1.
AM Radio (song)
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AM Radio is a rock song by the band Everclear. The song was recorded c.2000 for Everclears fourth album Songs from an American Movie Vol. One, the song was released as the second single from Everclears album Songs from an American Movie Vol. One, Learning How to Smile. It failed to reach the Billboard Hot 100, getting to one on the Bubbling Under Hot 100 Singles chart. The song was used in a television commercial for General Motors in early 2006. The song begins with a 1970s vintage jingle from Los Angeles radio station KHJ and it also contains a short sample of Those Were the Days, the theme song of the American sitcom All in the Family. However, certain versions of the song, including the version on later pressings of Songs from an American Movie Vol. One, Learning How to Smile omit the sample. The lyrics make reference to several items of 1970s nostalgia, the Ford Pinto, 8-track tapes, the television shows Good Times and Chico and the Man. The song was used as a tribute to AM Radio Top 40 by John Records Landecker to open his Memorial Day show on the 2008 WLS Big 89 Rewind. WLS in Chicago was one of the leading AM giants in Top 40 radio from the 1960s to the mid-1980s when it dropped music for all talk, the music video starts off with a radio announcer reading the recorded programming disclaimer from the KHJ sample, without the jingle. It then shows the band, along with some extra brass players, at first, the screen shows a bunch of smileys. A few scenes actually have members of Everclear doing 1970s things, art Alexakis is wearing a Portland Trail Blazers jersey in honor of that citys professional basketball team. Greg Eklund is wearing a Los Angeles Lakers jersey, camp Chaos Entertainment also created an animated cartoon version of the music video in SWF format. AM Radio Im On Your Time Santa Monica
2.
AM Radio (band)
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AM Radio is an American alternative rock band from Los Angeles, California. AM Radio, formed in Los Angeles in late 2001 and were formed by former Ridel High songwriter Kevin Ridel after his previous band Peel ended, the band were helped forming by Weezer frontman Rivers Cuomo, Rivers also managed the band for a short time until 2003. In 2002, Weezer frontman Rivers Cuomo and invited AM Radio to open for Weezers big summer tours Dusty West Tour, Japan World Cup Tour, and the Enlightenment Tour. After building serious road credibility with Weezer, Third Eye Blind, Eve 6 and The Psychedelic Furs, AM Radio was signed by Elektra Records, the release of Radioactive was supported by singles Taken for a Ride and I Just Wanna Be Loved. I Just Wanna Be Loved was featured on Smallville, a hit TV series on The WB, also in 2003, Taken for a Ride was featured on the videogame soundtrack for EA Sports’ John Madden Football 2003. The band received support from The WB when Taken for a Ride was featured on an episode of One Tree Hill. The song also appeared on a trailer for the FOX feature film The Girl Next Door that same year. Following their major label release Radioactive the band recorded demos for a planned 3rd album. Ridel signed with Sony Publishing Japan and pursued other Japanese side projects as well, the duo then restarted AM Radio in mid/2008 and pursued both groups. In December of that year, it was announced that AM Radio would record a new album. About a year later, in November, Bigger Better Bolder Brighter was released without the help of a record label, Ridel described their writing process for this album on the bands MySpace blog, Were using a new songwriting formula for this one. First, Jason writes and records the music, then he sends it over for me to sing and put lyrics to. Its really a fun and inspiring process, js tracks make me stand up and shout, Yea. In the same entry, Ridel called the albums title ironic. He said, The working title Bigger Better Bolder Brighter is ironic in that we are recording the album on our home computers
3.
Radio broadcasting
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Radio broadcasting is a unidirectional wireless transmission over radio waves intended to reach a wide audience. Stations can be linked in radio networks to broadcast a radio format. Audio broadcasting also can be done via radio, local wire television networks, satellite radio. The signal types can be either analog audio or digital audio, the earliest radio stations were simply radiotelegraphy systems and did not carry audio. For audio broadcasts to be possible, electronic detection and amplification devices had to be incorporated, the thermionic valve was invented in 1904 by the English physicist John Ambrose Fleming. He developed a device he called an oscillation valve, the heated filament, or cathode, was capable of thermionic emission of electrons that would flow to the plate when it was at a higher voltage. Electrons, however, could not pass in the direction because the plate was not heated. Later known as the Fleming valve, it could be used as a rectifier of alternating current and this greatly improved the crystal set which rectified the radio signal using an early solid-state diode based on a crystal and a so-called cats whisker. However, what was required was an amplifier. The triode was patented on March 4,1906, by the Austrian Robert von Lieben independent from that, on October 25,1906 and it wasnt put to practical use until 1912 when its amplifying ability became recognized by researchers. By about 1920, valve technology had matured to the point where radio broadcasting was quickly becoming viable, however, an early audio transmission that could be termed a broadcast may have occurred on Christmas Eve in 1906 by Reginald Fessenden, although this is disputed. Charles Herrold started broadcasting in California in 1909 and was carrying audio by the next year, in The Hague, the Netherlands, PCGG started broadcasting on November 6,1919, making it, arguably the first commercial broadcasting station. In 1916, Frank Conrad, an engineer employed at the Westinghouse Electric Corporation, began broadcasting from his Wilkinsburg. Later, the station was moved to the top of the Westinghouse factory building in East Pittsburgh, Westinghouse relaunched the station as KDKA on November 2,1920, as the first commercially licensed radio station in America. The commercial broadcasting designation came from the type of broadcast license, the first licensed broadcast in the United States came from KDKA itself, the results of the Harding/Cox Presidential Election. In 1920, wireless broadcasts for entertainment began in the UK from the Marconi Research Centre 2MT at Writtle near Chelmsford, England. A famous broadcast from Marconis New Street Works factory in Chelmsford was made by the famous soprano Dame Nellie Melba on 15 June 1920 and she was the first artist of international renown to participate in direct radio broadcasts. The 2MT station began to broadcast regular entertainment in 1922, the BBC was amalgamated in 1922 and received a Royal Charter in 1926, making it the first national broadcaster in the world, followed by Czech Radio and other European broadcasters in 1923
4.
Amplitude modulation
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Amplitude modulation is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. In amplitude modulation, the amplitude of the wave is varied in proportion to the waveform being transmitted. That waveform may, for instance, correspond to the sounds to be reproduced by a loudspeaker and this technique contrasts with frequency modulation, in which the frequency of the carrier signal is varied, and phase modulation, in which its phase is varied. AM was the earliest modulation method used to transmit voice by radio and it was developed during the first two decades of the 20th century beginning with Roberto Landell De Moura and Reginald Fessendens radiotelephone experiments in 1900. It remains in use today in many forms of communication, for example it is used in two way radios, VHF aircraft radio, Citizens Band Radio, and in computer modems. AM is often used to refer to mediumwave AM radio broadcasting, when it reaches its destination, the information signal is extracted from the modulated carrier by demodulation. In amplitude modulation, the amplitude or strength of the oscillations is what is varied. For example, in AM radio communication, a continuous wave signal has its amplitude modulated by an audio waveform before transmission. The audio waveform modifies the amplitude of the wave and determines the envelope of the waveform. In the frequency domain, amplitude modulation produces a signal with power concentrated at the carrier frequency, each sideband is equal in bandwidth to that of the modulating signal, and is a mirror image of the other. Standard AM is thus sometimes called double-sideband amplitude modulation to distinguish it more sophisticated modulation methods also based on AM. One disadvantage of all amplitude modulation techniques is that the receiver amplifies and detects noise, increasing the received signal to noise ratio, say, by a factor of 10, thus would require increasing the transmitter power by a factor of 10. For this reason AM broadcast is not favored for music and high fidelity broadcasting, another disadvantage of AM is that it is inefficient in power usage, at least two-thirds of the power is concentrated in the carrier signal. The carrier signal contains none of the information being transmitted. However its presence provides a means of demodulation using envelope detection, providing a frequency. The receiver may regenerate a copy of the frequency from a greatly reduced pilot carrier to use in the demodulation process. Even with the carrier totally eliminated in double-sideband suppressed-carrier transmission, carrier regeneration is possible using a Costas phase-locked loop and this doesnt work however for single-sideband suppressed-carrier transmission, leading to the characteristic Donald Duck sound from such receivers when slightly detuned. Single sideband is used widely in amateur radio and other voice communications both due to its power efficiency and bandwidth efficiency
5.
Medium wave
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Medium wave is the part of the medium frequency radio band used mainly for AM radio broadcasting. Practical groundwave reception typically extends to 200–300 miles, with distances over terrain with higher ground conductivity. Most broadcast stations use groundwave to cover their listening area, Medium waves can also reflect off charged particle layers in the ionosphere and return to Earth at much greater distances, this is called the skywave. At night, especially in winter months and at times of low solar activity, when this happens, MF radio waves can easily be received many hundreds or even thousands of miles away as the signal will be reflected by the higher F layer. This can allow very long-distance broadcasting, but can also interfere with distant local stations, due to the limited number of available channels in the MW broadcast band, the same frequencies are re-allocated to different broadcasting stations several hundred miles apart. On nights of good skywave propagation, the signals of distant station may interfere with the signals of local stations on the same frequency. These channels are called clear channels, and they are required to broadcast at higher powers of 10 to 50 kW and this arrangement had numerous practical difficulties. The Commerce Department rarely intervened in such cases but left it up to stations to enter into voluntary timesharing agreements amongst themselves, the addition of a third entertainment wavelength,400 meters, did little to solve this overcrowding. In 1923, the Commerce Department realized that as more and more stations were applying for commercial licenses, on 15 May 1923, Commerce Secretary Herbert Hoover announced a new bandplan which set aside 81 frequencies, in 10 kHz steps, from 550 kHz to 1350 kHz. Each station would be assigned one frequency, no longer having to broadcast weather, class A and B stations were segregated into sub-bands. Today in most of the Americas, mediumwave broadcast stations are separated by 10 kHz and have two sidebands of up to ±5 kHz in theory, in the rest of the world, the separation is 9 kHz, with sidebands of ±4.5 kHz. Both provide adequate quality for voice, but are insufficient for high-fidelity broadcasting. In the US and Canada the maximum power is restricted to 50 kilowatts. Those stations which shut down completely at night are known as daytimers. In most cases there are two limits, a lower one for omnidirectional and a higher one for directional radiation with minima in certain directions. The power limit can also be depending on daytime and it is possible, other countries may only operate low-powered transmitters on the same frequency, again subject to agreement. For example, Russia operates a transmitter, located in its Kaliningrad exclave and used for external broadcasting. Due to the demand for frequencies in Europe, many countries operate single frequency networks, in Britain
6.
Longwave
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In radio, longwave, also written as long wave or long-wave, and commonly abbreviated LW, refers to parts of the radio spectrum with relatively long wavelengths. The term is an one, dating from the early 20th century, when the radio spectrum was considered to consist of long, medium. Most modern radio systems and devices use wavelengths which would then have been considered ultra-short, in contemporary usage, the term longwave is not defined precisely, and its meaning varies across the world. Sometimes, part of the frequency band is included. The International Telecommunication Union Region 1 longwave broadcast band falls wholly within the low band of the radio spectrum. Broader definitions of longwave may extend below and/or above it, in the US, the Longwave Club of America is interested in frequencies below the AM broadcast band, i. e. all frequencies below 535 kHz. Because of their wavelength, radio waves in this frequency range can diffract over obstacles like mountain ranges and travel beyond the horizon. This mode of propagation, called ground wave, is the mode in the longwave band. The attenuation of signal strength with distance by absorption in the ground is lower than at higher frequencies, Low frequency ground waves can be received up to 2,000 kilometres from the transmitting antenna. Low frequency waves can also travel long distances by reflecting from the ionosphere, although this method. Reflection occurs at the ionospheric E layer or F layers, skywave signals can be detected at distances exceeding 300 kilometres from the transmitting antenna. Non-directional beacons transmit continuously for the benefit of radio direction finders in marine and they identify themselves by a callsign in Morse code. They can occupy any frequency in the range 190–1750 kHz, in North America, they occupy 190–535 kHz. In ITU Region 1 the lower limit is 280 kHz, there are government broadcast stations in the range 40–80 kHz that transmit coded time signals to radio clocks. Radio controlled clocks receive their time calibration signals with built-in long-wave receivers, long-waves travel by groundwaves that hug the surface of the earth, unlike medium-waves and short-waves. Those higher-frequency signals do not follow the surface of the Earth beyond a few kilometers and these different propagation paths can make the time lag different for every signal received. The military of the United Kingdom, Russian Federation, United States, Germany, in North America during the 1970s, the frequencies 167,179 and 191 kHz were assigned to the short-lived Public Emergency Radio of the United States. Nowadays, in the United States, Part 15 of FCC regulations allow unlicensed use of 136 kHz and this is called Low Frequency Experimental Radio
7.
