Internet service provider
An Internet service provider is an organization that provides services for accessing, using, or participating in the Internet. Internet service providers may be organized in various forms, such as commercial, community-owned, non-profit, or otherwise owned. Internet services provided by ISPs include Internet access, Internet transit, domain name registration, web hosting, Usenet service, colocation; the Internet was developed as a network between government research laboratories and participating departments of universities. Other companies and organizations joined by direct connection to the backbone, or by arrangements through other connected companies, sometime using dialup tools such as UUCP. By the late 1980s, a process was set in place towards commercial use of the Internet; the remaining restrictions were removed by 1991, shortly after the introduction of the World Wide Web. During the 1980s, online service providers such as CompuServe and America On Line began to offer limited capabilities to access the Internet, such as e-mail interchange, but full access to the Internet was not available to the general public.
In 1989, the first Internet service providers, companies offering the public direct access to the Internet for a monthly fee, were established in Australia and the United States. In Brookline, The World became the first commercial ISP in the US, its first customer was served in November 1989. These companies offered dial-up connections, using the public telephone network to provide last-mile connections to their customers; the barriers to entry for dial-up ISPs were low and many providers emerged. However, cable television companies and the telephone carriers had wired connections to their customers and could offer Internet connections at much higher speeds than dial-up using broadband technology such as cable modems and digital subscriber line; as a result, these companies became the dominant ISPs in their service areas, what was once a competitive ISP market became a monopoly or duopoly in countries with a commercial telecommunications market, such as the United States. On 23 April 2014, the U.
S. Federal Communications Commission was reported to be considering a new rule that will permit ISPs to offer content providers a faster track to send content, thus reversing their earlier net neutrality position. A possible solution to net neutrality concerns may be municipal broadband, according to Professor Susan Crawford, a legal and technology expert at Harvard Law School. On 15 May 2014, the FCC decided to consider two options regarding Internet services: first, permit fast and slow broadband lanes, thereby compromising net neutrality. On 10 November 2014, President Barack Obama recommended that the FCC reclassify broadband Internet service as a telecommunications service in order to preserve net neutrality. On 16 January 2015, Republicans presented legislation, in the form of a U. S. Congress H. R. discussion draft bill, that makes concessions to net neutrality but prohibits the FCC from accomplishing the goal or enacting any further regulation affecting Internet service providers. On 31 January 2015, AP News reported that the FCC will present the notion of applying Title II of the Communications Act of 1934 to the Internet in a vote expected on 26 February 2015.
Adoption of this notion would reclassify Internet service from one of information to one of the telecommunications and, according to Tom Wheeler, chairman of the FCC, ensure net neutrality. The FCC is expected to enforce net neutrality in its vote, according to The New York Times. On 26 February 2015, the FCC ruled in favor of net neutrality by adopting Title II of the Communications Act of 1934 and Section 706 in the Telecommunications Act of 1996 to the Internet; the FCC Chairman, Tom Wheeler, commented, "This is no more a plan to regulate the Internet than the First Amendment is a plan to regulate free speech. They both stand for the same concept." On 12 March 2015, the FCC released the specific details of the net neutrality rules. On 13 April 2015, the FCC published the final rule on its new "Net Neutrality" regulations; these rules went into effect on 12 June 2015. Upon becoming FCC chairman in April 2017, Ajit Pai proposed an end to net neutrality, awaiting votes from the commission. On 21 November 2017, Pai announced that a vote will be held by FCC members on 14 December on whether to repeal the policy.
On 11 June 2018, the repeal of the FCC's network neutrality rules took effect. Access provider ISPs provide Internet access, employing a range of technologies to connect users to their network. Available technologies have ranged from computer modems with acoustic couplers to telephone lines, to television cable, Wi-Fi, fiber optics. For users and small businesses, traditional options include copper wires to provide dial-up, DSL asymmetric digital subscriber line, cable modem or Integrated Services Digital Network. Using fiber-optics to end users is called Fiber To The Home or similar names. For customers with more demanding requirements can use higher-speed DSL, metropolitan Ethernet, gigabit Ethernet, Frame Relay, ISDN Primary Rate Interface, ATM and synchronous optical networking. Wireless access is another option, including satellite Internet access. A mailbox provider is an organization that provides services for hosting electronic mail domains with access to storage for mail boxes
A telephone, or phone, is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be heard directly. A telephone converts sound and most efficiently the human voice, into electronic signals that are transmitted via cables and other communication channels to another telephone which reproduces the sound to the receiving user. In 1876, Scottish emigrant Alexander Graham Bell was the first to be granted a United States patent for a device that produced intelligible replication of the human voice; this instrument was further developed by many others. The telephone was the first device in history that enabled people to talk directly with each other across large distances. Telephones became indispensable to businesses and households and are today some of the most used small appliances; the essential elements of a telephone are a microphone to speak into and an earphone which reproduces the voice in a distant location. In addition, most telephones contain a ringer to announce an incoming telephone call, a dial or keypad to enter a telephone number when initiating a call to another telephone.
