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131-522: The Bob Edwards Show was an American radio program broadcast from 2004 to 2014 by Sirius XM Satellite Radio every weekday morning at 8 a.m. Eastern, with repeats at 8 a.m. Central, 7 a.m. Pacific, 6 p.m. Mountain, and the next day at 7 a.m. Eastern. The program was heard on the Sirius XM Public Radio station at XM channel 121 and Sirius channel 205, and was also available 24/7 on XM Radio Online and Sirius Internet Radio . The show

262-471: A directional antenna transmits radio waves in a beam in a particular direction, or receives waves from only one direction. Radio waves travel at the speed of light in vacuum and at slightly lower velocity in air. The other types of electromagnetic waves besides radio waves, infrared , visible light , ultraviolet , X-rays and gamma rays , can also carry information and be used for communication. The wide use of radio waves for telecommunication

393-418: A microphone , a video signal representing moving images from a video camera , or a digital signal consisting of a sequence of bits representing binary data from a computer. The modulation signal is applied to a radio transmitter . In the transmitter, an electronic oscillator generates an alternating current oscillating at a radio frequency , called the carrier wave because it serves to generate

524-497: A radar screen . Doppler radar can measure a moving object's velocity, by measuring the change in frequency of the return radio waves due to the Doppler effect . Radar sets mainly use high frequencies in the microwave bands, because these frequencies create strong reflections from objects the size of vehicles and can be focused into narrow beams with compact antennas. Parabolic (dish) antennas are widely used. In most radars

655-474: A " push to talk " button on their radio which switches off the receiver and switches on the transmitter. Or the radio link may be full duplex , a bidirectional link using two radio channels so both people can talk at the same time, as in a cell phone. One way, unidirectional radio transmission is called simplex . This is radio communication between a spacecraft and an Earth-based ground station, or another spacecraft. Communication with spacecraft involves

786-550: A Jesuit priest who works with Latino gang members in east Los Angeles. The show earned a second Gabriel Award in 2007 for "Exploding Heritage," a documentary about mountaintop removal coal mining in Appalachia. "Exploding Heritage" also received the National Press Club's Robert L. Kozic Award for environmental reporting, a New York Festivals Gold World Medal for best program on the environment, and an award from

917-627: A Service Regulation specifying that "Radiotelegrams shall show in the preamble that the service is 'Radio ' ". The switch to radio in place of wireless took place slowly and unevenly in the English-speaking world. Lee de Forest helped popularize the new word in the United States—in early 1907, he founded the DeForest Radio Telephone Company, and his letter in the 22 June 1907 Electrical World about

1048-569: A blurry demonstration broadcast showed that it would not be in regular use for several months. The DuMont Television Network , which had begun experimental broadcasts before the war, launched what Newsweek called "the country's first permanent commercial television network" on 15 August 1946, connecting New York City with Washington. Not to be outdone, NBC launched what it called "the world's first regularly operating television network" on 27 June 1947, serving New York City, Philadelphia, Schenectady and Washington. Baltimore and Boston were added to

1179-541: A consolidation of each respective network's higher-rated programs onto one schedule); MyNetworkTV , a network formed from affiliates of UPN and The WB that did not affiliate with The CW, launched at the same time. FCC regulations in the United States restricted the number of television stations that could be owned by any one network, company or individual . This led to a system where most local television stations were independently owned, but received programming from

1310-412: A controller device control the actions of a remote device. The existence of radio waves was first proven by German physicist Heinrich Hertz on 11 November 1886. In the mid-1890s, building on techniques physicists were using to study electromagnetic waves, Italian physicist Guglielmo Marconi developed the first apparatus for long-distance radio communication, sending a wireless Morse Code message to

1441-582: A daily show. The Bob Edwards Show continued the tradition of interviewing interesting people in all walks of life that Edwards exemplified on Morning Edition , but now in long form. Edwards told the NewsHour with Jim Lehrer ' s Terrance Smith, "The longest interview I could do on the air for Morning Edition was eight minutes. Now I can interview someone for up to an hour. So it's a freer, more open, more relaxed and enjoyable conversation. The program's really about conversation." The show's first broadcast

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1572-645: A differentiation between them. Within the industry, a tiering is sometimes created among groups of networks based on whether their programming is simultaneously originated from a central point, and whether the network master control has the technical and administrative capability to take over the programming of their affiliates in real-time when it deems this necessary – the most common example being during national breaking news events. In North America in particular, many television networks available via cable and satellite television are branded as "channels" because they are somewhat different from traditional networks in

1703-421: A given bandwidth than analog modulation , by using data compression algorithms, which reduce redundancy in the data to be sent, and more efficient modulation. Other reasons for the transition is that digital modulation has greater noise immunity than analog, digital signal processing chips have more power and flexibility than analog circuits, and a wide variety of types of information can be transmitted using

1834-540: A government entity that was created in 1926 to regulate the radio industry. With some exceptions, radio stations east of the Mississippi River received official call signs beginning with the letter "W"; those west of the Mississippi were assigned calls beginning with a "K". The number of programs that these early stations aired was often limited, in part due to the expense of program creation. The idea of

1965-548: A government license, such as the general radiotelephone operator license in the US, obtained by taking a test demonstrating adequate technical and legal knowledge of safe radio operation. Exceptions to the above rules allow the unlicensed operation by the public of low power short-range transmitters in consumer products such as cell phones, cordless phones , wireless devices , walkie-talkies , citizens band radios , wireless microphones , garage door openers , and baby monitors . In

2096-547: A joint venture between Time Warner and the Tribune Company , and the United Paramount Network ( UPN ), formed through a programming alliance between Chris-Craft Industries and Paramount Television (whose parent, Viacom , would later acquire half and later all of the network over the course of its existence). In September 2006, The CW was launched as a "merger" of The WB and UPN (in actuality,

2227-521: A large amount of syndicated programming. Other networks are dedicated to specialized programming, such as religious content or programs presented in languages other than English, particularly Spanish. The largest television network in the United States, however, is the Public Broadcasting Service ( PBS ), a non-profit, publicly owned, non-commercial educational service. In comparison to the commercial television networks, there

