Radio masts and towers
Radio masts and towers are tall structures designed to support antennas for telecommunications and broadcasting, including television. There are two main types: self-supporting structures, they are among the tallest human-made structures. Masts are named after the broadcasting organizations that built them or use them. In the case of a mast radiator or radiating tower, the whole mast or tower is itself the transmitting antenna; the terms "mast" and "tower" are used interchangeably. However, in structural engineering terms, a tower is a self-supporting or cantilevered structure, while a mast is held up by stays or guys. Broadcast engineers in the UK use the same terminology. A mast is a ground-based or rooftop structure that supports antennas at a height where they can satisfactorily send or receive radio waves. Typical masts are of tubular steel construction. Masts themselves play no part in the transmission of mobile telecommunications. Masts tend to be cheaper to build but require an extended area surrounding them to accommodate the guy wires.
Towers are more used in cities where land is in short supply. There are a few borderline designs that are free-standing and guyed, called additionally guyed towers. For example: The Gerbrandy tower consists of a self-supporting tower with a guyed mast on top; the few remaining Blaw-Knox towers do the opposite: they have a guyed lower section surmounted by a freestanding part. Zendstation Smilde, a tall tower with a guyed mast on top with guys which go to ground. Torre de Collserola, a guyed tower with a guyed mast on top where the tower portion is not free-standing. Experimental radio broadcasting began in 1905, commercial radio broke through in the 1920s; until August 8, 1991, the Warsaw radio mast was the world's tallest supported structure on land. There are over 50 radio structures in the United States that are taller; the steel lattice is the most widespread form of construction. It provides great strength, low weight and wind resistance, economy in the use of materials. Lattices of triangular cross-section are most common, square lattices are widely used.
Guyed masts are used. When built as a tower, the structure may be taper over part or all of its height; when constructed of several sections which taper exponentially with height, in the manner of the Eiffel Tower, the tower is said to be an Eiffelized one. The Crystal Palace tower in London is an example. Guyed masts are sometimes constructed out of steel tubes; this construction type has the advantage that cables and other components can be protected from weather inside the tube and the structure may look cleaner. These masts are used for FM-/TV-broadcasting, but sometimes as mast radiator; the big mast of Mühlacker transmitting station is a good example of this. A disadvantage of this mast type is that it is much more affected by winds than masts with open bodies. Several tubular guyed masts have collapsed. In the UK, the Emley Moor and Waltham TV stations masts collapsed in the 1960s. In Germany the Bielstein transmitter collapsed in 1985. Tubular masts were not built in all countries. In Germany, France, UK, Czech Republic, Slovakia and the Soviet Union, many tubular guyed masts were built, while there are nearly none in Poland or North America.
In several cities in Russia and Ukraine several tubular guyed masts with crossbars running from the mast structure to the guys were built in the 1960s. All these masts, which are designed as 30107 KM, are used for FM and TV transmission and, except for the mast in Vinnytsia, are between 150–200-metre tall; the crossbars of these masts are equipped with a gangway that holds smaller antennas, though their main purpose is oscillation damping. Reinforced concrete towers are expensive to build but provide a high degree of mechanical rigidity in strong winds; this can be important when antennas with narrow beamwidths are used, such as those used for microwave point-to-point links, when the structure is to be occupied by people. In the 1950s, AT&T built numerous concrete towers, more resembling silos than towers, for its first transcontinental microwave route. In Germany and the Netherlands most towers constructed for point-to-point microwave links are built of reinforced concrete, while in the UK most are lattice towers.
Concrete towers can form prestigious landmarks, such as the CN Tower in Canada. In addition to accommodating technical staff, these buildings may have public areas such as observation decks or restaurants; the Stuttgart TV tower was the first tower in the world to be built in reinforced concrete. It was designed in 1956 by the local civil engineer Fritz Leonhardt. Fiberglass poles are used for low-power non-directional beacons or medium-wave broadcast transmitters. Carbon fibre monopoles and towers have traditionally been too expensive but recent developments in the way the carbon fibre tow is spun have resulted in solutions that offer strengths similar or exceeding steel for a fraction of the weight which has allowed monopoles and towers to be built in locations that were too expensive or difficult to access with the heavy lifting equipment, needed for a steel structure. Wood has been superseded in use by metal and composites for tower construction. Many wood towers were built in the UK during World War II because of a shortage of steel.