The receiver and transmitter are built into a handset, held up to the ear and mouth during conversation. The dial may be located either on a base unit to which the handset is connected; the transmitter converts the sound waves to electrical signals which are sent through a telephone network to the receiving telephone, which converts the signals into audible sound in the receiver or sometimes a loudspeaker. Telephones are duplex devices; the first telephones were directly connected to each other from one customer's office or residence to another customer's location. Being impractical beyond just a few customers, these systems were replaced by manually operated centrally located switchboards; these exchanges were soon connected together forming an automated, worldwide public switched telephone network. For greater mobility, various radio systems were developed for transmission between mobile stations on ships and automobiles in the mid-20th century. Hand-held mobile phones were introduced for personal service starting in 1973.
In decades their analog cellular system evolved into digital networks with greater capability and lower cost. Convergence has given most modern cell phones capabilities far beyond simple voice conversation, they may be able to record spoken messages and receive text messages and display photographs or video, play music or games, surf the Internet, do road navigation or immerse the user in virtual reality. Since 1999, the trend for mobile phones is smartphones that integrate all mobile communication and computing needs. A traditional landline telephone system known as plain old telephone service carries both control and audio signals on the same twisted pair of insulated wires, the telephone line; the control and signaling equipment consists of three components, the ringer, the hookswitch, a dial. The ringer, or beeper, light or other device, alerts the user to incoming calls; the hookswitch signals to the central office that the user has picked up the handset to either answer a call or initiate a call.
A dial, if present, is used by the subscriber to transmit a telephone number to the central office when initiating a call. Until the 1960s dials used exclusively the rotary technology, replaced by dual-tone multi-frequency signaling with pushbutton telephones. A major expense of wire-line telephone service is the outside wire plant. Telephones transmit both the outgoing speech signals on a single pair of wires. A twisted pair line rejects electromagnetic interference and crosstalk better than a single wire or an untwisted pair; the strong outgoing speech signal from the microphone does not overpower the weaker incoming speaker signal with sidetone because a hybrid coil and other components compensate the imbalance. The junction box arrests lightning and adjusts the line's resistance to maximize the signal power for the line length. Telephones have similar adjustments for inside line lengths; the line voltages are negative compared to earth. Negative voltage attracts positive metal ions toward the wires.
The landline telephone contains a switchhook and an alerting device a ringer, that remains connected to the phone line whenever the phone is "on hook", other components which are connected when the phone is "off hook". The off-hook components include a transmitter, a receiver, other circuits for dialing and amplification. A calling party wishing to speak to another party will pick up the telephone's handset, thereby operating a lever which closes the switchhook, which powers the telephone by connecting the transmitter and related audio components to the line; the off-hook circuitry has a low resistance which causes a direct current, which comes down the line from the telephone exchange. The exchange detects this current, attaches a digit receiver circuit to the line, sends a dial tone to indicate readiness. On a modern push-button telephone, the caller presses the number keys to send the telephone number of the called party; the keys control a tone generator circuit. A rotary-dial telephone uses pulse
DHL International GmbH is an American-founded company, now the international courier and express mail division of the German logistics company Deutsche Post DHL. Deutsche Post DHL is the world's largest logistics company in sea and air mail; the company delivers over 1.3 billion parcels per year. The company was founded in the United States in 1969 and expanded its service throughout the world by the late 1970s; the company was interested in offshore and intercontinental deliveries, but the success of FedEx prompted their own intra-US expansion starting in 1983. In 1998, Deutsche Post began to acquire shares in DHL, it reached controlling interest in 2001, acquired all outstanding shares by December 2002. The company absorbed DHL into its Express division, while expanding the use of the DHL brand to other Deutsche Post divisions, business units, subsidiaries. Today, DHL Express shares its DHL brand with business units such as DHL Global Forwarding and DHL Supply Chain, it gained a foothold in the United States.
