Radio is the technology of communicating using radio waves . Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates oscillating electrical energy, often characterized as a wave . They can be received by other antennas connected to a radio receiver ; this is the fundamental principle of radio communication. In addition to communication, radio is used for radar , radio navigation , remote control , remote sensing , and other applications.
122-701: WCSP-FM , also known as C-SPAN Radio , is a radio station owned by the Cable-Satellite Public Affairs Network (C-SPAN) in Washington, D.C. The station is licensed to C-SPAN's corporate owner, the National Cable Satellite Corporation, and broadcasts on 90.1 MHz 24 hours a day. Its studios are located near Capitol Hill in C-SPAN’s headquarters. In addition to WCSP-FM, C-SPAN Radio programming
244-561: A Alfred I. duPont–Columbia University Award for its reporting on Disney's America . By the late 1990s, WMAL transitioned its talk lineup into one similar to sister station WABC in New York City, with an emphasis on conservative talk. Chris Berry was named president and general manager November 19, 2002. Prior to joining WMAL, Berry was vice president, radio for ABC News , based in New York. In August 2005, host Michael Graham
366-471: 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
488-418: 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
610-497: 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
732-474: 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
854-627: 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
976-413: A bastion of liberalism on a rather conservative campus. In late 1970, Rev. Francis Heyden, former WGTB faculty moderator, leveled charges at the station that it had failed to conform to its approved format, played "indecent and anti-Semitic" records, and had purchased inferior equipment. Student board members, with the aid of an FCC official, investigated the charges and found them "entirely unfounded". After
1098-399: A brief suspension, WGTB-FM was allowed to return to the air by administration after an arbitration panel was convened to resolve the dispute. Even then, however, the station faced two new technical setbacks in the span of a month. In February 1971, administration ordered the station to go off air or revert to its former 771-watt status, claiming that the transmitter was disrupting equipment in
1220-412: 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
1342-596: A full freeform format As the 1960s became the 1970s, WGTB-FM transformed from a small educational outlet into a much more powerful station with a defined format. The station went to 24-hour broadcasting by February 1970; that June, the Federal Communications Commission approved a major power increase for the station, to 14,720 watts. Both changes in format and technical parameters brought growing pains, however. The station's new progressive rock format, eliminating all block programming, made it
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#17328024583331464-421: 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
1586-548: 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
1708-526: A jazz music station with weekend classical music programming and six hours a week in Spanish, with the station finally signing on May 1. The University of the District of Columbia constantly struggled to bring in money for the station, which had just three full-time employees and never raised more than $ 200,000 in any year since its launch. However, the station did win a major power boost in 1994 after ending
1830-587: 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
1952-516: A lineup of Fred Grandy and Andy Parks, Chris Plante , Rush Limbaugh , Sean Hannity , Mark Levin , Joe Scarborough , and Curtis Sliwa . Weekends include gardening host Jos Roozen, investing adviser Ric Edelman and lawyer Michael Collins. John Batchelor replaced Sliwa in November 2009. In April 2010, Parks was laid off from the station, resulting in Plante's and Grandy's shows being merged. At
2074-595: 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
2196-427: 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,
2318-576: A nighttime power reduction from 5,000 to 2,700 watts. In 2020, the decommissioned Bethesda site was sold to Toll Brothers for $ 74.1 million, and the Bethesda towers were demolished on November 4, 2020. On June 13, 2019, it was announced that WMAL would break away from the simulcast with WMAL-FM and flip to ESPN Radio on July 1, 2019, as ESPN 630 . WMAL replaced WTEM as ESPN Radio's Washington, D.C., affiliate, though both stations continue to share Redskins games, with WTEM as flagship. Concurrent with
2440-674: A nonprofit affiliate of Christian religious broadcaster Salem Communications , for $ 13 million; the university retained the station's recording library. This came after a joint bid by WAMU and WETA to preserve the station as a jazz outlet was priced out by religious bidders. One loud voice protesting the sale made its appeal directly to the Control Board: the Corporation for Public Broadcasting , which demanded to be reimbursed for $ 1 million in federal grants awarded to WDCU since 1991. Other public radio entities announced plans to challenge
2562-478: A poetry reading aired at 8 a.m. that had been approved for an 11 p.m. slot. On March 16, 1976, the university ordered the station off air in order to reorganize again and hire a new general manager. With the station in the middle of a license renewal, potential interest from other groups emerged; one of these, the Committee to Save Alternative Radio (headed by former manager Sleeman), filed a petition to deny against