2358-587: A large economic cost, but it can also be life-threatening (for example, in the case of interference with emergency communications or air traffic control ). To prevent interference between different users, the emission of radio waves is strictly regulated by national laws, coordinated by an international body, the International Telecommunication Union (ITU), which allocates bands in the radio spectrum for different uses. Radio transmitters must be licensed by governments, under

2489-536: A large number of channels, as does UKTV . Sweden had only one television network from 1956 until the early-1990s: the public broadcaster Sveriges Television (SVT). Commercial companies such as Modern Times Group , TV4 , Viasat , and SBS Discovery have established TV networks since the 1980s although they initially aired exclusively on satellite. In 1991, TV4 became Sweden's first commercial television network to air terrestrially. Most television programming in Sweden

2620-438: A larger area, often an entire state, and become full-time affiliates to one specific metropolitan network. As well as these free-to-air channels, there are others on Australia's Pay television network Foxtel . New Zealand has one public network, Television New Zealand (TVNZ), which consists of two main networks: TVNZ 1 is the network's flagship network which carries news, current affairs and sports programming as well as

2751-595: A metal conductor called an antenna . As they travel farther from the transmitting antenna, radio waves spread out so their signal strength ( intensity in watts per square meter) decreases (see Inverse-square law ), so radio transmissions can only be received within a limited range of the transmitter, the distance depending on the transmitter power, the antenna radiation pattern , receiver sensitivity, background noise level, and presence of obstructions between transmitter and receiver . An omnidirectional antenna transmits or receives radio waves in all directions, while

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2882-456: A method called "broadcast syndication", and today nearly every television station in the United States obtains syndicated programs in addition to network-produced fare. Late in the 20th century, cross-country microwave radio relays were replaced by fixed-service satellites. Some terrestrial radio relays remained in service for regional connections. After the failure and shutdown of DuMont in 1956, several attempts at new networks were made between

3013-427: A more limited information-carrying capacity and so work best with audio signals (speech and music), and the sound quality can be degraded by radio noise from natural and artificial sources. The shortwave bands have a greater potential range but are more subject to interference by distant stations and varying atmospheric conditions that affect reception. In the very high frequency band, greater than 30 megahertz,

3144-464: A national basis. Currently, licensed national or provincial networks must be carried by all cable providers (in the country or province, respectively) with a service area above a certain population threshold, as well as all satellite providers. However, they are no longer necessarily expected to achieve over-the-air coverage in all areas (APTN, for example, only has terrestrial coverage in parts of northern Canada). In addition to these licensed networks,

3275-541: A network system which would distribute programming to many stations simultaneously, saving each station the expense of creating all of their own programs and expandingus transmitted from station to station to listeners across the United States. Other companies, including CBS and the Mutual Broadcasting System , soon followed suit, each network signed hundreds of individual stations on as affiliates: stations which agreed to broadcast programs from one of

3406-488: A network, becoming Ostankino Channel One . The other five networks were operated by Ground Zero. This free airwave space allowed many private television networks like NTV and TV-6 to launch in the mid-1990s. The 2000s were marked by the increased state intervention in Russian television. On 14 April 2001 NTV experienced management changes following the expulsion of former oligarch and NTV founder Vladimir Gusinsky . As

3537-470: A primitive spark-gap transmitter . Experiments by Hertz and physicists Jagadish Chandra Bose , Oliver Lodge , Lord Rayleigh , and Augusto Righi , among others, showed that radio waves like light demonstrated reflection, refraction , diffraction , polarization , standing waves , and traveled at the same speed as light, confirming that both light and radio waves were electromagnetic waves, differing only in frequency. In 1895, Guglielmo Marconi developed

3668-420: A public audience. Analog audio is the earliest form of radio broadcast. AM broadcasting began around 1920. FM broadcasting was introduced in the late 1930s with improved fidelity . A broadcast radio receiver is called a radio . Most radios can receive both AM and FM. Television broadcasting is the transmission of moving images by radio, which consist of sequences of still images, which are displayed on

3799-459: A radio signal is usually concentrated in narrow frequency bands called sidebands ( SB ) just above and below the carrier frequency. The width in hertz of the frequency range that the radio signal occupies, the highest frequency minus the lowest frequency, is called its bandwidth ( BW ). For any given signal-to-noise ratio , an amount of bandwidth can carry the same amount of information ( data rate in bits per second) regardless of where in

3930-401: A rate of more than $ 5.00 per subscriber to ESPN). The providers also handle the sale of advertising inserted at the local level during national programming, in which case the broadcaster and the cable/satellite provider may share revenue . Networks that maintain a home shopping or infomercial format may instead pay the station or cable/satellite provider, in a brokered carriage deal. This

4061-489: A receiver that is typically colocated with the transmitter. In radio navigation systems such as GPS and VOR , a mobile navigation instrument receives radio signals from multiple navigational radio beacons whose position is known, and by precisely measuring the arrival time of the radio waves the receiver can calculate its position on Earth. In wireless radio remote control devices like drones , garage door openers , and keyless entry systems , radio signals transmitted from

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4192-533: A recipient over a kilometer away in 1895, and the first transatlantic signal on 12 December 1901. The first commercial radio broadcast was transmitted on 2 November 1920, when the live returns of the Harding-Cox presidential election were broadcast by Westinghouse Electric and Manufacturing Company in Pittsburgh, under the call sign KDKA . The emission of radio waves is regulated by law, coordinated by

4323-673: A reference to the radiotelegraph and radiotelegraphy . The use of radio as a standalone word dates back to at least 30 December 1904, when instructions issued by the British Post Office for transmitting telegrams specified that "The word 'Radio'... is sent in the Service Instructions." This practice was universally adopted, and the word "radio" introduced internationally, by the 1906 Berlin Radiotelegraphic Convention, which included

