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Kaliakra Transmitter
The Kaliakra transmitter was a huge facility for medium wave broadcasting, which was built after 1988 by the former Soviet Union as a relay transmitter for Southeast Europe. After the collapse of communism in 1989, there was no need for the facility and work was stopped. At that time, nine of the planned 10 masts were already completed and work on the final mast had begun. Some masts were already equipped with cage antennas, while others remained bare. All masts of the station were grounded guyed lattice masts with a triangular cross section, equipped with a cage antenna. Their height varied between and . The masts could work as either a directional antenna with low pattern by using two masts or as a highly directional antenna by using eight masts. The broadcasting company of Bulgaria had no interest in using the facility, as it already had several well-equipped high power medium wave broadcasting facilities in several parts of Bulgaria (e.g. in Vakarel, Pleven and Vidin). Fore ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kaliakra Bulgaria 1994 CIA Map
Kaliakra ( bg, Калиакра; ro, Caliacra) is a cape in the Southern Dobruja region of the northern Bulgarian Black Sea Coast, which ends with a long and narrow headland east of Kavarna, northeast of Varna and southwest of Mangalia. The coast is steep with vertical cliffs reaching down to the sea. Kaliakra is a nature reserve, where dolphins and cormorants can be observed. It sits on the Via Pontica, a major bird migration route from Africa into Eastern and Northern Europe. Many rare and migrant birds can be seen here in spring and autumn and, like much of this coastline, is home to several rare breeding birds (e.g. pied wheatear and a local race of European shag). The rest of the reserve also has unusual breeding birds; saker falcon, lesser grey shrike and a host of others. It also features the remnants of the fortified walls, water-main, baths and residence of Despot Dobrotitsa in the short-lived Despotate of Dobruja's medieval capital. The Bolata Cove with a small sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 radio ban ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national republics; in practice, both its government and its economy were highly centralized until its final years. It was a one-party state governed by the Communist Party of the Soviet Union, with the city of Moscow serving as its capital as well as that of its largest and most populous republic: the Russian SFSR. Other major cities included Leningrad (Russian SFSR), Kiev (Ukrainian SSR), Minsk ( Byelorussian SSR), Tashkent (Uzbek SSR), Alma-Ata (Kazakh SSR), and Novosibirsk (Russian SFSR). It was the largest country in the world, covering over and spanning eleven time zones. The country's roots lay in the October Revolution of 1917, when the Bolsheviks, under the leadership of Vladimir Lenin, overthrew the Russian Provisional Government ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relay Transmitter
A broadcast relay station, also known as a satellite station, relay transmitter, broadcast translator (U.S.), re-broadcaster (Canada), repeater (two-way radio) or complementary station (Mexico), is a broadcast transmitter which repeats (or transponds) the signal of a radio or television station to an area not covered by the originating station. It expands the broadcast range of a television or radio station beyond the primary signal's original coverage or improves service in the original coverage area. The stations may be (but are not usually) used to create a single-frequency network. They may also be used by an AM or FM radio station to establish a presence on the other band. Relay stations are most commonly established and operated by the same organisations responsible for the originating stations they repeat. However, depending on technical and regulatory restrictions, relays may also be set up by unrelated organisations. Types Broadcast translators In its simplest form, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cage Antenna
A cage antenna (British cage aerial) is a radio antenna where a conventional design has been augmented by replacing a single long conductor with several parallel wires, connected at their ends, and held in position by ring spacers or support struts mounted on a central mast (if any). The "cage" is either mounted around a central mast (either conducting or non-conducting) or suspended from overhead wires. Purpose A cage can improve any antenna design by replacing a single wire in any section that carries large, unbalanced (radiating) current; the only issue is whether the improvement will be substantial enough to warrant the extra effort. The multiple parallel wires electrically simulate a single fat wire, roughly equivalent to a wire with a diameter half as wide as the distance separating the cage wires, giving the modified antenna higher radiation resistance, lowered conductor resistance, and a wider bandwidth without as much weight and wind resistance as the equivalent fat wire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Directional Antenna