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#17328024583332684-470: 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
2806-420: 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
2928-459: 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
3050-489: 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
3172-533: 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
3294-621: A record price for radio properties at that time. Andrew Ockershausen was appointed executive vice president. On January 3, 1986, Capital Cities and ABC, Inc. merged in a $ 3.52 billion deal. Thomas S. Murphy was chairman and CEO of the new firm. Frederick Weinhaus became president and general manager following the resignation of Andrew Ockershausen in March 1986. Weinhaus was transferred to ABC Radio New York in January 1988. His replacement in May 1988
3416-673: 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
3538-523: A science building. A compromise was reached to keep the station off the air during daytime hours so as not to affect the equipment, used in laser research funded by the United States Air Force . While a solution was sought to the interference issue, weather intervened as gusty winds toppled the new tower mounted atop Copley Hall, destroying the antenna. While WGTB-FM was off the air, administration acted. Led by president Robert J. Henle ,
3660-446: 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,
3782-517: A six-year fight with television station WFTY , which broadcast from the Hughes Memorial Tower next to the site where WDCU was already broadcasting; the increase to 50,000 watts also filled in reception issues in parts of the District and added some 900,000 people to the station's coverage area. When the District's financial situation worsened and prompted the creation by Congress of a District of Columbia Financial Control Board with
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3904-441: 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
4026-496: A sports talk radio pioneer who hosted a call-in show from 1977 to 1995. The station also kept a local following for a time by broadcasting sports games featuring the Washington Redskins and University of Maryland, College Park Terrapins. Legendary jazz authority Felix Grant broadcast on WMAL for decades. Support of the local community has been a tradition for WMAL, which founded such innovative fund-raisers as
4148-400: A study was conducted in the summer of 1971 which recommended the station be returned to air as soon as possible, that a professional be appointed to manage it, and a move back to a more block format and away from the rock-heavy sound that WGTB had adopted in 1970. Broadcasting resumed at reduced power that fall using a portion of the fallen tower. The ultimate solution to the interference problem
4270-416: 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
4392-400: 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
4514-652: 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
4636-435: 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
4758-530: Is affiliated with ESPN Radio . It is one of the oldest radio stations in the Washington media market , continuously on the air from 1925. For most of its history, the station operated as WMAL ; on July 1, 2019, its talk programming was moved exclusively to co-owned WMAL-FM at 105.9 MHz , which had simulcast with 630 am since 2011. WSBN has two local hosts on weekdays, Andy Pollin in late mornings and Bram Weinstein in afternoon drive time . The rest of
4880-413: 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
5002-703: 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
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5124-565: Is a commercial AM sports radio station licensed to Washington, D.C. , and serving the Washington metro area . It operates with 10,000 watts in the daytime and 2,700 watts at night using a directional antenna around the clock. WSBN's studios are on Jenifer Street in Northwest Washington. The transmitter is located off Black Rock Road in Germantown, Maryland . WSBN is owned and operated by Cumulus Media and
5246-445: 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
5368-459: Is also available online at c-span.org and via satellite radio on SiriusXM channel 455. WCSP-FM broadcasts in the HD (digital) format. Prior to C-SPAN's acquisition of the 90.1 frequency in 1997, the station operated as WGTB-FM, the student radio station of Georgetown University , from 1960 to 1979. Increasingly contentious relations between students and university administration led Georgetown to sell
5490-433: 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
5612-525: Is broadcast on 90.1 HD1; 90.1 HD2 simulcasts C-SPAN, broadcasting coverage of the House of Representatives plus other C-SPAN programming; 90.1 HD3 simulcasts C-SPAN2, broadcasting coverage of the Senate and audio of Book TV. C-SPAN Radio broadcasts public-affairs programming, including some audio simulcasts of C-SPAN's flagship television programs like Washington Journal and some radio-only programming such as
5734-410: 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
5856-427: 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
5978-565: 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
6100-417: 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
6222-524: 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
