IPligence Geolocation Solutions

Today there are more than 1000 million internet users, a number which increases geometrically, as a direct result of the multiplication of the huge offer of services and products online.

It is now much more important to be able to physically locate our customer or visitor to be able to do effective geo-targeting, comply with localized legislation, eliminate business risk/fraud or maximize profit per client – visit.

In anticipation of your needs, IPligence offers you ip location solutions in the following areas:

Why Geolocation?

The benefits of geo-location may sound complex, but a simple example may help illustrate the possibilities. Consider a traveling businessman currently on the road to another city. After checking into his hotel, he pulls out his laptop and hops onto the wireless Internet access point provided by the hotel. He opens his chat program as well a Web browser. His friends and family see from his chat profile that he currently is away from home. Consequently, they can determine his local current time. By pulling up a Web browser the businessman can do a localized search to find nearby restaurants and theaters.

Without having to know the address of the hotel he’s staying in, the chat program and Web pages can determine his location based on the Internet address through which he is connecting. The following week, when he has returned to his home, he uses his laptop to log into a chat program, and his chat profile correctly places him in his home city. There is no need to change computer configurations, remember addresses or even be aware, as the user, that you are benefitting from geo-location services.

Possible applications for geolocation by IP address exist for banking applications, chat programs, user communities, forums, distributed computing environments, security, urban mapping and network robustness, online stores, etc… We encourage you to find out what applications and Web sites currently employ geolocation or could be enhanced by adding support.

Marketing, publicity and analysis

With IPligence, you can adapt your business (product or service), the content of the website, language, etc according to the geographic ip-location of the visitor, while at the same time obtaining statistical geographic information which permits you to know your customers and visitors better. With IPligence, it is much easier to take informed decisions regarding the direction of your business, segment markets so that language, publicity content, website content etc is provided to the end user in line with his needs, which leads to increased focus and profitabilty by market segmentation.

Fraud/Crime prevention, Risk control

Given the anonimity of your visitors, the incidence of fraud is greater than in normal commerce, to be able to locate the origin of a transaction is key in determining risk to a business and affording control over the situation With IPligence, you are able to trace fraudulent trades on your site, and determine and restrict those geographical locations which represent a potential or significant risk to the business. With IPligence, it is easy to block sales to those regions which are not profitable to the business, develop anti-phishing tools and in general protect your site from the cyber-criminal and pursue suspicious behaviour.

Conditional access

With IPligence you can limit, block, or condition content, software or services, based on the geographic location of the visitor or user. This includes platform management and administration of digital rights. IPligence is a geographic solution for the internet which allows high precision ip-location of visitors, immediately after entering on to a domain, without the need to store and analyze cookies or fill out tedious registration forms.

Compliance / legal

With IPligence you are able to tailor the content of the website to the legal jurisdiction applicable to the visitor. With IPligence, it is simple to offer goods and services adapted to the regional variations in terms of tax, guarantee period, special offers etc depending on the localization of the visitor. IPligence affords the possibility to comply with legislation in the location of the visitor as regards copyright, authors rights, product distribution services, publicity and allows restriction of sales to countries with which there may be a commercial restriction from the host country.

Microsoft Windows is the name of several families of software operating systems by Microsoft. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces (GUIs).^[1] Microsoft Windows eventually came to dominate the world’s personal computer market, overtaking Mac OS, which had been introduced previously. At the 2004 IDC Directions conference, IDC Vice President Avneesh Saxena stated that Windows had approximately 90% of the client operating system market.^[2] The current client version of Windows is Windows Vista. The current server version of Windows is Windows Server 2003. The successor to Windows Server 2003, Windows Server 2008, is currently being beta tested.

Versions

The term Windows collectively describes any or all of several generations of Microsoft (MS) operating system (OS) products. These products are generally categorized as follows:

16-bit operating environments

The early versions of Windows were often thought of as just graphical user interfaces, mostly because they ran on top of MS-DOS and used it for file system services.^{[citation needed]} However, even the earliest 16-bit Windows versions already assumed many typical operating system functions, notably, having their own executable file format and providing their own device drivers (timer, graphics, printer, mouse, keyboard and sound) for applications. Unlike MS-DOS, Windows allowed users to execute multiple graphical applications at the same time, through cooperative multitasking. Finally, Windows implemented an elaborate, segment-based, software virtual memory scheme, which allowed it to run applications larger than available memory: code segments and resources were swapped in and thrown away when memory became scarce, and data segments moved in memory when a given application had relinquished processor control, typically waiting for user input.^{[citation needed]} 16-bit Windows versions include Windows 1.0 (1985), Windows 2.0 (1987) and its close relative, Windows/286.

Hybrid 16/32-bit operating environments

Windows/386 introduced a 32-bit protected mode kernel and virtual machine monitor. For the duration of a Windows session, it created one or more virtual 8086 environments and provided device virtualization for the video card, keyboard, mouse, timer and interrupt controller inside each of them. The user-visible consequence was that it became possible to preemptively multitask multiple MS-DOS environments in separate Windows (graphical applications required switching the window to full screen mode). Windows applications were still multi-tasked cooperatively inside one of such real-mode environments.

Windows 3.0 (1990) and Windows 3.1 (1992) improved the design, mostly because of virtual memory and loadable virtual device drivers (VxDs) which allowed them to share arbitrary devices between multitasked DOS windows.^{[citation needed]} Because of this, Windows applications could now run in 16-bit protected mode (when Windows was running in Standard or 386 Enhanced Mode), which gave them access to several megabytes of memory and removed the obligation to participate in the software virtual memory scheme. They still ran inside the same address space, where the segmented memory provided a degree of protection, and multi-tasked cooperatively. For Windows 3.0, Microsoft also rewrote critical operations from C into assembly, making this release faster and less memory-hungry than its predecessors.

Hybrid 16/32-bit operating systems

With the introduction of the 32-bit Windows for Workgroups 3.11, Windows was able to stop relying on DOS for file management.^{[citation needed]} Levering this, Windows 95 introduced Long File Names, reducing the 8.3 filename DOS environment to the role of a boot loader. MS-DOS was now bundled with Windows; this notably made it (partially) aware of long file names when its utilities were run from within Windows. The most important novelty was the possibility of running 32-bit multi-threaded preemptively multitasked graphical programs. However, the necessity of keeping compatibility with 16-bit programs meant the GUI components were still 16-bit only and not fully reentrant, which resulted in reduced performance and stability.

There were three releases of Windows 95 (the first in 1995, then subsequent bug-fix versions in 1996 and 1997, only released to OEMs, which added extra features such as FAT32 and primitive USB support). Microsoft’s next OS was Windows 98; there were two versions of this (the first in 1998 and the second, named “Windows 98 Second Edition”, in 1999). In 2000, Microsoft released Windows Me (Me standing for Millennium Edition), which used the same core as Windows 98 but adopted the visual appearance of Windows 2000, as well as a new feature called System Restore, allowing the user to set the computer’s settings back to an earlier date.

32-bit operating systems

This family of Windows systems was fashioned and marketed for higher reliability business use, and was unencumbered by any Microsoft DOS patrimony.^{[citation needed]} The first release was Windows NT 3.1 (1993, numbered “3.1″ to match the Windows version and to one-up OS/2 2.1^{[citation needed]}, IBM’s flagship OS co-developed by Microsoft and was Windows NT’s main competitor at the time), which was followed by NT 3.5 (1994), NT 3.51 (1995), and NT 4.0 (1996); NT 4.0 was the first in this line to implement the “Windows 95″ user interface. Microsoft then moved to combine their consumer and business operating systems. Their first attempt, Neptune was cancelled and replaced with a new project, Whistler, which later became Windows XP, which came in both home and professional versions and improved backwards compatibility. Then, Windows Server 2003 brought Windows Server up to date with Windows XP. Since then, a new version, Windows Vista was released and Windows Server 2008 will bring Windows Server up to date with Windows Vista. Windows CE, Microsoft’s offering in the mobile and embedded markets, is also a true 32-bit operating system that offers various services for all sub-operating workstations.

64-bit operating systems

Windows NT included support for several different platforms before the x86-based personal computer became dominant in the professional world. Versions of NT from 3.1 to 4.0 supported DEC Alpha and MIPS R4000, which were 64-bit processors, although the operating system treated them as 32-bit processors.