The DHL Express financial results are published in the Deutsche Post AG annual report. In 2016, this division's revenue increased by 2.7 per cent to €14 billion. The earnings before interest and taxes increased by 11.3% over 2015 to €1.5 billion. While Larry Hillblom was studying law at University of California, Berkeley's Boalt Hall School of Law in the late 1960s, he accepted a job as a courier for the insurance company Michael's, Poe & Associates, he started running courier duty between Oakland International Airport and Los Angeles International Airport, picking up packages for the last flight of the day, returning on the first flight the next morning, up to five times a week. After he graduated, Hillblom met with MPA salesman Adrian Dalsey and they planned to expand MPA's concept of fast delivery to other business enterprises, they flew between Honolulu and Los Angeles, transporting bills of lading for their first client, Seatrain Lines. Hillblom put up a portion of his student loans to start the company, bringing in his two friends Adrian Dalsey and Robert Lynn as partners, with their combined initials of their surnames as the company name.
They shared a Plymouth Duster that they drove around San Francisco to pick up the documents in suitcases rushed to the airport to book flights using another new invention, the corporate credit card. As the business took off, they started hiring new couriers to join the company, their first hires were Max and Blanche Kroll, whose apartment in Hawaii became a makeshift flophouse for their couriers. In the 1970s, DHL was an international delivery company, the only one offering overnight service; the only major competitor in the overnight market was Federal Express, which did not open its first international service until 1981, expanding to Toronto, Canada. The domestic market was profitable, DHL was the third largest courier behind FedEx and UPS. Deutsche Post began to acquire shares in DHL in 1998, acquiring controlling interest in 2001. By the end of 2002, Deutsche Post had acquired all of DHL's remaining stock, absorbed the operation into its Express division; the DHL brand was expanded to business units and subsidiaries.
Today, DHL Express shares its DHL brand with other Deutsche Post business units, such as DHL Global Forwarding, DHL Freight, DHL Supply Chain, DHL Global Mail. All US domestic flights were handled by DHL Airways, Inc. which in 2003 was renamed ASTAR Air Cargo following a management buyout. DHL's first airline still remains with over 550 pilots in service, as of October 2008. 2001: Deutsche Post acquires a majority of DHL's shares, the remaining 49% in 2002. The new DHL is launched by merging the old DHL, Securicor Omega Euro Express. 2001: The Packstation, an automated delivery booth, is introduced as a pilot project in Dortmund and Mainz. 2002: Bashkirian Airlines Flight 2937, a Tupolev Tu-154 passenger jet, collides with DHL Flight 611, a Boeing 757-200 cargo jet, at 35,000 ft over Überlingen, Germany. The 69 people aboard the Tupolev and the two pilots of the Boeing were killed. December 2002: Introduces red and yellow new color scheme and logo. August 2003: Deutsche Post acquires Airborne Express, begins to integrate it into DHL.
The Airborne Express Airline named ABX Air is to provide contract ACMI service until 2011. 22 November 2003: DHL shootdown incident in Baghdad wherein Iraqi insurgents fire an SA-7 "Grail" surface-to-air missile at a European Air Transport Airbus A300 operating on behalf of DHL. The aircraft takes off from Baghdad airport and the missile strikes the left wing, disabling all three hydraulic systems and setting the wing on fire; the aircraft begins a dangerous phugoid but the crew manages to land safely at the airport, despite being able to control the aircraft only by adjusting the engine thrust. September 2004: a planned expansion by DHL at Brussels Airport creates a political crisis in Belgium. 21 October 2004: DHL Express announces that it will move its European hub from Brussels to Leipzig, Germany. DHL's unions call a strike in response. 8 November 2004: DHL Express invests €120 million in Indian domestic courier Blue Dart and becomes the majority shareholder in the company. September 2005: Deutsche Post makes an offer to buy contract logistics company Exel plc, which had just acquired Tibbett & Britten Group.