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#17328024583336344-473: 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 WSBN WSBN (630 kHz )
6466-595: 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
6588-651: The University of Maryland was also interested, but Georgetown wanted the new owners to be based in D.C. If the UDC had turned down the bid, the Roman Catholic Archdiocese of Washington would have purchased WGTB-FM to operate as a Spanish-language station; Spanish-language WFAN (1340 AM) closed that same month after a series of indiscretions by ownership led to the revocation of its license. Station volunteer staff blamed recent troubles facing WGTB-FM on
6710-619: The Washington Commanders , then named the Washington Redskins, as an affiliate station for the first time since the team's Super Bowl XXVI win in 1992. WMAL previously carried the team's games from 1942 to 1956, and again from 1963 to 1991. WTEM (570 AM), a new sports station at the time, acquired the radio broadcast rights from WMAL for the 1992 NFL season . As of January 3, 2017, WMAL's weekday lineup consisted of local talent Brian Wilson and Mary Walter in
6832-504: 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
6954-400: 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
7076-531: 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
7198-582: The Board of Directors that we sell the license and close the station". Even as university administration tried to steer its station in a new direction, new controversies arose over its broadcast of public service announcements for the Washington Free Clinic , which distributed information about abortions and birth control, resulting in the firing of general manager Ken Sleeman. The review board seized operational and editorial control of WGTB from
7320-474: 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
7442-644: The Evening Star Broadcasting Company, until his resignation in August 1954. His replacement as general manager was Frederick S. Houwink. Also in 1954, John W. Thompson Jr. replaced S. H. Kauffman as president of Evening Star Broadcasting Co. Andrew Martin Ockershausen was appointed station manager of WMAL in 1960. One of Ockershausen's first moves was to team Frank Harden with Jackson Weaver for WMAL's morning drive show after
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#17328024583337564-520: The Georgetown campus were not being equipped to radiate the station. At the time of WGTB's debut on FM, programming included discussions on issues, taped programs from other colleges, Georgetown sports, and "every kind of music with the exception of rock and roll". Like many campus stations of its day, WGTB only broadcast during the school year. Carrier current broadcasts were discontinued in 1963, citing poor performance and high costs. Few people outside
7686-736: The Leukemia Radiothon and the Gross National Parade, which supported the D.C. Police Boys & Girls Club. In addition to providing talk programming, WMAL provided local news coverage. With morning anchor Bill Thompson, afternoon anchor Mark Weaver and the team covers news stories affecting the Washington, D.C., area. The station aired a radio talk show on November 26, 2006, to gauge his audience's reaction to saying that "force should be applied to ensure that all Muslims in America wear identifying markers...." The hoax
7808-476: The M.A. Leese Radio Corporation was acquired by publishers of the now-defunct Washington Evening Star newspaper , a family-owned concern headed by board chairman and president Samuel H. Kauffman. Norman Leese remained president and K. H. Berkeley continued as general manager of WMAL. The operating arrangement between NBC and the M.A. Leese Radio Corporation ended in February 1942. The station then reverted to
7930-560: The Trans-Lux Theatre Building, 724 14th Street NW. Transmitting facilities continued to be located at 712 Eleventh Street NW. In the late months of 1937, the lease to NBC was terminated, with station operation reverting to the Leese Family interests. NBC, however, continued to operate it under a managerial agreement executed in fall 1937. Norman Leese was president of WMAL's licensee at that time. On May 1, 1938,
8052-508: 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
8174-513: The WGTB rally marked the most protest activity on the campus since 1971. On March 12, 1980, the FCC approved the sale of WGTB-FM to UDC; the call letters were changed to WDCU on June 6. However, the 90.1 frequency remained silent for another two years following FCC approval, with the university seeking a move of the studios and transmitter. It was not until March 1982 that the station unveiled its plans for
8296-530: The ailing newspaper were acquired from the Kauffman, Noyes and Adams families by publisher Joseph L. Albritton ’s Perpetual Corporation and Albritton became board chairman and chief owner of WMAL's license. On January 21, 1976, WMAL's licensee name was changed to Washington Star Communications of Delaware, Inc. Richard S. Stakes became station president, but resigned in December 1976. Mr. Albritton then assumed
8418-405: 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
8540-437: The authority to close its financial shortfalls, combined with a $ 16 million budget deficit at UDC, it became obvious that WDCU was going to be sold. After months of speculation and rumors of interest by George Washington University , WETA and others, WDCU was put up for sale in May 1997, when the board retained a station brokerage. In late June 1997, UDC trustees voted to sell WDCU to Community Resource Educational Association,
