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Medium Wave
Medium wave (MW) is the 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 have not reached momentum yet. MW was the main radi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ground Conductivity
Ground conductivity refers to the electrical conductivity of the subsurface of the earth. In the International System of Units (SI) it is measured in millisiemens per meter (mS/m). Radio propagation Ground conductivity is an extremely important factor in determining the field strength and propagation of surface wave (ground wave) radio transmissions. Low frequency (30–300 kHz) and medium frequency (300–3000 kHz) radio transmissions are particularly reliant on good ground conductivity as their primary propagation is by surface wave. It also affects the real world radiation pattern of high frequency (3-30 MHz) antennas, as the so called "takeoff angle" is not an inherent property of the antenna but a result of a ground reflection. For this reason ITU publishes an extensive world atlas of ground conductivities. Other uses Ground conductivity is sometimes used in determining the efficiency of a septic tank, using electromagnetic induction Electromagnetic or m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Industry Canada
Innovation, Science and Economic Development Canada (ISED; french: Innovation, Sciences et Développement économique Canada; french: ISDE, label=none)''Innovation, Science and Economic Development Canada'' is the applied title under the Federal Identity Program; the legal title is Department of Industry (). is a department of the Government of Canada. ISED is responsible for a number of the federal government's functions in regulating industry and commerce, promoting science and innovation, and supporting economic development. The department was known as Industry Canada (IC) prior to 2015. The department is led by the minister of innovation, science and industry (currently François-Philippe Champagne), who also serves as the registrar general of Canada and is responsible for the department to Parliament. Several other ministerial portfolios are associated with the department. While the minister is head of the department, and provides policy/political direction, the day-t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Propagation
Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. Understanding the effects of varying conditions on radio propagation has many practical applications, from choosing frequencies for amateur radio communications, international shortwave broadcasters, to designing reliable mobile telephone systems, to radio navigation, to operation of radar systems. Several different types of propagation are used in practical radio transmission systems. ''Line-of-sight propagation'' means radio waves which travel in a straight line from the transmitting antenna to the receiving antenna. Line of sight transmission is used for medium-distance radio transmission, such as cell phones, cordless phones, wal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Federal Communications Commission
The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdiction over the areas of broadband access, fair competition, radio frequency use, media responsibility, public safety, and homeland security. The FCC was formed by the Communications Act of 1934 to replace the radio regulation functions of the Federal Radio Commission. The FCC took over wire communication regulation from the Interstate Commerce Commission. The FCC's mandated jurisdiction covers the 50 states, the District of Columbia, and the territories of the United States. The FCC also provides varied degrees of cooperation, oversight, and leadership for similar communications bodies in other countries of North America. The FCC is funded entirely by regulatory fees. It has an estimated fiscal-2022 budget of US $388 million. It h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. Comprising the westernmost peninsulas of Eurasia, it shares the continental landmass of Afro-Eurasia with both Africa and Asia. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south and Asia to the east. Europe is commonly considered to be separated from Asia by the watershed of the Ural Mountains, the Ural River, the Caspian Sea, the Greater Caucasus, the Black Sea and the waterways of the Turkish Straits. "Europe" (pp. 68–69); "Asia" (pp. 90–91): "A commonly accepted division between Asia and Europe ... is formed by the Ural Mountains, Ural River, Caspian Sea, Caucasus Mountains, and the Blac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weather Forecasting
Weather forecasting is the application of science and technology to predict the conditions of the atmosphere for a given location and time. People have attempted to predict the weather informally for millennia and formally since the 19th century. Weather forecasts are made by collecting quantitative data about the current state of the atmosphere, land, and ocean and using meteorology to project how the atmosphere will change at a given place. Once calculated manually based mainly upon changes in barometric pressure, current weather conditions, and sky condition or cloud cover, weather forecasting now relies on computer-based models that take many atmospheric factors into account. Human input is still required to pick the best possible forecast model to base the forecast upon, which involves pattern recognition skills, teleconnections, knowledge of model performance, and knowledge of model biases. The inaccuracy of forecasting is due to the chaotic nature of the atmosphere, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herbert Hoover