In Germany before World War II wooden towers were used at nearly all medium-wave transmission sites which hav
Baden-Württemberg is a state in southwest Germany, east of the Rhine, which forms the border with France. It is Germany's third-largest state, with an area of 11 million inhabitants. Baden-Württemberg is a parliamentary republic and sovereign, federated state, formed in 1952 by a merger of the states of Württemberg-Baden, Baden and Württemberg-Hohenzollern; the largest city in Baden-Württemberg is the state capital of Stuttgart, followed by Karlsruhe and Mannheim. Other cities are Freiburg im Breisgau, Heilbronn, Pforzheim and Ulm; the sobriquet Ländle is sometimes used as a synonym for Baden-Württemberg. Baden-Württemberg is formed from the historical territories of Baden, Prussian Hohenzollern, Württemberg, parts of Swabia. In 100 AD, the Roman Empire invaded and occupied Württemberg, constructing a limes along its northern borders. Over the course of the third century AD, the Alemanni forced the Romans to retreat west beyond the Rhine and Danube rivers. In 496 AD the Alemanni were defeated by a Frankish invasion led by Clovis I.
The Holy Roman Empire was established. The majority of people in this region continued to be Roman Catholics after the Protestant Reformation influenced populations in northern Germany. In the late-nineteenth and early-twentieth centuries, numerous people emigrated from this rural area to the United States for economic reasons. After World War II, the Allies established three federal states in the territory of modern-day Baden-Württemberg: Württemberg-Hohenzollern, Württemberg-Baden. Baden and Württemberg-Hohenzollern were occupied by France, while Württemberg-Baden was occupied by the United States. In 1949, each state became a founding member of the Federal Republic of Germany, with Article 118 of the German constitution providing an accession procedure. On 16 December 1951, Württemberg-Baden, Württemberg-Hohenzollern and Baden voted via referendum in favor of a joint merger. Baden-Württemberg became a state in West Germany on 25 April 1952. Baden-Württemberg shares borders with the German states of Rhineland Palatinate and Bavaria, Switzerland.
Most of the major cities of Baden-Württemberg straddle the banks of the Neckar River, which runs downstream through the state past Tübingen, Heilbronn and Mannheim. The Rhine forms the western border as well as large portions of the southern border; the Black Forest, the main mountain range of the state, rises east of the Upper Rhine valley. The high plateau of the Swabian Alb, between the Neckar, the Black Forest, the Danube, is an important European watershed. Baden-Württemberg shares Lake Constance with Switzerland and Bavaria, the international borders within its waters not being defined, it shares the foothills of the Alps with Bavaria and the Austrian Vorarlberg, but Baden-Württemberg does not border Austria over land. The Danube River has its source in Baden-Württemberg near the town of Donaueschingen, in a place called Furtwangen in the Black Forest. Baden-Württemberg is divided into thirty-five districts and nine independent cities, both grouped into the four Administrative Districts of Freiburg, Stuttgart, Tübingen.
Map Baden-Württemberg contains nine additional independent cities not belonging to any district: The state parliament of Baden-Württemberg is the Landtag. The politics of Baden-Württemberg have traditionally been dominated by the conservative Christian Democratic Union of Germany, who until 2011 had led all but one government since the establishment of the state in 1952. In the Landtag elections held on 27 March 2011 voters replaced the Christian Democrats and centre-right Free Democrats coalition by a Greens-led alliance with the Social Democrats which secured a four-seat majority in the state parliament. From 1992 to 2001, the Republicans party held seats in the Landtag; the Baden-Württemberg General Auditing Office acts as an independent body to monitor the correct use of public funds by public offices. Although Baden-Württemberg has few natural resources compared to other regions of Germany, the state is among the most prosperous and wealthiest regions in Europe with a low unemployment rate historically.
