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Shortwave Radio
Shortwave radio is radio transmission using radio frequencies in the shortwave bands (SW). There is no official definition of the band range, but it always includes all of the High frequency, high frequency band (HF), which extends from 3 to 30 MHz (approximately 100 to 10 metres in wavelength). It lies between the Medium frequency, medium frequency band (MF) and the bottom of the Very high frequency, VHF band. Radio waves in the shortwave band can be reflected or refracted from a layer of electrically 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, beyond the horizon. This is called skywave or "skip" radio propagation, propagation. Thus shortwave radio can be used for communication over very long distances, in contrast to radio waves of higher frequency, which travel in straight lines (line-of-sight propagation) and are generally limited by the visual horizon, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grundig Satellit Professional 400
Grundig ( , , ) is a Turkey, Turkish home appliances and consumer electronics brand. It is owned by Arçelik, Arçelik A.Ş., the Major appliance, white goods (major appliance) manufacturer of Turkish conglomerate Koç Holding. Originally a Germany, German consumer electronics company, Grundig Gesellschaft mit beschränkter Haftung, GmbH was founded in 1945 by Max Grundig and was headquartered for the most part in Nuremberg until its insolvency in 2003. The Grundig company helped fuel the Wirtschaftswunder, post-war economic miracle of West Germany and it grew to become one of the leading manufacturers in the world of radio, TV, recording and other electronic equipment in the following decades. In the 1970s, Philips began acquiring Grundig's shares, leading to complete control in 1993, but Philips divested Grundig by 1998. Grundig filed for bankruptcy in April 2003 after years of losses and strong competition from cheaper Asian competitors. Most of the former Grundig business ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cable Radio
Cable radio is radio broadcasting into homes and businesses via a cable. This can be a coaxial cable used for television, or a telephone line. It is generally used for the same reason as cable TV was in its early days when it was "community antenna television", in order to enhance the quality of over-the-air radio signals that are difficult to receive in an area. However, cable-only radio outlets also exist. It can be both FM or AM. The use of cable radio varies from area to area - some cable TV systems don't include it at all, and others only have something approaching it on digital cable systems. Additionally, some stations may just transmit audio in the background while a public-access television cable TV channel is operating in between periods of video programming. From the late 1970s to the late 1980s, before the advent of Multichannel Television Sound, MTS Stereo television broadcasts, an additional cable decoder was offered to cable TV subscribers, which was connected to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guglielmo Marconi
Guglielmo Giovanni Maria Marconi, 1st Marquess of Marconi ( ; ; 25 April 1874 – 20 July 1937) was an Italian electrical engineer, inventor, and politician known for his creation of a practical radio wave-based Wireless telegraphy, wireless telegraph system. This led to Marconi being credited as the inventor of radio and sharing the 1909 Nobel Prize in Physics with Karl Ferdinand Braun "in recognition of their contributions to the development of wireless telegraphy". His work laid the foundation for the development of radio, television, and all modern wireless communication systems. Marconi was also an entrepreneur and businessman who founded the Wireless Telegraph & Signal Company (which became the Marconi Company) in the United Kingdom of Great Britain and Ireland, United Kingdom in 1897. In 1929, Marconi was ennobled as a marchese, marquess (''marchese'') by Victor Emmanuel III. In 1931, he set up Vatican Radio for Pope Pius XI. Biography Early years Guglielmo Giovanni Mar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmitter
In electronics and telecommunications, a radio transmitter or just transmitter (often abbreviated as XMTR or TX in technical documents) is an electronic device which produces radio waves with an antenna (radio), antenna with the purpose of signal transmission to a radio receiver. The transmitter itself generates a radio frequency alternating current, which is applied to the Antenna (radio), antenna. When excited by this alternating current, the antenna Electromagnetic radiation, radiates radio waves. Transmitters are necessary component parts of all electronic devices that communicate by radio communication, radio, such as radio broadcasting, radio (audio) and television broadcasting stations, cell phones, walkie-talkies, Wireless LAN, wireless computer networks, Bluetooth enabled devices, garage door openers, two-way radios in aircraft, ships, spacecraft, radar sets and navigational beacons. The term ''transmitter'' is usually limited to equipment that generates radio waves fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kilohertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base units is 1/s or s−1, meaning that one hertz is one per second or the reciprocal of one second. It is used only in the case of periodic events. It is named after Heinrich Rudolf Hertz (1857–1894), the first person to provide conclusive proof of the existence of electromagnetic waves. For high frequencies, the unit is commonly expressed in multiples: kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz). Some of the unit's most common uses are in the description of periodic waveforms and musical tones, particularly those used in radio- and audio-related applications. It is also used to describe the clock speeds at which computers and other electronics are driven. The units are sometimes also used as a representation o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Telegraphy