8662-414: 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
8784-400: The campus listened; a 1968 survey showed that WGTB had the second-lowest FM listenership in Washington, only ahead of WAMU at American University . Concentration will be on selecting people who are interested in a particular area of music and providing them with complete freedom to express this interest. Peter Barry Chowka, WGTB-FM program director in 1970, on the station's move to
8906-548: The city's border with Maryland . WMAL's former transmitting facility, located in the Bradley Hills section of suburban Bethesda, Maryland , once housed studios for WMAL and WMAL-FM. Among the WMAL broadcasters over the years have been Frank Harden and Jackson Weaver , who co-hosted WMAL's morning show for more than four decades until Weaver's death in the early 1990s; Tom Gauger, who also spent several decades at WMAL on
9028-668: 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,
9150-665: The court decision at the end of the recording. The broadcasts of the Supreme Court arguments have provided listeners in the U.S. and Canada with the opportunity to hear spoken words during oral arguments for several of the Court's most influential cases, including the Texas v. Johnson argument over flag-burning in 1989, and the Miranda v. Arizona argument in 1966. In September 2010 the Supreme Court began releasing audio recordings of
9272-466: 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
9394-478: The damage had been done. In April 1978, Georgetown president Timothy S. Healy , describing WGTB as "a great animal in the wrong zoo", announced that the university planned to shutter the station and sell the facility. After approaching Duke Ellington School of the Arts , which said it was not ready to handle operations, Georgetown opted to transfer the station to the University of the District of Columbia (UDC) for $ 1;
9516-585: The direct control of the Evening Star Broadcasting Company, of which K. H. Berkeley was executive vice president. Berkeley was also WMAL's general manager. In October 1947, WMAL-TV signed on as the first high-band VHF television station in the United States. It became an ABC Network affiliate a year later. By 1946, S. H. Kauffman, president and part owner of the Evening Star , was given additional duties as president of its broadcasting subsidiary,
9638-461: The duo had a successful tryout hosting an evening comedy show patterned after Bob and Ray ; Harden and Weaver took off in popularity and quickly became the top-rated morning show in the Washington market, featuring a blend of news, interviews, light music and comedy. In 1962, Fred Houwink became a company vice president while continuing as WMAL's general manager. In 1965 Houwink was named vice president of Evening Star Broadcasting and Ockershausen
9760-490: The early period of C-SPAN Radio's existence, programming also included coverage of local events and government hearings affecting only the Washington region. A unique part of WCSP's programming is its rebroadcast of five Sunday morning talk shows , without commercials, in rapid succession. All programs on C-SPAN Radio are broadcast commercial-free. WCSP-FM is the first radio station to broadcast audiotape of historical U.S. Supreme Court oral arguments, with announcers explaining
9882-570: 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
10004-634: The famous tape-recorded Oval Office conversations from the Johnson and Nixon administrations, oral histories, and some committee meetings and press conferences not shown on television due to programming commitments. The radio station does not try to duplicate C-SPAN television coverage, and takes a more selective approach to its broadcast content. Regular programs broadcast on the radio station include Today in Washington and Prime Minister's Question Time . The station also broadcasts full gavel-to-gavel coverage of political conventions in election years. In
10126-413: 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
10248-592: 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
10370-497: The format change, WMAL changed its call letters to WSBN; prior to the change, it had been Washington's oldest station to be operating under its original call letters. WSBN signed a four-year radio broadcast rights agreement on June 15, 2022, to broadcast Baltimore Ravens games. WMAL broadcast from various facilities in Washington, D.C., and suburban Maryland until July 25, 1973, when it settled in at its current studio facility at 4400 Jenifer Street NW in Washington, two blocks from
10492-618: 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
10614-469: The initials of Martin A. Leese, a local optician who began selling radio sets at 720 11th Street NW in Washington, D.C. He started WMAL as a low-power station. The shutdown of station WCAP left Washington with WRC (now WTEM ) as its only high-power station, so local business leaders affiliated with the City Club of Washington banded together to create a second high-powered station. Their original plan
10736-411: The license to the University of the District of Columbia , which operated a jazz-format station as WDCU from 1982 to 1997. On May 25, 1960, Georgetown University received a construction permit to build a new noncommercial radio station which would operate with 771 watts on 90.1 MHz, a move five years in the planning. WGTB had operated since 1946 as a carrier current station, but new buildings on
10858-402: 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