Herbert Clark Hoover (August 10, 1874 – October 20, 1964) was an American politician who served as the 31st president of the United States from 1929 to 1933 and a member of the Republican Party (United States), Republican Party, holding office during the onset of the Great Depression in the United States. A self-made man who became rich as a mining engineer, Hoover led the Commission for Relief in Belgium, served as the director of the U.S. Food Administration, and served as the U.S. Secretary of Commerce. Hoover was born to a Quaker family in West Branch, Iowa, but he grew up in Oregon. He was one of the first graduates of the new Stanford University in 1895. He took a position with a London-based mining company working in Australia and China. He rapidly became a wealthy mining engineer. In 1914 at the outbreak of World War I, he organized and headed the Commission for Relief in Belgium, an international relief organization that provided food to occupied Belgium. When the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Department Of Commerce
The United States Department of Commerce is an executive department of the U.S. federal government concerned with creating the conditions for economic growth and opportunity. Among its tasks are gathering economic and demographic data for business and government decision making, and helping to set industrial standards. Its main purpose is to create jobs, promote economic growth, encourage sustainable development and block harmful trade practices of other nations. Steve Charnovitz, "Reinventing the Commerce Dept.", ''Journal of Commerce'', July 12, 1995. It is headed by the Secretary of Commerce, who reports directly to the President of the United States and is a member of the president's Cabinet. The Department of Commerce is headquartered in the Herbert C. Hoover Building in Washington, DC. History Organizational history The department was originally created as the United States Department of Commerce and Labor on February 14, 1903. It was subsequently renamed the Departmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clear-channel Station
A clear-channel station is an AM radio station in North America that has the highest protection from interference from other stations, particularly concerning night-time skywave propagation. The system exists to ensure the viability of cross-country or cross-continent radio service enforced through a series of treaties and statutory laws. Known as Class A stations since 1982, they are occasionally still referred to by their former classifications of Class I-A (the highest classification), Class I-B (the next highest class), or Class I-N (for stations in Alaska too far away to cause interference to the primary clear-channel stations in the lower 48 states). The term "clear-channel" is used most often in the context of North America and the Caribbean, where the concept originated. Since 1941, these stations have been required to maintain an effective radiated power of at least 10,000 watts to retain their status. Nearly all such stations in the United States, Canada and The Baham ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North American Regional Broadcasting Agreement
The North American Regional Broadcasting Agreement (NARBA, es, Convenio Regional Norteamericano de Radiodifusión) refers to a series of international treaties that defined technical standards for AM band ( mediumwave) radio stations. These agreements also addressed how frequency assignments were distributed among the signatories, with a special emphasis on high-powered clear channel allocations. The initial NARBA bandplan, also known as the "Havana Treaty", was signed by the United States, Canada, Mexico, Cuba, the Dominican Republic, and Haiti on December 13, 1937, and took effect March 29, 1941. A series of modifications and adjustments followed, also under the NARBA name. NARBA's provisions were largely supplanted in 1983, with the adoption of the Regional Agreement for the Medium Frequency Broadcasting Service in Region 2 (Rio Agreement), which covered the entire Western hemisphere. However, current AM band assignments in North America largely reflect the standards first e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F Layer
The F region of the ionosphere is home to the F layer of ionization, also called the Appleton–Barnett layer, after the English physicist Edward Appleton and New Zealand physicist and meteorologist Miles Barnett. As with other ionospheric sectors, 'layer' implies a concentration of plasma, while 'region' is the volume that contains the said layer. The F region contains ionized gases at a height of around 150–800 km (100 to 500 miles) above sea level, placing it in the Earth's thermosphere, a hot region in the upper atmosphere, and also in the heterosphere, where chemical composition varies with height. Generally speaking, the F region has the highest concentration of free electrons and ions anywhere in the atmosphere. It may be thought of as comprising two layers, the F1 and F2 layers. The F-region is located directly above the E region (formerly the Kennelly-Heaviside layer) and below the protonosphere. It acts as a dependable reflector of HF radio signals as it is n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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