Shortwave radio
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Shortwave radio is radio transmission using shortwave frequencies, generally 1. 6–30 MHz, just above the medium wave AM broadcast band. Radio waves in this band can be reflected or refracted from a layer of charged atoms in the atmosphere called the ionosphere. Therefore, short waves directed at an angle into the sky can be reflected back to Earth at great distances and this is called skywave or skip propagation. Shortwave radio is used for broadcasting of voice and music to listeners over very large areas. It is also used for military radar, diplomatic communication. The widest popular definition of the frequency interval is the ITU Region 1 definition, and is the span 1. 6–30 MHz, just above the medium wave band. In reality, the definition of the frequency band is a mess. The broadcast medium wave band now extends above the 200 m/1500 kHz limit, early radio telegraphy had used long wave transmissions. The drawbacks to this included a very limited spectrum available for long distance communication. It was also difficult to beam the radio wave directionally with long wave, prior to the 1920s, the shortwave frequencies above 1.5 MHz were regarded as useless for long distance communication and were designated in many countries for amateur use. Franklin rigged up an antenna at Poldhu Wireless Station, Cornwall. In June and July 1923, wireless transmissions were completed during nights on 97 meters from Poldhu to Marconis yacht Elettra in the Cape Verde Islands, in September 1924, Marconi transmitted daytime and nighttime on 32 meters from Poldhu to his yacht in Beirut. Franklin went on to refine the directional transmission, by inventing the curtain array aerial system, the UK-to-Canada shortwave Beam Wireless Service went into commercial operation on 25 October 1926. Beam Wireless Services from the UK to Australia, South Africa, Shortwave communications began to grow rapidly in the 1920s, similar to the internet in the late 20th century. Shortwave also ended the need for investments in massive longwave wireless stations. The cable companies began to lose large sums of money in 1927, the British government convened the Imperial Wireless and Cable Conference in 1928 to examine the situation that had arisen as a result of the competition of Beam Wireless with the Cable Services. The name of the company was changed to Cable and Wireless Ltd. in 1934, long-distance cables had a resurgence beginning in 1956 with the laying of TAT-1 across the Atlantic Ocean, the first voice frequency cable on this route. This provided 36 high quality telephone channels and was followed by even higher capacity cables all around the world
8.
Vacuum tube
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In electronics, a vacuum tube, an electron tube, or just a tube, or valve, is a device that controls electric current between electrodes in an evacuated container. Vacuum tubes mostly rely on thermionic emission of electrons from a hot filament or a cathode heated by the filament and this type is called a thermionic tube or thermionic valve. A phototube, however, achieves electron emission through the photoelectric effect, the simplest vacuum tube, the diode, contains only a heater, a heated electron-emitting cathode, and a plate. Current can only flow in one direction through the device between the two electrodes, as electrons emitted by the travel through the tube and are collected by the anode. Adding one or more control grids within the tube allows the current between the cathode and anode to be controlled by the voltage on the grid or grids, Tubes with grids can be used for many purposes, including amplification, rectification, switching, oscillation, and display. In the 1940s the invention of devices made it possible to produce solid-state devices, which are smaller, more efficient, more reliable, more durable. Hence, from the mid-1950s solid-state devices such as transistors gradually replaced tubes, the cathode-ray tube remained the basis for televisions and video monitors until superseded in the 21st century. However, there are still a few applications for which tubes are preferred to semiconductors, for example, the used in microwave ovens. One classification of vacuum tubes is by the number of active electrodes, a device with two active elements is a diode, usually used for rectification. Devices with three elements are used for amplification and switching. Additional electrodes create tetrodes, pentodes, and so forth, which have additional functions made possible by the additional controllable electrodes. X-ray tubes are vacuum tubes. Phototubes and photomultipliers rely on electron flow through a vacuum, though in those cases electron emission from the cathode depends on energy from photons rather than thermionic emission, since these sorts of vacuum tubes have functions other than electronic amplification and rectification they are described in their own articles. A vacuum tube consists of two or more electrodes in a vacuum inside an airtight enclosure, most tubes have glass envelopes, though ceramic and metal envelopes have been used. The electrodes are attached to leads which pass through the envelope via an airtight seal, Tubes were a frequent cause of failure in electronic equipment, and consumers were expected to be able to replace tubes themselves. In addition to the terminals, some tubes had an electrode terminating at a top cap. The principal reason for doing this was to avoid leakage resistance through the tube base, the bases were commonly made with phenolic insulation which performs poorly as an insulator in humid conditions. There was even a design that had two top cap connections
9.
Golden Age of Radio
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The old-time radio era, sometimes referred to as the Golden Age of Radio, was an era of radio programming in the United States during which radio was the dominant electronic home entertainment medium. It began with the beginning of broadcasting in the early 1920s and lasted until the 1950s. During this period radio was the only broadcast medium, and people regularly tuned into their favourite radio programs, according to a 1947 C. E. Hooper survey,82 out of 100 Americans were found to be radio listeners. Since this era, radio programming has shifted to a narrow format of news, talk, sports. It allowed subscribers to eavesdrop on live performances and hear news reports by means of a network of telephone lines. The development of radio eliminated the wires and subscription charges from this concept, on Christmas Eve 1906, Reginald Fessenden is said to have broadcast the first radio program, consisting of some violin playing and passages from the Bible. The first apparent published reference to the event was made in 1928 by H. P, davis, Vice President of Westinghouse, in a lecture given at Harvard University. In 1932 Fessenden cited the Christmas Eve 1906 broadcast event in a letter he wrote to Vice President S. M, Fessendens wife Helen recounts the broadcast in her book Fessenden, Builder of Tomorrows, eight years after Fessendens death. The issue of whether the 1906 Fessenden broadcast actually happened is discussed in Donna Halpers article In Search of the Truth About Fessenden and also in James ONeals essays. It was not until after the Titanic catastrophe in 1912 that radio for communication came into vogue. Radio was especially important during World War I as it was vital for air, after the war, numerous radio stations were born in the United States and set the standard for later radio programs. The first radio program was broadcast on August 31,1920 on the station 8MK in Detroit, owned by The Detroit News. This was followed in 1920 with the first commercial station in the United States, KDKA. The first regular entertainment programs were broadcast in 1922, and on March 10, Variety carried the front page headline, a highlight of this time was the first Rose Bowl being broadcast on January 1,1923 on the Los Angeles station KHJ. Several radio networks broadcast in the United States, airing programs nationwide and their distribution made the golden age of radio possible. The networks declined in the early 1960s, Mutual and NBC both closed down their operations in the 1980s, while ABC lasted until 2007 and CBS still operates its network as of 2016. Mutual, ABC and NBCs radio assets now reside with Cumulus Medias Westwood One division through numerous mergers, cBSs radio assets are in the process of being integrated with Entercom as of 2017. Mutual was run as a cooperative in which the stations owned the network
10.
FM broadcasting
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FM broadcasting is a method of radio broadcasting using frequency modulation technology. Invented in 1933 by American engineer Edwin Armstrong, it is used worldwide to provide high-fidelity sound over broadcast radio, FM broadcasting is capable of better sound quality than AM broadcasting, the chief competing radio broadcasting technology, so it is used for most music broadcasts. FM radio stations use the VHF frequencies, the term FM band describes the frequency band in a given country which is dedicated to FM broadcasting. Throughout the world, the FM broadcast band falls within the VHF part of the radio spectrum. Usually 87.5 to 108.0 MHz is used, or some portion thereof, with few exceptions, In the former Soviet republics, and some former Eastern Bloc countries, assigned frequencies are at intervals of 30 kHz. This band, sometimes referred to as the OIRT band, is slowly being phased out in many countries, in those countries the 87. 5–108.0 MHz band is referred to as the CCIR band. In Japan, the band 76–95 MHz is used, the frequency of an FM broadcast station is usually an exact multiple of 100 kHz. In most of South Korea, the Americas, the Philippines, in some parts of Europe, Greenland and Africa, only even multiples are used. In the UK odd or even are used, in Italy, multiples of 50 kHz are used. There are other unusual and obsolete FM broadcasting standards in countries, including 1,10,30,74,500. Random noise has a triangular spectral distribution in an FM system and this can be offset, to a limited extent, by boosting the high frequencies before transmission and reducing them by a corresponding amount in the receiver. Reducing the high frequencies in the receiver also reduces the high-frequency noise. These processes of boosting and then reducing certain frequencies are known as pre-emphasis and de-emphasis, the amount of pre-emphasis and de-emphasis used is defined by the time constant of a simple RC filter circuit. In most of the world a 50 µs time constant is used, in the Americas and South Korea,75 µs is used. This applies to both mono and stereo transmissions, for stereo, pre-emphasis is applied to the left and right channels before multiplexing. They cannot be pre-emphasized as much because it would cause excessive deviation of the FM carrier, systems more modern than FM broadcasting tend to use either programme-dependent variable pre-emphasis, e. g. dbx in the BTSC TV sound system, or none at all. Long before FM stereo transmission was considered, FM multiplexing of other types of audio level information was experimented with. Edwin Armstrong who invented FM was the first to experiment with multiplexing and these original FM multiplex subcarriers were amplitude modulated
11.
Digital audio broadcasting
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Digital audio broadcasting is a digital radio standard for broadcasting digital audio radio services, used in several countries across Europe and Asia Pacific. The DAB standard was initiated as a European research project in the 1980s, the Norwegian Broadcasting Corporation launched the first DAB channel in the world on 1 June 1995, and the BBC and Swedish Radio launched their first DAB digital radio broadcasts in September 1995. DAB receivers have been available in many countries since the end of the 1990s, DAB may offer more radio programmes over a specific spectrum than analogue FM radio. Audio quality varies depending on the used and audio material. Most stations use a bit rate of 128 kbit/s or less with the MP2 audio codec, which requires 160 kbit/s to achieve perceived FM quality. 128 kbit/s gives better dynamic range or signal-to-noise ratio than FM radio, but a more smeared stereo image, however, CD quality sound with MP2 is possible with 256…192 kbps. An upgraded version of the system was released in February 2007, DAB is not forward compatible with DAB+, which means that DAB-only receivers are not able to receive DAB+ broadcasts. However, broadcasters can mix DAB and DAB+ programs inside the same transmission, DAB+ is approximately twice as efficient as DAB, and more robust. In spectrum management, the bands that are allocated for public DAB services, are abbreviated with T-DAB, where the T stands for terrestrial. More than 30 countries provide DAB transmissions, and several countries, such as Norway, UK, Australia, Italy, Malta, Switzerland, The Netherlands, in many countries it is expected that DAB will gradually replace FM radio. Norway was the first country to announce national FM radio analog switchoff starting from 2017, DAB has been under development since 1981 at the Institut für Rundfunktechnik. In 1985 the first DAB demonstrations were held at the WARC-ORB in Geneva, later DAB was developed as a research project for the European Union, which started in 1987 on initiative by a consortium formed in 1986. The MPEG-1 Audio Layer II codec was created as part of the EU147 project, a choice of audio codec, modulation and error-correction coding schemes and first trial broadcasts were made in 1990. Public demonstrations were made in 1993 in the United Kingdom, the protocol specification was finalized in 1993 and adopted by the ITU-R standardization body in 1994, the European community in 1995 and by ETSI in 1997. Pilot broadcasts were launched in countries in 1995. The UK was the first country to receive a range of radio stations via DAB. Commercial DAB receivers began to be sold in 1999 and over 50 commercial, the standard was coordinated by the European DAB forum, formed in 1995 and reconstituted to the World DAB Forum in 1997, which represents more than 30 countries. In 2006 the World DAB Forum became the World DMB Forum which now presides over both the DAB and DMB standard, in October 2005, the World DMB Forum instructed its Technical Committee to carry out the work needed to adopt the AAC+ audio codec and stronger error correction coding
12.