10980-448: The mid-day shift from 10am-3pm; Bill Trumbull was the afternoon drivetime host and paired with several others through two decades, Felix Grant's evening show featured traditional jazz. Grant is credited with introducing Brazil's "bossa nova" music to the US. Arthur Godfrey , a national radio and early-TV personality who briefly broadcast on WMAL in 1933 as "Red" Godfrey; Bill Mayhugh, a mellow-voiced overnight broadcaster; and Ken Beatrice ,
11102-560: The morning, then Chris Plante, followed by the syndicated Rush Limbaugh, then Larry O'Connor hosts a local afternoon drive show, followed by the syndicated shows of Mark Levin , John Batchelor , and overnight the syndicated show Red Eye Radio , hosted by Eric Harley and Gary McNamara . Brian Wilson was released in May 2017. In 2015, Cumulus announced that it was planning to sell the station's 75 acre (30 hectare) Bethesda, Maryland transmitter site, in use since 1941, so it could be redeveloped for high-end housing. On May 12, 2016, WMAL
11224-472: 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
11346-505: 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
11468-563: The presidency, with Robert Nelson becoming president of the broadcasting division. General Manager Charles Macatee resigned in January 1977. A requirement of the purchase of the Evening Star properties included the sale of the radio or television properties. In March 1977, WMAL and WMAL-FM were spun off to ABC Radio, while the TV station was retained and became WJLA-TV , named after Albritton's initials. ABC paid $ 16 million for WMAL and WMAL-FM,
11590-451: 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,
11712-409: 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
11834-451: 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
11956-456: 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
12078-578: The renewal in April 1976. Another group, the Catholic University of America , examined entering the fray but opted against it. CSAR members blasted the new WGTB, which returned to the air in June, as "a sterile college radio station" and even picked up former station host and district councilman John A. Wilson as an ally. WGTB returned to the air, and its license was renewed in November 1977, but
12200-477: The sale at the FCC, including formal petitions by NPR and the Media Access Project . The opposition prompted Salem to ask C-SPAN, which had previously bid $ 10.5 million, if it was willing to increase its bid to $ 13 million and buy out Salem's portion of the contract; the move alleviated some of the pressure on the university, though it still displaced all of WDCU's jazz and specialty shows. Once
12322-481: 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
12444-501: The same time, Scarborough's show was put on extended hiatus. Austin Hill began filling in the middays for the time being, while Mark Simone handled Scarborough's shift. Grandy left WMAL in March 2011. On September 19, 2011, WMAL began simulcasting its AM signal on 105.9 FM, now WMAL-FM . The former WMAL-FM, renamed WRQX in 1977, has since become WLVW ; it remained co-owned with WMAL until 2019. In 2017, WMAL started broadcasting games from
12566-571: The schedule is largely made up of programs from ESPN Radio . As of 2022, WSBN broadcasts the games of the Baltimore Ravens and Virginia Cavaliers football and men's basketball . It announced on March 24, 2021, that it joined the Baltimore Orioles Radio Network as an affiliate station beginning with the upcoming season . WMAL first went on the air on October 12, 1925, using call letters incorporating
12688-652: The station board, removing records with sensitive language from airplay and leading to a full special edition of student newspaper The Hoya . Georgetown leadership began to examine its options for the station; while students overwhelmingly sought its continued operation, one administrator fretted that the money needed to make the station "productive to the University" could turn it into a financial liability, and others warned that if GU exited broadcasting by selling WGTB-FM, it would be very difficult to return. In February 1976, new obscenity complaints emerged, this time about
12810-515: The station manager that been brought on board following the 1976 shutdown. Despite the formation of an Alliance to Preserve Radio at Georgetown that opposed the UDC sale, WGTB-FM went off the air at 12:34 p.m. on January 31, 1979, as a crowd of 400 people protested in Healy Circle , with most of them marching to FCC headquarters. Together with protests about United States involvement in Iran,
12932-437: The station was purchased, broadcasting of C-SPAN Radio on WCSP-FM began on October 9, 1997. There are people all over this country who are addicted to C-SPAN, and especially in this town. Now they can listen during all those hours they spend in the car. Leo Hindery , president of the board of C-SPAN, on the launch of C-SPAN Radio in 1997 C-SPAN Radio expanded its coverage by signing programming agreements in 1998 with
13054-624: The station, and Kenneth H. Berkeley was appointed station director of WMAL in 1933. While still owned by the Leese family, WMAL was eventually leased to the National Broadcasting Company in 1934, joining it with owned-and-operated station WRC. NBC's Washington vice president Frank M. Russell supervised the operation of both WMAL and WRC by 1935 when studios were moved from the National Press Building to