A number of well-known enterprises are headquartered in the state, for example Daimler AG, Robert Bosch GmbH, Carl Zeiss AG, SAP SE and Heidelberger Druckmaschinen. In spite of this, Baden-Württemberg's economy is dominated by medium-sized enterprises. Although poor in workable natural resources and still rural in many areas, the region is industrialised. In 2003, there were 8,800 manufacturing enterprises with more than 20 employees, but only 384 with more than 500; the latter category accounts for 43% of the 1.2 million persons employed in industry. The Mittelstand or mid-sized company is the backbone of the Baden-Württemberg economy. Medium-sized businesses and a tradition of branching out into different industrial sectors have ensured specialization over a wide range. A fifth of the "old" Federal Republic's industrial gross value added is generated by Baden-Württemberg. Turnover for manufacturing in 2003 e
The Fernsehturm Heidelberg is a transmission tower for FM and DVB-T on the Königstuhl hill of Heidelberg at 49°24′16″N 8°43′46″E. It was the property of the City of Heidelberg and sold to the SWR; because of its exposed location on the crest of the hill the tower itself is only 82 meters high. The Heidelberg TV tower has an open-air observation deck 30 metres up its height, which can be reached by an elevator; the observation deck is now permanently closed for visitors due to safety concerns. The sale of the tower sealed the fate of the observation deck which used to enable tourist a spectacular 360 degrees view of the region. In the first years of its existence the tower was used as a water tower; the water tank is located within the main body behind the observation deck. 11 digital TV channels on 3 Multiplexes are broadcast from the TV tower. DVB-T Frequencies are channel 21 for the ZDF 49 and 60 for the ARD/SWR transponders. TV channels broadcast are ARD, ZDF, SWR, HR, WDR, BR, 3Sat, Doku/Kika, Phoenix and EinsPlus.
Each Multiplex is broadcast with plans to double that to 100 kW near or mid-term. On November 5, 2008, frequencies were changed for all 3 transponders; that transition canceled the SFN with the Stuttgart region. 4 analog FM radio channels are broadcast from this tower. SWR1 97.8 MHz, SWR2 88.8 MHz, SWR3 99.9 MHz and SWR4 104.1 MHz. One digital radio multiplex is broadcast from this tower on DAB channel 12A. Available channels on that digital channel are SWR 1 Baden–Württemberg, SWR 2, SWR 3, DASDING and SWR cont.ra. The Telecom Telecommunication Tower Heidelberg and former Telecommunication Tower of US-Forces Heidelberg are located close by. Both are off limits to the public. List of towers Fernsehturm Heidelberg at Structurae http://www.skyscraperpage.com/diagrams/?b7805
United States Armed Forces
The United States Armed Forces are the military forces of the United States of America. It consists of the Army, Marine Corps, Air Force, Coast Guard; the President of the United States is the Commander-in-Chief of the Armed Forces and forms military policy with the Department of Defense and Department of Homeland Security, both federal executive departments, acting as the principal organs by which military policy is carried out. All five armed services are among the seven uniformed services of the United States. From the time of its inception, the U. S. Armed Forces played a decisive role in the history of the United States. A sense of national unity and identity was forged as a result of victory in the First Barbary War and the Second Barbary War. So, the founders of the United States were suspicious of a permanent military force, it played a critical role in the American Civil War, continuing to serve as the armed forces of the United States, although a number of its officers resigned to join the military of the Confederate States.
The National Security Act of 1947, adopted following World War II and during the Cold War's onset, created the modern U. S. military framework. The Act established the National Military Establishment, headed by the Secretary of Defense, it was amended in 1949, renaming the National Military Establishment the Department of Defense, merged the cabinet-level Department of the Army, Department of the Navy, Department of the Air Force, into the Department of Defense. The U. S. Armed Forces are one of the largest militaries in terms of the number of personnel, it draws its personnel from a large pool of paid volunteers. Although conscription has been used in the past in various times of both war and peace, it has not been used since 1973, but the Selective Service System retains the power to conscript males, requires that all male citizens and residents residing in the U. S. between the ages of 18–25 register with the service. On February 22, 2019, however, a federal judge ruled that registering only males for Selective Service is unconstitutional.