4454-502: A result, most of the prominent reporters featured on NTV left the network. Later on 22 January 2002, the second largest private television network TV-6 , where the former NTV staff took refuge, was shut down allegedly because of its editorial policy. Five months later on 1 June, TVS was launched, mostly employing NTV/TV-6 staff, only to cease operations the following year. Since then, the four largest television networks (Channel One, Russia 1, NTV and Russia 2) have been state-owned. Still,

4585-446: A screen on a television receiver (a "television" or TV) along with a synchronized audio (sound) channel. Television ( video ) signals occupy a wider bandwidth than broadcast radio ( audio ) signals. Analog television , the original television technology, required 6 MHz, so the television frequency bands are divided into 6 MHz channels, now called "RF channels". The current television standard, introduced beginning in 2006,

4716-491: A second channel, BBC 2 (with the original service being renamed BBC 1 ). A second national commercial network was launched Channel 4 , although Wales instead introduced a Welsh-language service, S4C . These were later followed by the launch of a third commercial network, Channel 5 . Since the introduction of digital television, the BBC, ITV, Channel 4 and Channel 5 each introduced a number of digital-only channels. Sky operates

4847-468: A second or even third station providing a greater variety of content. Commercial television services also became available when private companies applied for television broadcasting licenses. Often, each new network would be identified with their channel number, so that individual stations would often be numbered "One", "Two", "Three" and so forth. The first television network in the United Kingdom

4978-508: A single company (as is the case with the BBC), each local area had a separate television channel that was independently owned and operated, although most of these channels shared a number of programmes, particularly during peak evening viewing hours. These channels formed the ITV network . When the advent of UHF broadcasting allowed a greater number of television channels to broadcast, the BBC launched

5109-446: A small number of stations still operating as affiliates. Most television services outside North America are national networks established by a combination of publicly funded broadcasters and commercial broadcasters. Most nations established television networks in a similar way: the first television service in each country was operated by a public broadcaster , often funded by a television licensing fee, and most of them later established

5240-441: A smaller bandwidth than the old analog channels, saving scarce radio spectrum space. Therefore, each of the 6 MHz analog RF channels now carries up to 7 DTV channels – these are called "virtual channels". Digital television receivers have different behavior in the presence of poor reception or noise than analog television, called the " digital cliff " effect. Unlike analog television, in which increasingly poor reception causes

5371-406: A telephone improvement device. Its high capacity (transmitting 240 telephone calls simultaneously) also made it ideal for long-distance television transmission, where it could handle a frequency band of 1 MHz. German television first demonstrated such an application in 1936 by relaying televised telephone calls from Berlin to Leipzig , 180 km (110 mi) away, by cable. AT&T laid

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5502-416: A television (video) signal has a greater data rate than an audio signal . The radio spectrum , the total range of radio frequencies that can be used for communication in a given area, is a limited resource. Each radio transmission occupies a portion of the total bandwidth available. Radio bandwidth is regarded as an economic good which has a monetary cost and is in increasing demand. In some parts of

5633-400: A transmitter to a receiver, by modulating the radio signal (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter. In radar, used to locate and track objects like aircraft, ships, spacecraft and missiles, a beam of radio waves emitted by a radar transmitter reflects off the target object, and the reflected waves reveal the object's location to

5764-652: A transmitter to control the actions of a device at a remote location. Remote control systems may also include telemetry channels in the other direction, used to transmit real-time information on the state of the device back to the control station. Uncrewed spacecraft are an example of remote-controlled machines, controlled by commands transmitted by satellite ground stations . Most handheld remote controls used to control consumer electronics products like televisions or DVD players actually operate by infrared light rather than radio waves, so are not examples of radio remote control. A security concern with remote control systems

5895-531: A unionwide network. Until 1989, there were six television networks, all owned by the USSR Gosteleradio. This changed during Mikhail Gorbachev 's Perestroika program, when the first independent television network, 2×2 , was launched. Following the breakup of the Soviet Union, USSR Gosteleradio ceased to exist as well as its six networks. Only Channel One had a smooth transition and survived as

6026-435: A variety of license classes depending on use, and are restricted to certain frequencies and power levels. In some classes, such as radio and television broadcasting stations, the transmitter is given a unique identifier consisting of a string of letters and numbers called a call sign , which must be used in all transmissions. In order to adjust, maintain, or internally repair radiotelephone transmitters, individuals must hold

6157-488: Is TV3 , which competes directly with both TVNZ broadcast networks. MediaWorks also operates a second network, FOUR , which airs mostly imported programmes with children's shows airing in the daytime and shows targeted at teenagers and adult between 15 and 39 years of age during prime time. MediaWorks also operates a timeshift network, TV3 + 1, and a 24-hour music network, C4 . All television networks in New Zealand air

6288-413: Is amplified in the transmitter and applied to a transmitting antenna which radiates the energy as radio waves. The radio waves carry the information to the receiver location. At the receiver, the radio wave induces a tiny oscillating voltage in the receiving antenna which is a weaker replica of the current in the transmitting antenna. This voltage is applied to the radio receiver , which amplifies

6419-703: Is spoofing , in which an unauthorized person transmits an imitation of the control signal to take control of the device. Examples of radio remote control: Radio jamming is the deliberate radiation of radio signals designed to interfere with the reception of other radio signals. Jamming devices are called "signal suppressors" or "interference generators" or just jammers. During wartime, militaries use jamming to interfere with enemies' tactical radio communication. Since radio waves can pass beyond national borders, some totalitarian countries which practice censorship use jamming to prevent their citizens from listening to broadcasts from radio stations in other countries. Jamming

6550-445: Is a telecommunications network for the distribution of television content , where a central operation provides programming to many television stations , pay television providers or, in the United States, multichannel video programming distributors . Until the mid-1980s, broadcast programming on television in most countries of the world was dominated by a small number of terrestrial networks . Many early television networks such as

6681-445: Is a digital format called high-definition television (HDTV), which transmits pictures at higher resolution, typically 1080 pixels high by 1920 pixels wide, at a rate of 25 or 30 frames per second. Digital television (DTV) transmission systems, which replaced older analog television in a transition beginning in 2006, use image compression and high-efficiency digital modulation such as OFDM and 8VSB to transmit HDTV video within