With the introduction of the Intel Itanium architecture, which is referred to as IA-64, Microsoft released new versions of Windows 2000 to support it. Itanium versions of Windows XP and Windows Server 2003 were released at the same time as their mainstream x86 (32-bit) counterparts. On April 25, 2005, Microsoft released Windows XP Professional x64 Edition and x64 versions of Windows Server 2003 to support the AMD64/Intel64 (or x64 in Microsoft terminology) architecture. Microsoft dropped support for the Itanium version of Windows XP in 2005. Windows Vista is the first end-user version of Windows that Microsoft has released simultaneously in 32-bit and x64 editions. Windows Vista does not support the Itanium architecture. The modern 64-bit Windows family comprises AMD64/Intel64 versions of Windows Vista, and Windows Server 2003, in both Itanium and x64 editions.

History

Main article: History of Microsoft Windows

Microsoft has taken two parallel routes in its operating systems. One route has been for the home user and the other has been for the professional IT user. The dual routes have generally led to home versions having greater multimedia support and less functionality in networking and security, and professional versions having inferior multimedia support and better networking and security.

The first version of Microsoft Windows, version 1.0, released in November 1985, lacked a degree of functionality and achieved little popularity, and was to compete with Apple’s own operating system.^{[citation needed]} Windows 1.0 is not a complete operating system; rather, it extends MS-DOS. Microsoft Windows version 2.0 was released in November, 1987 and was slightly more popular than its predecessor. Windows 2.03 (release date January 1988) had changed the OS from tiled windows to overlapping windows. The result of this change led to Apple Computer filing a suit against Microsoft alleging infringement on Apple’s copyrights.

Microsoft Windows version 3.0, released in 1990, was the first Microsoft Windows version to achieve broad commercial success, selling 2 million copies in the first six months.^{[citation needed]} It featured improvements to the user interface and to multitasking capabilities. It received a facelift in Windows 3.1, made generally available on March 1, 1992. Windows 3.1 support ended on December 31, 2001.^[4]

In July 1993, Microsoft released Windows NT based on a new kernel. NT was considered to be the professional OS and was the first Windows version to utilize preemptive multitasking.^{[citation needed]}. Windows NT would later be retooled to also function as a home operating system, with Windows XP.

On August 24th 1995, Microsoft released Windows 95, a new, and major, consumer version that made further changes to the user interface, and also used preemptive multitasking. Windows 95 was designed to replace not only Windows 3.1, but also Windows for Workgroups, and MS-DOS. It was also the first Windows operating system to use Plug and Play capabilities. The changes Windows 95 brought to the desktop were revolutionary, as opposed to evolutionary, such as those in Windows 98 and Windows Me. Mainstream support for Windows 95 ended on December 31, 2000 and extended support for Windows 95 ended on December 31, 2001.^[5]

The next in the consumer line was Microsoft Windows 98 released on June 25th, 1998. It was substantially criticized for its slowness and for its unreliability compared with Windows 95, but many of its basic problems were later rectified with the release of Windows 98 Second Edition in 1999.^{[citation needed]} Mainstream support for Windows 98 ended on June 30, 2002 and extended support for Windows 98 ended on July 11, 2006.^[6]

As part of its “professional” line, Microsoft released Windows 2000 in February 2000. The consumer version following Windows 98 was Windows Me (Windows Millennium Edition). Released in September 2000, Windows Me attempted to implement a number of new technologies for Microsoft: most notably publicized was “Universal Plug and Play.” However, the OS was heavily criticized for its lack of compatibility and stability and it was even rated by PC World as the fourth worst product of all time.^[7]

In October 2001, Microsoft released Windows XP, a version built on the Windows NT kernel that also retained the consumer-oriented usability of Windows 95 and its successors. This new version was widely praised in computer magazines.^[8] It shipped in two distinct editions, “Home” and “Professional”, the former lacking many of the superior security and networking features of the Professional edition. Additionally, the first “Media Center” edition was released in 2002,^[9] with an emphasis on support for DVD and TV functionality including program recording and a remote control. Mainstream support for Windows XP will continue until April 14, 2009 and extended support will continue until April 8, 2014.^[10]

In April 2003, Windows Server 2003 was introduced, replacing the Windows 2000 line of server products with a number of new features and a strong focus on security; this was followed in December 2005 by Windows Server 2003 R2.

On January 30, 2007 Microsoft released Windows Vista. It contains a number of new features, from a redesigned shell and user interface to significant technical changes, with a particular focus on security features. It is available in a number of different editions, more than any previous version of Windows.

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On mobile phones, a ringtone is a brief audio file played to indicate an incoming call. A contemporary ringtone might consist of several bars of a familiar musical tune. Such ringtones are popular because, in a crowd of people with many cellular phone sets, they make it easy to tell whose phone is calling out for attention. The proliferation of cellular telephones in recent years has given rise to a wide variety of ringtones. The earliest usage of ringtone (or ring tone) is for the tone a caller hears indicating that the phone at the recipient’s end is ringing. (Somewhat confusingly, this meaning is also called ringback.) On a traditional phone, the tone is sent back in between the ring sequence at the receiving end. The pulsing rate is one on, two off from a 3-phase generator with each call using a single phase. The called and calling phones would not necessarily use the same phase, so if you wanted to ring someone’s phone (for example, to wake them up), you would need to hear it ringing for a full cycle to make sure that the phone actually rang at the other end.

Definition: Ringtone refers to a variety of sound effects and melodies used to alert a phone owner of an incoming call. Ringtones can be a sound effect, a monophonic melody made of similar tones, polyphonic melodies made of various instruments or even an actual song, in the form of MP3 music. Most manufacturers design their phones so that users can not only choose from many musical ringtones but also program their own for a very personalized ringtone and, in other cases, ringtones can be downloaded through a WAP connection.

However, be cautious when you buy a phone, not all phones let you add programmable ringtones for free, in a do-it-yourself manner. Some lock that function. So before buying a phone, check The Ringtones FAQ for the most recent compatibility list.

Alternate Spellings: Mobile Melody, Ringing Tone,

iPod is a brand of portable media players designed and marketed by Apple and launched on October 23, 2001. The line-up currently consists of the hard drive-based flagship iPod classic, the high-end touchscreen iPod touch, the mid-level video-capable iPod nano, and the entry-level screenless iPod shuffle. Former products include the compact iPod mini (replaced by the iPod nano) and the high-end spin-off iPod photo (re-integrated into the main iPod classic line). iPod classic models store media on an internal hard drive, while all other models, aside from the Microdrive-based mini, use flash memory to enable their smaller size. As with many other digital music players, iPods, excluding the iPod Touch, can also serve as external data storage devices.

Apple’s iTunes software is used to transfer music to the devices. As a jukebox application, iTunes stores a music library on the user’s computer and can play, burn, and rip music from a CD. It also transfers photos, videos, games, and calendars to those iPod models that support them. Apple focused its development on the iPod’s unique user interface and its ease of use, rather than on technical capability. As of October 2007, the iPod had sold over 119 million units worldwide (stated in “The Beat Goes On” conference) making it the best-selling digital audio player series in history.

History and design

iPod came from Apple’s digital hub strategy,^[1] when the company began creating software for the growing market of digital devices being purchased by consumers. Digital cameras, camcorders and organizers had well-established mainstream markets, but the company found existing digital music players “big and clunky or small and useless” with user interfaces that were “unbelievably awful,”^[1] so Apple decided to develop its own. Apple’s hardware engineering chief, Jon Rubinstein, ordered by Steve Jobs, assembled a team of engineers to design it, including hardware engineers Tony Fadell and Michael Dhuey,^[2] and design engineer Jonathan Ive.^[1] The product was developed in less than a year and unveiled on October 23, 2001. CEO Steve Jobs announced it as a Mac-compatible product with a 5 GB hard drive that put “1,000 songs in your pocket.”