Satellite radio
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Satellite radio is – according to article 1.39 of the International Telecommunication Union´s ITU Radio Regulations – a Broadcasting-satellite service. The satellites signals are broadcast nationwide, across a wider geographical area than terrestrial radio stations. It is available by subscription, mostly free, and offers subscribers more stations. Satellite radio technology was inducted into the Space Foundation Space Technology Hall of Fame in 2002, Satellite radio uses the 2.3 GHz S band in North America for nationwide digital audio broadcasting. In other parts of the world, satellite radio uses the 1.4 GHz L band allocated for DAB, Sirius Satellite Radio was founded by Martine Rothblatt, David Margolese and Robert Briskman. In June 1990, Rothblatts shell company, Satellite CD Radio, Inc. petitioned the Federal Communications Commission to assign new frequencies for satellites to broadcast digital sound to homes and cars. The company identified and argued in favor of the use of the S-band frequencies that the FCC subsequently decided to allocate to digital audio broadcasting, the National Association of Broadcasters contended that satellite radio would harm local radio stations. In April 1992, Rothblatt resigned as CEO of Satellite CD Radio and former NASA engineer Robert Briskman, six months later, Rogers Wireless co-founder David Margolese, who had provided financial backing for the venture, acquired control of the company and succeeded Briskman. XM was founded by Lon Levin and Gary Parsons, who served as chairman until November 2009, CD Radio purchased their license for $83.3 million, and American Mobile Radio Corporation bought theirs for $89.9 million. Digital Satellite Broadcasting Corporation and Primosphere were unsuccessful in their bids for licenses, sky Highway Radio Corporation had also expressed interest in creating a satellite radio network, before being bought out by CD Radio in 1993 for $2 million. In November 1999, Margolese changed the name of CD Radio to Sirius Satellite Radio, xM’s first satellite was launched on March 18,2001 and its second on May 8,2001. Its first broadcast occurred on September 25,2001, nearly four months before Sirius, Sirius launched the initial phase of its service in four cities on February 14,2002, expanding to the rest of the contiguous United States on July 1,2002. The two companies spent over $3 billion combined to develop satellite radio technology, build and launch the satellites, stating that it was the only way satellite radio could survive, Sirius and XM announced their merger on February 19,2007, becoming Sirius XM Radio. The FCC approved the merger on July 25,2008, concluding that it was not a monopoly, primarily due to Internet audio-streaming competition, XM satellite radio was launched in Canada on November 29,2005. Sirius followed two days later on December 1,2005, Sirius Canada and XM Radio Canada announced their merger into Sirius XM Canada on November 24,2010. It was approved by the Canadian Radio-television and Telecommunications Commission on April 12,2011, ondas Media was a Spanish company which had proposed to launch a subscription-based satellite radio system to serve Spain and much of Western Europe, but failed to acquire licenses throughout Europe. WorldSpace was founded by Ethiopia-born lawyer Noah Samara in Washington, D. C. in 1990, on June 22,1991, the FCC gave WorldSpace permission to launch a satellite to provide digital programming to Africa and the Middle East. WorldSpace first began broadcasting radio on October 1,1999
13.
HD Radio
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It was selected by the U. S. It is officially known as NRSC-5, with the latest version being NRSC-5-C, other digital radio systems include FMeXtra, Digital Audio Broadcasting, Digital Radio Mondiale, and Compatible AM-Digital. Although HD Radio broadcastings content is currently subscription-free, listeners must purchase new receivers in order to receive the portion of the signal. As of May 2009, there were stations in the world on the air with HD Radio technology than any other digital radio technology. More than 1,700 stations covering approximately 84% of the United States are broadcasting with this technology, according to iBiquitys website, the HD is simply a brand name and has no meaning. There is no connection with television, although like digital television the HD Radio specification provides enhanced capabilities over the analog format. Thus, there is no deadline by which consumers must buy an HD Radio receiver, in addition, there are many more analog AM/FM radio receivers than there were analog televisions, and many of these are car stereos or portable units that cannot be upgraded. Digital information is transmitted using OFDM with a compression algorithm called HDC. The cost of converting a radio station can run between $100,000 and $200,000, if the primary digital signal is lost the HD Radio receiver will revert to the analog signal, thereby providing seamless operation between the newer and older transmission methods. The extra HD-2 and HD-3 streams are not simulcast on analog, alternatively the HD Radio signal can revert to a more-robust 20 kilobit per second stream, though the sound is reduced to AM-like quality. Datacasting is also possible, with metadata providing song titles or artist information, by using spectral band replication the HDC+SBR codec is able to simulate the recreation of sounds up to 15,000 Hz, thus achieving moderate quality on the bandwidth-tight AM band. The HD Radio AM hybrid mode offers two options which can carry approximately 40 or 60 kbit/s of data, but most AM digital stations default to the more-robust 40 kbit/s mode which features redundancy. HD Radio also provides a digital mode, which lacks an analog signal for fallback. The pure digital mode transmissions will stay within the AM stations channel instead of spilling into the next to the station transmitting HD radio as the hybrid stations do. The AM version of HD Radio technology uses the 20 kHz channel, when operating in pure digital mode, the AM HD Radio signal fits inside a standard 20 kHz channel or an extended 30 kHz channel, at the discretion of the station manager. As AM radio stations are spaced at 9 kHz or 10 kHz intervals, some nighttime listeners have expressed concern this design harms reception of adjacent channels with one formal complaint filed regarding the matter, WYSL owner Bob Savage against WBZ in Boston. The HD Radio also provides several digital modes with up to 300 kbit/s bitrate. Like AM, pure digital FM provides a fallback condition where it reverts to a more robust 25 kbit/s signal, FM stations have the option to subdivide their datastream into sub-channels of varying audio quality
14.
Frequency modulation
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In telecommunications and signal processing, frequency modulation is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. This contrasts with amplitude modulation, in which the amplitude of the wave varies. This modulation technique is known as frequency-shift keying, FSK is widely used in modems and fax modems, and can also be used to send Morse code. Frequency modulation is used for FM radio broadcasting. For this reason, most music is broadcast over FM radio, frequency modulation has a close relationship with phase modulation, phase modulation is often used as an intermediate step to achieve frequency modulation. Mathematically both of these are considered a case of quadrature amplitude modulation. While most of the energy of the signal is contained within fc ± fΔ, the frequency spectrum of an actual FM signal has components extending infinitely, although their amplitude decreases and higher-order components are often neglected in practical design problems. Mathematically, a baseband modulated signal may be approximated by a continuous wave signal with a frequency fm. This method is also named as Single-tone Modulation. As in other systems, the modulation index indicates by how much the modulated variable varies around its unmodulated level. e. The maximum deviation of the frequency from the carrier frequency. For a sine wave modulation, the index is seen to be the ratio of the peak frequency deviation of the carrier wave to the frequency of the modulating sine wave. If h ≪1, the modulation is called narrowband FM, sometimes modulation index h<0.3 rad is considered as Narrowband FM otherwise Wideband FM. In the case of digital modulation, the carrier f c is never transmitted, rather, one of two frequencies is transmitted, either f c + Δ f or f c − Δ f, depending on the binary state 0 or 1 of the modulation signal. If h ≫1, the modulation is called wideband FM, if the frequency deviation is held constant and the modulation frequency increased, the spacing between spectra increases. The carrier and sideband amplitudes are illustrated for different modulation indices of FM signals, for particular values of the modulation index, the carrier amplitude becomes zero and all the signal power is in the sidebands. Since the sidebands are on sides of the carrier, their count is doubled, and then multiplied by the modulating frequency to find the bandwidth. For example,3 kHz deviation modulated by a 2.2 kHz audio tone produces an index of 1.36. Suppose that we limit ourselves to only those sidebands that have an amplitude of at least 0.01
15.
Modulation
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Most radio systems in the 20th century used frequency modulation or amplitude modulation to make the carrier carry the radio broadcast. Modulation of a sine waveform transforms a narrow frequency range baseband message signal into a passband signal, a modulator is a device that performs modulation. A demodulator is a device that performs demodulation, the inverse of modulation, a modem can perform both operations. The aim of digital modulation is to transfer a digital bit stream over an analog bandpass channel, in music synthesizers, modulation may be used to synthesise waveforms with an extensive overtone spectrum using a small number of oscillators. In this case the carrier frequency is typically in the order or much lower than the modulating waveform. In analog modulation, the modulation is applied continuously in response to the information signal. Where an AM carrier also carries a variable phase f. TM is f In digital modulation, a carrier signal is modulated by a discrete signal. Digital modulation methods can be considered as digital-to-analog conversion, and the corresponding demodulation or detection as analog-to-digital conversion, the changes in the carrier signal are chosen from a finite number of M alternative symbols. A simple example, A telephone line is designed for transferring audible sounds, for example tones, computers may however communicate over a telephone line by means of modems, which are representing the digital bits by tones, called symbols. If there are four symbols, the first symbol may represent the bit sequence 00, the second 01, the third 10. If the modem plays a melody consisting of 1000 tones per second, since each tone represents a message consisting of two digital bits in this example, the bit rate is twice the symbol rate, i. e.2000 bits per second. This is similar to the used by dialup modems as opposed to DSL modems. According to one definition of digital signal, the signal is a digital signal. According to another definition, the modulation is a form of digital-to-analog conversion, most textbooks would consider digital modulation schemes as a form of digital transmission, synonymous to data transmission, very few would consider it as analog transmission. The most fundamental digital modulation techniques are based on keying, PSK, FSK, a finite number of frequencies are used. ASK, a number of amplitudes are used. QAM, a number of at least two phases and at least two amplitudes are used
16.
Radio studio
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A recording studio is a facility for sound recording and mixing. Ideally both the recording and monitoring spaces are designed by an acoustician or audio engineer to achieve optimum acoustic properties. The engineers and producers listen to the music and the recorded tracks on monitor speakers and/or headphones. Major recording studios typically have a range of large, heavy, Isolation booths are small sound-insulated rooms with doors, designed for instrumentalists. This equipment may interfere with the recording process, Recording studios are carefully designed around the principles of room acoustics to create a set of spaces with the acoustical properties required for recording sound with precision and accuracy. This will consist of both room treatment and soundproofing to prevent sound from leaving the property. Even though sound isolation is a key goal, the musicians, singers, audio engineers and record producers still need to be able to see other, to see cue gestures. As such, the room, isolation booths, vocal booths. Some smaller studios do not have instruments, and bands and artists are expected to bring their own instruments, having musical instruments and equipment in the studio creates additional costs for a studio, as pianos have to be tuned and instruments need to be maintained. However, it makes it convenient for recording artists, as they do not have to bring in large. As well, less costly studio time is spent moving in gear, drummers bring their own snare drum, cymbals and sticks/brushes. The types and brands of equipment owned by a studio depends on the styles of music for the bands. A studio that mainly records heavy metal music will be likely to have large, powerful guitar amp heads, in contrast, a studio which mainly records country bands will likely have a selection of small, vintage combo amps. A studio that records a lot of 1970s-style funk may have an electric piano. General purpose computers have rapidly assumed a role in the recording process. A computer thus outfitted is called a Digital Audio Workstation, or DAW, other software applications include Ableton Live, Mixcraft, Cakewalk Sonar, ACID Pro, FL Studio, Adobe Audition, Auto-Tune, Audacity, and Ardour. While Apple Macintosh is used for most studio work, there is a breadth of available for Microsoft Windows. If no mixing console is used and all mixing is done using only a keyboard and mouse, the OTB is used when mixing with other hardware and not just the PC software
17.