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6812-433: Is an audio transceiver , a receiver and transmitter in the same device, used for bidirectional person-to-person voice communication with other users with similar radios. An older term for this mode of communication is radiotelephony . The radio link may be half-duplex , as in a walkie-talkie , using a single radio channel in which only one radio can transmit at a time, so different users take turns talking, pressing

6943-410: Is called "tuning". The oscillating radio signal from the desired station causes the tuned circuit to resonate , oscillate in sympathy, and it passes the signal on to the rest of the receiver. Radio signals at other frequencies are blocked by the tuned circuit and not passed on. A modulated radio wave, carrying an information signal, occupies a range of frequencies . The information ( modulation ) in

7074-427: Is called an uplink , while a link that transmits data from the spacecraft to the ground is called a downlink. Radar is a radiolocation method used to locate and track aircraft, spacecraft, missiles, ships, vehicles, and also to map weather patterns and terrain. A radar set consists of a transmitter and receiver. The transmitter emits a narrow beam of radio waves which is swept around the surrounding space. When

7205-523: Is centralised except for local news updates that air on SVT2 and TV4. Until 1989, Netherlands Public Broadcasting was the only television network in the Netherlands, with three stations, Nederland 1 , Nederland 2 and Nederland 3 . Rather than having a single production arm, there are a number of public broadcasting organizations that create programming for each of the three stations, each working relatively independently. Commercial broadcasting in

7336-418: Is especially common with low-power television stations, and in recent years, even more so for stations that used this revenue stream to finance their conversion to digital broadcasts, which in turn provides them with several additional channels to transmit different programming sources. Television broadcasting in the United States was heavily influenced by radio. Early individual experimental radio stations in

7467-407: Is explained by author Tim P. Vos in his abstract A Cultural Explanation of Early Broadcast , where he determines targeted group/non-targeted group representations as well as the cultural specificity employed in the television network entity. Vos notes that policymakers did not expressly intend to create a broadcast order dominated by commercial networks. In fact, legislative attempts were made to limit

7598-565: Is in radio clocks and watches, which include an automated receiver that periodically (usually weekly) receives and decodes the time signal and resets the watch's internal quartz clock to the correct time, thus allowing a small watch or desk clock to have the same accuracy as an atomic clock. Government time stations are declining in number because GPS satellites and the Internet Network Time Protocol (NTP) provide equally accurate time standards. A two-way radio

7729-417: Is mainly due to their desirable propagation properties stemming from their longer wavelength. In radio communication systems, information is carried across space using radio waves. At the sending end, the information to be sent is converted by some type of transducer to a time-varying electrical signal called the modulation signal. The modulation signal may be an audio signal representing sound from

7860-548: Is no central unified arm of broadcast programming, meaning that each PBS member station has a significant amount of freedom to schedule television shows as they consent to. Some public television outlets, such as PBS, carry separate digital subchannel networks through their member stations (for example, Georgia Public Broadcasting ; in fact, some programs airing on PBS were branded on other channels as coming from GPB Kids and PBS World ). This works as each network sends its signal to many local affiliated television stations across

7991-544: Is the British Broadcasting Corporation ( BBC ), which is perhaps most-well known for its news agency BBC News . Owned by the Crown , the BBC funds itself in two ways. UK services branded under BBC are funded by the television license paid by British residents, as a result no advertising appears on these services. The advertising-funded arm ( BBC Studios ) employs 23,000 people worldwide including

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8122-524: Is the one-way transmission of information from a transmitter to receivers belonging to a public audience. Since the radio waves become weaker with distance, a broadcasting station can only be received within a limited distance of its transmitter. Systems that broadcast from satellites can generally be received over an entire country or continent. Older terrestrial radio and television are paid for by commercial advertising or governments. In subscription systems like satellite television and satellite radio

8253-526: Is usually accomplished by a powerful transmitter which generates noise on the same frequency as the target transmitter. US Federal law prohibits the nonmilitary operation or sale of any type of jamming devices, including ones that interfere with GPS, cellular, Wi-Fi and police radars. ELF 3 Hz/100 Mm 30 Hz/10 Mm SLF 30 Hz/10 Mm 300 Hz/1 Mm ULF 300 Hz/1 Mm 3 kHz/100 km Television broadcasting A television broadcaster or television network

8384-688: The BBC , CBC , PBS , PTV , NBC or ABC in the US and in Australia evolved from earlier radio networks. In countries where most networks broadcast identical, centrally originated content to all of their stations, and where most individual television transmitters therefore operate only as large " repeater stations ", the terms "television network", " television channel " (a numeric identifier or radio frequency ) and "television station" have become mostly interchangeable in everyday language, with professionals in television-related occupations continuing to make

8515-1059: The Big Three television networks , the American Broadcasting Company (ABC), CBS (formerly the Columbia Broadcasting System) and the National Broadcasting Company ( NBC ); however, the Fox Broadcasting Company (Fox), which launched in October 1986, has gained prominence and is now considered part of the "Big Four". The Big Three provide a significant number of programs to each of their affiliates, including newscasts , prime time, daytime and sports programming, but still reserve periods during each day where their affiliate can air local programming , such as local news or syndicated programs . Since

8646-595: The International Telecommunication Union (ITU), which allocates frequency bands in the radio spectrum for various uses. The word radio is derived from the Latin word radius , meaning "spoke of a wheel, beam of light, ray". It was first applied to communications in 1881 when, at the suggestion of French scientist Ernest Mercadier  [ fr ] , Alexander Graham Bell adopted radiophone (meaning "radiated sound") as an alternate name for his photophone optical transmission system. Following Hertz's discovery of

8777-553: The Nine Network ; while their equivalents on VHF channels 7 and 10 respectively formed the Seven Network and Network 10 . Until 1989, areas outside these main cities had access to only a single commercial station, and these rural stations often formed small networks such as Prime Television . Beginning in 1989, however, television markets in rural areas began to aggregate, allowing these rural networks to broadcast over