Uncharacteristically, Apple did not develop iPod’s software entirely in-house. Apple instead used PortalPlayer’s reference platform which was based on 2 ARM cores. The platform had rudimentary software running on a commercial microkernel embedded operating system. PortalPlayer had previously been working on an IBM-branded MP3 player with Bluetooth headphones.^[1] Apple contracted another company, Pixo, to help design and implement the user interface, under the direct supervision of Steve Jobs.^[1] Once established, Apple continued to refine the software’s look and feel. Starting with iPod mini, the Chicago font was replaced with Espy Sans. Later iPods switched fonts again to Podium Sans — a font similar to Apple’s corporate font Myriad. iPods with color displays then adopted some Mac OS X themes like Aqua progress bars, and brushed metal in the lock interface. In 2007, Apple modified the iPod interface again with the introduction of the sixth-generation iPod classic and third-generation iPod nano by changing the font to Helvetica, and in most cases, splitting the screen in half by displaying the menus on the left and album artwork, photos, or videos on the right (whichever was appropriate for the selected item).

Trademark

The name iPod was proposed by Vinnie Chieco, a freelance copywriter, who (with others) was called by Apple to figure out how to introduce the new player to the public. After Chieco saw a prototype, he thought of the movie 2001: A Space Odyssey and the phrase “Open the pod bay door, Hal!”, which refers to the white EVA Pods of the Discovery One spaceship.^[1] Apple researched the trademark and found that it was already in use. Joseph N. Grasso of New Jersey had originally listed an “iPod” trademark with the U.S. Patent and Trademark Office in July 2000 for Internet kiosks. The first iPod kiosks had been demonstrated to the public in New Jersey in March 1998, and commercial use began in January 2000. The trademark was registered by the USPTO in November 2003, and Grasso assigned it to Apple Computer, Inc. in 2005.^[3]

Software

iPod can play MP3, AAC/M4A, Protected AAC, AIFF, WAV, Audible audiobook, and Apple Lossless audio file formats. The iPod photo introduced the ability to display JPEG, BMP, GIF, TIFF, and PNG image file formats. Fifth and sixth generation iPod classics, as well as third generation iPod nanos, can additionally play MPEG-4 (H.264/MPEG-4 AVC) and QuickTime video formats, with restrictions on video dimensions, encoding techniques and data-rates. Originally, iPod software only worked with Macs; however, starting with the second generation model, iPod software worked with Windows and Macs. Unlike most other media players, Apple does not support Microsoft’s WMA audio format — but a converter for WMA files without Digital Rights Management (DRM) is provided with the Windows version of iTunes. MIDI files also cannot be played, but can be converted to audio files using the “Advanced” menu in iTunes. Alternative open-source audio formats such as Ogg Vorbis and FLAC are not supported without installing custom firmware onto the iPod.

The iPod is associated with one host computer. Each time an iPod connects to its host computer, iTunes can synchronize entire music libraries or music playlists either automatically or manually. Song ratings can be set on the iPod and synchronized later to the iTunes library, and vice versa. A user can access, play, and add music on a second computer if the iPod is set to manual and not automatic sync, but anything added or edited will be reversed upon connecting and syncing with the main computer and its library. If a user wishes to automatically sync music with a another computer, the iPod’s library will be entirely wiped and replaced with the other computer’s library.

Mahjong

Mahjong (also spelled mahjongg, Simplified Chinese: 麻将; Pinyin: májiàng) is a game for four players that originated in China. Mahjong involves skill, strategy, and calculation, as well as a certain degree of luck. Depending on the variation which is played, luck can be anything from a minor to a dominant factor in success. In Asia, mahjong is also popularly played as a gambling game. The object of the game is to build complete suits, or melds, usually of threes, from either 13 or 16 tiles. The first person to achieve this goal wins the game. The winning tile completes the player’s set of either 14 or 17 tiles.

History

Mahjong in China

One of the myths of the origin of Mahjong suggests that Confucius,[1] the great Chinese philosopher, had developed the game in about 500 BC. This assertion is likely to be apocryphal. According to this myth, the appearance of the game in the various Chinese states coincided with Confucius’ travels at the time he was teaching his new doctrines. The three dragon (Cardinal) tiles also agree with the three Cardinal virtues bequeathed by Confucius. Zhōng (中 , lit. middle) the Red, Fā (發 , lit. prosperity) the Green, Bái (白 , lit. white) the White represent Benevolence, Sincerity, and Filial piety respectively, again under this myth. In fact, the “middle” is likely a reference to 中国 (zhōngguó) — China’s name in Chinese.

Also, this myth claims that Confucius was fond of birds, which would explain the name “Mahjong” (sparrow). However, there is no evidence of Mahjong’s existence before the Taiping era in the 19th century, which eliminates Confucius as a likely inventor.

The general consensus is that the game was developed from existing Chinese card and domino games sometime around 1850.[citation needed] Many historians believe it was based on a Chinese card game called Mádiào (馬吊) (also known as Ma Tiae, lit. Hanging Horse; or Yèzí (葉子), lit. Leaf) in the early Ming dynasty.[2] This game was played with 40 paper cards similar in appearance to the cards used in the game Ya Pei. These 40 cards, numbered 1 to 9 in four different suits along with four extra flower cards, are quite similar to the numbering of Mahjong tiles today.

There is still a healthy debate about who created the game. One theory is that Chinese army officers serving during the Taiping Rebellion created the game to pass the time. Another theory is that a noble living in the Shanghai area created the game between 1870 and 1875. Others believe that around 1850 in the city of Níngpō two brothers had created Mahjong from the earlier game of Mádiào.

This traditional Chinese game was banned in its homeland in 1949, when the People’s Republic of China was founded. The new Communist government forbade any gambling activities, which were regarded as symbols of capitalist corruption. After the Cultural Revolution, the game was revived, and once again Mahjong has become a favorite pastime of the Chinese. In Hong Kong, Macao and elsewhere, however, Mahjong has always been popular, particularly among the Cantonese.

Mahjong in the western world

By 1895, Stewart Culin, an American anthropologist, wrote a paper in which Mahjong was mentioned. This is the first known written account of Mahjong in any language other than Chinese. By 1910, there were written accounts in many languages including French and Japanese. In 1920, Abercrombie & Fitch became the first ever American brand to introduce the game.[3] It became a success in New York, and owner of the Company, Ezra Fitch, sent emissaries to Chinese villages to buy every set of Mahjong they could find. In the end, Abercrombie & Fitch sold a number of 12,000 sets.[4] Later, an important English book was Joseph Park Babcock’s Rules of Mah-Jongg, which, simplified in 1920, was simply known as the “red book”. Although this was the earliest version of Mahjong that had been introduced to America, many of Babcock’s simplifications were abandoned when the 1920s fad died out.

The game was a sensation in America when it was imported from China in the 1920s, as the same Mahjong game took on a number of trademarked names, such as Pung Chow or the Game of Thousand Intelligences. Part of Mahjong nights in America was to decorate rooms in Chinese style and dress like Chinese.[5] Several hit songs were also recorded during the mahjong fad, most notably “Since Ma is Playing Mah Jong” by Eddie Cantor.[6]

American Mahjong, which was mainly played by women during the time, grew from this craze. By the 1930s, many revisions of the rules developed that were substantially different from Babcock’s classical version (including some that were considered fundamentals in other variants, such as the notion of a standard hand). Standardization came with the formation of the National Mah Jongg League (NMJL) in 1937, along with the first American mahjong rulebook, Maajh: The American Version of the Ancient Chinese Game.

While Mahjong was accepted by U.S. players of all ethnic backgrounds during the Babcock era, many consider the modern American version a Jewish game,[7] as many American Mahjong players are of Jewish descent. (Also, the NMJL was founded by Jewish players and considered a Jewish organization.) In addition, players usually use the American game as a family-friendly social activity, not as gambling.

British author Alan D. Millington revived the Chinese Classical game of the 1920s with his book, The Complete Book of Mah-jongg (1977). This handbook includes a formal rules set for the game. Many players in Western countries consider Millington’s work authoritative.

Current development

Today, the popularity and the characteristics of players of Mahjong vary from country to country. There are also many governing bodies, which often host exhibition games and tournaments. It remains far more popular in Asia than in the West.

In Japan, there is a traditional emphasis on gambling and the typical player is male. Many devotees there believe the game is losing popularity and have taken efforts to revive it. In addition, Japanese video arcades have introduced Mahjong arcade machines that can be connected to others over the internet.

Mahjong culture is still deeply ingrained in the Chinese community: Sam Hui wrote Cantopop songs, using Mahjong as their themes. Hong Kong movies have often included scenes of Mahjong games. Gambling movies have been filmed time and again in Hong Kong, and a recent sub-genre is the Mahjong movie.