Amplitude
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The amplitude of a periodic variable is a measure of its change over a single period. There are various definitions of amplitude, which are all functions of the magnitude of the difference between the extreme values. In older texts the phase is called the amplitude. Peak-to-peak amplitude is the change between peak and trough, with appropriate circuitry, peak-to-peak amplitudes of electric oscillations can be measured by meters or by viewing the waveform on an oscilloscope. Peak-to-peak is a measurement on an oscilloscope, the peaks of the waveform being easily identified and measured against the graticule. This remains a common way of specifying amplitude, but sometimes other measures of amplitude are more appropriate. In audio system measurements, telecommunications and other areas where the measurand is a signal that swings above and below a value but is not sinusoidal. If the reference is zero, this is the absolute value of the signal, if the reference is a mean value. Semi-amplitude means half the peak-to-peak amplitude, some scientists use amplitude or peak amplitude to mean semi-amplitude, that is, half the peak-to-peak amplitude. It is the most widely used measure of orbital wobble in astronomy, the RMS of the AC waveform. For complicated waveforms, especially non-repeating signals like noise, the RMS amplitude is used because it is both unambiguous and has physical significance. For example, the power transmitted by an acoustic or electromagnetic wave or by an electrical signal is proportional to the square of the RMS amplitude. For alternating current electric power, the practice is to specify RMS values of a sinusoidal waveform. One property of root mean square voltages and currents is that they produce the same heating effect as direct current in a given resistance, the peak-to-peak value is used, for example, when choosing rectifiers for power supplies, or when estimating the maximum voltage that insulation must withstand. Some common voltmeters are calibrated for RMS amplitude, but respond to the value of a rectified waveform. Many digital voltmeters and all moving coil meters are in this category, the RMS calibration is only correct for a sine wave input since the ratio between peak, average and RMS values is dependent on waveform. If the wave shape being measured is greatly different from a sine wave, true RMS-responding meters were used in radio frequency measurements, where instruments measured the heating effect in a resistor to measure current. The advent of microprocessor controlled meters capable of calculating RMS by sampling the waveform has made true RMS measurement commonplace
18.
Frequency
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Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as frequency, which emphasizes the contrast to spatial frequency. The period is the duration of time of one cycle in a repeating event, for example, if a newborn babys heart beats at a frequency of 120 times a minute, its period—the time interval between beats—is half a second. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as vibrations, audio signals, radio waves. For cyclical processes, such as rotation, oscillations, or waves, in physics and engineering disciplines, such as optics, acoustics, and radio, frequency is usually denoted by a Latin letter f or by the Greek letter ν or ν. For a simple motion, the relation between the frequency and the period T is given by f =1 T. The SI unit of frequency is the hertz, named after the German physicist Heinrich Hertz, a previous name for this unit was cycles per second. The SI unit for period is the second, a traditional unit of measure used with rotating mechanical devices is revolutions per minute, abbreviated r/min or rpm. As a matter of convenience, longer and slower waves, such as ocean surface waves, short and fast waves, like audio and radio, are usually described by their frequency instead of period. Spatial frequency is analogous to temporal frequency, but the axis is replaced by one or more spatial displacement axes. Y = sin = sin d θ d x = k Wavenumber, in the case of more than one spatial dimension, wavenumber is a vector quantity. For periodic waves in nondispersive media, frequency has a relationship to the wavelength. Even in dispersive media, the frequency f of a wave is equal to the phase velocity v of the wave divided by the wavelength λ of the wave. In the special case of electromagnetic waves moving through a vacuum, then v = c, where c is the speed of light in a vacuum, and this expression becomes, f = c λ. When waves from a monochrome source travel from one medium to another, their remains the same—only their wavelength. For example, if 71 events occur within 15 seconds the frequency is, the latter method introduces a random error into the count of between zero and one count, so on average half a count. This is called gating error and causes an error in the calculated frequency of Δf = 1/, or a fractional error of Δf / f = 1/ where Tm is the timing interval. This error decreases with frequency, so it is a problem at low frequencies where the number of counts N is small, an older method of measuring the frequency of rotating or vibrating objects is to use a stroboscope
19.
History of radio
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The early history of radio is the history of technology that produce and use radio instruments that use radio waves. Within the timeline of radio, many people contributed theory and inventions in what became radio, Radio development began as wireless telegraphy. Later radio history increasingly involves matters of broadcasting, james Clerk Maxwell showed in theoretical and mathematical form in 1864 that electromagnetic waves could propagate through free space. In 1888 Heinrich Rudolf Hertz was able to conclusively prove transmitted airborne electromagnetic waves in an experiment confirming Maxwells theory of electromagnetism, over several years starting in 1894 the Italian inventor Guglielmo Marconi built the first complete, commercially successful wireless telegraphy system based on airborne Hertzian waves. Marconi demonstrated application of radio in military and marine communications and started a company for the development and propagation of radio communication services and equipment. In 1886–88 Heinrich Rudolf Hertz conducted a series of experiments that proved the existence of Maxwells electromagnetic waves, many individuals—inventors, engineers, developers and businessmen—constructed systems based on their own understanding of these and other phenomenon, some predating Maxwell and Hertzs discoveries. Thus wireless telegraphy and radio wave-based systems can be attributed to multiple inventors, development from a laboratory demonstration to a commercial entity spanned several decades and required the efforts of many practitioners. In 1878, David E. Hughes noticed that sparks could be heard in a telephone receiver when experimenting with his carbon microphone and he developed this carbon-based detector further and eventually could detect signals over a few hundred yards. He demonstrated his discovery to the Royal Society in 1880, but was told it was merely induction, thomas Edison came across the electromagnetic phenomenon while experimenting with a telegraph at Menlo Park. He noted an unexplained transmission effect while experimenting with a telegraph and he referred to this as etheric force in an announcement on November 28,1875. Elihu Thomson published his findings on Edisons new force, again attributing it to induction, Edison would go on the next year to take out U. S. Patent 465,971 on a system of wireless communication between ships based on electrostatic coupling using the water and elevated terminals. Although this was not a system the Marconi Company would purchase the rights in 1903 to protect them legally from lawsuits. Between 1886 and 1888 Heinrich Rudolf Hertz published the results of his experiments where he was able to transmit electromagnetic waves through the air, early on after their discovery, radio waves were referred to as Hertzian waves. Tesla, concluding that Hertz had not demonstrated airborne electromagnetic waves, went on to develop a system based on what he thought was the primary conductor, during the demonstration a radio signal was sent from the neighboring Clarendon Laboratory building, and received by apparatus in the lecture theater. Bose wrote in a Bengali essay, Adrisya Alok, The invisible light can pass through brick walls. Therefore, messages can be transmitted by means of it without the mediation of wires, Bose’s first scientific paper, On polarisation of electric rays by double-refracting crystals was communicated to the Asiatic Society of Bengal in May 1895. His second paper was communicated to the Royal Society of London by Lord Rayleigh in October 1895, in December 1895, the London journal The Electrician published Bose’s paper, On a new electro-polariscope
20.
Radio 2XG
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Presidential election returns by spoken word instead of Morse code. Initially all radio stations used spark transmitters, which could only transmit Morse code messages, in 1914, de Forest established a laboratory at 1391 Sedgewick Avenue in the Highbridge section of the Bronx in New York City. In the summer of 1915, the received a license for an Experimental station, with the call sign 2XG. There were no government regulations restricting broadcasting at this time. 2XGs original audience was mostly amateur radio operators, an early report stated that 2XG was broadcasting on a wave length of approximately 800 meters. Carl Dreher would later recall, The quality was quite good, some of the programming was oriented toward a more general audience. Also featured were Columbia recordings that included The Star Spangled Banner, Columbia and it was estimated that 7,000 persons received the broadcast. The concerts continued, with listeners reported as far away at Cape Hatteras, a radio dance held in Morristown, New Jersey at the end of the year received widespread publicity. However, with the entry of the United States into World War One on April 6,1917, all radio stations were ordered shut down. Effective October 1,1919, the ban on radio stations was ended, and the De Forest Highbridge Station soon renewed operation, once more with an Experimental license. For this revival Bob Gowen and Bill Garity worked as announcers, phonograph records were now supplied by the Brunswick-Balke-Collender company, again in exchange for promotional announcements. There were also performances, including multiple appearances by Vaughn De Leath—for these broadcasts she earned the sobriquet The Original Radio Girl. In early 1920, the 2XG transmitter was moved from the Bronx to Manhattan to take advantage of an offer by Emil J. Simon to use an antenna located atop the Worlds Tower building and this also brought the stations studio closer to artists in the theatrical district. However, the move had not been approved by government regulators, however, shortly thereafter de Forest would cease involvement with radio work altogether, in order to concentrate on developing the Phonofilm sound-on-film system. The De Forest company eventually returned to the New York City airwaves on a limited basis. This was the first broadcasting license issued for a station in New York City proper, however, despite its heritage there was minimal, if any, but a mid-1922 agreement covering the New York City area didnt even list WJX as being active. In June,1924, WJX was officially deleted by the government
21.
Spark-gap transmitter
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A spark-gap transmitter is a device that generates radio frequency electromagnetic waves using a spark gap. Spark gap transmitters were the first devices to demonstrate practical radio transmission, later, more efficient transmitters were developed based on rotary machines like the high-speed Alexanderson alternators and the static Poulsen Arc generators. Even when vacuum tube based transmitters had been installed, many retained their crude. However, by 1940, the technology was no longer used for communication, use of the spark-gap transmitter led to many radio operators being nicknamed Sparks long after they ceased using spark transmitters. Even today, the German verb funken, literally, to spark, the effects of sparks causing unexplained action at a distance, such as inducing sparks in nearby devices, had been noticed by scientists and experimenters well before the invention of radio. Extensive experiments were conducted by Joseph Henry, Thomas Edison and David Edward Hughes, with no other theory to explain the phenomenon, it was usually written off as electromagnetic induction. Hertz used a spark gap transmitter and a tuned spark gap detector located a few meters from the source. Many experimenters used the spark gap setup to further investigate the new Hertzian wave phenomenon, including Oliver Lodge, the Italian inventor Guglielmo Marconi used a spark-gap transmitter in his experiments to develop the radio phenomenon into a wireless telegraphy system in the early 1890s. In 1895 he succeeded in transmitting over a distance of 1 1/4 miles and his first transmitter consisted of an induction coil connected between a wire antenna and ground, with a spark gap across it. Every time the induction coil pulsed, the antenna was momentarily charged up to tens of thousands of volts until the gap started to arc. This acted as a switch, essentially connecting the antenna to ground. While the various systems of spark transmitters worked well enough to prove the concept of wireless telegraphy. The biggest problem was that the power that could be transmitted was directly determined by how much electrical charge the antenna could hold. Because the capacitance of practical antennas is quite small, the way to get a reasonable power output was to charge it up to very high voltages. However, this made transmission impossible in rainy or even damp conditions, also, it necessitated a quite wide spark gap, with a very high electrical resistance, with the result that most of the electrical energy was used simply to heat up the air in the spark gap. Another problem with the transmitter was a result of the shape of the waveform produced by each burst of electromagnetic radiation. These transmitters radiated an extremely dirty wide band signal that could interfere with transmissions on nearby frequencies. Receiving sets relatively close to such a transmitter had entire sections of a band masked by this wide band noise, reginald Fessendens first attempts to transmit voice employed a spark transmitter operating at approximately 10,000 sparks/second
22.
Morse code
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Morse code is a method of transmitting text information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment. It is named for Samuel F. B, Morse, an inventor of the telegraph. Because many non-English natural languages use more than the 26 Roman letters, each Morse code symbol represents either a text character or a prosign and is represented by a unique sequence of dots and dashes. The duration of a dash is three times the duration of a dot, each dot or dash is followed by a short silence, equal to the dot duration. The letters of a word are separated by an equal to three dots, and the words are separated by a space equal to seven dots. The dot duration is the unit of time measurement in code transmission. To increase the speed of the communication, the code was designed so that the length of each character in Morse varies approximately inversely to its frequency of occurrence in English. Thus the most common letter in English, the letter E, has the shortest code, Morse code is used by some amateur radio operators, although knowledge of and proficiency with it is no longer required for licensing in most countries. Pilots and air controllers usually need only a cursory understanding. Aeronautical navigational aids, such as VORs and NDBs, constantly identify in Morse code, compared to voice, Morse code is less sensitive to poor signal conditions, yet still comprehensible to humans without a decoding device. Morse is, therefore, an alternative to synthesized speech for sending automated data to skilled listeners on voice channels. Many amateur radio repeaters, for example, identify with Morse, in an emergency, Morse code can be sent by improvised methods that can be easily keyed on and off, making it one of the simplest and most versatile methods of telecommunication. The most common signal is SOS or three dots, three dashes, and three dots, internationally recognized by treaty. Beginning in 1836, the American artist Samuel F. B, Morse, the American physicist Joseph Henry, and Alfred Vail developed an electrical telegraph system. This system sent pulses of current along wires which controlled an electromagnet that was located at the receiving end of the telegraph system. A code was needed to transmit natural language using only these pulses, around 1837, Morse, therefore, developed an early forerunner to the modern International Morse code. Around the same time, Carl Friedrich Gauss and Wilhelm Eduard Weber as well as Carl August von Steinheil had already used codes with varying lengths for their telegraphs. In 1837, William Cooke and Charles Wheatstone in England began using a telegraph that also used electromagnets in its receivers
23.