Wireless telegraphy or radiotelegraphy is the transmission of text messages by radio waves, analogous to electrical telegraphy using cables. Before about 1910, the term ''wireless telegraphy'' was also used for other experimental technologies for transmitting telegraph signals without wires. In radiotelegraphy, information is transmitted by pulses of radio waves of two different lengths called "dots" and "dashes", which spell out text messages, usually in Morse code. In a manual system, the sending operator taps on a switch called a telegraph key which turns the transmitter on and off, producing the pulses of radio waves. At the receiver the pulses are audible in the receiver's speaker as beeps, which are translated back to text by an operator who knows Morse code. Radiotelegraphy was the first means of radio communication. The first practical radio transmitters and receivers invented in 1894–1895 by Guglielmo Marconi used radiotelegraphy. It continued to be the only type o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of Radio
The early history of radio is the history of technology that produces and uses 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. Discovery In an 1864 presentation, published in 1865, James Clerk Maxwell proposed theories of electromagnetism and mathematical proofs demonstrating that light, radio and x-rays were all types of electromagnetic waves propagating through free space. Between 1886 and 1888 Heinrich Rudolf Hertz published the results of experiments wherein he was able to transmit electromagnetic waves (radio waves) through the air, proving Maxwell's electromagnetic theory. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medium Frequency
Medium frequency (MF) is the International Telecommunication Union, ITU designation for Radio frequency, radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz). Part of this band is the medium wave (MW) AM broadcast band. The MF band is also known as the hectometer band as the wavelengths range from ten to one hectometers (1000 to 100 m). Frequencies immediately below MF are denoted as low frequency (LF), while the first band of higher frequencies is known as high frequency (HF). MF is mostly used for AM broadcasting, AM radio broadcasting, Radio beacon, navigational radio beacons, maritime ship-to-shore communication, and transoceanic air traffic control. Propagation Radio waves at MF wavelengths propagate via ground waves and reflection from the ionosphere (called skywaves). Ground waves travel just above the earth's surface, following the terrain. At these wavelengths, they can bend (diffraction, diffract) over hills, and travel be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medium Wave
Medium wave (MW) is a part of the medium frequency (MF) radio band used mainly for AM radio broadcasting. The spectrum provides about 120 channels with more limited sound quality than FM stations on the FM broadcast band. During the daytime, reception is usually limited to more local stations, though this is dependent on the signal conditions and quality of radio receiver used. Improved signal propagation at night allows the reception of much longer distance signals (within a range of about 2,000 km or 1,200 miles). This can cause increased interference because on most channels multiple transmitters operate simultaneously worldwide. In addition, amplitude modulation (AM) is often more prone to interference by various electronic devices, especially power supplies and computers. Strong transmitters cover larger areas than on the FM broadcast band but require more energy and longer antennas. Digital modes are possible but had not yet reached momentum. MW was the main radio b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long Wave
In radio, longwave (also spelled long wave or long-wave and commonly abbreviated LW) is the part of the radio spectrum with wavelengths longer than what was originally called the medium-wave (MW) broadcasting band. The term is historic, dating from the early 20th century, when the radio spectrum was considered to consist of LW, MW, and short wave radio, short-wave (SW) radio bands. Most modern radio systems and devices use wavelengths which would then have been considered 'ultra-short' (i.e. very high frequency, VHF, ultra high frequency, UHF, and microwave). In contemporary usage, the term ''longwave'' is not defined precisely, and its intended meaning varies. It may be used for radio wavelengths longer than 1,000 m i.e. Frequency, frequencies smaller than 300 kilohertz (kHz), including the International Telecommunication Union (ITU) low frequency (LF, 30–300 kHz) and very low frequency (VLF, 3–30 kHz) bands. Sometimes the upper limit is taken to be hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Spectrum
The radio spectrum is the part of the electromagnetic spectrum with frequencies from 3 Hz to 3,000 GHz (3 THz). Electromagnetic waves in this frequency range, called radio waves, are widely used in modern technology, particularly in telecommunication. To prevent interference between different users, the generation and transmission of radio waves is strictly regulated by national laws, coordinated by an international body, the International Telecommunication Union (ITU). Different parts of the radio spectrum are allocated by the ITU for different radio transmission technologies and applications; some 40 radiocommunication services are defined in the ITU's Radio Regulations (RR). In some cases, parts of the radio spectrum are sold or licensed to operators of private radio transmission services (for example, cellular telephone operators or broadcast television stations). Ranges of allocated frequencies are often referred to by their provisioned use (for exampl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guglielmo Marconi 1901 Wireless Signal
Guglielmo () is the Italian form of the masculine name William. It may refer to: People with the given name Guglielmo: * Guglielmo I Gonzaga (1538–1587), Duke of Mantua and Montferrat * Guglielmo Agnelli (c. 1238 – 1313), Italian sculptor and architect * Guglielmo Arena (born 1973), Swiss football manager * Guglielmo Bergamasco (c. 1485 – 1550), Italian architect * Guglielmo Borremans (1670–1744), Baroque painter * Guglielmo Bosca (born 1993), Italian alpine skier * Guglielmo Caccia (1568–1625), Italian painter * Guglielmo Achille Cavellini (1914–1990), influential Italian art collector and mail artist * Guglielmo da Leoni (c. 1664 – 1740), Italian painter and engraver * Guglielmo da Marsiglia (1475–1537), Italian painter of stained glass * Guglielmo della Porta (c. 1500 – 1577), Italian architect and sculptor * Guglielmo della Scala (died 1404), Lord of Verona * Guglielmo Ebreo da Pesaro (c. 1420 – c. 1484), Italian dancing-master * Guglielmo Emb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