A recent study by doctors in Hong Kong has found that the game can cause epileps

Arcade game

An arcade game is a coin-operated entertainment machine, typically installed in businesses such as restaurants, pubs, video arcades, and Family Entertainment Centers. Most arcade games are redemption games, merchandisers, video games or pinball machines.

History

The first popular “arcade games” were early amusement park midway games such as Shooting galleries, ball toss games, and the earliest coin-operated machines, such as those which claim to tell a person their fortune or played mechanical music. The old midways of 1920s-era amusement parks (such as Coney Island in New York) provided the inspiration and atmosphere of later arcade games.

In the 1930s, the earliest coin-operated pinball machines were made. These early amusement devices were distinct from their later electronic cousins in that they were made of wood, did not have plungers or lit-up bonus surfaces on the playing field, and used mechanical instead of electronic scoring readouts. By around 1977, most pinball machines in production switched to using solid state electronics for both operation and scoring. Stanford University set up the Galaxy Game, a coin-operated version of the Spacewar computer game. This is the earliest known instance of a coin-operated video game. Later in the same year, Nolan Bushnell created the first mass-manufactured such game, Computer Space, for Nutting Associates.

In 1972, Atari was formed by Nolan Bushnell and Ted Dabney. Atari essentially created the coin-operated video game industry with the game Pong, the smash hit electronic ping pong video game. Pong proved to be popular, but imitators helped keep Atari from dominating the fledging coin-operated video game market. Video game arcades sprang up in shopping malls, and small “corner arcades” appeared in restaurants, grocery stores, bars and movie theaters all over the United States and other countries during the late 1970s and early 1980s. Games such as Space Invaders (1978), Galaxian (1979), Pac-Man (1980), Battlezone (1980), and Donkey Kong (1981) were especially popular.

During the late 70s and 80s, chains such as Chuck E Cheese, Ground Round, Dave and Busters, and Gatti’s Pizza combined the traditional restaurant and/or bar environment with arcades. [2]

By the late-1980s, the arcade video game craze was beginning to fade due to the reputation of arcades as being seedy, unsafe places as well as the advances in home video game console technology. Arcade video games experienced a resurgence with the advent of two-player fighting games such as Street Fighter II (1991) by Capcom, Mortal Kombat (1992) by Midway Games, Fatal Fury (1992), Killer Instinct (1994) by Rare, and King of Fighters (1994-2005) by SNK.

However by 1996, home video game consoles and computers with 3D accelerator cards had reached technological parity with arcade equipment—arcade games had always been based on commodity technology, but their advantage over previous generations of home system was in their ability to customize and use the latest graphics and sound chips, much as PC games of today do. Declines in arcade sales volume meant that this approach was no longer cost-effective. Furthermore, by the late 1990s and early 2000s, networked gaming via console and computers across the Internet had also appeared[3], replacing the venue of head to head competition and social atmosphere once provided solely by arcades[4].

The arcades also lost their status as the forefront of new game releases. Given the choice between playing a game at an arcade three or four times (perhaps 15 minutes of play for a typical arcade game), and renting, at about the same price, the exact same game—for a video game console—the console was the clear winner. Fighting games were the most attractive feature for arcades, since they offered the prospect of face-to-face competition and tournaments, which correspondingly led players to practice more (and spend more money in the arcade), but they could not support the business all by themselves. To remain viable, arcades added other elements to compliment the video games such as redemption games, merchandisers, and food service. Referred to as “fun centers” or “family fun centers” [5], some of the longstanding chains such as Chuck E. Cheese and Gatti’s Pizza (“GattiTowns”)[6] also changed to this format. Many old video game arcades have long since closed, and classic coin-operated games have become largely the province of dedicated hobbyists.

Today’s arcades have found a niche in games that use special controllers largely inaccessible to home users. An alternative interpretation (one which includes fighting games, which continue to thrive and require no special controller) is that the arcade game is now a more socially-oriented hangout, with games that focus on an individual’s performance, rather than the game’s content, as the primary form of novelty. Examples of today’s popular genres are rhythm games such as Dance Dance Revolution (1998) and DrumMania (1999), and rail shooters such as House of the Dead (1998) and Time Crisis.

Technology

Virtually all modern arcade games (other than the very traditional midway-type games at county fairs) make extensive use of solid state electronics and integrated circuits. Coin-operated arcade video games generally use custom per-game hardware with multiple CPUs, highly specialized sound and graphics chips and/or boards, and the latest in computer graphics display technology. Sometimes, arcade games are controllable via more immersing and realistic means than either PC or console games, and feature specialized ambiance or control accessories, including fully enclosed dynamic cabinets with force feedback controls, dedicated lightguns, rear-projection displays, reproductions of car or plane cockpits and even motorcycle or horse-shaped controllers, or even highly dedicated controllers such as dancing mats and fishing rods. These accessories are usually what set modern arcade games apart from PC or console games, as they are usually too bulky, expensive and specialized to be used with typical home PCs and consoles.

Arcade genre

Arcade games often have very short levels, simple, easy to grasp controllers, iconic characters, and rapidly increasing difficulty. They are designed as quick bursts of adrenaline-fueled thrills, as opposed to most console games, which feature more in-depth gameplay, and stronger storylines. This is due to being coin-operated, where the player is essentially renting the game for as long as their game avatar can stay alive (or until they run out of tokens). Games on consoles or PCs can be referred to as an “arcade game” if it shares these qualities, or if it’s a direct port of an arcade title.

Many independent developers are now producing games in the arcade genre that are designed specifically for use on the Internet. These games are usually designed with Flash/Java/DHTML and run directly in web-browsers.

Arcade racing games are those which have a simplified physics engine and do not require much learning time, in opposition to racing simulators. Cars can turn sharply without losing speed or overdrifting, and the AI rivals are sometimes programmed so they are always near the player (rubberband effect).

Arcade flight games also use simplified physics and controls in comparison to flight simulators. These are meant to have an easy learning curve, in order to preserve their action component. Increasing numbers of console flight arcade games, from Crimson Skies to Secret Weapons Over Normandy indicate the falling of manual-heavy flight sim popularity in favor of instant arcade flight action.

Wi-Fi (pronounced wye-fye, IPA: /ˈwaɪfaɪ/) is a wireless technology brand owned by the Wi-Fi Alliance intended to improve the interoperability of wireless local area network products based on the IEEE 802.11 standards. Common applications for Wi-Fi include Internet and VoIP phone access, gaming, and network connectivity for consumer electronics such as televisions, DVD players, and digital cameras.

The Wi-Fi Alliance is a consortium of separate and independent companies agreeing to a set of common interoperable products based on the family of IEEE 802.11 standards.^[1] The Wi-Fi Alliance certifies products via a set of established test procedures to establish interoperability. Those manufacturers that are members of Wi-Fi Alliance whose products pass these interoperability tests can mark their products and product packaging with the Wi-Fi logo.^[2]

Wi-Fi technologies have gone through several generations since their inception in 1997. Wi-Fi is supported to different extents under Microsoft Windows, Apple Mac OS X and open source Unix and Linux operating systems।

Uses

A Wi-Fi enabled device such as a PC, game console, cell phone, MP3 player or PDA can connect to the Internet when within range of a wireless network connected to the Internet. The area covered by one or more interconnected access points is called a hotspot. Hotspots can cover as little as a single room with wireless-opaque walls or as much as many square miles covered by overlapping access points. Wi-Fi has been used to create mesh networks, for example, in London.^[3] Both architectures are used in community networks.^{[citation needed]}

Wi-Fi also allows connectivity in peer-to-peer (wireless ad-hoc network) mode, which enables devices to connect directly with each other. This connectivity mode is useful in consumer electronics and gaming applications.

When the technology was first commercialized there were many problems because consumers could not be sure that products from different vendors would work together. The Wi-Fi Alliance began as a community to solve this issue so as to address the needs of the end user and allow the technology to mature. The Alliance created the branding Wi-Fi CERTIFIED to show consumers that products are interoperable with other products displaying the same branding.

Many consumer devices use Wi-Fi. Amongst others, personal computers can network to each other and connect to the Internet, mobile computers can connect to the Internet from any Wi-Fi hotspot, and digital cameras can transfer images wirelessly.

Routers which incorporate a DSL or cable modem and a Wi-Fi access point are often used in homes and other premises, and provide Internet access and internetworking to all devices connected wirelessly or by cable into them. Devices supporting Wi-Fi can also be connected in ad-hoc mode for client-to-client connections without a router.