13176-677: The station, and the following year the Federal Radio Commission 's national frequency allocation plan assigned WMAL the AM 630 frequency. WMAL was a CBS Radio Network affiliate from 1928 until October 19, 1932, and then was briefly unaffiliated until joining the NBC Blue Network in January 1933. The Blue Network later became ABC , with which WMAL was affiliated for many years, and which owned WMAL for several decades. By mid-1932, M. R. Baker had been appointed manager of
13298-435: The station, though this was still a higher share than WMAL , then the city's leading commercial station with 18 percent of the market. President Henle ordered a new reorganization in 1975, which put the station under the control of a six-member review board; in doing so, he warned, "if the station cannot be made to contribute to the educational and religious mission of this University, then after another year, I will recommend to
13420-431: 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
13542-458: The two subscription-only satellite radio systems: CD Radio (later renamed Sirius Satellite Radio ) and General Motors ' XM Satellite Radio , bringing the station to a nationwide audience in 2001. Temporarily for a year during the Sirius XM merger in 2007 and 2008, it was not heard on Sirius, and it is not currently available on radios only compatible with the older Sirius system. The station
13664-510: 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
13786-721: The week's oral arguments each Friday, thereby allowing C-SPAN Radio to broadcast a selection of current arguments. Prior to this arrangement, recordings of oral arguments were occasionally made available on a same-day basis, which C-SPAN would request in cases of high public interest. When the court began live telephonic oral arguments during the COVID-19 pandemic , C-SPAN Radio began carrying those. 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
13908-544: Was Thomas Bresnahan, who continued in that role until his retirement in 2002. WMAL morning co-host Jackson Weaver died on October 20, 1992, with Harden and Weaver still at or near the top of the local ratings; Weaver also garnered fame nationally as the first voice of Smokey Bear . Frank Harden continued the morning show with co-hosts Tim Brant and Andy Parks until his retirement in 1998. Brant and Parks continued until Brant's departure in May 2002, his replacement would be former congressman Fred Grandy . In 1996, WMAL won
14030-598: 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
14152-571: Was added to XM Radio Canada on April 1, 2007. The FM range of the radio station extends as far north as Hanover, Pennsylvania , south around 15 miles beyond Fredericksburg, Virginia , west to 5 miles east of Front Royal, Virginia , and east to Cambridge, Maryland . C-SPAN offers three channels of programming for listeners within the FM signal radius with HD radios, using digital technology to multicast all three channels at 90.1 FM. The three channels offer different programming: WCSP-FM's usual programming
14274-429: Was dropped in February 2009 due to Levin's show expanding and Sliwa's show moving up an hour. Plante, a popular talk host who hosted evenings and later middays, was yanked in favor of Joe Scarborough 's Morning Joe in April 2009, only to return to middays six months later after Scarborough's show was cancelled. By late 2009, WMAL's morning-drive through midnight weekday format was uninterrupted conservative talk, with
14396-402: Was elevated to general manager of WMAL. In 1970 Houwink retired and Ockershausen was named vice president, operations. Also in 1970 Richard S. Stakes was named general manager and Harold L. Green was named station manager. In 1974 Charles A. Macatee became WMAL's general manager. In early January 1976, the Evening Star Broadcasting Company's WMAL, WMAL-FM and WMAL-TV and majority control of
14518-497: Was fired after refusing to apologize for calling the Council on American-Islamic Relations (CAIR) a "terrorist organization." ABC sold its non- Radio Disney and ESPN Radio stations, including WMAL, to Citadel Broadcasting in 2007; Citadel merged with Cumulus Media on September 16, 2011. Longtime Washington broadcaster Chris Core was dismissed from WMAL in 2008 as part of a broad cost-cutting move; his replacement, Austin Hill
14640-428: Was granted a Federal Communications Commission construction permit for a transmitter site relocation. Transmissions from Bethesda ceased on the afternoon of May 1, 2018, with operations switched to the replacement facility at Germantown, Maryland , northwest of the original site and now diplexed with an existing station, WSPZ (later WWRC ). Although daytime power remained at 10,000 watts, this relocation resulted in
14762-489: Was to buy WCAP and convert it to a municipal station, but instead they worked with Leese to boost WMAL's signal and make it the city's second large station. The new high-power WMAL went on the air from studios at 710-712 11th Street NW on October 2, 1926, with former WCAP announcer William T. Pierson as director and with a policy of encouraging young broadcasting talent in hopes of creating "a people's forum". In 1927, Leese left his optical business to focus full-time on running
14884-492: Was to move the transmitter off the campus: it was relocated to the American University campus in 1973. The station's rock format also attracted renewed attention over its service to the community versus its responsiveness to the needs of students. Critics inside and outside student government pushed for changes to the format, such as basketball game broadcasts, and noted that just 30 percent of students listened to
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