On 14 December 2005, Deutsche Post announces the completion of the acquisition of Exel plc. When integrating Exel into its Logistics division, it adds its well-known DHL brand acquired with th
Verizon Communications Inc. is an American multinational telecommunications conglomerate and a corporate component of the Dow Jones Industrial Average. The company is based at 1095 Avenue of the Americas in Midtown Manhattan, New York City, but is incorporated in Delaware. In 1984, the United States Department of Justice mandated AT&T Corporation to break up the Bell System and split into seven companies, called "Baby Bells". One of the baby bells, Bell Atlantic, came into existence in 1984 consisting of the separate operating companies New Jersey Bell, Bell of Pennsylvania, Diamond State Telephone, C&P Telephone, with a footprint from New Jersey to Virginia; this company would become Verizon. As part of a rebranding of the Baby Bells in the mid-1990s, all of Bell Atlantic's operating companies assumed the holding company's name. In 1997, Bell Atlantic expanded into New York and the New England states by merging with fellow Baby Bell NYNEX. Although Bell Atlantic was the surviving company name, the merged company moved its headquarters from Philadelphia to NYNEX's old headquarters in New York City.
In 2000, Bell Atlantic acquired GTE, which operated telecommunications companies across most of the rest of the country, not in Bell Atlantic's footprint. Bell Atlantic, the surviving entity, changed its name to "Verizon", a portmanteau of veritas and horizon. In 2015, Verizon expanded its business into content ownership by acquiring AOL, two years it acquired Yahoo!. AOL and Yahoo were amalgamated into a new division named Oath Inc.. As of 2016, Verizon is one of three remaining companies that had their roots in the former Baby Bells; the other two, like Verizon, exist as a result of mergers among fellow former Baby Bell members. SBC Communications, bought out the Bells' former parent AT&T Corporation, assumed the AT&T name. CenturyLink was formed in 2011 by the acquisition of Qwest. Verizon's subsidiary Verizon Wireless is the largest U. S. wireless communications service provider as of September 2014, with 147 million mobile customers. And as of 2017, Verizon is the only publicly-traded telecommunications company to have two stock listings in its home country, both the NYSE and NASDAQ.
As of 2017, it is the second largest telecommunications company by revenue after AT&T. Bell Atlantic Corporation was created as one of the original Regional Bell Operating Companies in 1984, during the breakup of the Bell System. Bell Atlantic's original roster of operating companies included: The Bell Telephone Company of Pennsylvania New Jersey Bell Diamond State Telephone C&P Telephone Bell Atlantic operated in the states of New Jersey, Delaware, West Virginia, Virginia, as well as Washington, DC. In 1996, CEO and Chairman Raymond W. Smith orchestrated Bell Atlantic's merger with NYNEX; when it merged, it moved its corporate headquarters from Philadelphia to New York City. NYNEX was consolidated into this name by 1997. Bell Atlantic changed its name to Verizon Communications in June 2000 when the Federal Communications Commission approved the US$64.7 billion Merger with telephone company GTE, nearly two years after the deal was proposed in July 1998. The approval came with 25 stipulations to preserve competition between local phone carriers, including investing in new markets and broadband technologies.
The new entity was headed by co-CEOs Charles Lee the CEO of GTE, Bell Atlantic CEO Ivan Seidenberg. Verizon became the largest local telephone company in the United States, operating 63 million telephone lines in 40 states; the company inherited 25 million mobile phone customers. Additionally, Verizon offered internet services and long-distance calling in New York, before expanding long-distance operations to other states; the name Verizon derives from the combination of the words veritas, Latin for truth, horizon. The name was chosen from 8,500 candidates and the company spent $300 million on marketing the new brand. Two months before the FCC gave final approval on the formation of Verizon Communications, Bell Atlantic formed Verizon Wireless in a joint venture with the British telecommunications company Vodafone in April 2000; the companies established Verizon Wireless as its own business operated by Bell Atlantic, which owned 55% of the venture. Vodafone retained 45% of the company; the deal was valued at $70 billion and created a mobile carrier with 23 million customers.
Verizon Wireless merged Bell Atlantic's wireless network, Vodafone's AirTouch and PrimeCo holdings, the wireless division of GTE. Due to its size, Verizon Wireless was able to offer national coverage at competitive rates, giving it an advantage over regional providers typical of the time. During its first operational year, Verizon Wireless released Mobile Web, an Internet service that allowed customers to access partner sites such as E*Trade, ABC News, ESPN, Amazon.com, Ticketmaster and MSN, as well as the "New Every Two" program, which gave customers a free phone with every two-year service contract. In another partnership with MSN in 2002, Verizon Wireless launched the mobile content service "VZW with MSN" and a phone that utilized the Microsoft Windows operating system. In August 2000 85,000 Verizon workers went on an 18-day labor strike after their union contracts expired; the strike affected quarterly revenues, resulting in Verizon Wireless' postponement of the company's IPO, created a backlog of repairs.
