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Superette (radio)
In 1931 RCA introduced a new line of Superette radio receivers. These used the superheterodyne principle but were lower cost than earlier products, in an attempt to maintain sales during the onset of the Great Depression. Background Edwin Howard Armstrong invented the superheterodyne receiver in 1918. Armstrong and RCA (under David Sarnoff) had a business and technical relationship, that would last into the 1940s. Funded by RCA, Armstrong designed a radio that can receive stations easily without complex tuning or interference from other stations. Early radio designs by Armstrong and others produced radios that were very sensitive but hard to keep under control due to the nature of radio waves operating at higher frequencies. Armstrong's superheterodyne receiver converted these high frequencies into one lower frequency. This allow the radio to be more stable or easier to tune, with less interference. The result was the RCA Radiola AR-812 and Radiola VIII Superheterodynes in 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superheterodyne
A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency. It was long believed to have been invented by US engineer Edwin Armstrong, but after some controversy the earliest patent for the invention is now credited to French radio engineer and radio manufacturer Lucien Lévy. Virtually all modern radio receivers use the superheterodyne principle; except those software-defined radios using ''direct sampling''. History Heterodyne Early Morse code radio broadcasts were produced using an alternator connected to a spark gap. The output signal was at a carrier frequency defined by the physical construction of the gap, modulated by the alternating current signal from the alternator. Since the output frequency of the alternator was generally in the audible range, this produces an audible a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comparison Of RCA Superette R7 Table Versus R9 Console (1931)
Comparison or comparing is the act of evaluating two or more things by determining the relevant, comparable characteristics of each thing, and then determining which characteristics of each are similar to the other, which are different, and to what degree. Where characteristics are different, the differences may then be evaluated to determine which thing is best suited for a particular purpose. The description of similarities and differences found between the two things is also called a comparison. Comparison can take many distinct forms, varying by field: To compare things, they must have characteristics that are similar enough in relevant ways to merit comparison. If two things are too different to compare in a useful way, an attempt to compare them is colloquially referred to in English as "comparing apples and oranges." Comparison is widely used in society, in science and in the arts. General usage Comparison is a natural activity, which even animals engage in when decid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RCA R7 Superette Superheterodyne Table Radio (1931)
The RCA Corporation was a major American electronics company, which was founded as the Radio Corporation of America in 1919. It was initially a patent trust owned by General Electric (GE), Westinghouse, AT&T Corporation and United Fruit Company. In 1932, RCA became an independent company after the partners were required to divest their ownership as part of the settlement of a government antitrust suit. An innovative and progressive company, RCA was the dominant electronics and communications firm in the United States for over five decades. RCA was at the forefront of the mushrooming radio industry in the early 1920s, as a major manufacturer of radio receivers, and the exclusive manufacturer of the first superheterodyne sets. RCA also created the first nationwide American radio network, the National Broadcasting Company (NBC). The company was also a pioneer in the introduction and development of television, both black and white and especially color television. During this perio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edwin Howard Armstrong
Edwin Howard Armstrong (December 18, 1890 – February 1, 1954) was an American electrical engineer and inventor, who developed FM (frequency modulation) radio and the superheterodyne receiver system. He held 42 patents and received numerous awards, including the first Medal of Honor awarded by the Institute of Radio Engineers (now IEEE), the French Legion of Honor, the 1941 Franklin Medal and the 1942 Edison Medal. He was inducted into the National Inventors Hall of Fame and included in the International Telecommunication Union's roster of great inventors. Armstrong attended Columbia University, and served as a professor there for most of his life. Early life Armstrong was born in the Chelsea district of New York City, the oldest of John and Emily (née Smith) Armstrong's three children. His father began working at a young age at the American branch of the Oxford University Press, which published bibles and standard classical works, eventually advancing to the positio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superheterodyne Receiver