Business and industrial Wi-Fi is widespread as of 2007. In business environments, increasing the number of Wi-Fi access points provides redundancy, support for fast roaming and increased overall network capacity by using more channels or creating smaller cells. Wi-Fi enables wireless voice applications (VoWLAN or WVOIP). Over the years, Wi-Fi implementations have moved toward ‘thin’ access points, with more of the network intelligence housed in a centralized network appliance, relegating individual Access Points to be simply ‘dumb’ radios. Outdoor applications may utilize true mesh topologies. As of 2007 Wi-Fi installations can provide a secure computer networking gateway, firewall, DHCP server, intrusion detection system, and other functions.

In addition to restricted use in homes and offices, Wi-Fi is publicly available at Wi-Fi hotspots provided either free of charge or to subscribers to various providers. Free hotspots are often provided by businesses such as hotels, restaurants, and airports who offer the service to attract or assist clients. Sometimes free Wi-Fi is provided by enthusiasts, or by organizations or authorities who wish to promote business in their area. Metropolitan-wide WiFi (Muni-Fi) already has more than 300 projects in प्रोसेस।

Advantages

Wi-Fi allows LANs to be deployed without cabling for client devices, typically reducing the costs of network deployment and expansion. Spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs.

As of 2007 wireless network adapters are built into most modern laptops. The price of chipsets for Wi-Fi continues to drop, making it an economical networking option included in even more devices. Wi-Fi has become widespread in corporate infrastructures, which also helps with the deployment of RFID technology that can piggyback on Wi-Fi.^[5]

Different competitive brands of access points and client network interfaces are inter-operable at a basic level of service. Products designated as “Wi-Fi Certified” by the Wi-Fi Alliance are backwards inter-operable. Wi-Fi is a global set of standards. Unlike mobile telephones, any standard Wi-Fi device will work anywhere in the world.

Wi-Fi is widely available in more than 250,000^{[citation needed]} public hotspots and tens of millions of homes and corporate and university campuses worldwide. WPA is not easily cracked if strong passwords are used and WPA2 encryption has no known weaknesses. New protocols for Quality of Service (WMM) make Wi-Fi more suitable for latency-sensitive applications (such as voice and video), and power saving mechanisms (WMM Power Save) improve battery operation.

Disadvantages

Spectrum assignments and operational limitations are not consistent worldwide. Most of Europe allows for an additional 2 channels beyond those permitted in the U.S. for the 2.4 GHz band. (1–13 vs. 1–11); Japan has one more on top of that (1–14). Europe, as of 2007, is now essentially homogeneous in this respect. A very confusing aspect is the fact a Wi-Fi signal actually occupies five channels in the 2.4 GHz band resulting in only three non-overlapped channels in the U.S.: 1, 6, 11, and four in Europe: 1, 5, 9, 13.

Some countries, such as Italy, formerly required a ‘general authorization’ for any Wi-Fi used outside an operator’s own premises, or require something akin to an operator registration.^{[citation needed]} Equivalent isotropically radiated power (EIRP) in the EU is limited to 20 dBm (0.1 W).

Power consumption is fairly high compared to some other low-bandwidth standards, such as Zigbee and Bluetooth, making battery life a concern.

The most common wireless encryption standard, Wired Equivalent Privacy or WEP, has been shown to be easily breakable even when correctly configured. Wi-Fi Protected Access (WPA and WPA2), which began shipping in 2003, aims to solve this problem and is now available on most products. Wi-Fi Access Points typically default to an “open” (encryption-free) mode. Novice users benefit from a zero-configuration device that works out of the box, but this default is without any wireless security enabled, providing open wireless access to their LAN. To turn security on requires the user to configure the device, usually via a software graphical user interface (GUI). Wi-Fi networks that are open (unencrypted) can be monitored and used to read and copy data (including personal information) transmitted over the network, unless another security method is used to secure the data, such as a VPN or a secure web page. (See HTTPS/Secure Socket Layer.)

Many 2.4 GHz 802.11b and 802.11g Access points default to the same channel on initial startup, contributing to congestion on certain channels. To change the channel of operation for an access point requires the user to configure the device.

Wi-Fi networks have limited range. A typical Wi-Fi home router using 802.11b or 802.11g with a stock antenna might have a range of 32 m (120 ft) indoors and 95 m (300 ft) outdoors. Range also varies with frequency band. Wi-Fi in the 2.4 GHz frequency block has slightly better range than Wi-Fi in the 5 GHz frequency block. Outdoor range with improved (directional) antennas can be several kilometres or more with line-of-sight.

Wi-Fi performance also decreases exponentially as the range increases.

Wi-Fi pollution, or an excessive number of access points in the area, especially on the same or neighboring channel, can prevent access and interfere with the use of other access points by others, caused by overlapping channels in the 802.11g/b spectrum, as well as with decreased signal-to-noise ratio (SNR) between access points. This can be a problem in high-density areas, such as large apartment complexes or office buildings with many Wi-Fi access points. Additionally, other devices use the 2.4 GHz band: microwave ovens, security cameras, Bluetooth devices and (in some countries) Amateur radio, video senders, cordless phones and baby monitors can cause significant additional interference. General guidance to those who suffer these forms of interference or network crowding is to migrate to a WiFi 5 GHz product, (802.11a or the newer 802.11n IF it has 5GHz/11a support) as the 5 GHz band is relatively unused and there are many more channels available. This also requires users to set up the 5 GHz band to be the preferred network in the client and to configure each network band to a different name (SSID).

It is also an issue when municipalities,^[6] or other large entities such as universities, seek to provide large area coverage. This openness is also important to the success and widespread use of 2.4 GHz Wi-Fi.

Interoperability issues between non WiFi brands or proprietary deviations from the standard can disrupt connections or lower throughput speeds on all user’s devices that are within range, to include the non-WiFi or proprietary product।

Standard devices
Wireless access points connects a group of wireless devices to an adjacent wired LAN. An access point is similar to a network hub, relaying data between connected wireless devices in addition to a (usually) single connected wired device, most often an ethernet hub or switch, allowing wireless devices to communicate with other wired devices.

Wireless adapters allow devices to connect to a wireless network. These adapters connect to devices using various external or internal interconnects such as PCI, miniPCI, USB, ExpressCard, Cardbus and PC card. Most newer laptop computers are equipped with internal adapters. Internal cards are generally more difficult to install.

Wireless routers integrate a WAP, ethernet switch, and internal Router firmware application that provides IP Routing, NAT, and DNS forwarding through an integrated WAN interface. A wireless router allows wired and wireless ethernet LAN devices to connect to a (usually) single WAN device such as cable modem or DSL modem. A wireless router allows all three devices (mainly the access point and router) to be configured through one central utility. This utility is most usually an integrated web server which serves web pages to wired and wireless LAN clients and often optionally to WAN clients. This utility may also be an application that is run on a desktop computer such as Apple’s AirPort.

Wireless network bridges connect a wired network to a wireless network. This is different from an access point in the sense that an access point connects wireless devices to a wired network at the data-link layer. Two wireless bridges may be used to connect two wired networks over a wireless link, useful in situations where a wired connection may be unavailable, such as between two separate homes.

Wireless range extenders or wireless repeaters can extend the range of an existing wireless network। Range extenders can be strategically placed to elongate a signal area or allow for the signal area to reach around barriers such as those created in L-shaped corridors. Wireless devices connected through repeaters will suffer from an increased latency for each hop. Additionally, a wireless device connected to any of the repeaters in the chain throughput that is limited by the weakest link between the two nodes in the chain from which the connection originates to where the connection ends.

Embedded systems

Wi-Fi availability in the home is on the increase. This extension of the Internet into the home space will increasingly be used for remote monitoring. Examples of remote monitoring include security systems and tele-medicine. In all these kinds of implementation, if the Wi-Fi provision is provided using a system running one of operating systems mentioned above, then it becomes unfeasible due to weight, power consumption and cost issues.

Increasingly in the last few years (particularly as of early 2007), embedded Wi-Fi modules have become available which come with a real-time operating system and provide a simple means of wireless enabling any device which has and communicates via a serial port.