Oliver Lodge
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For the British poet and author, see Oliver W. F. Lodge Sir Oliver Joseph Lodge, FRS was a British physicist and writer involved in the development of, and holder of key patents for, radio. He identified electromagnetic radiation independent of Hertz proof and at his 1894 Royal Institution lectures, in 1898 he was awarded the syntonic patent by the United States Patent Office. Lodge was Principal of the University of Birmingham from 1900 to 1920, Oliver Lodge was born in 1851 at The Views Penkhull in what is now Stoke-on-Trent, and educated at Adams Grammar School, Newport, Shropshire. He was the eldest of eight sons and a daughter of Oliver Lodge – later a ball clay merchant at Wolstanton, Staffordshire – and his wife, Grace, née Heath. Lodges siblings included Sir Richard Lodge, historian, Eleanor Constance Lodge, historian and principal of Westfield College, London, in 1865, Lodge, at the age of 14, entered his fathers business as an agent for B. Fayle & Co selling Purbeck blue clay to the potteries, travelling as far as Scotland and he continued to assist his father until he reached the age of 22. His fathers wealth obtained from selling Purbeck ball clay enabled Lodge to attend lectures in London. Lodge obtained a Bachelor of Science degree from the University of London in 1875 and he was appointed professor of physics and mathematics at University College, Liverpool in 1881. In 1900 Lodge moved from Liverpool back to the Midlands and became the first principal of the new Birmingham University and he oversaw the start of the move of the university from Edmund Street in the city centre to its present Edgbaston campus. Lodge was awarded the Rumford Medal of the Royal Society in 1898 and was knighted by King Edward VII in 1902, in 1928 he was made Freeman of his native city, Stoke-on-Trent. Lodge married Mary Fanny Alexander Marshall at St Georges Church, Newcastle-under-Lyme in 1877. They had twelve children, six boys and six girls, Oliver William Foster, Francis Brodie, Alec, Lionel, Noel, Violet, Raymond, Honor, Lorna, Norah, Barbara, four of his sons went into business using Lodges inventions. Brodie and Alec created the Lodge Plug Company, which manufactured sparking plugs for cars, Lionel and Noel founded a company that produced an electrostatic device for cleaning factory and smelter smoke in 1913, called the Lodge Fume Deposit Company Limited. Oliver, the eldest son, became a poet and author, after his retirement in 1920, Lodge and his wife settled in Normanton House, near Lake in Wiltshire, just a few miles from Stonehenge. Lodge and his wife are buried at the parish church, St. Michaels. Their eldest son Oliver and eldest daughter Violet are buried at the same church, in 1873 J. C. Maxwell published A Treatise on Electricity and Magnetism and by 1876 Lodge was studying it intently. Indeed, Lodge is probably best known for his advocacy and elaboration of Maxwells aether theory – a later deprecated model postulating a wave-bearing medium filling all space. He explained his views on the aether in Modern Views of Electricity, as early as 1879 Lodge became interested in generating electromagnetic waves, something Maxwell had never considered
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Nathan Stubblefield
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Nathan Beverly Stubblefield, self-described practical farmer, fruit grower and electrician, was an American inventor best known for his wireless telephone work. While this initial design employed conduction, in 1908 he received a U. S. patent for a telephone system that used magnetic induction. However, he was unsuccessful in commercializing his inventions. He later went into seclusion, and died alone in 1928, disagreement exists whether Stubblefields communications technology can be classified as radio, and if his 1902 demonstrations could be considered the first radio broadcasts. Stubblefield was the second of seven sons of William Captain Billy Jefferson Stubblefield, an army veteran and lawyer, and Victoria Bowman. Stubblefield grew up in Murray, Kentucky, and his education included tutoring by a governess and his formal education ended in 1874, at the age of 14, with his fathers death, which left Stubblefield an orphan in the care of his step-mother. However, he continued to develop his knowledge by reading contemporary scientific publications, such as Scientific American. In 1881 he married Ada Mae Buchannan and they had nine children, six of Nathans seven children did not bear descendants. Initially he supported himself and his family by farming on a plot of family land, from 1907 to 1911, he operated a home school called The Nathan Stubblefield Industrial School, or Teléph-on-délgreen Industrial School. Despite very limited finances, in his spare time Stubblefield worked on developing a series of inventions, Patent 329,864, was issued on November 3,1885, for a tool for lighting coal oil lamps without having to remove the glass chimney. Although most installations were around Murray, he also made sales as far away as Mississippi, on February 21,1888, Stubblefield and partner Samuel Holcomb received U. S. Patent 378,183 for their mechanical telephone design, however, the establishment of a local Bell Telephone franchise, whose electric telephones were far superior to Stubblefields offerings, ended most of the acoustic sales by 1890. In 1898, Stubblefield was issued U. S, Patent 600,457 for an electric battery, which was an electrolytic coil of iron and insulated copper wire that was immersed in liquid or buried in the ground. Stubblefield made the claim that, combined with normal battery operation. However, it did serve as both a power source and ground terminal for wireless telephony. Because he never filed for a patent for his early work, but, based on contemporary descriptions, it appears that they initially employed induction, similar to a wireless telephone developed by Amos Dolbear, which was issued U. S. Information for this period is limited, but in 1935 a former neighbor. Because later references refer to earth connections, it appears that Stubblefield subsequently switched to using ground currents instead of induction, a much more ambitious demonstration was given on January 1,1902
25.
Electromagnetic induction
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Electromagnetic or magnetic induction is the production of an electromotive force across an electrical conductor due to its dynamic interaction with a magnetic field. Michael Faraday is generally credited with the discovery of induction in 1831, Lenzs law describes the direction of the induced field. Faradays law was later generalized to become the Maxwell-Faraday equation, one of the four Maxwells equations in James Clerk Maxwells theory of electromagnetism, electromagnetic induction has found many applications in technology, including electrical components such as inductors and transformers, and devices such as electric motors and generators. Electromagnetic induction was first discovered by Michael Faraday, who made his discovery public in 1831 and it was discovered independently by Joseph Henry in 1832. In Faradays first experimental demonstration, he wrapped two wires around opposite sides of a ring or torus. He plugged one wire into a galvanometer, and watched it as he connected the wire to a battery. He saw a transient current, which he called a wave of electricity and this induction was due to the change in magnetic flux that occurred when the battery was connected and disconnected. Within two months, Faraday found several other manifestations of electromagnetic induction, Faraday explained electromagnetic induction using a concept he called lines of force. However, scientists at the time widely rejected his theoretical ideas, an exception was James Clerk Maxwell, who used Faradays ideas as the basis of his quantitative electromagnetic theory. Heavisides version is the form recognized today in the group of known as Maxwells equations. In 1834 Heinrich Lenz formulated the law named after him to describe the flux through the circuit, Lenzs law gives the direction of the induced EMF and current resulting from electromagnetic induction. Faradays law of induction makes use of the magnetic flux ΦB through a region of space enclosed by a wire loop. The magnetic flux is defined by an integral, Φ B = ∫ Σ B ⋅ d A. The dot product B·dA corresponds to an amount of magnetic flux. In more visual terms, the flux through the wire loop is proportional to the number of magnetic flux lines that pass through the loop. When the flux through the changes, Faradays law of induction says that the wire loop acquires an electromotive force. The direction of the force is given by Lenzs law which states that an induced current will flow in the direction that will oppose the change which produced it. This is due to the sign in the previous equation
26.
Eiffel Tower
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The Eiffel Tower is a wrought iron lattice tower on the Champ de Mars in Paris, France. It is named after the engineer Gustave Eiffel, whose company designed, the Eiffel Tower is the most-visited paid monument in the world,6.91 million people ascended it in 2015. The tower is 324 metres tall, about the height as an 81-storey building. Its base is square, measuring 125 metres on each side, due to the addition of a broadcasting aerial at the top of the tower in 1957, it is now taller than the Chrysler Building by 5.2 metres. Excluding transmitters, the Eiffel Tower is the second-tallest structure in France after the Millau Viaduct, the tower has three levels for visitors, with restaurants on the first and second levels. The top levels upper platform is 276 m above the ground – the highest observation deck accessible to the public in the European Union, tickets can be purchased to ascend by stairs or lift to the first and second levels. The climb from ground level to the first level is over 300 steps, although there is a staircase to the top level, it is usually only accessible by lift. Eiffel openly acknowledged that inspiration for a tower came from the Latting Observatory built in New York City in 1853, sauvestre added decorative arches to the base of the tower, a glass pavilion to the first level, and other embellishments. Little progress was made until 1886, when Jules Grévy was re-elected as president of France and Édouard Lockroy was appointed as minister for trade. On 12 May, a commission was set up to examine Eiffels scheme and its rivals, which, after some debate about the exact location of the tower, a contract was signed on 8 January 1887. Eiffel was to all income from the commercial exploitation of the tower during the exhibition. He later established a company to manage the tower, putting up half the necessary capital himself. The proposed tower had been a subject of controversy, drawing criticism from those who did not believe it was feasible and these objections were an expression of a long-standing debate in France about the relationship between architecture and engineering. And for twenty years … we shall see stretching like a blot of ink the hateful shadow of the column of bolted sheet metal. Gustave Eiffel responded to criticisms by comparing his tower to the Egyptian pyramids. Will it not also be grandiose in its way, and why would something admirable in Egypt become hideous and ridiculous in Paris. Indeed, Garnier was a member of the Tower Commission that had examined the various proposals, some of the protesters changed their minds when the tower was built, others remained unconvinced. Guy de Maupassant supposedly ate lunch in the restaurant every day because it was the one place in Paris where the tower was not visible
27.
Amateur radio
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The amateur radio service is established by the International Telecommunication Union through the International Telecommunication Regulations. National governments regulate technical and operational characteristics of transmissions and issue individual stations licenses with a call sign. Prospective amateur operators are tested for their understanding of key concepts in electronics, according to an estimate made in 2011 by the American Radio Relay League, two million people throughout the world are regularly involved with amateur radio. About 830,000 amateur radio stations are located in IARU Region 2 followed by IARU Region 3 with about 750,000 stations, a significantly smaller number, about 400,000, are located in IARU Region 1. The origins of amateur radio can be traced to the late 19th century, the First Annual Official Wireless Blue Book of the Wireless Association of America, produced in 1909, contains a list of amateur radio stations. This radio callbook lists wireless telegraph stations in Canada and the United States, as with radio in general, amateur radio was associated with various amateur experimenters and hobbyists. Amateur radio enthusiasts have significantly contributed to science, engineering, industry, research by amateur operators has founded new industries, built economies, empowered nations, and saved lives in times of emergency. Ham radio can also be used in the classroom to teach English, map skills, geography, math, science, the term ham radio was first a pejorative that mocked amateur radio operators with a 19th-century term for being bad at something, like ham-fisted or ham actor. It had already used for bad wired telegraph operators. Subsequently, the community adopted it as a moniker, much like the Know-Nothing Party, or other groups. Other, more entertaining explanations have grown up throughout the years, the many facets of amateur radio attract practitioners with a wide range of interests. Many amateurs begin with a fascination of radio communication and then combine other personal interests to make pursuit of the hobby rewarding, some of the focal areas amateurs pursue include radio contesting, radio propagation study, public service communication, technical experimentation, and computer networking. Amateur radio operators use various modes of transmission to communicate, the two most common modes for voice transmissions are frequency modulation and single sideband. FM offers high quality audio signals, while SSB is better at long distance communication when bandwidth is restricted. Radiotelegraphy using Morse code, also known as CW from continuous wave, is the extension of landline telegraphy developed by Samuel Morse. Morse, using internationally agreed message encodings such as the Q code, a similar legacy mode popular with home constructors is amplitude modulation, pursued by many vintage amateur radio enthusiasts and aficionados of vacuum tube technology. Demonstrating a proficiency in Morse code was for years a requirement to obtain an amateur license to transmit on frequencies below 30 MHz. Following changes in regulations in 2003, countries are no longer required to demand proficiency
28.