As of 2017, the U. S. spends about US$610 billion annually to fund its military forces and Overseas Contingency Operations. Put together, the U. S. constitutes 40 percent of the world's military expenditures. The U. S. Armed Forces has significant capabilities in both defense and power projection due to its large budget, resulting in advanced and powerful technologies which enables a widespread deployment of the force around the world, including around 800 military bases outside the United States; the U. S. Air Force is the world's largest air force, the U. S. Navy is the world's largest navy by tonnage, the U. S. Navy and the U. S. Marine Corps combined are the world's second largest air arm. In terms of size, the U. S. Coast Guard is the world's 12th largest naval force; the history of the U. S. Armed Forces dates to 14 June 1775, with the creation of the Continental Army before the Declaration of Independence marked the establishment of the United States; the Continental Navy, established on 13 October 1775, Continental Marines, established on 10 November 1775, were created in close succession by the Second Continental Congress in order to defend the new nation against the British Empire in the American Revolutionary War.
These forces demobilized in 1784. The Congress of the Confederation created the current United States Army on 3 June 1784; the United States Congress created the current United States Navy on 27 March 1794 and the current United States Marine Corps on 11 July 1798. All three services trace their origins to their respective Continental predecessors; the 1787 adoption of the Constitution gave the Congress the power to "raise and support armies", to "provide and maintain a navy" and to "make rules for the government and regulation of the land and naval forces", as well as the power to declare war. The President is the U. S. Armed Forces' commander-in-chief; the United States Coast Guard traces its origin to the founding of the Revenue Cutter Service on 4 August 1790 which merged with the United States Life-Saving Service on 28 January 1915 to establish the Coast Guard. The United States Air Force was established as an independent service on 18 September 1947. S. Signal Corps, formed 1 August 1907 and was part of the Army Air Forces before becoming an independent service as per the National Security Act of 1947.
The United States Public Health Service Commissioned Corps was considered to be a branch of the United States Armed Forces from 29 July 1945 until its status as such was revoked on 3 July 1952. On March 1st, 2019, the Department of Defense sent a proposal to Congress that would establish the United States Space Force as an independent military service within the Department of the Air Force. If approved, this would become the sixth military service branch to be created. Command over the U. S. Armed Forces is established in the Constitution; the sole power of command is vested in the President by Article II as Commander-in-Chief. The Constitution presumes the existence of "executive Departments" headed by "principal officers", whose appointment mechanism is provided for in the Appointments Clause; this allowance in the Constitution formed the basis for creation of the Department of Defense in 1947 by the National Security Act. The DoD is headed by the Secretary of Defense, a civilian and member of the Cabinet.
The Defense Secretary is second in the U. S. Armed Forces chain of command, with the exception of the Coast Guard, under the Secretary of Homeland Security, is just below the President and serves as the
DVB-T is an abbreviation for "Digital Video Broadcasting — Terrestrial". This system transmits compressed digital audio, digital video and other data in an MPEG transport stream, using coded orthogonal frequency-division multiplexing modulation, it is the format used worldwide for Electronic News Gathering for transmission of video and audio from a mobile newsgathering vehicle to a central receive point. Rather than carrying one data carrier on a single radio frequency channel, COFDM works by splitting the digital data stream into a large number of slower digital streams, each of which digitally modulates a set of spaced adjacent sub-carrier frequencies. In the case of DVB-T, there are two choices for the number of carriers known as 8K-mode; these are 1,705 or 6,817 sub-carriers that are 4 kHz or 1 kHz apart. DVB-T offers three different modulation schemes. DVB-T has been adopted or proposed for digital television broadcasting by many countries, using VHF 7 MHz and UHF 8 MHz channels whereas Taiwan, Colombia and Trinidad and Tobago use 6 MHz channels.