This allows simple monitoring devices – for example, a portable ECG monitor hooked up to a patient in their home – to be created. This Wi-Fi enabled device effectively becomes part of the internet cloud and can communicate with any other node on the internet. The data collected can hop via the home’s Wi-Fi access point to anywhere on the internet.

These Wi-Fi modules are designed so that designers need minimal Wi-Fi knowledge to wireless-enable their products.

Unintended and Intended use by outsider

During the early popular adoption of 802.11, providing open access points for anyone within range to use was encouraged to cultivate wireless community networks;^[7] particularly since people on average use only a fraction of their upstream bandwidth at any given time. Later, equipment manufacturers and mass-media advocated isolating users to a predetermined whitelist of authorized users—referred to as “securing” the access point.

Measures to deter unauthorized users include suppressing the AP’s SSID broadcast, allowing only computers with known MAC addresses to join the network, and various encryption standards. Suppressed SSID and MAC filtering are ineffective security methods as the SSID is broadcast in the open in response to a client SSID query and a MAC address can easily be spoofed. If the eavesdropper has the ability to change his MAC address, then he can potentially join the network by spoofing an authorized address.

WEP encryption can protect against casual snooping, but may also produce a misguided sense of security since freely available tools such as AirSnort or aircrack can quickly recover WEP encryption keys. Once it has seen 5-10 million encrypted packets, AirSnort will determine the encryption password in under a second^[8]; newer tools such as aircrack-ptw can use Klein’s attack to crack a WEP key with a 50% success rate using only 40,000 packets. The newer Wi-Fi Protected Access (WPA) and IEEE 802.11i (WPA2) encryption standards do not have any of the serious weaknesses of WEP encryption.

Recreational logging and mapping of other people’s access points has become known as wardriving. It is also common for people to use open (unencrypted) Wi-Fi networks as a free service, termed piggybacking. Indeed, many access points are intentionally installed without security turned on so that they can be used as a free service. These activities do not result in sanctions in most jurisdictions, however legislation and case law differ considerably across the world. A proposal to leave graffiti describing available services was called warchalking. The universal rule is a Wi-Fi Access Point that has not turned on its security is a service that welcomes its free use, while an access point that has turned its security on does not. The burden is on the access point owner to properly configure and control the access to his internet connection. In a Florida court case^{[citation needed]}, owner laziness was determined not to be a valid excuse.

Piggybacking is often unintentional. Most access points are configured without encryption by default, and operating systems such as Windows XP SP2 and Mac OS X may be configured to automatically connect to any available wireless network. A user who happens to start up a laptop in the vicinity of an access point may find the computer has joined the network without any visible indication. Moreover, a user intending to join one network may instead end up on another one if the latter’s signal is stronger. In combination with automatic discovery of other network resources (see DHCP and Zeroconf) this could possibly lead wireless users to send sensitive data to the wrong middle man when seeking a destination (see Man-in-the-middle attack). For example, a user could inadvertently use an insecure network to login to a website, thereby making the login credentials available to anyone listening, if the website is using an insecure protocol like HTTP, rather than a secure protocol like HTTPS.

Wi-Fi and amateur radio

In the U.S., Canada, Australia and Europe, a portion of the 2.4 GHz Wi-Fi radio spectrum is also allocated to amateur radio users. In the U.S., FCC Part 15 rules govern non-licensed operators (i.e. most Wi-Fi equipment users). Under Part 15 rules, non-licensed users must “accept” (i.e. endure) interference from licensed users and not cause harmful interference to licensed users. Amateur radio operators are licensed users, and retain what the FCC terms “primary status” on the band, under a distinct set of rules (Part 97). Under Part 97, licensed amateur operators may construct their own equipment, use very high-gain antennas, and boost output power to 100 watts on frequencies covered by Wi-Fi channels 2-6. However, Part 97 rules mandate using only the minimum power necessary for communications, forbid obscuring the data, and require station identification every 10 minutes. Therefore, output power control is required to meet regulations, and the transmission of any encrypted data (for example https) is questionable.

In practice, microwave power amplifiers are expensive. On the other hand, the short wavelength at 2.4 GHz allows for simple construction of very high gain directional antennas. Although Part 15 rules forbid any modification of commercially constructed systems, amateur radio operators may modify commercial systems for optimized construction of long links, for example. Using only 200 mW link radios and high gain directional antennas, a very narrow beam may be used to construct reliable links with minimal radio frequency interference to other users.

Question of health risks

The UK’s Health Protection Agency considers there is no consistent evidence of harm from the low power transmissions of Wi-Fi equipment. Consensus amongst scientists is that there is no evidence of harm, and the continuing calls for more research into the effects on human health remain limited. However, in September 2007, Germany’s Environment Ministry announced that its citizens should minimise their exposure to radiation from Wi-Fi by choosing conventional wired connections,^[9] without any evidence and contrary to current internationally accepted safety criteria. Dr Michael Clark, of the Health Protection Agency, says published research on mobile phones and masts does not add up to an indictment of Wi-Fi:

All the expert reviews done here and abroad indicate that there is unlikely to be a health risk from wireless networks. … When we have conducted measurements in schools, typical exposures from Wi-Fi are around 20 millionths of the international guideline levels of exposure to radiation. As a comparison, a child on a mobile phone receives up to 50 per cent of guideline levels. So a year sitting in a classroom near a wireless network is roughly equivalent to 20 minutes on a mobile. If Wi-Fi should be taken out of schools, then the mobile phone network should be shut down, too—and FM radio and TV, as the strength of their signals is similar to that from Wi-Fi in classrooms.

History

Wi-Fi uses both single carrier direct-sequence spread spectrum radio technology (part of the larger family of spread spectrum systems) and multi-carrier OFDM (Orthogonal Frequency Division Multiplexing) radio technology. These regulations then enabled the development of Wi-Fi, its onetime competitor HomeRF, and Bluetooth.

Unlicensed spread spectrum was first made available in the US by the Federal Communications Commission in 1985 and these FCC regulations were later copied with some changes in many other countries enabling use of this technology in all major countries.^[11] The FCC action was proposed by Michael Marcus of the FCC staff in 1980 and the subsequent regulatory action took 5 more years. It was part of a broader proposal to allow civil use of spread spectrum technology and was opposed at the time by main stream equipment manufacturers and many radio system operators.

The precursor to Wi-Fi was invented in 1991 by NCR Corporation/AT&T (later Lucent & Agere Systems) in Nieuwegein, the Netherlands. It was initially intended for cashier systems; the first wireless products were brought on the market under the name WaveLAN with speeds of 1 Mbit/s to 2 Mbit/s. Vic Hayes, who held the chair of IEEE 802.11 for 10 years and has been named the ‘father of Wi-Fi,’ was involved in designing standards such as IEEE 802.11b, and 802.11a.

City wide Wi-Fi

St. cloud, Florida became the first city in the United States to offer city wide free Wi-Fi,^[12] although many others have plans to offer the service. Corpus Christi, Texas had offered free Wi-Fi until May 31, 2007 when the network was purchased by Earthlink.^[13] Philadelphia is also using Earthlink for its city wide Wi-Fi.^[14] New Orleans had free city wide Wi-Fi shortly after Hurricane Katrina.^[15] City wide Wi-Fi is available in nine cities in the UK, including Leeds, Manchester and London.

Origin and meaning of the term “Wi-Fi”

Despite the similarity between the terms “Wi-Fi” and “Hi-Fi“, statements reportedly made by Phil Belanger of the Wi-Fi Alliance contradict the conclusion that “Wi-Fi” stands for “Wireless Fidelity”.^[17][18][19] According to Belanger, the Interbrand Corporation developed the brand “Wi-Fi” for the Wi-Fi Alliance to use to describe WLAN products that are based on the IEEE 802.11 standards. In Belanger’s words,

Wi-Fi and the yin yang style logo were invented by Interbrand. We [the founding members of the Wireless Ethernet Compatibility Alliance, now called as the Wi-Fi Alliance] hired Interbrand to come up with the name and logo that we could use for our interoperability seal and marketing efforts. We needed something that was a little catchier than ‘IEEE 802.11b Direct Sequence’.^[20]

The Wi-Fi Alliance themselves invoked the term “Wireless Fidelity” with the marketing of a tag line “The Standard for Wireless Fidelity,” but later removed the tag from their marketing. The Wi-Fi Alliance now seems to discourage the propagation of the notion that “Wi-Fi” stands for “Wireless Fidelity”, but it has been referred to as such by the Wi-Fi Alliance in White Papers currently held in their knowledge base: “… a promising market for wireless fidelity (Wi-Fi) network equipment.”^[21] and “A Short History of WLANs.” The association created the Wi-Fi (Wireless Fidelity) logo to indicate that a product had been certified for interoperability.