Telephone newspaper
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Telephone Newspapers, introduced in the 1890s, transmitted news and entertainment to subscribers over telephone lines. They were the first example of electronic broadcasting, although only a few were established and these systems predated the development, in the 1920s, of radio broadcasting. The introduction of the telephone in the mid-1870s included numerous demonstrations of its use for transmitting musical concerts over various distances, the concept also appeared in Edward Bellamys influential 1888 utopian novel, Looking Backward, 2000-1887, which foresaw audio entertainment sent over telephone lines to private homes. The initial scattered demonstrations were followed by the development of more organized services transmitting news and entertainment, during this era telephones were often costly, near-luxury items, so subscribers tended to be among the well-to-do. Some systems also accepted paid advertising, in two cases, the Telefon Hírmondó and the Araldo Telefonico, the systems were later merged with radio station operations, becoming relays for the radio programs. Below is an overview of some of the systems that were developed. The first organized telephone-based entertainment service appears to be the Théâtrophone and this system evolved from Clément Aders demonstration at the 1881 Paris Electrical Exhibition by Compagnie du Théâtrophone of MM. Although the service received most of its programming from lines run to local theaters, home listeners could connect to the service, with an 1893 report stating that the system had grown to over 1,300 subscribers. The company also established coin-operated receivers, in such as hotels, charging 50 centimes for five minutes of listening. By 1925, the system had adopted vacuum tube amplification, which allowed listeners to hear over loudspeakers instead of headphones, the service continued in operation until 1932, when it was found it could no longer compete with radio broadcasting. The Telefon Hírmondó — the name was translated into English as the Telephone Herald or Telephone News-teller — was created by inventor. Puskás had participated in Clément Aders demonstration at the 1881 Paris Electrical Exhibition and he had also been an important early developer of the telephone switchboard, and he later developed the basic technology for transmitting a single audio source to multiple telephones. On February 15,1893 the Telefon Hírmondó, which would become the most prominent and longest-lived of all the Telephone Newspaper systems, the system eventually offering a wide assortment of news, stock quotations, concerts and linguistic lessons. Tivadar Puskás died just one month after the system went into operation, the Telefon Hírmondó was classified and regulated by the Hungarian government as a newspaper, with a designated editor-in-chief legally responsible for content. Both the Italian Araldo Telefonico and the United States Telephone Herald Company later licensed the Telefon Hírmondó technology for use in their respective countries. A loud buzzer, which could be heard throughout a room even when the service was not being monitored, was used to draw attention to important transmissions. Service was supplied to homes as well as commercial establishments, including hotels. At its peak, the service had thousands of subscribers, initially the Telefon Hírmondó provided a short hourly news program using subscribers regular phone lines
29.
Radiotelephone
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A radiotelephone is a communications system for transmission of speech over radio. Radiotelephone systems are not necessarily interconnected with the land line telephone network. Radiotelephony means transmission of sound by radio, in contrast to radiotelegraphy or video transmission, the word phone has a long precedent beginning with early US wireless voice systems. The term means voice as opposed to telegraph or Morse code and this would include systems fitting into the category of two-way radio or one-way voice broadcasts such as coastal maritime weather. The term is popular in the amateur radio community and in US Federal Communications Commission regulations. A standard landline telephone allows both users to talk and listen simultaneously, effectively there are two channels between the two end-to-end users of the system. It is, however, the most comfortable method of communication for users. The most common method of working for radiotelephones is half-duplex, operation, which one person to talk. If a single channel is used, both take turns to transmit on it. An eavesdropper would hear both sides of the conversation, dual-frequency working splits the communication into two separate channels, but only one is used to transmit at a time. The end users have the experience as single frequency simplex. The user presses a switch on the transmitter when they wish to talk—this is called the press-to-talk switch or PTT. It is usually fitted on the side of the microphone or other obvious position, users may use a special code-word such as over to signal that they have finished transmitting, or it may follow from the conversation. Radiotelephones may operate at any frequency where they are licensed to do so and they may use simple modulation schemes such as AM or FM, or more complex techniques such as digital coding, spread spectrum, and so on. Licensing terms for a band will usually specify the type of modulation to be used. For example, airband radiotelephones used for air to ground communication between pilots and controllers operates in the VHF band from 118.0 to 136.975 MHz, Radiotelephone receivers are usually designed to a very high standard, and are usually of the double-conversion superhet design. Multiple channels are provided using a frequency synthesizer. Receivers usually features a squelch circuit to cut off the output from the receiver when there is no transmission to listen to
30.
Crystal radio
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A crystal radio receiver, also called a crystal set or cats whisker receiver, is a very simple radio receiver, popular in the early days of radio. It needs no power source but that received solely from the power of radio waves received by a wire antenna. It gets its name from its most important component, known as a crystal detector and this component is now called a diode. Thus, crystal sets produce rather weak sound and must be listened to with sensitive earphones, Crystal radios were the first widely used type of radio receiver, and the main type used during the wireless telegraphy era. Around 1920, crystal sets were superseded by the first amplifying receivers and they continued to be built by hobbyists, youth groups, and the Boy Scouts however, as a way of learning about the technology of radio. A few receive shortwave bands, but strong signals are required, the first crystal sets received wireless telegraphy signals broadcast by spark-gap transmitters at frequencies as low as 20 kHz. Crystal radio was invented by a long, partly obscure chain of discoveries in the late 19th century that gradually evolved into more and more practical radio receivers in the early 20th century. The earliest practical use of radio was to receive Morse code radio signals transmitted, from spark-gap transmitters. As electronics evolved, the ability to send signals by radio caused a technological explosion in the years around 1920 that evolved into todays radio broadcasting industry. Early radio telegraphy used spark gap and arc transmitters as well as high-frequency alternators running at radio frequencies, the Branley Coherer was the first means of detecting a radio signal. These, however, lacked the sensitivity to weak signals. In the early 20th century, various researchers discovered that certain metallic minerals, such as galena, could be used to detect radio signals. In 1901, Bose filed for a U. S. patent for A Device for Detecting Electrical Disturbances that mentioned the use of a galena crystal, the device depended on the large variation of a semiconductors conductance with temperature, today we would call his invention a bolometer. Boses patent is frequently, but erroneously, cited as a type of rectifying detector, on August 30,1906, Greenleaf Whittier Pickard filed a patent for a silicon crystal detector, which was granted on November 20,1906. Pickards detector was revolutionary in that he found that a fine pointed wire known as a whisker, in delicate contact with a mineral. A crystal detector includes a crystal, a thin wire that contacts the crystal. The most common crystal used is a piece of galena, pyrite was also often used, as it was a more easily adjusted and stable mineral. Several other minerals also performed well as detectors, another benefit of crystals was that they could demodulate amplitude modulated signals
31.
Loudspeaker
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A loudspeaker is an electroacoustic transducer, which converts an electrical audio signal into a corresponding sound. The most widely used type of speaker in the 2010s is the speaker, invented in 1925 by Edward W. Kellogg. The dynamic speaker operates on the basic principle as a dynamic microphone. Besides this most common method, there are several technologies that can be used to convert an electrical signal into sound. The sound source must be amplified or strengthened with a power amplifier before the signal is sent to the speaker. Speakers are typically housed in an enclosure or speaker cabinet which is often a rectangular or square box made of wood or sometimes plastic. The enclosures materials and design play an important role in the quality of the sound, where high fidelity reproduction of sound is required, multiple loudspeaker transducers are often mounted in the same enclosure, each reproducing a part of the audible frequency range. In this case the individual speakers are referred to as drivers, drivers made for reproducing high audio frequencies are called tweeters, those for middle frequencies are called mid-range drivers, and those for low frequencies are called woofers. Smaller loudspeakers are found in such as radios, televisions, portable audio players, computers. Larger loudspeaker systems are used for music, sound reinforcement in theatres and concerts, the term loudspeaker may refer to individual transducers or to complete speaker systems consisting of an enclosure including one or more drivers. To adequately reproduce a range of frequencies with even coverage, most loudspeaker systems employ more than one driver. Individual drivers are used to different frequency ranges. The drivers are named subwoofers, woofers, mid-range speakers, tweeters, the terms for different speaker drivers differ, depending on the application. In two-way systems there is no mid-range driver, so the task of reproducing the mid-range sounds falls upon the woofer and tweeter, home stereos use the designation tweeter for the high frequency driver, while professional concert systems may designate them as HF or highs. When multiple drivers are used in a system, a network, called a crossover. Loudspeaker driver of the type pictured are termed dynamic to distinguish them from earlier drivers, or speakers using piezoelectric or electrostatic systems, or any of several other sorts. Johann Philipp Reis installed an electric loudspeaker in his telephone in 1861, it was capable of reproducing clear tones, alexander Graham Bell patented his first electric loudspeaker as part of his telephone in 1876, which was followed in 1877 by an improved version from Ernst Siemens. In 1898, Horace Short patented a design for a loudspeaker driven by compressed air, he sold the rights to Charles Parsons
32.
Reginald Fessenden
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Reginald Aubrey Fessenden was a Canadian-born inventor, who did a majority of his work in the United States and also claimed U. S. citizenship through his American-born father. During his life he received hundreds of patents in fields, most notably ones related to radio. Fessenden is best known for his work developing radio technology. His achievements included the first transmission of speech by radio, in 1932 he reported that, in late 1906, he also made the first radio broadcast of entertainment and music, although a lack of verifiable details has led to some doubts about this claim. Reginald Fessenden was born October 6,1866, in East-Bolton, Quebec, Elisha Fessenden was a Church of England in Canada minister, and the family moved to a number of postings throughout the province of Ontario. While growing up, Fessenden attended a number of educational institutions, at the age of nine, he was enrolled in the DeVeaux Military school for a year. He next attended Trinity College School in Port Hope, Ontario and he also spent a year working for the Imperial Bank at Woodstock, because he had not yet reached the age of 16 needed to enroll in college. At the age of fourteen, Bishops College School in Lennoxville, Quebec, thus, while Fessenden was still a teenager, he taught mathematics to the younger students at the School, while simultaneously studying with older students at the College. While in Bermuda, he engaged to Helen Trott. They married in September 1890 and later had a son, Reginald Kennelly Fessenden, Fessendens classical education provided him with only a limited amount of scientific and technical training. Interested in increasing his skills in the field, he moved to New York City in 1886, with hopes of gaining employment with the famous inventor. He quickly proved his worth, and received a series of promotions, in late 1886, Fessenden began working directly for Edison at the inventors new laboratory in West Orange, New Jersey as a junior technician. He participated in a range of projects, which included work in solving problems in chemistry, metallurgy. However, in 1890, facing problems, Edison was forced to lay off most of the laboratory employees. Taking advantage of his recent practical experience, Fessenden was able to find positions with a series of manufacturing companies, by 1899 he was able to send radiotelegraph messages between Pittsburgh and Allegheny City, using a receiver of his own design. The provisions of his contract called for him to be paid $3,000 per year, and provided with space, assistance. The agreement gave the Weather Bureau access to any devices Fessenden developed, Fessenden quickly made major advances, especially in receiver design, as he worked to develop audio reception of signals. Fessendens initial Weather Bureau work took place at Cobb Island, Maryland, located in the Potomac River about 80 kilometers downstream from Washington, as the experimentation expanded, additional stations were built along the Atlantic Coast in North Carolina and Virginia
33.
Damped wave
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A damped wave is a wave whose amplitude of oscillation decreases with time, eventually going to zero. This term also refers to a method of radio transmission produced by spark gap transmitters. Information was carried on this signal by telegraphy, turning the transmitter on, damped waves were the first practical means of radio communication, used during the wireless telegraphy era which ended around 1920. In radio engineering it is now referred to as Class B emission. However, such transmissions have a bandwidth and generate electrical noise which interferes with other radio transmissions. Continuous wave Damping On-off keying Amplitude modulation Types of radio emissions Sparks Telegraph Key Review A complete listing with photos of damped wave telegraph keys by manufacturer, 47cfr2.201 FCC rules where Type B damped wave emissions are forbidden
34.