8908-504: The ionosphere without refraction , and at microwave frequencies the high-gain antennas needed to focus the radio energy into a narrow beam pointed at the receiver are small and take up a minimum of space in a satellite. Portions of the UHF , L , C , S , k u and k a band are allocated for space communication. A radio link that transmits data from the Earth's surface to a spacecraft

9039-400: The radio spectrum into 12 bands, each beginning at a wavelength which is a power of ten (10 ) metres, with corresponding frequency of 3 times a power of ten, and each covering a decade of frequency or wavelength. Each of these bands has a traditional name: It can be seen that the bandwidth , the range of frequencies, contained in each band is not equal but increases exponentially as

9170-510: The "prime-time" programs that the network offered. Local stations occasionally break from regularly scheduled network programming however, especially when a breaking news or severe weather situation occurs in the viewing area. Moreover, when stations return to network programming from commercial breaks , station identifications are displayed in the first few seconds before switching to the network's logo. A number of different definitions of "network" are used by government agencies, industry, and

9301-531: The 1920s with the introduction of broadcasting. Electromagnetic waves were predicted by James Clerk Maxwell in his 1873 theory of electromagnetism , now called Maxwell's equations , who proposed that a coupled oscillating electric field and magnetic field could travel through space as a wave, and proposed that light consisted of electromagnetic waves of short wavelength . On 11 November 1886, German physicist Heinrich Hertz , attempting to confirm Maxwell's theory, first observed radio waves he generated using

9432-567: The 1950s and the 1970s, with little success. The Fox Broadcasting Company , founded by the Rupert Murdoch -owned News Corporation (now owned by Fox Corporation ), was launched on 9 October 1986 after the company purchased the television assets of Metromedia ; it would eventually ascend to the status of the fourth major network by 1994. Two other networks launched within a week of one another in January 1995: The WB Television Network,

9563-465: The 2000s saw a rise of several independent television networks such as REN (its coverage increased vastly allowing it to become a federal network), Petersburg – Channel Five (overall the same), the relaunched 2×2 . The Russian television market is mainly shared today by five major companies: Channel One, Russia 1, NTV, TNT and CTC. The major commercial television network in Brazil is Rede Globo , which

9694-578: The CRTC: government-owned CBC Television (English) and Ici Radio-Canada Télé (French), French-language private network TVA , and APTN , a network focused on Indigenous peoples in Canada . A third French-language service, Noovo (formerly V), is licensed as a provincial network within Quebec , but is not licensed or locally distributed (outside of carriage on the digital tiers of pay television providers) on

9825-474: The Earth's atmosphere has less of an effect on the range of signals, and line-of-sight propagation becomes the principal mode. These higher frequencies permit the great bandwidth required for television broadcasting. Since natural and artificial noise sources are less present at these frequencies, high-quality audio transmission is possible, using frequency modulation . Radio broadcasting means transmission of audio (sound) to radio receivers belonging to

9956-549: The NBC television network in late 1947. DuMont and NBC would be joined by CBS and ABC in 1948. In the 1940s, the term "chain broadcasting" was used when discussing network broadcasts, as the television stations were linked together in long chains along the East Coast . But as the television networks expanded westward, the interconnected television stations formed major networks of connected affiliate stations. In January 1949, with

10087-492: The Netherlands is currently operated by two networks, RTL Nederland and SBS Broadcasting , which together broadcast seven commercial stations. The first television network in the Soviet Union launched on 7 July 1938 when Petersburg – Channel 5 of Leningrad Television became a unionwide network. The second television network in the Soviet Union launched on 22 March 1951 when Channel One of USSR Central Television became

10218-732: The Society of Environmental Journalists. In 2008, The Bob Edwards Show received an Edward R. Murrow Award from the Radio-Television News Directors Association and a New York Festivals/United Nations Gold Award for a documentary called "The Invisible—Children Without Homes." "The Invisible" also was honored by the Journalism Center on Children and Families and by the Catholic Academy for Communication Arts Professionals. In 2009,

10349-596: The US, these fall under Part 15 of the Federal Communications Commission (FCC) regulations. Many of these devices use the ISM bands , a series of frequency bands throughout the radio spectrum reserved for unlicensed use. Although they can be operated without a license, like all radio equipment these devices generally must be type-approved before the sale. Below are some of the most important uses of radio, organized by function. Broadcasting

10480-611: The United States began limited operations in the 1910s. In November 1920, Westinghouse signed on "the world's first commercially licensed radio station", KDKA in Pittsburgh , Pennsylvania. Other companies built early radio stations in Detroit, Boston , New York City and other areas. Radio stations received permission to transmit through broadcast licenses obtained through the Federal Radio Commission (FRC),

10611-405: The air simultaneously without interfering with each other because each transmitter's radio waves oscillate at a different rate, in other words, each transmitter has a different frequency , measured in hertz (Hz), kilohertz (kHz), megahertz (MHz) or gigahertz (GHz). The receiving antenna typically picks up the radio signals of many transmitters. The receiver uses tuned circuits to select

10742-414: The beam strikes a target object, radio waves are reflected back to the receiver. The direction of the beam reveals the object's location. Since radio waves travel at a constant speed close to the speed of light , by measuring the brief time delay between the outgoing pulse and the received "echo", the range to the target can be calculated. The targets are often displayed graphically on a map display called

10873-668: The continuous waves which were needed for audio modulation , so radio was used for person-to-person commercial, diplomatic and military text messaging. Starting around 1908 industrial countries built worldwide networks of powerful transoceanic transmitters to exchange telegram traffic between continents and communicate with their colonies and naval fleets. During World War I the development of continuous wave radio transmitters, rectifying electrolytic, and crystal radio receiver detectors enabled amplitude modulation (AM) radiotelephony to be achieved by Reginald Fessenden and others, allowing audio to be transmitted. On 2 November 1920,

11004-399: The country. These local stations then carry the "network feed", which can be viewed by millions of households across the country. In such cases, the signal is sent to as many as 200+ stations or as little as just a dozen or fewer stations, depending on the size of the network. With the adoption of digital television , television networks have also been created specifically for distribution on

