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
Digital television is the transmission of television signals, including the sound channel, using digital encoding, in contrast to the earlier television technology, analog television, in which the video and audio are carried by analog signals. It is an innovative advance that represents the first significant evolution in television technology since color television in the 1950s. Digital TV transmits in a new image format called HDTV, with greater resolution than analog TV, in a wide screen aspect ratio similar to recent movies in contrast to the narrower screen of analog TV, it makes more economical use of scarce radio spectrum space. A transition from analog to digital broadcasting began around 2006 in some countries, many industrial countries have now completed the changeover, while other countries are in various stages of adaptation. Different digital television broadcasting standards have been adopted in different parts of the world; this standard has been adopted in Europe, Asia, total about 60 countries.
Advanced Television System Committee uses eight-level vestigial sideband for terrestrial broadcasting. This standard has been adopted by 6 countries: United States, Mexico, South Korea, Dominican Republic and Honduras. Integrated Services Digital Broadcasting is a system designed to provide good reception to fixed receivers and portable or mobile receivers, it utilizes two-dimensional interleaving. It supports hierarchical transmission of up to three layers and uses MPEG-2 video and Advanced Audio Coding; this standard has been adopted in Japan and the Philippines. ISDB-T International is an adaptation of this standard using H.264/MPEG-4 AVC that been adopted in most of South America and is being embraced by Portuguese-speaking African countries. Digital Terrestrial Multimedia Broadcasting adopts time-domain synchronous OFDM technology with a pseudo-random signal frame to serve as the guard interval of the OFDM block and the training symbol; the DTMB standard has been adopted in the People's Republic including Hong Kong and Macau.
Digital Multimedia Broadcasting is a digital radio transmission technology developed in South Korea as part of the national IT project for sending multimedia such as TV, radio and datacasting to mobile devices such as mobile phones, laptops and GPS navigation systems. Digital TV's roots have been tied closely to the availability of inexpensive, high performance computers, it wasn't until the 1990s. In the mid-1980s, as Japanese consumer electronics firms forged ahead with the development of HDTV technology, as the MUSE analog format was proposed by Japan's public broadcaster NHK as a worldwide standard, Japanese advancements were seen as pacesetters that threatened to eclipse U. S. electronics companies. Until June 1990, the Japanese MUSE standard—based on an analog system—was the front-runner among the more than 23 different technical concepts under consideration. An American company, General Instrument, demonstrated the feasibility of a digital television signal; this breakthrough was of such significance that the FCC was persuaded to delay its decision on an ATV standard until a digitally based standard could be developed.
In March 1990, when it became clear that a digital standard was feasible, the FCC made a number of critical decisions. First, the Commission declared that the new ATV standard must be more than an enhanced analog signal, but be able to provide a genuine HDTV signal with at least twice the resolution of existing television images. To ensure that viewers who did not wish to buy a new digital television set could continue to receive conventional television broadcasts, it dictated that the new ATV standard must be capable of being "simulcast" on different channels; the new ATV standard allowed the new DTV signal to be based on new design principles. Although incompatible with the existing NTSC standard, the new DTV standard would be able to incorporate many improvements; the final standard adopted by the FCC did not require a single standard for scanning formats, aspect ratios, or lines of resolution. This outcome resulted from a dispute between the consumer electronics industry and the computer industry over which of the two scanning processes—interlaced or progressive—is superior.
Interlaced scanning, used in televisions worldwide, scans even-numbered lines first odd-numbered ones. Progressive scanning, the format used in computers, scans lines in sequences, from top to bottom; the computer industry argued that progressive scanning is superior because it does not "flicker" in the manner of interlaced scanning. It argued that progressive scanning enables easier connections with the Internet, is more cheaply converted to interlaced formats than vice versa; the film industry supported progressive scanning because it offers a more efficient means of converting filmed programming into digital formats. For their part, the consumer electronics industry and broadcasters argued that interlaced scanning was the only technology that could transmit the highest quality pictures feasible, i.e. 1,080 lines per picture and 1,920 pixels per line. Broadcasters favored interlaced scanning because their vast archive of interlaced
Cable television is a system of delivering television programming to consumers via radio frequency signals transmitted through coaxial cables, or in more recent systems, light pulses through fiber-optic cables. This contrasts with broadcast television, in which the television signal is transmitted over the air by radio waves and received by a television antenna attached to the television. FM radio programming, high-speed Internet, telephone services, similar non-television services may be provided through these cables. Analog television was standard in the 20th century, but since the 2000s, cable systems have been upgraded to digital cable operation. A "cable channel" is a television network available via cable television; when available through satellite television, including direct broadcast satellite providers such as DirecTV, Dish Network and Sky, as well as via IPTV providers such as Verizon FIOS and AT&T U-verse is referred to as a "satellite channel". Alternative terms include "non-broadcast channel" or "programming service", the latter being used in legal contexts.