Continuous wave
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A continuous wave or continuous waveform is an electromagnetic wave of constant amplitude and frequency, a sine wave. In mathematical analysis, it is considered to be of infinite duration, continuous wave is also the name given to an early method of radio transmission, in which a sinusoidal carrier wave is switched on and off. Information is carried in the duration of the on and off periods of the signal. Very early radio transmitters used a gap to produce radio-frequency oscillations in the transmitting antenna. The signals produced by these spark-gap transmitters consisted of strings of brief pulses of radio frequency oscillations which died out rapidly to zero. The disadvantage of damped waves was that their energy was spread over a wide band of frequencies. As a result they produced electromagnetic interference that spread over the transmissions of stations at other frequencies and this motivated efforts to produce radio frequency oscillations that decayed more slowly, had less damping. Manufacturers produced spark transmitters which generated long ringing waves with minimal damping and it was realized that the ideal radio wave for radiotelegraphic communication would be a sine wave with zero damping, a continuous wave. An unbroken continuous sine wave theoretically has no bandwidth, all its energy is concentrated at a single frequency, continuous waves could not be produced with an electric spark, but were achieved with the vacuum tube electronic oscillator, invented around 1913 by Edwin Armstrong and Alexander Meissner. Damped wave spark transmitters were replaced by continuous wave vacuum tube transmitters around 1920, what is transmitted in the extra bandwidth used by a transmitter that turns on/off more abruptly is known as key clicks. Certain types of power used in transmission may increase the effect of key clicks. The first transmitters capable of producing continuous wave, the Alexanderson alternator and vacuum tube oscillators, early radio transmitters could not be modulated to transmit speech, and so CW radio telegraphy was the only form of communication available. Continuous-wave radio was called radiotelegraphy because like the telegraph, it worked by means of a switch to transmit Morse code. However, instead of controlling the electricity in a cross-country wire and this mode is still in common use by amateur radio operators. In military communications and amateur radio, the terms CW and Morse code are used interchangeably. Morse code may be sent using direct current in wires, sound, or light, a carrier wave is keyed on and off to represent the dots and dashes of the code elements. The carriers amplitude and frequency remains constant during each code element, at the receiver, the received signal is mixed with a heterodyne signal from a BFO to change the radio frequency impulses to sound. Though most commercial traffic has now ceased operation using Morse it is popular with amateur radio operators
35.
Alternator
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An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a magnetic field with a stationary armature. Occasionally, an alternator or a rotating armature with a stationary magnetic field is used. In principle, any AC electrical generator can be called an alternator, an alternator that uses a permanent magnet for its magnetic field is called a magneto. Alternators in power stations driven by steam turbines are called turbo-alternators, large 50 or 60 Hz three phase alternators in power plants generate most of the worlds electric power, which is distributed by electric power grids. Alternating current generating systems were known in simple forms from the discovery of the induction of electric current in the 1830s. Rotating generators naturally produced alternating current but, since there was use for it, it was normally converted into direct current via the addition of a commutator in the generator. The early machines were developed by such as Michael Faraday. Faraday developed the rotating rectangle, whose operation was heteropolar – each active conductor passed successively through regions where the field was in opposite directions. Lord Kelvin and Sebastian Ferranti also developed early alternators, producing frequencies between 100 and 300 Hz, supplying the proper amount of voltage from generating stations in these early systems was left up to the engineers skill in riding the load. In 1883 the Ganz Works invented the constant voltage generator that could produce an output voltage. The introduction of transformers in the led to the widespread use of alternating current. After 1891, polyphase alternators were introduced to supply currents of multiple differing phases, later alternators were designed for various alternating current frequencies between sixteen and about one hundred hertz, for use with arc lighting, incandescent lighting and electric motors. A conductor moving relative to a magnetic field develops an electromotive force in it and this emf reverses its polarity when it moves under magnetic poles of opposite polarity. Typically, a magnet, called the rotor turns within a stationary set of conductors wound in coils on an iron core. The field cuts across the conductors, generating an induced EMF, the rotating magnetic field induces an AC voltage in the stator windings. Since the currents in the stator windings vary in step with the position of the rotor, the rotors magnetic field may be produced by permanent magnets, or by a field coil electromagnet. Automotive alternators use a rotor winding which allows control of the generated voltage by varying the current in the rotor field winding
36.
Arc converter
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The arc converter used an electric arc to convert direct current electricity into radio frequency alternating current. It was used as a transmitter from 1903 until the 1920s when it was replaced by vacuum tube transmitters. One of the first transmitters that could generate continuous sinusoidal waves and it is on the list of IEEE Milestones as a historic achievement in electrical engineering. Elihu Thomson discovered that a carbon arc shunted with a tuned circuit would sing. This singing arc was probably limited to audio frequencies, Bureau of Standards credits William Duddell with the shunt resonant circuit around 1900. The English engineer William Duddell discovered how to make a resonant circuit using an arc lamp. Duddells musical arc operated at frequencies, and Duddell himself concluded that it was impossible to make the arc oscillate at radio frequencies. Valdemar Poulsen, who had demonstrated the Telegraphone at the Paris Exhibition of 1900, poulsens arc could generate frequencies of up to 200 kilohertz and was patented in 1903. After a few years of development the arc technology was transferred to Germany and Great Britain in 1906 by Poulsen, his collaborator Peder Oluf Pedersen, in 1909 the American patents as well as a few arc converters were bought by Cyril F. Elwell. Later the US Navy also adopted the Poulsen system, only the arc converter with passive frequency conversion was suitable for portable and maritime use. This made it the most important mobile radio system for about a decade until it was superseded by vacuum tube systems, in 1922, the Bureau of Standards stated, the arc is the most widely used transmitting apparatus for high-power, long-distance work. It is estimated that the arc is now responsible for 80 per cent of all the energy actually radiated into space for radio purposes during a given time, unlike the existing radio transmitter of the time, the spark-gap transmitter, the arc converter produces undamped or continuous waves. This was an important feature as the use of damped waves resulted in lower efficiency and communications effectiveness. This more refined method for generating continuous-wave radio signals was initially developed by Danish inventor Valdemar Poulsen, there are three cases for an arc oscillator. In the first case, the AC current in the condenser i0 is much smaller than the DC supply current i1, the Duddell arc is an example of the first case, but the first case is not practical for RF transmitters. In the second case, the condenser AC discharge current is enough to extinguish the arc. This second case is the Poulsen arc, in the third case, the arc extinguishes but may reignite when the condenser current reverses. The third case is a spark gap and produces damped oscillations
37.
Hertz
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The hertz is the unit of frequency in the International System of Units and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide proof of the existence of electromagnetic waves. Hertz are commonly expressed in SI multiples kilohertz, megahertz, gigahertz, kilo means thousand, mega meaning million, giga meaning billion and tera for trillion. Some of the units most common uses are in the description of waves and musical tones, particularly those used in radio-. It is also used to describe the speeds at which computers, the hertz is equivalent to cycles per second, i. e. 1/second or s −1. In English, hertz is also used as the plural form, as an SI unit, Hz can be prefixed, commonly used multiples are kHz, MHz, GHz and THz. One hertz simply means one cycle per second,100 Hz means one hundred cycles per second, and so on. The unit may be applied to any periodic event—for example, a clock might be said to tick at 1 Hz, the rate of aperiodic or stochastic events occur is expressed in reciprocal second or inverse second in general or, the specific case of radioactive decay, becquerels. Whereas 1 Hz is 1 cycle per second,1 Bq is 1 aperiodic radionuclide event per second, the conversion between a frequency f measured in hertz and an angular velocity ω measured in radians per second is ω =2 π f and f = ω2 π. This SI unit is named after Heinrich Hertz, as with every International System of Units unit named for a person, the first letter of its symbol is upper case. Note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, the hertz is named after the German physicist Heinrich Hertz, who made important scientific contributions to the study of electromagnetism. The name was established by the International Electrotechnical Commission in 1930, the term cycles per second was largely replaced by hertz by the 1970s. One hobby magazine, Electronics Illustrated, declared their intention to stick with the traditional kc. Mc. etc. units, sound is a traveling longitudinal wave which is an oscillation of pressure. Humans perceive frequency of waves as pitch. Each musical note corresponds to a frequency which can be measured in hertz. An infants ear is able to perceive frequencies ranging from 20 Hz to 20,000 Hz, the range of ultrasound, infrasound and other physical vibrations such as molecular and atomic vibrations extends from a few femtoHz into the terahertz range and beyond. Electromagnetic radiation is described by its frequency—the number of oscillations of the perpendicular electric and magnetic fields per second—expressed in hertz. Radio frequency radiation is measured in kilohertz, megahertz, or gigahertz
38.
Carbon microphone
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The carbon microphone, also known as carbon button microphone, button microphone, or carbon transmitter, is a type of microphone, a transducer that converts sound to an electrical audio signal. It consists of two plates separated by granules of carbon. One plate is very thin and faces toward the speaking person, sound waves striking the diaphragm cause it to vibrate, exerting a varying pressure on the granules, which in turn changes the electrical resistance between the plates. Higher pressure lowers the resistance as the granules are pushed closer together, a steady direct current is passed between the plates through the granules. The varying resistance results in a modulation of the current, creating an electric current that reproduces the varying pressure of the sound wave. In telephony, this current is directly passed through the telephone wires to the central office. In public address systems or recording devices it is amplified by an audio amplifier, the frequency response of the carbon microphone, however, is limited to a narrow range, and the device produces significant electrical noise. Before the proliferation of vacuum tube amplifiers in the 1920s, carbon microphones were the practical means of obtaining high-level audio signals. They were widely used in telephone systems until the 1980s, while other applications used different microphone designs much earlier and their low cost, inherently high output and frequency response characteristic were well suited for telephony. For plain old telephone service, carbon-microphone based telephones can still be used without modification and they continued to be widely used for low-end public address, and military and amateur radio applications for some decades afterward. The first microphone that enabled proper voice telephony was the carbon microphone and this was independently developed by David Edward Hughes in England and Emile Berliner and Thomas Edison in the US. Although Edison was awarded the first patent in mid-1877, Hughes had demonstrated his working device in front of many witnesses some years earlier, Hughes also coined the word microphone. He demonstrated his apparatus to the Royal Society by magnifying the sound of insects scratching through a sound box, contrary to Edison, Hughes decided not to take out a patent, instead, he made his invention a gift to the world. In America, Edison and Berliner fought a legal battle over the patent rights. The carbon microphone is the prototype of todays microphones and was critical in the development of telephony, broadcasting. Later, carbon granules were used between carbon buttons, Carbon microphones were widely used in telephones from 1890 until the 1980s. Carbon microphones can be used as amplifiers and this capability was used in early telephone repeaters, making long distance phone calls possible in the era before vacuum tube amplifiers. In these repeaters, a telephone receiver was mechanically coupled to a carbon microphone
39.