A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency. It was long believed to have been invented by US engineer Edwin Armstrong, but after some controversy the earliest patent for the invention is now credited to French radio engineer and radio manufacturer Lucien Lévy. Virtually all modern radio receivers use the superheterodyne principle; except those software-defined radios using ''direct sampling''. History Heterodyne Early Morse code radio broadcasts were produced using an alternator connected to a spark gap. The output signal was at a carrier frequency defined by the physical construction of the gap, modulated by the alternating current signal from the alternator. Since the output frequency of the alternator was generally in the audible range, this produces an aud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
David Sarnoff
David Sarnoff (February 27, 1891 – December 12, 1971) was an American businessman and pioneer of American radio and television. Throughout most of his career, he led the Radio Corporation of America (RCA) in various capacities from shortly after its founding in 1919 until his retirement in 1970. He ruled over an ever-growing telecommunications and media empire that included both RCA and NBC, and became one of the largest companies in the world. Named a Reserve Brigadier General of the Signal Corps in 1945, Sarnoff thereafter was widely known as "The General." Sarnoff is credited with ''Sarnoff's law'', which states that the value of a broadcast network is proportional to the number of viewers. Early life and career David Sarnoff was born to a Jewish family in Uzlyany, a small town in the Russian Empire, now part of Belarus, the son of Abraham Sarnoff and Leah Privin. Abraham emigrated to the United States and raised funds to bring the family. Sarnoff spent much of his earl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Batteryless Radio
A batteryless radio is a radio receiver which does not require the use of a battery to provide it with electrical power. Originally this referred to units which could be used directly by AC mains supply (mains radio); it can also refer to units which do not require a power source at all, except for the power that they receive from radio waves. History The line-operated vacuum tube receiver was invented in 1925 by Edward S. Rogers, Sr. The unit operated with 5 Rogers AC vacuum tubes and the Rogers Battery-Eliminator Power Unit (power supply). This unit was later marketed for $120 as "Type 120". He established the Toronto station CFRB (an abbreviation of ''Canada's First Rogers Batteryless'') to promote sales of the product. Batteryless radios were not introduced into the United States until May 1926 and then into Europe in 1927. Crystal radio receivers are a very simple kind of batteryless radio receiver. They do not need a battery or power source, except for the power that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Automatic Gain Control
Automatic gain control (AGC) is a closed-loop feedback regulating circuit in an amplifier or chain of amplifiers, the purpose of which is to maintain a suitable signal amplitude at its output, despite variation of the signal amplitude at the input. The average or peak output signal level is used to dynamically adjust the gain of the amplifiers, enabling the circuit to work satisfactorily with a greater range of input signal levels. It is used in most radio receivers to equalize the average volume ( loudness) of different radio stations due to differences in received signal strength, as well as variations in a single station's radio signal due to fading. Without AGC the sound emitted from an AM radio receiver would vary to an extreme extent from a weak to a strong signal; the AGC effectively reduces the volume if the signal is strong and raises it when it is weaker. In a typical receiver the AGC feedback control signal is usually taken from the detector stage and applied to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Electronics
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by another antenna connected to a radio receiver. Radio is very widely used in modern technology, in radio communication, radar, radio navigation, remote control, remote sensing, and other applications. In radio communication, used in radio and television broadcasting, cell phones, two-way radios, wireless networking, and satellite communication, among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter. In radar, used to locate and track objects like aircraft, ships, spacecraft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of Radio In The United States
Radio broadcasting in the United States has been used since the early 1920s to distribute news and entertainment to a national audience. In 1923, 1 percent of U.S. households owned at least one radio receiver, while a majority did by 1931 and 75 percent did by 1937. It was the first electronic "media of the United States, mass medium" technology, and its introduction, along with the subsequent development of sound films, ended the print monopoly of mass media. During the Golden Age of Radio it had a major cultural and financial impact on the country. However, the rise of television broadcasting in the 1950s relegated radio to a secondary status, as much of its programming and audience shifted to the new "sight joined with sound" service. Originally the term "radio" only included transmissions freely received over-the-air, such as the AM and FM bands, now commonly called "terrestrial radio". However, the term has evolved to more broadly refer to streaming audio services in general, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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