Verizon launched 3G service in 2002, which doubled the Internet speeds of t
A telephone number is a sequence of digits assigned to a fixed-line telephone subscriber station connected to a telephone line or to a wireless electronic telephony device, such as a radio telephone or a mobile telephone, or to other devices for data transmission via the public switched telephone network or other public and private networks. A telephone number serves as an address for switching telephone calls using a system of destination code routing. Telephone numbers are entered or dialed by a calling party on the originating telephone set, which transmits the sequence of digits in the process of signaling to a telephone exchange; the exchange completes the call either to another locally connected subscriber or via the PSTN to the called party. Telephone numbers are assigned within the framework of a national or regional telephone numbering plan to subscribers by telephone service operators, which may be commercial entities, state-controlled administrations, or other telecommunication industry associations.
Telephone numbers were first used in 1879 in Lowell, when they replaced the request for subscriber names by callers connecting to the switchboard operator. Over the course of telephone history, telephone numbers had various lengths and formats, included most letters of the alphabet in leading positions when telephone exchange names were in common use until the 1960s. Telephone numbers are dialed in conjunction with other signaling code sequences, such as vertical service codes, to invoke special telephone service features; when telephone numbers were first used they were short, from one to three digits, were communicated orally to a switchboard operator when initiating a call. As telephone systems have grown and interconnected to encompass worldwide communication, telephone numbers have become longer. In addition to telephones, they have been used to access other devices, such as computer modems and fax machines. With landlines and pagers falling out of use in favor of all-digital always-connected broadband Internet and mobile phones, telephone numbers are now used by data-only cellular devices, such as some tablet computers, digital televisions, video game controllers, mobile hotspots, on which it is not possible to make or accept a call.
The number contains the information necessary to identify uniquely the intended endpoint for the telephone call. Each such endpoint must have a unique number within the public switched telephone network. Most countries use fixed-length numbers and therefore the number of endpoints determines the necessary length of the telephone number, it is possible for each subscriber to have a set of shorter numbers for the endpoints most used. These "shorthand" or "speed calling" numbers are automatically translated to unique telephone numbers before the call can be connected; some special services have their own short numbers The dialing plan in some areas permits dialing numbers in the local calling area without using area code or city code prefixes. For example, a telephone number in North America consists of a three-digit area code, a three-digit central office code, four digits for the line number. If the area has no area code overlays or if the provider allows it, seven-digit dialing may be permissible for calls within the area, but some areas have implemented mandatory ten-digit dialing.
Other special phone numbers are used for high-capacity numbers with several telephone circuits a request line to a radio station where dozens or hundreds of callers may be trying to call in at once, such as for a contest. For each large metro area, all of these lines will share the same prefix, the last digits corresponding to the station's frequency, callsign, or moniker. In the international telephone network, the format of telephone numbers is standardized by ITU-T recommendation E.164. This code specifies that the entire number should be 15 digits or shorter, begin with a country prefix. For most countries, this is followed by an area code or city code and the subscriber number, which might consist of the code for a particular telephone exchange. ITU-T recommendation E.123 describes how to represent an international telephone number in writing or print, starting with a plus sign and the country code. When calling an international number from a landline phone, the + must be replaced with the international call prefix chosen by the country the call is being made from.
Many mobile phones allow the + to be entered directly, by pressing and holding the "0" for GSM phones, or sometimes "*" for CDMA phones. The format and allocation of local phone numbers are controlled by each nation's respective government, either directly or by sponsored organizations. In the United States, each state's public service commission regulates, as does the Federal Communications Commission. In Canada, which shares the same country code with the U. S. regulation is through the Canadian Radio-television and Telecommunications Commission. Local number portability allows a subscriber to requ
City of Brussels
The City of Brussels is the largest municipality and historical centre of the Brussels-Capital Region, the de jure capital of Belgium. Besides the strict centre, it covers the immediate northern outskirts where it borders municipalities in Flanders, it is the administrative centre of the European Union, thus dubbed, along with the region, the EU's capital city. The City of Brussels is a municipality consisting of the central historic town and certain additional areas within the greater Brussels-Capital Region, namely Haren and Neder-Over-Heembeek to the north, Avenue Louise/Louizalaan and the Bois de la Cambre/Ter Kamerenbos park to the south; as of 1 January 2017, the City of Brussels had a total population of 176,545. The total area is 32.61 km2 which gives a population density of 5,475 inhabitants per square kilometre. As of 2007, there were 50,000 registered non-Belgians in the City of Brussels. In common with all the Brussels municipalities, it is bilingual. At first, the City of Brussels was defined, being the area within the second walls of Brussels, the modern-day small ring.