Examples of cable/satellite channels/cable networks available in many countries are HBO, Cinemax, MTV, Cartoon Network, AXN, E!, FX, Discovery Channel, Canal+, Fox Sports, Disney Channel, Nickelodeon, CNN International, ESPN. The abbreviation CATV is used for cable television, it stood for Community Access Television or Community Antenna Television, from cable television's origins in 1948. In areas where over-the-air TV reception was limited by distance from transmitters or mountainous terrain, large "community antennas" were constructed, cable was run from them to individual homes; the origins of cable broadcasting for radio are older as radio programming was distributed by cable in some European cities as far back as 1924. To receive cable television at a given location, cable distribution lines must be available on the local utility poles or underground utility lines. Coaxial cable brings the signal to the customer's building through a service drop, an overhead or underground cable. If the subscriber's building does not have a cable service drop, the cable company will install one.
The standard cable used in the U. S. is RG-6, which has a 75 ohm impedance, connects with a type F connector. The cable company's portion of the wiring ends at a distribution box on the building exterior, built-in cable wiring in the walls distributes the signal to jacks in different rooms to which televisions are connected. Multiple cables to different rooms are split off the incoming cable with a small device called a splitter. There are two standards for cable television. All cable companies in the United States have switched to or are in the course of switching to digital cable television since it was first introduced in the late 1990s. Most cable companies require a set-top box or a slot on one's TV set for conditional access module cards to view their cable channels on newer televisions with digital cable QAM tuners, because most digital cable channels are now encrypted, or "scrambled", to reduce cable service theft. A cable from the jack in the wall is attached to the input of the box, an output cable from the box is attached to the television the RF-IN or composite input on older TVs.
Since the set-top box only decodes the single channel, being watched, each television in the house requires a separate box. Some unencrypted channels traditional over-the-air broadcast networks, can be displayed without a receiver box; the cable company will provide set top boxes based on the level of service a customer purchases, from basic set top boxes with a standard definition picture connected through the standard coaxial connection on the TV, to high-definition wireless DVR receivers connected via HDMI or component. Older analog television sets are "cable ready" and can receive the old analog cable without a set-top box. To receive digital cable channels on an analog television set unencrypted ones, requires a different type of box, a digital television adapter supplied by the cable company. A new distribution method that takes advantage of the low cost high quality DVB distribution to residential areas, uses TV gateways to convert the DVB-C, DVB-C2 stream to IP for distribution of TV over IP network in the home.
In the most common system, multiple television channels are distributed to subscriber residences through a coaxial cable, which comes from a trunkline supported on utility poles originating at the cable company's local distribution facility, called the "headend". Many channels can be transmitted through one coaxial cable by a technique called frequency division multiplexing. At the headend, each television channel is translated to a different frequency. By giving each channel a different frequency "slot" on the cable, the separate television signals do not interfere with each other. At an outdoor cable box on the subscriber's residence the company's service drop cable is connected to cables distributing the signal to different rooms in the building. At each television, the subscriber's television or a set-top box provided by the cable company translates the desired channel back to its original frequency, it is displayed onscreen. Due to widespread cable theft in earlier analog systems, the signals are encrypted on m
2018 FIFA World Cup
The 2018 FIFA World Cup was the 21st FIFA World Cup, an international football tournament contested by the men's national teams of the member associations of FIFA once every four years. It took place in Russia from 14 June to 15 July 2018, it was the first World Cup to be held in Eastern Europe, the 11th time that it had been held in Europe. At an estimated cost of over $14.2 billion, it was the most expensive World Cup. It was the first World Cup to use the video assistant referee system; the finals involved 32 teams, of which 31 came through qualifying competitions, while the host nation qualified automatically. Of the 32 teams, 20 had appeared in the previous tournament in 2014, while both Iceland and Panama made their first appearances at a FIFA World Cup. A total of 64 matches were played in 12 venues across 11 cities. Germany were eliminated in the group stage; the final took place on 15 July at the Luzhniki Stadium between France and Croatia. France won the match 4–2 to claim their second World Cup title, marking the fourth consecutive title won by a European team.