Antena
Antena Rhombic UHF

ANTENA RHOMBIC merupakan salah satu antena yang sederhana pembuatan dan bahannya, tetapi penguatan (gain)-nya tinggi. Sehingga mampu menerima pancaran sinyal UHF di daerah daerah yang mulai lemah. Konstruksi antena Rhombic UHF ini tidak rumit, mudah dibuat dari kawat email, tembaga bekas, batang aluminium, kuningan, maupun kawat seng, yang berdiameter antara 2.5 mm sampai 5 mm.

Antena Rhombic merupakan bentangan kawat berbentuk ketupat, yang kalau sudah di atas tiang dan dilihat dari bawah, seperti sebuah layangan. Besar bidang yang dibentuk bisa dimodifikasi sendiri. Tergantung pada berapa frekuensi kerja, dan elemennya berupa lambda. Makin panjang elemen, dalam ukuran lambda, daya terima atau pancarannya akan makin kuat. Antena Rhombic sebetulnya jarang dipergunakan untuk penerimaan siaran televisi.

Pemakai terbesar adalah kalangan HAM, amatir radio, eksperimenter, operator radio perhubungan, serta militer. Pemakaian terbanyak pada band HF, di mana untuk mendapatkan penguatan yang tinggi, segulung kabel bekas ternyata mampu mengganti konduktor perak yang mahal, konstruksi rumit, spreader spreader atau antena direksional jenis lain, yang lebih sulit dinaikkan ke atas tiang.

Pemakaian kedua ada pada band VHF, namun tidak sedikit HAM yang memanfaatkan pada band UHF. Umumnya antena Rhombic dirancang untuk memberikan penguatan antara 10 dB sampai 18 dB, pada band VHF dan UHF. Jika ia dipasang dengan ketinggian yang cukup, akan mampu dan sesuai untuk menjangkau daerah yang berjarak antara 100 sampai 225 km dari lokasi pemancar, band width pun relatif lebar.

Pada band HF, lambda-nya panjang sekali, minimal dibutuhkan empat buah tiang untuk memegang sudut-sudutnya. Namun, pada band UHF, yang lambda-nya pendek, cukup disangga dengan satu tiang saja, yang bisa berupa kerangka kayu kecil berkaki empat, yang dipasang di pucuk tiang sebagai pengganti empat tiang yang dibutuhkan. Setiap kita ingin menambah panjang sisi antena tersebut, besar sudut di antara sisi-sisinya perlu disesuaikan, agar antena bisa bekerja optimum.

Di sini, kita mempelajari cara membuat antena Rhombic UHF 4.5 atau 6 lambda. Pembaca dapat memilih sendiri, untuk membuat salah satu di antaranya. Tabel 1 menunjukkan ukuran-ukuran untuk masing-masing panjang gelombang. Jika diinginkan sudut vertikal main lobe berada pada nol derajat, maka besar sudut S harus disesuaikan setiap kali panjang L diubah. Grafik 1 menunjukkan hasil-hasil dari percobaan antara Rhombic pada ujung atas band VHF, dan ujung bawah band UHF.

Untuk frekuensi pada pertengahan band UHF (TV), ada kemungkinan lengkung kurva sedikit berubah. Gambar 1 menunjukkan sebuah antena Rhombic UHF dipandang dari sisi atas atau bawah. Panjang sisinya masing-masing adalah S sedangkan W dan T menyatakan jarak keempat kaki penyangga, yang diperlukan untuk menyiapkan pembuatan kaki kayu penyangga. W adalah jarak antara kaki kiri dan kaki kanan, dan T adalah jarak antara kaki depan dan belakang.

Rancangan tersebut di atas didasarkan pada posisi datar 0 derajat (horizon). Tetapi, jika elevasi horizon sekitar 3 derajat, atau di hadapan lokasi penerima tertutup oleh bukit kecil, ataupun lereng gunung, namun sinyal pantulan masih bisa diharapkan datang dari arah agak tinggi, maka antena perlu dibuat lebih kurus. Dengan kata lain, sisi kiri kanannya agak ditarik ke dalam. Sedangkan kaki depan belakang ditarik memanjang ke luar.

Pada ujung antena, kedua ujung elemennya ditutup dengan dua buah resistor dari jenis, dari bahan, karbon. Nilainya 390 ohm, dihubungkan seri. Sisi yang lain, yang juga mempunyai dua ujung kawat, yaitu terminal F. Dipakai sebagai terminal antena, dan dihubungkan dengan kabel penyalur ke televisi, yang memiliki impedansi karakteristik sekitar 450-600 ohm. Umumnya dipakai open line, tetapi karena pembuatannya rumit, kita ganti saja dengan kabel antena televisi pipih 300 ohm.

Di antara kabel dan terminal antena Rhombic, perlu dipasang penyesuai impedansi, sebuah trafo penyesuai yang memiliki impedansi karakteristik 400 ohm balans. Cara membuatnya adalah dengan membuat dua buah silinder dari lembaran kuningan, tembaga, seng yang baik, dilingkarkan membentuk tabung atau silinder, dengan rongga dalamnya berdiameter 4.2 cm, panjangnya 11.3 cm.

Jajarkan kedua silinder tersebut. Lantas, sisi sisinya yang bersentuhan disolder. Boleh juga ditambahkan plat penguat, disolder di kiri kanannya. Sebagai penutup lubang silinder tersebut, perlu dibuat empat buah, yang dibuat dari bahan plastik ataupun mika. Lubangi keempat tutup plastik tersebut, persis di tengah-tengahnya. Lantas masing-masing silinder itu ditembus kawat email, berdiameter 1.5 mm, dengan panjang 14 cm.

Setelah keempat tutup direkatkan dengan kuat, keempat ujung dari dua tabung, masukkan kedua kawat tadi ke lubang di tengah tutup. Rekatkan bagian kawat yang menembus tutup kuat-kuat. Ujung kawat dinyatakan dengan A, B, C, serta D. Solderkan A dan B ke terminal F antena Rhombic. Dan solderkan C dan D ke kabel TV 300 ohm. Ikat tabung ke kaki kayunya, agar tidak goyah.

Kabel antena TV 300 ohm yang menuju ke pesawat TV harus dipelintir atau dipilin sebanyak 3-5 ulir tiap meternya. Sehingga kapasitansinya terhadap tiang, tanah, ataupun benda di sekitarnya tetap seimbang atau balans, antara konduktor satu dan lainnya. Pada ujung kabel yang dekat televisi, masih harus dipasang sebuah balun 4:1 atau trafo berimpedansi 300 ohm ke 75 ohm, yang bisa dibeli di toko elektronik.

Jadi, harus diperhatikan, yang dipakai adalah kabel antena televisi 300 ohm yang bentuknya pipih, bukan kabel televisi 75 ohm yang bentuknya bulat. Setelah antena terpasang kuat di atas tiang, arahkan antena ke pemancar, atau ke gunung, tebing, yang akan memantulkan gelombang, bila lokasinya agak terhalang. Apabila perlu, tambahkan booster UHF. Perhatikan cara pemasangannya, seperti yang ditunjukkan pada gambar 3. (Joko Haryono, Jawa Pos / Amir Makhmud, Ahmad Kadafi)

UPS (Uninterruptible power supply)

An Uninterruptible Power Supply (UPS), also known as an Uninterruptible Power Source, Uninterruptible Power System, Continuous Power Supply (CPS) or a battery backup is a device which maintains a continuous supply of electric power to connected equipment by supplying power from a separate source when utility power is not available. There are three distinct types of UPS: off-line, line-interactive and double conversion (also called on-line).

An off-line UPS remains idle until a power failure occurs, and then switches from utility power to its own power source, almost instantaneously. An on-line UPS continuously powers the protected load from its reserves (usually lead-acid batteries or stored kinetic energy), while simultaneously replenishing the reserves from the AC power.

The on-line type of UPS, in addition to providing protection against complete failure of the utility supply, provides protection against all common power problems, and for this reason it is also known as a power conditioner and a line conditioner.