General Electric
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General Electric, often abbreviated as GE, is an American multinational conglomerate corporation incorporated in New York and headquartered in Boston, Massachusetts. In 2011, GE ranked among the Fortune 500 as the 68th-largest firm in the U. S. by gross revenue, as of 2012, the company was listed the fourth-largest in the world among the Forbes Global 2000, further metrics being taken into account. The Nobel Prize has twice been awarded to employees of General Electric, Irving Langmuir in 1932, on January 13,2016, it was announced that GE will be moving its corporate headquarters from Fairfield, Connecticut to the South Boston Waterfront neighborhood of Boston, Massachusetts. The first group of workers arrived in the summer of 2016, morgan and the Vanderbilt family for Edisons lighting experiments. The new company also acquired Sprague Electric Railway & Motor Company in the same year, both plants continue to operate under the GE banner to this day. The company was incorporated in New York, with the Schenectady plant used as headquarters for years thereafter. Around the same time, General Electrics Canadian counterpart, Canadian General Electric, was formed, in 1896, General Electric was one of the original 12 companies listed on the newly formed Dow Jones Industrial Average. After 120 years, it is the one of the original companies still listed on the Dow index. In 1911, General Electric absorbed the National Electric Lamp Association into its lighting business, GE established its lighting division headquarters at Nela Park in East Cleveland, Ohio. Nela Park is still the headquarters for GEs lighting business, owen D. Young, through GE, founded the Radio Corporation of America in 1919 to further international radio. GE used RCA as its retail arm for radio sales from 1919, in 1927, Ernst Alexanderson of GE made the first demonstration of his television broadcasts at his General Electric Realty Plot home at 1132 Adams Rd, Schenectady, NY. The sound was broadcast on GEs WGY, experimental television station W2XAD evolved into station WRGB which—along with WGY and WGFM —was owned and operated by General Electric until 1983. GEs history of working with turbines in the field gave them the engineering know-how to move into the new field of aircraft turbosuperchargers. Led by Sanford Alexander Moss, GE introduced the first superchargers during World War I, superchargers became indispensable in the years immediately prior to World War II, and GE was the world leader in exhaust-driven supercharging when the war started. This experience, in turn, made GE a natural selection to develop the Whittle W.1 jet engine that was demonstrated in the United States in 1941, GE ranked ninth among United States corporations in the value of wartime production contracts. In 2002, GE acquired the assets of Enron during its bankruptcy proceedings. Some consumers boycotted GE light bulbs, refrigerators and other products in the 1980s and 1990s to protest GEs role in weapons production. With IBM, Burroughs, NCR, Control Data Corporation, Honeywell, RCA and UNIVAC, GE had a line of general purpose and special purpose computers
40.
Microphone
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A microphone, colloquially nicknamed mic or mike, is a transducer that converts sound into an electrical signal. Several different types of microphone are in use, which employ different methods to convert the air pressure variations of a wave to an electrical signal. Microphones typically need to be connected to a preamplifier before the signal can be recorded or reproduced, in order to speak to larger groups of people, a need arose to increase the volume of the human voice. The earliest devices used to achieve this were acoustic megaphones, some of the first examples, from fifth century BC Greece, were theater masks with horn-shaped mouth openings that acoustically amplified the voice of actors in amphitheatres. In 1665, the English physicist Robert Hooke was the first to experiment with an other than air with the invention of the lovers telephone made of stretched wire with a cup attached at each end. German inventor Johann Philipp Reis designed an early sound transmitter that used a strip attached to a vibrating membrane that would produce intermittent current. Better results were achieved with the transmitter design in Scottish-American Alexander Graham Bells telephone of 1876 – the diaphragm was attached to a conductive rod in an acid solution. These systems, however, gave a poor sound quality. The first microphone that enabled proper voice telephony was the carbon microphone and this was independently developed by David Edward Hughes in England and Emile Berliner and Thomas Edison in the US. Although Edison was awarded the first patent in mid-1877, Hughes had demonstrated his working device in front of many witnesses some years earlier, the carbon microphone is the direct prototype of todays microphones and was critical in the development of telephony, broadcasting and the recording industries. Thomas Edison refined the carbon microphone into his carbon-button transmitter of 1886 and this microphone was employed at the first ever radio broadcast, a performance at the New York Metropolitan Opera House in 1910. In 1916, E. C. Wente of Western Electric developed the next breakthrough with the first condenser microphone, in 1923, the first practical moving coil microphone was built. The Marconi Skykes or magnetophon, developed by Captain H. J. Round, was the standard for BBC studios in London and this was improved in 1930 by Alan Blumlein and Herbert Holman who released the HB1A and was the best standard of the day. Also in 1923, the microphone was introduced, another electromagnetic type, believed to have been developed by Harry F. Olson. Over the years these microphones were developed by companies, most notably RCA that made large advancements in pattern control. With television and film technology booming there was demand for high fidelity microphones, electro-Voice responded with their Academy Award-winning shotgun microphone in 1963. During the second half of 20th century development advanced quickly with the Shure Brothers bringing out the SM58, digital was pioneered by Milab in 1999 with the DM-1001. The latest research developments include the use of optics, lasers and interferometers
41.
Alexanderson alternator
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An Alexanderson alternator is a rotating machine invented by Ernst Alexanderson in 1904 for the generation of high-frequency alternating current for use as a radio transmitter. It was one of the first devices capable of generating the continuous radio waves needed for transmission of amplitude modulation by radio and it was used from about 1910 in a few superpower longwave radiotelegraphy stations to transmit transoceanic message traffic by Morse code to similar stations all over the world. Although obsolete by the early 1920s due to the development of vacuum-tube transmitters and it is on the list of IEEE Milestones as a key achievement in electrical engineering. Efforts were made to invent transmitters that would produce continuous waves, in an 1891 lecture, Frederick Thomas Trouton pointed out that, if an electrical alternator were run at a great enough cycle speed it would generate continuous waves at radio frequency. In 1904, Reginald Fessenden contracted with General Electric for an alternator that generated a frequency of 100,000 hertz for continuous wave radio, the alternator was designed by Ernst Alexanderson. The Alexanderson alternator was used for long-wave radio communications by shore stations. In 1906 the first 50-kilowatt alternators were delivered, one was to Reginald Fessenden at Brant Rock, Massachusetts, another to John Hays Hammond, Jr. in Gloucester, Massachusetts and another to the American Marconi Company in New Brunswick, New Jersey. Alexanderson would receive a patent in 1911 for his device, the Alexanderson alternator followed Fessendens rotary spark-gap transmitter as the second radio transmitter to be modulated to carry the human voice. The last remaining operable Alexanderson alternator is at the VLF transmitter Grimeton in Sweden and was in service until 1996. It continues to be operated for a few minutes on Alexanderson Day, starting in 1942 four stations were operated by US Navy, the station at Haiku, Hawaii until 1958, Bolinas until 1946, Marion, and Tuckerton. Two alternators were shipped to Hawaii in 1942, one each from Marion, MA and Bolinas, the other went to Guam but returned to Haiku after World War 2. Haiku began operation of the first 200 kW alternator in 1943, the second alternator went into operation at Haiku in 1949. Both alternators were sold for salvage in 1969, possibly to Kreger Company of California, one of the alternators was scrapped in 1961 and another one was handed over to the US office of standard, it now resides in a Smithsonian Institution warehouse. The two machines in Brazil were never used because of problems there. They were returned to Radio Central after 1946, the Alexanderson alternator works similarly to an AC electric generator, but generates higher-frequency current, in the radio range. The space between the teeth is filled with material, to give the rotor a smooth surface to decrease aerodynamic drag. The rotor is turned at a speed by an electric motor. The machine operates by variable reluctance, changing the magnetic flux linking two coils, the periphery of the rotor is embraced by a circular iron stator with a C-shaped cross-section, divided into narrow poles, the same number as the rotor has, carrying two sets of coils
42.
Valdemar Poulsen
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Valdemar Poulsen was a Danish engineer who made significant contributions to early radio technology. He was born on 23 November 1869 in Copenhagen, the magnetic recording was demonstrated in principle as early as 1898 by Valdemar Poulsen in his telegraphone. Magnetic wire recording, and its successor, magnetic tape recording, an electrical signal, which is analogous to the sound that is to be recorded, is fed to the recording head, inducing a pattern of magnetization similar to the signal. A playback head can then pick up the changes in the field from the tape. Poulsen obtained a Telegraphone Patent in 1898, and with his assistant, Peder O. Pedersen, later developed other magnetic recorders that recorded on steel wire, tape, or disks. None of these devices had electronic amplification, but the signal was easily strong enough to be heard through a headset or even transmitted on telephone wires. At the 1900 Worlds Fair in Paris, Poulsen had the chance to record the voice of Emperor Franz Josef of Austria which is believed to be the oldest surviving magnetic audio recording today. Poulsen developed an arc converter in 1908, referred to as the Poulsen Arc Transmitter, the system was able to communicate between Lyngby and Newcastle with a 100-foot mast. A stamp was issued in honor of Poulsen in 1969, the Valdemar Poulsen Gold Medal was awarded each year for outstanding research in the field of radio techniques and related fields by the Danish Academy of Technical Sciences. The award was presented on November 23, the anniversary of his birth, the award was discontinued in 1993. Timeline of historic inventions Sound recording List of people on stamps of Denmark 1898 –1998 Poulsens patent, ten-second video of the 1900 recording of the Austro-Hungarian emperor Franz Joseph on YouTube. Katz, Eugenii, Valdemar Poulsen at the Wayback Machine, Poulsen, Valdemar, US PAT No.661,619 Method of Recordings and Reproducing Sounds or Signals. 1900 World Exposition recording of Emperor Franz Joseph of Austria at the Wayback Machine by means of Poulsens telegraphone
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Quirino Majorana
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Quirino Majorana was an Italian experimental physicist who investigated a wide range of phenomena during his long career as professor of physics at the Universities of Rome, Turin, and Bologna, Italy. He performed a series of very sensitive gravity shielding experiments from 1918 to 1922. Majoranas experiments determined that mercury or lead around a lead sphere acted as a screen. No attempts have been made to reproduce his results using the experimental techniques. Other researchers have concluded from other data that if gravitational absorption does exist it must be at least five orders of magnitude smaller than Majoranas experiments suggest, Majorana also confirmed Isaac Newton’s law of universal gravitation to high precision. His later work at Bologna was influenced by correspondence with his nephew Ettore Majorana, quirino Majorana, Su di un fenomeno fotoelettrico constabile con gli audion, Rendiconti Accademia dei Lincei, V7, pp. 801–806. Quirino Majorana, Azione della luce su sottili lamine metalliche, La Ricerca Scientifica National Research Council, galvani e la scienza moderna, Sapere, pp. 261–265. Quirino Majorana, Ulteriori ricerche sullazione della luce su sottili lamine metallische, Il Nuovo Cimento, V15, pp. 573–593
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Charles Herrold
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Charles David Doc Herrold was an American inventor and pioneer radio broadcaster, who began experimenting with audio radio transmissions in 1909. Beginning in 1912 he apparently became the first person to make entertainment broadcasts on a schedule, from his station in San Jose. Born in Fulton, Illinois, Herrold grew up in San Jose, in 1895 he enrolled in Stanford University, where he studied astronomy and physics for three years, but withdrew due to illness and never graduated. While at Stanford he was inspired by reports of Guglielmo Marconis demonstrations that radio signals could be used for wireless communication, after recovering from his illness, Herrold moved to San Francisco, where he developed a number of inventions for dentistry, surgery, and underwater illumination. However, the April 18,1906 San Francisco earthquake destroyed his work site and he next took an engineering teaching position for three years, at Healds College of Mining and Engineering in Stockton, California. While there, his various projects included the remote detonation of mines using radio signals. Herrold began to speculate about the possibilities of using radio signals to distribute the programming more efficiently. The original spark-gap transmitters used for radio signalling could only transmit Morse code messages, even with this limitation, there was some broadcasting by early radio stations, beginning in 1905 with daily noon time signals transmitted by U. S. Naval stations. To realize his idea of distributing entertainment by radio, Herrold first needed to perfect a radiotelephone transmitter and he was not unique in this endeavor. Although he would claim that only he had conceived of entertainment broadcasting. However, Fessenden would almost exclusively focus on point-to-point transmissions intended to supplement the wire telephone system, lee DeForest was even more ambitious, although Herrold would later incorrectly assert that Certainly de Forest had no thought of a broadcast. DeForest made a series of demonstrations from 1907 to 1910, although he would not actually begin regular broadcasts until 1916. The colleges primary purpose was to train operators, for handling communications aboard ship or staffing shore stations. Although he would never get a degree, Herrold became known as Doc as a sign of his students respect, Ray Newby, just 16 years old, acted as his primary assistant. At the time Herrold began his work, there was no regulation of radio stations in the United States, later the Radio Act of 1912 mandated the licensing of stations, and Herrold was issued a license for an Experimental station in late 1915, with the callsign 6XF. Herrolds primary radiotelephone effort was developing a commercial system suitable for point-to-point service. Working with Ray Newby, he initially used high-frequency spark transmitters, however, the limitations of the high-frequency spark soon became apparent, and he switched to developing refined versions of the Poulsen arc, which was more stable and had better audio fidelity. In early 1912, Herrold was hired as chief engineer of the National Wireless Telephone, the judge sided with NWT&T and denied Herrolds claim