The bidding procedure to host the 2018 and 2022 FIFA World Cup tournaments began in January 2009, national associations had until 2 February 2009 to register their interest. Nine countries placed bids for the 2018 FIFA World Cup, but Mexico withdrew from proceedings, Indonesia's bid was rejected by FIFA in February 2010 after the Indonesian government failed to submit a letter to support the bid. During the bidding process, the three remaining non-UEFA nations withdrew from the 2018 bids, the UEFA nations were thus ruled out of the 2022 bid; as such, there were four bids for the 2018 FIFA World Cup, two of which were joint bids: England, Netherlands/Belgium, Portugal/Spain. The 22-member FIFA Executive Committee convened in Zürich on 2 December 2010 to vote to select the hosts of both tournaments. Russia won the right to be the 2018 host in the second round of voting; the Portugal/Spain bid came second, that from Belgium/Netherlands third. England, bidding to host its second tournament, was eliminated in the first round.
The voting results were as follows: The English Football Association and others raised concerns of bribery on the part of the Russian team and corruption from FIFA members. They claimed that four members of the executive committee had requested bribes to vote for England, Sepp Blatter had said that it had been arranged before the vote that Russia would win; the 2014 Garcia Report, an internal investigation led by Michael J. Garcia, was withheld from public release by Hans-Joachim Eckert, FIFA's head of adjudication on ethical matters. Eckert instead released a shorter revised summary, his reluctance to publish the full report caused Garcia to resign in protest; because of the controversy, the FA refused to accept Eckert's absolving of Russia from blame, with Greg Dyke calling for a re-examination of the affair and David Bernstein calling for a boycott of the World Cup. For the first time in the history of the FIFA World Cup, all eligible nations – the 209 FIFA member associations minus automatically qualified hosts Russia – applied to enter the qualifying process.
Zimbabwe and Indonesia were disqualified before playing their first matches, while Gibraltar and Kosovo, who joined FIFA on 13 May 2016 after the qualifying draw but before European qualifying had begun entered the competition. Places in the tournament were allocated to continental confederations, with the allocation unchanged from the 2014 World Cup; the first qualification game, between Timor-Leste and Mongolia, began in Dili on 12 March 2015 as part of the AFC's qualification, the main qualifying draw took place at the Konstantinovsky Palace in Strelna, Saint Petersburg, on 25 July 2015. Of the 32 nations qualified to play at the 2018 FIFA World Cup, 20 countries competed at the previous tournament in 2014. Both Iceland and Panama qualified for the first time, with the former becoming the smallest country in terms of population to reach the World Cup. Other teams returning after absences of at least three tournaments include: Egypt, returning to the finals after their last appearance in 1990.
It is the first time four Arab nations have qualified for the World Cup. Notable countries that failed to qualify include four-time champions Italy, three-time runners-up and third placed in 2014 the Netherlands, four reigning continental champions: 2017 Africa Cup of Nations winners Cameroon, two-time Copa América champions and 2017 Confederations Cup runners-up Chile, 2016 OFC Nations Cup winners New Zealand, 2017 CONCACAF Gold Cup champions United States; the other notable qualifying streaks broken were for Ghana and Ivory Coast, who had both made the previous three tournaments. Note: Numbers in parentheses indicate positions in the FIFA World Rankings at the time of the tournament; the draw was held on 1 December 2017 at 18:00 MSK at the State Kremlin Palace in Moscow. The 32 teams were drawn by selecting one team from each of the 4 ranked pots. For the draw, the teams were allocated to four pots based on the FIFA World Rankings of October 2017. Pot 1 contained the hosts Russia and the best seven teams, pot 2 contained the next best eight teams, so on for pots 3 and 4.