Examples include the UK's Freeview. The DVB-T Standard is published as EN 300 744, Framing structure, channel coding and modulation for digital terrestrial television; this is available from the ETSI website, as is ETSI TS 101 154, Specification for the use of Video and Audio Coding in Broadcasting Applications based on the MPEG-2 Transport Stream, which gives details of the DVB use of source coding methods for MPEG-2 and, more H.264/MPEG-4 AVC as well as audio encoding systems. Many countries that have adopted DVB-T have published standards for their implementation; these include the D-book in the UK, the Italian DGTVi, the ETSI E-Book and the Nordic countries and Ireland NorDig. DVB-T has been further developed into newer standards such as DVB-H, a commercial failure and is no longer in operation, DVB-T2, finalised in August 2011. DVB-T as a digital transmission delivers data in a series of discrete blocks at the symbol rate. DVB-T is a COFDM transmission technique, it allows the receiver to cope with strong multipath situations.
Within a geographical area, DVB-T allows single-frequency network operation, where two or more transmitters carrying the same data operate on the same frequency. In such cases the signals from each transmitter in the SFN needs to be time-aligned, done by sync information in the stream and timing at each transmitter referenced to GPS; the length of the Guard Interval can be chosen. It is a trade-off between SFN capability; the longer the guard interval the larger is the potential SFN area without creating intersymbol interference. It is possible to operate SFNs which do not fulfill the guard interval condition if the self-interference is properly planned and monitored. With reference to the figure, a short description of the signal processing blocks follows. Source coding and MPEG-2 multiplexing: Compressed video, compressed audio, data streams are multiplexed into MPEG program streams. One or more MPEG-PS's are joined together into an MPEG transport stream. Allowed bitrates for the transported data depend on a number of coding and modulation parameters: it can range from about 5 to about 32 Mbit/s.
Splitter: Two different MPEG-TSs can be transmitted at the same time, using a technique called Hierarchical Transmission. It may be used to transmit, for example a standard definition SDTV signal and a high definition HDTV signal on the same carrier; the SDTV signal is more robust than the HDTV one. At the receiver, depending on the quality of the received signal, the STB may be able to decode the HDTV stream or, if signal strength lacks, it can switch to the SDTV one. MUX adaptation and energy dispersal: The MPEG-TS is identified as a sequence of data packets, of fixed length. With a technique called energy dispersal, the byte sequence is decorrelated. External encoder: A first level of error correction is applied to the transmitted data, using a non-binary block code, a Reed-Solomon RS code, allowing the correction of up to a maximum of 8 wrong bytes for each 188-byte packet. External interleaver: Convolutional interleaving is used to rearrange the transmitted data sequence, in such a way that it becomes more rugged to long sequences of errors.
Internal encoder: A second level of error correction is given by a punctured convolutional code, denoted in STBs menus as FEC. There are five valid coding rates: 1/2, 2/3, 3/4, 5/6, 7/8. Internal interleaver: Data sequence is rearranged again, aiming to reduce the influence of burst errors; this time, a block interleaving technique is adopted, with a pseudo-random assignment scheme. Mapper: The digital bit sequence is mapped into a base band modulated sequence of complex symbols. There are three valid modulation schemes: QPSK, 16-QAM, 64-QAM. Frame adaptation: the complex symbols are grouped in blocks of const
Heidelberg is a university town in Baden-Württemberg situated on the river Neckar in south-west Germany. In the 2016 census, its population was 159,914, with a quarter of its population being students. Located about 78 km south of Frankfurt, Heidelberg is the fifth-largest city in the German state of Baden-Württemberg. Heidelberg is part of the densely populated Rhine-Neckar Metropolitan Region. Founded in 1386, Heidelberg University is Germany's oldest and one of Europe's most reputable universities. A scientific hub in Germany, the city of Heidelberg is home to several internationally renowned research facilities adjacent to its university, including four Max Planck Institutes. A former residence of the Electorate of the Palatinate, Heidelberg is a popular tourist destination due to its romantic cityscape, including Heidelberg Castle, the Philosophers' Walk, the baroque style Old Town. Heidelberg is in the Rhine Rift Valley, on the left bank of the lower part of the Neckar in a steep valley in the Odenwald.