11135-440: The creation of Fox, the number of American television networks has increased, though the amount of programming they provide is often much less: for example, The CW only provides fifteen hours of primetime programming each week (along with three hours on Saturdays), while MyNetworkTV only provides ten hours of primetime programming each week, leaving their affiliates to fill time periods where network programs are not broadcast with

11266-466: The customer pays a monthly fee. In these systems, the radio signal is encrypted and can only be decrypted by the receiver, which is controlled by the company and can be deactivated if the customer does not pay. Broadcasting uses several parts of the radio spectrum, depending on the type of signals transmitted and the desired target audience. Longwave and medium wave signals can give reliable coverage of areas several hundred kilometers across, but have

11397-503: The digital subchannels of television stations (including networks focusing on classic television series and films operated by companies like Weigel Broadcasting (owners of Movies! and Me-TV ) and Nexstar Media Group (owners of Rewind TV and Antenna TV ), along with networks focusing on music, sports and other niche programming). Cable and satellite providers pay the networks a certain rate per subscriber (the highest charge being for ESPN , in which cable and satellite providers pay

11528-570: The existence of radio waves in 1886, the term Hertzian waves was initially used for this radiation. The first practical radio communication systems, developed by Marconi in 1894–1895, transmitted telegraph signals by radio waves, so radio communication was first called wireless telegraphy . Up until about 1910 the term wireless telegraphy also included a variety of other experimental systems for transmitting telegraph signals without wires, including electrostatic induction , electromagnetic induction and aquatic and earth conduction , so there

11659-546: The federal regulator enacted the Prime Time Access Rule , which restricted the amount of time that the networks could air programs; officials hoped that the rules would foster the development of quality local programs, but in practice, most local stations did not want to bear the burden of producing many of their own programs, and instead chose to purchase programs from independent producers. Sales of television programs to individual local stations are done through

11790-665: The first L-carrier coaxial cable between New York City and Philadelphia , with automatic signal booster stations every 10 miles (16 km), and in 1937 it experimented with transmitting televised motion pictures over the line. Bell Labs gave demonstrations of the New York–Philadelphia television link in 1940 and 1941. AT&T used the coaxial link to transmit the Republican National Convention in June 1940 from Philadelphia to New York City, where it

11921-413: The first commercial radio broadcast was transmitted by Westinghouse Electric and Manufacturing Company in Pittsburgh, under the call sign KDKA featuring live coverage of the Harding-Cox presidential election . Radio waves are radiated by electric charges undergoing acceleration . They are generated artificially by time-varying electric currents , consisting of electrons flowing back and forth in

12052-592: The first radio communication system, using a spark-gap transmitter to send Morse code over long distances. By December 1901, he had transmitted across the Atlantic Ocean. Marconi and Karl Ferdinand Braun shared the 1909 Nobel Prize in Physics "for their contributions to the development of wireless telegraphy". During radio's first two decades, called the radiotelegraphy era, the primitive radio transmitters could only transmit pulses of radio waves, not

12183-518: The four major television networks originally only broadcast a few hours of programs a week to their affiliate stations, mostly between 8:00 and 11:00 p.m. Eastern Time , when most viewers were watching television. Most of the programs broadcast by the television stations were still locally produced. As the networks increased the number of programs that they aired, however, officials at the Federal Communications Commission (FCC) grew concerned that local television might disappear altogether. Eventually,

12314-618: The frequency increases; each band contains ten times the bandwidth of the preceding band. The term "tremendously low frequency" (TLF) has been used for wavelengths from 1–3 Hz (300,000–100,000 km), though the term has not been defined by the ITU. The airwaves are a resource shared by many users. Two radio transmitters in the same area that attempt to transmit on the same frequency will interfere with each other, causing garbled reception, so neither transmission may be received clearly. Interference with radio transmissions can not only have

12445-573: The general public. Under the Broadcasting Act , a network is defined as "any operation where control over all or any part of the programs or program schedules of one or more broadcasting undertakings is delegated to another undertaking or person", and must be licensed by the Canadian Radio-television and Telecommunications Commission (CRTC). Only three national over-the-air television networks are currently licensed by

12576-490: The idea of networking television signals (sending one station's video and audio signal to outlying stations) was born. However, the signal from an electronic television system, containing much more information than a radio signal, required a broadband transmission medium. Transmission by a nationwide series of radio relay towers would be possible but extremely expensive. Researchers at AT&T subsidiary Bell Telephone Laboratories patented coaxial cable in 1929, primarily as

12707-402: The longest transmission distances of any radio links, up to billions of kilometers for interplanetary spacecraft . In order to receive the weak signals from distant spacecraft, satellite ground stations use large parabolic "dish" antennas up to 25 metres (82 ft) in diameter and extremely sensitive receivers. High frequencies in the microwave band are used, since microwaves pass through

12838-443: The majority of the locally produced shows broadcast by TVNZ and imported shows. TVNZ's second network, TV2 , airs mostly imported shows with some locally produced programs such as Shortland Street . TVNZ also operates a network exclusive to pay television services, TVNZ Heartland , available on providers such as Sky . TVNZ previously operated a non-commercial public service network, TVNZ 7 , which ceased operations in June 2012 and

12969-565: The manufacture of television and radio equipment for civilian use from 1 April 1942 to 1 October 1945, temporarily shutting down expansion of television networking. However, in 1944 a short film, " Patrolling the Ether ", was broadcast simultaneously over three stations as an experiment. AT&T made its first postwar addition in February 1946, with the completion of a 225-mile (362 km) cable between New York City and Washington, D.C., although

13100-472: The need for legal restrictions warned that "Radio chaos will certainly be the result until such stringent regulation is enforced." The United States Navy would also play a role. Although its translation of the 1906 Berlin Convention used the terms wireless telegraph and wireless telegram , by 1912 it began to promote the use of radio instead. The term started to become preferred by the general public in