A directional antenna or beam antenna is an antenna which radiates or receives greater power in specific directions allowing increased performance and reduced interference from unwanted sources. Directional antennas provide increased performance over dipole antennas—or omnidirectional antennas in general—when greater concentration of radiation in a certain direction is desired. A high-gain antenna (HGA) is a directional antenna with a focused, narrow radiowave beam width, permitting more precise targeting of the radio signals. Most commonly referred to during space missions, these antennas are also in use all over Earth, most successfully in flat, open areas where there are no mountains to disrupt radiowaves. By contrast, a low-gain antenna (LGA) is an omnidirectional antenna with a broad radiowave beam width, that allows the signal to propagate reasonably well even in mountainous regions and is thus more reliable regardless of terrain. Low-gain antennas are often used in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vakarel Radio Transmitter
The Vakarel Transmitter was a large broadcasting facility for long- and medium wave near Vakarel, Bulgaria. The Vakarel Transmitter was inaugurated in 1937. It had one directional antenna consisting of three guyed masts and another consisting of two masts. The most remarkable mast of the Vakarel Transmitter was the Blaw-Knox tower, built in 1937 by the company Telefunken. Along with Lakihegy Tower, Hungary, Riga LVRTC Transmitter, Latvia and Lisnagarvey Radio Mast, Northern Ireland it was one of the few Blaw-Knox towers in Europe until its demolition on 16 September 2020. The transmitter was shut down at 22:00 UTC on 31 December 2014. Transmitter internal structure The modulation method used by the transmitter in Vakarel is called a tube voltage modulation and was successfully used in all powerful AM transmitters at that time. The Vakarel transmitter is supplied with electricity from a substation in Samokov via a medium voltage transmission line. The transmitter uses six ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pleven
Pleven ( bg, Плèвен ) is the seventh most populous city in Bulgaria. Located in the northern part of the country, it is the administrative centre of Pleven Province, as well as of the subordinate Pleven municipality. It is the biggest economic center in Northwestern Bulgaria. At the 2021 census its population was 89,823. Internationally known for the siege of Plevna of 1877, it is today a major economic centre of the Bulgarian Northwest and Central North and the third largest city of Northern Bulgaria after Varna and Ruse. Name The name comes from the Slavic word ''plevnya'' ("barn") or from ''plevel'', meaning "weed", sharing the same root, and the Slavic suffix ''-en''. Geography Pleven is in an agricultural region in the middle of the Danubian Plain, the historical region of Moesia, surrounded by low limestone hills, the Pleven Heights. The city's central location in Northern Bulgaria defines its importance as a big administrative, economic, political, cultura ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vidin
Vidin ( bg, Видин, ; Old Romanian: Diiu) is a port city on the southern bank of the Danube in north-western Bulgaria. It is close to the borders with Romania and Serbia, and is also the administrative centre of Vidin Province, as well as of the Metropolitan of Vidin (since 870). An agricultural and trade centre, Vidin has a fertile hinterland renowned for its wines. Name The name is archaically spelled as ''Widdin'' in English. Old name ''Dunonia'' itself meant "fortified hill" in Celtic with the typically ''dun'' found frequently in Celtic place names. Geography Vidin is the westernmost important Bulgarian Danube port and is situated on one of the southernmost sections of the river. The New Europe Bridge, completed in 2013, connects Vidin to the Romanian town of Calafat on the opposite bank of the Danube. Previously, a ferry located from the town was in use for that purpose. History Vidin emerged at the place of an old Celtic settlement known as ''Dunonia''. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blaw-Knox Tower
The Blaw-Knox company was an American manufacturer of steel structures and construction equipment based in Pittsburgh, Pennsylvania. The company is today best known for its radio towers, most of which were constructed during the 1930s in the United States. Although Blaw-Knox built many kinds of towers, the term Blaw-Knox tower (or radiator) usually refers to the company's unusual "diamond cantilever" design, which is stabilized by guy wires attached only at the vertical center of the mast, where its cross-section is widest. During the 1930s AM radio broadcasting stations adopted single mast radiator antennas, and the Blaw-Knox design was the first type used. A 1942 advertisement claims that 70% of all radio towers in the United States at the time were built by Blaw-Knox. The distinctive diamond-shaped towers became an icon of early radio. Several are listed on the United States National Register of Historic Places, [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effective Radiated Power
Effective radiated power (ERP), synonymous with equivalent radiated power, is an IEEE standardized definition of directional radio frequency (RF) power, such as that emitted by a radio transmitter. It is the total power in watts that would have to be radiated by a half-wave dipole antenna to give the same radiation intensity (signal strength or power flux density in watts per square meter) as the actual source antenna at a distant receiver located in the direction of the antenna's strongest beam (main lobe). ERP measures the combination of the power emitted by the transmitter and the ability of the antenna to direct that power in a given direction. It is equal to the input power to the antenna multiplied by the gain of the antenna. It is used in electronics and telecommunications, particularly in broadcasting to quantify the apparent power of a broadcasting station experienced by listeners in its reception area. An alternate parameter that measures the same thing is effec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
