|
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] |
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, so that contaminants do n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Industry Canada
Innovation, Science and Economic Development Canada (ISED; ; )''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 Industry (currently Mélanie Joly), who also serves as the Minister responsible for Canada Economic Development for Quebec Regions. Several other ministerial portfolios are associated with the department. While the minister is head of the department, and provides policy/political direction, the day-to-day operations of the department are managed by the deputy minister, who is a public servant. The department headquarters are located at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Propagation
Radio propagation is the behavior of radio waves as they travel, or are wave propagation, 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 (physics), reflection, refraction, diffraction, absorption (electromagnetic radiation), absorption, polarization (waves), 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 Broadcasting, broadcasters, to designing reliable Mobile phone, 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 ante ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Federal Communications Commission
The Federal Communications Commission (FCC) is an independent agency of the United States government that regulates communications by radio, television, wire, internet, wi-fi, 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 established pursuant to the Communications Act of 1934 to replace the radio regulation functions of the previous 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 in North America. The FCC is funded entirely by regulatory fees. It has an estimated fiscal-2022 budg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Europe
Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. 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 shares the landmass of Eurasia with Asia, and of Afro-Eurasia with both Africa and Asia. Europe is commonly considered to be Boundaries between the continents#Asia and Europe, separated from Asia by the Drainage divide, watershed of the Ural Mountains, the Ural (river), Ural River, the Caspian Sea, the Greater Caucasus, the Black Sea, and the waterway of the Bosporus, Bosporus Strait. "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 Black Sea with its outlets, the Bosporus and Dardanelles." Europe covers approx. , or 2% of Earth#Surface, Earth's surface (6.8% of Earth's land area), making it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weather Forecasting
Weather forecasting or weather prediction is the application of science and technology forecasting, to predict the conditions of the Earth's atmosphere, atmosphere for a given location and time. People have attempted to predict the weather informally for thousands of years 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 atmospheric pressure, barometric pressure, current weather conditions, and sky conditions or cloud cover, weather forecasting now relies on numerical weather prediction, computer-based models that take many atmospheric factors into account. Human input is still required to pick the best possible model to base the forecast upon, which involves pattern recognition skills, teleconnections, knowledge of model performance, and kn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herbert Hoover
Herbert Clark Hoover (August 10, 1874 – October 20, 1964) was the 31st president of the United States, serving from 1929 to 1933. A wealthy mining engineer before his presidency, Hoover led the wartime Commission for Relief in Belgium and was the director of the U.S. Food Administration, followed by post-war relief of Europe. As a member of the Republican Party (United States), Republican Party, he served as the third United States secretary of commerce from 1921 to 1928 before being 1928 United States presidential election, elected president in 1928. His presidency was dominated by the Great Depression, and his policies and methods to combat it were seen as lackluster. Amid his unpopularity, he decisively lost reelection to Franklin D. Roosevelt in 1932 United States presidential election, 1932. Born to a Quaker family in West Branch, Iowa, Hoover grew up in Oregon. He was one of the first graduates of the new Stanford University in 1895. Hoover took a position with a Lond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Department Of Commerce
The United States Department of Commerce (DOC) is an executive department of the U.S. federal government. It is responsible for gathering data for business and governmental decision making, establishing industrial standards, catalyzing economic development, promoting foreign direct investment, and safeguarding national economic security. The Department of Commerce is one of four federal agencies authorized to appoint personnel in the United States Foreign Service, and its NOAA Corps — formerly the Coast and Geodetic Survey Corps — is one of the eight branches of the uniformed services of the United States. During a large-scale disaster or catastrophe, it assumes the coordinating responsibilities for the economic recovery support function under the national disaster recovery framework. Since 2023, it has led U.S. government activities related to safe artificial intelligence development and, from 1913 to 1939, it managed the National Aquarium. The department is head ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clear-channel Station
A clear-channel station is a North American AM radio station that has the highest level of protection from interference from other stations, particularly from nighttime skywave signals. This classification 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 the 1983 adoption of the Regional Agreement for the Medium Frequency Broadcasting Service in Region 2 (Rio Agreement), 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 a transmitter power output ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North American Regional Broadcasting Agreement
The North American Regional Broadcasting Agreement (NARBA, ; ) 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 station, 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 established by the NARBA agreement ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