As the city grew, the surrounding villages grew as well growing into a contiguous city, though the local governments retained control of their respective areas. The construction of Avenue Louise/Louizalaan was commissioned in 1847 as a monumental avenue bordered by chestnut trees that would allow easy access to the popular recreational area of the Bois de la Cambre/Ter Kamerenbos. However, fierce resistance to the project was put up by the town of Ixelles through whose land the avenue was supposed to run. After years of fruitless negotiations, Brussels annexed the narrow band of land needed for the avenue plus the Bois de la Cambre itself in 1864; that decision accounts for the unusual southeastern protrusion of the City of Brussels and for Ixelles being split in two separate parts. Part of the Université libre de Bruxelles' Solbosch campus is part of the City of Brussels accounting for the bulge in the southeast end. Unlike most of the municipalities in Belgium, the ones located in the Brussels-Capital Region were not merged with others during mergers occurring in 1964, 1970, 1975.
However, a few neighbouring municipalities have been merged into the City of Brussels, including Haren and Neder-Over-Heembeek in 1921. These comprise the northern bulge in the municipality. To the south-east is a strip of land along Avenue Louise, annexed from the Ixelles municipality, it is in the heart of the Saint-Géry/Sint-Goriks Island, formed by the Senne and on which a first keep was built around 979, that the origin of the city is located. Today, the neighbourhood around the Halles Saint-Géry/Sint-Gorikshallen, a former covered market, is one of the trendy districts of the capital. In the centre of the city, there are some vestiges of the 13th century first walls of Brussels, which surrounded the first port on the Senne, the Romanesque church replaced by the Cathedral of St. Michael and St. Gudula, the ducal castle of Coudenberg. In the centre of this triangle are the Grand Place, the Îlot Sacré district, itself crossed by the Galeries Royales Saint-Hubert, the Saint-Jacques/Sint-Jacobs district which welcomed the pilgrims on their way to Santiago de Compostela, the Brussels Stock Exchange, built on the site of a former convent, whose remains have been uncovered.
Thus named because it houses, on the one hand, the Royal Square, built under Charles-Alexander of Lorraine on the Coudenberg hill, on the site of the former Palace of the Dukes of Brabant, of which certain levels of foundation still exist, on the other hand, the Royal Palace of Brussels, which faces the Brussels Park, on the other side of, the Belgian Parliament. Below is the Central Station and the Mont des Arts/Kunstberg where are located the Royal Library of Belgium, the Royal Belgian Film Archive, the Brussels Centre for Fine Arts, the Museum of Cinema, the Musical Instrument Museum, the BELvue Museum, the Royal Museums of Fine Arts of Belgium. From the Royal Square, rue de la Régence/Regentschapsstraat crosses the neighbourhoods of the Small and Large Sablon/Zavel, a swanky district where the Church of Our Blessed Lady of the Sablon is located and where an antiques market is held, in which antique dealers, art dealers and other luxury shops have businesses. Not far from there was the Maison du Peuple/Volkshuis by Victor Horta, in Art Nouveau style.