This was different from previous
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
Coulommiers is a commune in the Seine-et-Marne department in the Île-de-France in north-central France. It is the name of a cheese of the Brie family produced around that city. Inhabitants of Coulommiers are called Columériens. Coulommiers was twinned with Leighton Buzzard in 1958 and with Titisee-Neustadt in 1971; the twinning was renewed in 1982. Coulommiers has been selected to be the first town in France to go digital for its terrestrial television, with analog switch-off in January 2009. Communes of the Seine-et-Marne department INSEE Site of Coulommiers Site of Coulommiers 1999 Land Use, from IAURIF French Ministry of Culture list for Coulommiers Map of Coulommiers on Michelin
Color television is a television transmission technology that includes information on the color of the picture, so the video image can be displayed in color on the television set. It is an improvement on the earliest television technology, monochrome or black and white television, in which the image is displayed in shades of gray. Television broadcasting stations and networks in most parts of the world upgraded from black and white to color transmission in the 1970s and 1980s; the invention of color television standards is an important part of the history of television, it is described in the technology of television article. Transmission of color images using mechanical scanners had been conceived as early as the 1880s. A practical demonstration of mechanically-scanned color television was given by John Logie Baird in 1928, but the limitations of a mechanical system were apparent then. Development of electronic scanning and display made an all-electronic system possible. Early monochrome transmission standards were developed prior to the Second World War, but civilian electronics developments were frozen during much of the war.
In August 1944, Baird gave the world's first demonstration of a practical electronic color television display. In the United States, commercially competing color standards were developed resulting in the NTSC standard for color that retained compatibility with the prior monochrome system. Although the NTSC color standard was proclaimed in 1953 and limited programming became available, it was not until the early 1970s that color television in North America outsold black and white or monochrome units. Color broadcasting in Europe was not standardized on the SECAM formats until the 1960s. Broadcasters began to switch from analog color television technology to digital television around 2006; this changeover is now complete in many countries, but analog television is still the standard elsewhere. The human eye's detection system, in the retina, consists of two types of light detectors: rod cells that capture light and shapes/figures, the cone cells that detect color. A typical retina contains 120 million rods and 4.5 million to 6 million cones, which are divided among three groups that are sensitive to red and blue light.
This means that the eye has far more resolution in "luminance", than in color. However, post-processing of the optic nerve and other portions of the human visual system combine the information from the rods and cones to re-create what appears to be a high-resolution color image; the eye has limited bandwidth to the rest of the visual system, estimated at just under 8 Mbit/s. This manifests itself in a number of ways, but the most important in terms of producing moving images is the way that a series of still images displayed in quick succession will appear to be continuous smooth motion; this illusion starts to work at about 16 frame/s, common motion pictures use 24 frame/s. Television, using power from the electrical grid, tunes its rate in order to avoid interference with the alternating current being supplied – in North America, some Central and South American countries, Korea, part of Japan, the Philippines, a few other countries, this is 60 video fields per second to match the 60 Hz power, while in most other countries it is 50 fields per second to match the 50 Hz power.
In its most basic form, a color broadcast can be created by broadcasting three monochrome images, one each in the three colors of red and blue. When displayed together or in rapid succession, these images will blend together to produce a full-color image as seen by the viewer. One of the great technical challenges of introducing color broadcast television was the desire to conserve bandwidth three times that of the existing black-and-white standards, not use an excessive amount of radio spectrum. In the United States, after considerable research, the National Television Systems Committee approved an all-electronic system developed by RCA which encoded the color information separately from the brightness information and reduced the resolution of the color information in order to conserve bandwidth; the brightness image remained compatible with existing black-and-white television sets at reduced resolution, while color televisions could decode the extra information in the signal and produce a limited-resolution color display.
The higher resolution black-and-white and lower resolution color images combine in the eye to produce a high-resolution color image. The NTSC standard represented a major technical achievement. Experiments in television systems using radio broadcasts date to the 19th century, but it was not until the 20th century that advances in electronics and light detectors made development practical. A key problem was the need to convert a 2D image into a "1D" radio signal. Early systems used a device known as a "Nipkow disk", a spinning disk with a series of holes punched in it that caused a spot to scan across and down the image. A single photodetector behind the disk captured the image brightness at any given spot, converted into a radio signal and broadcast. A similar disk was used at the receiver side, with a light source behind the disk instead of a detector. A number of such systems were being used experimentally in the 1920s; the best-known was John Logie Baird's, used for regular public broadcasting in Britain for several years.
Indeed, Baird's system was demonstrated to members of the Royal Institution in London in 1926 in what is recognized as the first demonstration of a true, working television system. In spite of these early successes, all mechanical television systems sh