It is bordered by the Gaisberg mountains. The Neckar here flows in an east-west direction. On the right bank of the river, the Heiligenberg mountain rises to a height of 445 meters; the Neckar flows into the Rhine 22 kilometres north-west in Mannheim. Villages incorporated during the 20th century stretch from the Neckar Valley along the Bergstraße, a road running along the Odenwald hills. Heidelberg is on European walking route E1. Since Heidelberg is among the warmest regions of Germany, plants atypical of the central-European climate flourish there, including almond and fig trees. Alongside the Philosophenweg on the opposite side of the Old Town, winegrowing was restarted in 2000. There is a wild population of African rose-ringed parakeets, a wild population of Siberian swan geese, which can be seen on the islands in the Neckar near the district of Bergheim. Heidelberg is a unitary authority within the Regierungsbezirk Karlsruhe; the Rhein-Neckar-Kreis rural district surrounds it and has its seat in the town, although the town is not a part of the district.
Heidelberg is a part of the Rhine-Neckar Metropolitan Region referred to as the Rhein-Neckar Triangle. This region consists of the southern part of the State of Hessen, the southern part of the State of Rhineland-Palatinate, the administrative districts of Mannheim and Heidelberg, the southern municipalities of the Rhein-Neckar-Kreis; the Rhein-Neckar Triangle became a European metropolitan area in 2005. Heidelberg consists of 15 districts distributed in six sectors of the town. In the central area are Altstadt and Weststadt; the new district will have 5,000–6,000 residents and employment for 7,000. Further new residential space for 10,000-15,000 residents was made available in Patrick Henry Village following the departure of the US Armed Forces; the following towns and communes border the city of Heidelberg, beginning in the west and in a clockwise direction: Edingen-Neckarhausen, Schriesheim, Schönau, Neckargemünd, Gaiberg, Sandhausen, Plankstadt and Mannheim. Heidelberg has an oceanic climate, defined by the protected valley between the Pfälzerwald and the Odenwald.
Year-round, the mild temperatures are determined by maritime air masses coming from the west. In contrast to the nearby Upper Rhine Plain, Heidelberg's position in the valley leads to more frequent easterly winds than average; the hillsides of the Odenwald favour precipitation. The warmest month is July, the coldest is January. Temperatures rise beyond 30 °C in midsummer. According to the German Meteorological Service, Heidelberg was the warmest place in Germany in 2009. Between 600,000 and 200,000 years ago, "Heidelberg Man" died at nearby Mauer, his jaw bone was discovered in 1907. Scientific dating determined his remains as the earliest evidence of human life in Europe. In the 5th century BC, a Celtic fortress of refuge and place of worship were built on the Heiligenberg, or "Mountain of Saints". Both places can still be identified. In 40 AD, a fort occupied by the 24th Roman cohort and the 2nd Cyrenaican cohort; the early Byzantine/late Roman Emperor Valentinian I, in 369 AD, built new and maintained older castra and a signal tower on the bank of the Neckar.
They built a wooden bridge based on stone pillars across it. The camp protected the first civilian settlements; the Romans remained until 260 AD. The local administrative center in Roman times was the nearby city of Lopodunum. Modern Heidelberg can trace its beginnings to the fifth century; the village Bergheim is first mentioned for that period in documents dated to 769 AD. Bergheim now lies in the middle of modern Heidelberg; the people converted to Christianity. In 863 AD, the monastery of St. Michael was founded on the Heiligenberg inside the double rampart of the Celtic fortress. Around 1130, the Neuburg Monastery was founded in the Neckar valley. At the same time, the bishopric of Worms extended its influence into the valley, founding Schönau Abbey in 1142. Modern He