There is the Egmont Palace and the Royal Conservatory of Brussels. In the shadow of the gigantic Palace of Justice lies the old Marolles/Marollen district. From the Place de la Chapelle/Kapellemarkt to the Place du Jeu de Balle/Vossenplein, where a daily flea market has been held since 1873, along rue Haute/Hogestraat and rue Blaes/Blaestraat, second-hand and popular shops have for some years given way to antique shops, marking a profound change in the neighbourhood; the Hellemans City, a remarkable example of collective housing complexes of the early 20th century, was built on the site of the many squalid cul-de-sacs in the neighbourhood. Rue Haute/Hogestraat, one of the longest and oldest streets in the city, follows the course of an old Gallo-Roman road, runs along the Saint Pierre University Hospital, built in 1935 on the site of a leper hospital, to end at the Halle Gate, the only survivor of the series of gates which allowed passage inside the second
Coaxial cable, or coax is a type of electrical cable that has an inner conductor surrounded by a tubular insulating layer, surrounded by a tubular conducting shield. Many coaxial cables have an insulating outer sheath or jacket; the term coaxial comes from the outer shield sharing a geometric axis. Coaxial cable was invented by English engineer and mathematician Oliver Heaviside, who patented the design in 1880. Coaxial cable is a type of transmission line, used to carry high frequency electrical signals with low losses, it is used in such applications as telephone trunklines, broadband internet networking cables, high speed computer data busses, carrying cable television signals, connecting radio transmitters and receivers to their antennas. It differs from other shielded cables because the dimensions of the cable and connectors are controlled to give a precise, constant conductor spacing, needed for it to function efficiently as a transmission line. Coaxial cable is used as a transmission line for radio frequency signals.
Its applications include feedlines connecting radio transmitters and receivers to their antennas, computer network connections, digital audio, distribution of cable television signals. One advantage of coaxial over other types of radio transmission line is that in an ideal coaxial cable the electromagnetic field carrying the signal exists only in the space between the inner and outer conductors; this allows coaxial cable runs to be installed next to metal objects such as gutters without the power losses that occur in other types of transmission lines. Coaxial cable provides protection of the signal from external electromagnetic interference. Coaxial cable conducts electrical signal using an inner conductor surrounded by an insulating layer and all enclosed by a shield one to four layers of woven metallic braid and metallic tape; the cable is protected by an outer insulating jacket. The shield is kept at ground potential and a signal carrying voltage is applied to the center conductor; the advantage of coaxial design is that electric and magnetic fields are restricted to the dielectric with little leakage outside the shield.
Conversely and magnetic fields outside the cable are kept from interfering with signals inside the cable. Larger diameter cables and cables with multiple shields have less leakage; this property makes coaxial cable a good choice for carrying weak signals that cannot tolerate interference from the environment or for stronger electrical signals that must not be allowed to radiate or couple into adjacent structures or circuits. Common applications of coaxial cable include video and CATV distribution, RF and microwave transmission, computer and instrumentation data connections; the characteristic impedance of the cable is determined by the dielectric constant of the inner insulator and the radii of the inner and outer conductors. In radio frequency systems, where the cable length is comparable to the wavelength of the signals transmitted, a uniform cable characteristic impedance is important to minimize loss; the source and load impedances are chosen to match the impedance of the cable to ensure maximum power transfer and minimum standing wave ratio.
Other important properties of coaxial cable include attenuation as a function of frequency, voltage handling capability, shield quality. Coaxial cable design choices affect physical size, frequency performance, power handling capabilities, flexibility and cost; the inner conductor might be stranded. To get better high-frequency performance, the inner conductor may be silver-plated. Copper-plated steel wire is used as an inner conductor for cable used in the cable TV industry; the insulator surrounding the inner conductor may be solid plastic, a foam plastic, or air with spacers supporting the inner wire. The properties of the dielectric insulator determine some of the electrical properties of the cable. A common choice is a solid polyethylene insulator, used in lower-loss cables. Solid Teflon is used as an insulator; some coaxial lines have spacers to keep the inner conductor from touching the shield. Many conventional coaxial cables use braided copper wire forming the shield; this allows the cable to be flexible, but it means there are gaps in the shield layer, the inner dimension of the shield varies because the braid cannot be flat.
Sometimes the braid is silver-plated. For better shield performance, some cables have a double-layer shield; the shield might be just two braids, but it is more common now to have a thin foil shield covered by a wire braid. Some cables may invest in more than two shield layers, such as "quad-shield", which uses four alternating layers of foil and braid. Other shield designs sacrifice flexibility for better performance; those cables cannot be bent as the shield will kink, causing losses in the cable. When a foil shield is used a small wire conductor incorporated into the foil makes soldering the shield termination easier. For high-power radio-frequency transmission up to about 1 GHz, coaxial cable with a solid copper outer conductor is available in sizes of 0.25 inch upward. The outer conductor is corrugated like a bellows to permit flexibility and the inner conductor is held in position by a plastic spiral to approximate an air dielectric. One brand name for such cable is Heliax. Coaxial cables require an internal structure of an insulating material to maintain the spacing between the center conductor and shield.