13231-577: The network for their own programming, a method known as regional variation . This is common where small networks are members of larger networks. The majority of commercial television stations are self-owned, even though a variety of these instances are the property of an owned-and-operated television network. The commercial television stations can also be linked with a noncommercial educational broadcasting agency. Some countries have launched national television networks, so that individual television stations can act as common repeaters of nationwide programs. On

13362-530: The network through a franchising contract, except in a few major cities that had owned-and-operated stations (O&O) of a network and independent stations. In the early days of television, when there were often only one or two stations broadcasting in a given market, the stations were usually affiliated with multiple networks and were able to choose which programs would air. Eventually, as more stations were licensed, it became common for each station to be exclusively affiliated with only one network and carry all of

13493-490: The network's preferred position. As to individual stations, modern network operations centers usually use broadcast automation to handle most tasks. These systems are not only used for programming and for video server playout , but use exact atomic time from Global Positioning Systems or other sources to maintain perfect synchronization with upstream and downstream systems, so that programming appears seamless to viewers. A major international television broadcaster

13624-458: The networks. As radio prospered throughout the 1920s and 1930s, experimental television stations, which broadcast both an audio and a video signal, began sporadic broadcasts. Licenses for these experimental stations were often granted to experienced radio broadcasters, and thus advances in television technology closely followed breakthroughs in radio technology. As interest in television grew, and as early television stations began regular broadcasts,

13755-582: The next. Citytv originally began operating as a television system in 2002 when CKVU-TV in Vancouver started to carry programs originating from CITY-TV in Toronto and adopted that station's "Citytv" branding, but gradually became a network by virtue of national coverage through expansions into other markets west of Atlantic Canada between 2005 and 2013. Most local television stations in Canada are now owned and operated directly by their network, with only

13886-522: The operation of broadcaster UKTV in the UK itself. Experimental television broadcasts were started in 1929, using an electromechanical 30-line system developed by John Logie Baird . Limited regular broadcasts using this system began in 1934 and an expanded service (now known as BBC Television ) started from Alexandra Palace in November 1936. Television in the United States had long been dominated by

14017-410: The other hand, television networks also undergo the impending experience of major changes related to cultural varieties. The emergence of cable television has made available in major media markets, programs such as those aimed at American bi-cultural Latinos. Such a diverse captive audience presents an occasion for the networks and affiliates to advertise the best programming that needs to be aired. This

14148-505: The picture quality to gradually degrade, in digital television picture quality is not affected by poor reception until, at a certain point, the receiver stops working and the screen goes black. Government standard frequency and time signal services operate time radio stations which continuously broadcast extremely accurate time signals produced by atomic clocks , as a reference to synchronize other clocks. Examples are BPC , DCF77 , JJY , MSF , RTZ , TDF , WWV , and YVTO . One use

14279-502: The public and the broadcasters themselves will often refer to them as "networks" regardless. Some of these systems, such as CTV 2 and the now-defunct E! , essentially operate as mini-networks, but have reduced geographical coverage. Others, such as Omni Television or the Crossroads Television System , have similar branding and a common programming focus, but schedules may vary significantly from one station to

14410-451: The radio frequency spectrum it is located, so bandwidth is a measure of information-carrying capacity . The bandwidth required by a radio transmission depends on the data rate of the information (modulation signal) being sent, and the spectral efficiency of the modulation method used; how much data it can transmit in each kilohertz of bandwidth. Different types of information signals carried by radio have different data rates. For example,

14541-409: The radio signal desired out of all the signals picked up by the antenna and reject the others. A tuned circuit (also called resonant circuit or tank circuit) acts like a resonator , similar to a tuning fork . It has a natural resonant frequency at which it oscillates. The resonant frequency of the receiver's tuned circuit is adjusted by the user to the frequency of the desired radio station; this

14672-451: The radio spectrum, the right to use a frequency band or even a single radio channel is bought and sold for millions of dollars. So there is an incentive to employ technology to minimize the bandwidth used by radio services. A slow transition from analog to digital radio transmission technologies began in the late 1990s. Part of the reason for this is that digital modulation can often transmit more information (a greater data rate) in

14803-456: The radio waves that carry the information through the air. The modulation signal is used to modulate the carrier, varying some aspect of the carrier wave, impressing the information in the modulation signal onto the carrier. Different radio systems use different modulation methods: Many other types of modulation are also used. In some types, a carrier wave is not transmitted but just one or both modulation sidebands . The modulated carrier

14934-481: The same digital modulation. Because it is a fixed resource which is in demand by an increasing number of users, the radio spectrum has become increasingly congested in recent decades, and the need to use it more effectively is driving many additional radio innovations such as trunked radio systems , spread spectrum (ultra-wideband) transmission, frequency reuse , dynamic spectrum management , frequency pooling, and cognitive radio . The ITU arbitrarily divides

15065-955: The same programming across the entire country with the only regional deviations being for local advertising; a regional news service existed in the 1980s, carrying a regional news programme from TVNZ's studios in New Zealand's four largest cities, Auckland, Wellington , Christchurch and Dunedin . In the 1960s, the service operated at the time by the New Zealand Broadcasting Corporation was four separate television stations – AKTV2 in Auckland, WNTV1 in Wellington, CHTV3 in Christchurch and DNTV2 in Dunedin – which each ran their own newscast and produced some in-house programmes, with other shows being shared between

15196-562: The sense defined above, as they are singular operations – they have no affiliates or component stations, but instead are distributed to the public via cable or direct-broadcast satellite providers. Such networks are commonly referred to by terms such as " specialty channels " in Canada or " cable networks " in the U.S. A network may or may not produce all of its own programming. If not, production companies (such as Warner Bros. Television , Universal Television , Sony Pictures Television and TriStar Television ) can distribute their content to

15327-719: The show received a Sigma Delta Chi Award from the Society of Professional Journalists for the documentary, "Stories from Third Med: Surviving a Jungle ER." The documentary also earned a Gabriel Award. In 2013, Bob's program was awarded a Robert F. Kennedy Journalism Award for the documentary, "An Occupational Hazard: Rape in the Military." Radio In radio communication , used in radio and television broadcasting , cell phones, two-way radios , wireless networking , and satellite communication , among numerous other uses, radio waves are used to carry information across space from

