 kHz and 180 kHz (20 kHz) is an engineering allowance for the imperfections in the communication system.
Telecommunication
1607203#29
VHF Radio waves do not travel far beyond the visual horizon, so reception distances for FM stations are usually limited to 30–40 miles (50–65 km) They can also be blocked by hills or buildings.
FM broadcasting
491851#11
The signal strength of radio waves decreases the farther they travel from the transmitter, so a radio station can only be received within a limited range of its transmitter. The range depends on the power of the transmitter, the sensitivity of the receiver, atmospheric and internal noise, as well as any geographical obstructions such as hills between transmitter and receiver. AM broadcast band radio waves travel as ground waves which follow the contour of the Earth, so AM radio stations can be reliably received at hundreds of miles distance. Due to their higher frequency, FM band radio signals cannot travel far beyond the visual horizon; limiting reception distance to about 40 miles (64 km), and can be blocked by hills between the transmitter and receiver. However FM radio is less susceptible to interference from radio noise (RFI, sferics, static) and has higher fidelity; better frequency response and less audio distortion, than AM. So in many countries serious music is only broadcast by FM stations, and AM stations specialize in radio news, talk radio, and sports. Like FM, DAB signals travel by line of sight so reception distances are limited by the visual horizon to about 30–40 miles (48–64 km).
Radio receiver
173088#9
Broadcasting by radio takes several forms. These include AM and FM stations. There are several subtypes, namely commercial broadcasting, non-commercial educational (NCE) public broadcasting and non-profit varieties as well as community radio, student-run campus radio stations, and hospital radio stations can be found throughout the world. Many stations broadcast on shortwave bands using AM technology that can be received over thousands of miles (especially at night). For example, the BBC, VOA, VOR, and Deutsche Welle have transmitted via shortwave to Africa and Asia. These broadcasts are very sensitive to atmospheric conditions and solar activity.
Radio broadcasting
1720678#9
Radio news broadcasts can range from as little as one minute to as much as the station's entire schedule, such as the case of all-news radio, or talk radio. Stations dedicated to news or talk content will often feature newscasts, or bulletins, usually at the top of the hour, usually between three and eight minutes in length. They can be a mix of local, regional, national, and international news, as well as sport, entertainment, weather, and traffic reports, or they may be incorporated into separate bulletins. There may also be shorter bulletins at the bottom of the hour, or three at 15-minute intervals, or two at 20-minute intervals. All-news radio stations exist in some countries (most commonly in North America), primarily located in major metropolitan areas such as Chicago, Los Angeles, New York City, and Toronto, which often broadcast local, national, and international news and feature stories on a set time schedule (sometimes known as a "wheel" format, which schedules the presentation of certain segments focused on a specific type of news content at a specific point each hour).
News broadcasting
178808#125
In the UK there are also small community broadcasters. There are now 228 stations with FM broadcast licences (licensed by Ofcom). Community radio stations typically cover a small geographical area with a coverage radius of up to 5 km and run on a nonprofit basis. They can cater for whole communities or for different areas of interest—such as a particular ethnic group, age group or interest group. Community radio stations reflect a diverse mix of cultures and interests. For example, you can listen to stations catering to urban or experimental music, while others are aimed at younger people, religious communities or the armed forces and their families.
Public broadcasting
67066#14
Ground stations transmit signals to the satellites which are 35,786 kilometers (22,236 miles) above the Equator in Clarke belt orbits. The satellites send the signals back down to radio receivers in cars and homes. This signal contains scrambled broadcasts, along with meta data about each specific broadcast. The signals are unscrambled by the radio receiver modules, which display the broadcast information. In urban areas, ground repeaters enable signals to be available even if the satellite signal is blocked. The technology allows for nationwide broadcasting, so that, for instance US listeners can hear the same stations anywhere in the country.
Satellite radio
113604#9
The first regular television broadcasts started in 1937. Broadcasts can be classified as "recorded" or "live". The former allows correcting errors, and removing superfluous or undesired material, rearranging it, applying slow-motion and repetitions, and other techniques to enhance the program. However, some live events like sports television can include some of the aspects including slow-motion clips of important goals/hits, etc., in between the live television telecast. American radio-network broadcasters habitually forbade prerecorded broadcasts in the 1930s and 1940s requiring radio programs played for the Eastern and Central time zones to be repeated three hours later for the Pacific time zone (See: Effects of time on North American broadcasting). This restriction was dropped for special occasions, as in the case of the German dirigible airship "Hindenburg" disaster at Lakehurst, New Jersey, in 1937. During World War II, prerecorded broadcasts from war correspondents were allowed on U.S. radio. In addition, American radio programs were recorded for playback by Armed Forces Radio radio stations around the world.
Broadcasting
630006#32
Law No 9612/1998 deals with community radio broadcasting, sound stations belonging to foundations or associations representing a public contained therein, living in a neighborhood or united by a social cause and that the station presents itself as a spokesperson of these people. It has to operate with a maximum power of 25 watts ERP and its tower will have the limit of 30 meters. These technical characteristics delineate a portion coverage of an urban area, a partial coverage in the municipality. As said, the community broadcaster has a cultural function, there can be no explicit commercial breaks but cultural supports of the content of the grid. Programming times can not be sold to third parties and broadcasting to other stations is prohibited (going against the idea of a "community radio").
Community radio
253491#1
VHF/UHF television and radio signals are normally limited to a maximum "deep fringe" reception service area of approximately in areas where the broadcast spectrum is congested, and about 50 percent farther in the absence of interference. However, providing favourable atmospheric conditions are present, television and radio signals sometimes can be received hundreds or even thousands of miles outside their intended coverage area. These signals are often received using a large outdoor antenna system connected to a sensitive TV or FM receiver, although this may not always be the case. Many times smaller antennas and receivers such as those in vehicles will receive stations farther than normal depending on how favourable conditions are.
TV and FM DX