15458-460: The sign-on of DuMont's WDTV in Pittsburgh, the Midwest and East Coast networks were finally connected by coaxial cable (with WDTV airing the best shows from all four networks). By 1951, the four networks stretched from coast to coast, carried on the new microwave radio relay network of AT&T Long Lines . Only a few local television stations remained independent of the networks. Each of

15589-624: The stations. Programmes and news footage were distributed via mail, with a programme airing in one region being mailed to another region for broadcast the following week. A network was finally established in 1969, with the same programmes being relayed to all regions simultaneously. From the 1970s to the 1990s, locally produced programmes that aired on TV One and TV2 were produced out of one of the four main studios, with TVNZ's network hub based in Wellington. Today, most locally produced programmes that are aired by both TVNZ and other networks are not actually produced in-house, instead they are often produced by

15720-431: The transmitting antenna also serves as the receiving antenna; this is called a monostatic radar . A radar which uses separate transmitting and receiving antennas is called a bistatic radar . Radiolocation is a generic term covering a variety of techniques that use radio waves to find the location of objects, or for navigation. Radio remote control is the use of electronic control signals sent by radio waves from

15851-545: The two main private English-language over-the-air services, CTV and Global , are also generally considered to be "networks" by virtue of their national coverage, although they are not officially licensed as such. CTV was previously a licensed network, but relinquished this license in 2001 after acquiring most of its affiliates, making operating a network license essentially redundant (per the above definition). Smaller groups of stations with common branding are often categorized by industry watchers as television systems , although

15982-471: The various networks, and it is common that a certain production firm may have programs that air on two or more rival networks. Similarly, some networks may import television programs from other countries, or use archived programming to help complement their schedules. Some stations have the capability to interrupt the network through the local insertion of television commercials, station identifications and emergency alerts . Others completely break away from

16113-510: The weak radio signal so it is stronger, then demodulates it, extracting the original modulation signal from the modulated carrier wave. The modulation signal is converted by a transducer back to a human-usable form: an audio signal is converted to sound waves by a loudspeaker or earphones, a video signal is converted to images by a display , while a digital signal is applied to a computer or microprocessor, which interacts with human users. The radio waves from many transmitters pass through

16244-530: The weekday program. The show's last live episode aired on September 26, 2014. Public Radio International, which paid Sirius XM to broadcast the show on weekends, continued to air reruns, but no longer does. In 2006, interviews with musicians earned The Bob Edwards Show the Deems Taylor Award from ASCAP. The program also received a Gabriel Award from the Catholic Academy for Communication Arts Professionals for an interview with Father Gregory Boyle,

16375-598: Was a need for a more precise term referring exclusively to electromagnetic radiation. The French physicist Édouard Branly , who in 1890 developed the radio wave detecting coherer , called it in French a radio-conducteur . The radio- prefix was later used to form additional descriptive compound and hyphenated words, especially in Europe. For example, in early 1898 the British publication The Practical Engineer included

16506-1486: Was founded in 1965. It grew to become the largest and most successful media conglomerate in the country, having a dominating presence in various forms of media including television, radio, print (newspapers and magazines) and the Internet. Other networks include Rede Bandeirantes , RecordTV , SBT , RedeTV! , TV Cultura , and TV Brasil . Australia has two national public networks, ABC Television and SBS . The ABC operates eight stations as part of its main network ABC TV , one for each state and territory, as well as three digital-only networks, ABC Kids / ABC TV Plus , ABC Me and ABC News . SBS currently operates six stations, SBS , SBS Viceland , SBS World Movies , SBS Food , NITV and SBS WorldWatch . The first commercial networks in Australia involved commercial stations that shared programming in Sydney , Melbourne , Brisbane , Adelaide and later Perth , with each network forming networks based on their allocated channel numbers: TCN-9 in Sydney, GTV-9 in Melbourne, QTQ-9 in Brisbane, NWS-9 in Adelaide and STW-9 in Perth together formed

16637-595: Was hosted by Bob Edwards , a Peabody Award-winning member of the National Radio Hall of Fame. Edwards was once the co-host of National Public Radio 's All Things Considered , and hosted NPR's Morning Edition from the first episode to April 30, 2004 when he was reassigned to another position within NPR, despite email objections from more than 50,000 listeners. Edwards left his new assignment almost immediately, as Hugh Panero , CEO of XM Radio, offered Edwards

16768-629: Was on October 4, 2004, staffed by experienced public radio veterans. The first program included weekly political commentator Washington Post columnist David S. Broder , USA Today Supreme Court reporter Joan Biskupic , former CBS News anchor Walter Cronkite , and Eugene Robinson , author of Last Dance in Havana . Sirius XM Radio also produced the compilation program Bob Edwards Weekend , distributed by Public Radio International for use by "terrestrial" public radio stations. It premiered on January 7–8, 2006, consisting of re-edited interviews from

16899-431: Was operated by the British Broadcasting Corporation ( BBC ). On 2 November 1936 the BBC opened the world's first regular high-definition television service, from a 405 lines transmitter at Alexandra Palace. The BBC remained dominant until eventually on 22 September 1955, commercial broadcasting was established to create a second television network. Rather than creating a single network with local channels owned and operated by

17030-441: Was replaced by the timeshift channel TV One Plus 1. The network operated by Television New Zealand has progressed from operating as four distinct local stations within the four main centers in the 1960s, to having the majority of the content produced from TVNZ's Auckland studios at present. New Zealand also has several privately owned television networks with the largest being operated by MediaWorks . MediaWorks' flagship network

17161-782: Was televised to a few hundred receivers over the NBC station W2XBS (which evolved into WNBC ) as well as seen in Schenectady, New York via W2XB (which evolved into WRGB ) via off-air relay from the New York station. NBC had earlier demonstrated an inter-city television broadcast on 1 February 1940, from its station in New York City to another in Schenectady , New York by General Electric relay antennas, and began transmitting some programs on an irregular basis to Philadelphia and Schenectady in 1941. Wartime priorities suspended

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