While not limited to safeguarding any particular type of equipment, a UPS is typically used to protect computers, telecommunication equipment or other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss. UPS units come in sizes ranging from units which will back up a single computer without monitor (around 200 VA) to units which will power entire data centers or buildings (several megawatts). Larger UPS units typically work in conjunction with generators.

Historically, UPSs were expensive and were most likely to be used on expensive computer systems and in areas where the power supply is interrupted frequently. As prices have fallen, UPS units have become an essential piece of equipment for data centers and business computers, and are also used for personal computers, entertainment systems and more.

In certain countries, where the electrical grid is under strain, providers struggle to ensure supply during peak demand (such as summer, when air-conditioning usage increases). To prevent unplanned blackouts, electrical utilities will sometimes use a process called rolling blackouts or load shedding, which involves cutting the power to large groups of customers for short periods of time. Several major blackouts occurred in 2003, most notably the 2003 North America blackout in the north-eastern US and eastern Canada and the 2003 Italy blackout, both of which affected over 50 million people, and brought attention to the need for UPS power backup units.

A UPS should not be confused with a standby generator, which does not provide protection from a momentary power interruption and may result in an interruption when it is switched into service, whether manually or automatically. Such generators are typically placed upstream of the UPS to provide cover for lengthy outages. Integrated systems that have UPS and standby-generator components are often referred to as emergency power systems.

Common power problems

There are various common power problems that UPS units are used to correct. They are as follows (with a typical example of damage that might be caused):

1. Power failure — Total loss of utility power: Causes electrical equipment to stop working.
2. Voltage sag — Transient (short term) under-voltage: Causes flickering of lights.
3. Voltage spike — Transient (short term) over-voltage i.e. spike or peak: Causes wear or acute damage to electronic equipment.
4. Under-voltage (brownout) — Low line voltage for an extended period of time: Causes overheating in motors.
5. Over-voltage — Increased voltage for an extended period of time: Causes light bulbs to fail.
6. Line noise — Distortions superimposed on the power waveform: Causes electro magnetic interference.
7. Frequency variation — Deviation from the nominal frequency (50 or 60 Hz): Causes motors to increase or decrease speed and line-driven clocks and timing devices to gain or lose time.
8. Switching transient — Instantaneous undervoltage (notch) in the range of milliseconds to seconds: May cause erratic behavior in some equipment, memory loss, data error, data loss and component stress.
9. Harmonic distortion — Multiples of power frequency superimposed on the power waveform: Causes excess heating in wiring and fuses.

UPS units are divided into categories based on which of the above problems they address. Some manufacturers categorize their supplies as a level 3, 5, or 9, if they address the first 3, 5, or 9 power problem respectively.

UPS Technologies

The general categories of modern UPS systems are on-line, line-interactive, and standby. An on-line UPS uses a “double conversion” method of accepting AC input, rectifying to DC for passing through the battery (or battery strings), then inverting back to AC for powering the protected equipment. A line-interactive UPS maintains the inverter in line and redirecting the battery’s DC current path from the normal charging mode to supplying current when power is lost. In a standby (“off-line”) system the load is powered directly by the input power and the backup power circuitry is only invoked when the utility power fails. Most UPS below 1 kVA are of the line-interactive or standby variety which are usually less expensive.

For large power units, Dynamic Uninterruptible Power Supply are sometimes used. A synchronous motor/alternator is connected on the mains via a choke. Energy is stored in a flywheel. When the mains power fails, an Eddy-current regulation maintains the power on the load. DUPS are sometimes combined or integrated with a diesel-genset.

Fuel cell UPS have been developed in recent years using hydrogen and a fuel cell as a power source, potentially providing long run times in a small space. A fuel cell replaces the batteries used in other UPS designs.

Offline / Standby

The Offline / Standby UPS offers only the most basic features, providing surge protection and battery backup. Usually the Standby UPS offers no battery capacity monitoring or self-test capability, making it the least reliable type of UPS since it could fail at any moment without warning. These are also the least expensive, selling for as little as US$75. The Standby UPS may be worse than using nothing at all, because it gives the user a false sense of security of being assurred protection that may not work when needed the most.

With this type of UPS, a user’s equipment is normally connected directly to incoming utility power with the same voltage transient clamping devices used in a common surge protected plug strip connected across the power line. When the incoming utility voltage falls below a predetermined level the UPS turns on its internal DC-AC inverter circuitry, which is powered from an internal storage battery. The SBS then mechanically switches the connected equipment on to its DC-AC inverter output. The switch over time is stated by most manufacturers as being less than 4 milliseconds, but typically can be as long as 25 milliseconds depending on the amount of time it takes the Standby UPS to detect the lost utility voltage.

Line-interactive

The Line-Interactive UPS is similar in operation to a Standby UPS, but with the addition of a multi-tap variable-voltage autotransformer. This is a special type of electrical transformer that can add or subtract powered coils of wire, thereby increasing or decreasing the magnetic field and the output voltage of the transformer.

This type of UPS is able to tolerate continuous undervoltage brownouts and overvoltage surges without consuming the limited reserve battery power. It instead compensates by auto-selecting different power taps on the autotransformer. Changing the autotransformer tap can cause a very brief output power disruption, so the UPS may chirp for a moment, as it briefly switches to battery before changing the selected power tap.

Autotransformers can be engineered to cover a wide range of varying input voltages, but this also increases the number of taps and the size, weight, complexity, and expense of the UPS. It is common for the autotransformer to only cover a range from about 90v to 140v for 120v power, and then switch to battery if the voltage goes much higher or lower than that range.

In low-voltage conditions the UPS will use more amperage than normal so it may need a higher amperage circuit than a normal device. For example to power a 1000 watt device at 120 volts, the UPS will draw 8.32 amps. If a brownout occurs and the voltage drops to 100 volts, the UPS will draw 10 amps to compensate. This also works in reverse, so that in an overvoltage condition, the UPS will need fewer amps of current.

Double-Conversion / Online

The Online UPS is ideal for environments where electrical isolation is necessary or for equipment that is very sensitive to power fluctuations. Although once previously reserved for very large installations of 10kW or more, advances in technology have permitted it to now be available as a common consumer device, supplying 500 watts or less. The Online UPS is generally more expensive but may be necessary when the power environment is “noisy” such as in industrial settings, for larger equipment loads like data centers, or when operation from an extended-run backup generator is necessary.

The basic technology of the Online UPS is the same as in a Standby or Line-Interactive UPS. However it typically costs much more, due to it having a much greater amperage AC-to-DC battery-charger/rectifier, and with the rectifier and inverter designed to run continuously with improved cooling systems. It is called a Double-Conversion UPS due to the rectifier directly driving the inverter, even when powered from normal AC current.

In an Online UPS, the batteries are always connected to the inverter, so that no power transfer switches are necessary. When power loss occurs, the rectifier simply drops out of the circuit and the batteries keep the power steady and unchanged. When power is restored, the rectifier resumes carrying most of the load and begins charging the batteries, though the charging current may be limited to prevent the high-power rectificer from overheating the batteries and boiling off the electrolyte.

The main advantage to the on-line UPS is its ability to provide an electrical firewall between the incoming utility power and sensitive electronic equipment. While the Standby and Line-Interactive UPS merely filters the input utility power, the Double-Conversion UPS provides a layer of insulation from power quality problems. It allows control of output voltage and frequency regardless of input voltage and frequency.

Ferro-resonant

Ferro-resonant units operate in the same way as a standby UPS unit with the exception that a ferro-resonant transformer is used to filter the output. This transformer is designed to hold energy long enough to cover the time between switching from line power to battery power and effectively eliminates the transfer time. Many ferro-resonant UPSs are 90-93% efficient and offer excellent isolation.

While this used to be the dominant type of UPS, they are no longer used for common applications. Power factor correcting equipment found in newer computer systems interacts with static ferro-resonant transformers, causing potentially damaging oscillations, and the transformer itself can create distortions which yield power less acceptable than poor quality line AC. These units are still used in some industrial settings, but have mostly disappeared from use with general computer equipment. Many ferro-resonant UPSs utilizing controlled ferro technology may not interact with power-factor-correcting equipment.

DC-Power Supply

A UPS designed for powering DC equipment is very similar to an online UPS, except that it does not need an output inverter, and often the powered device does not need a power supply. Rather than converting AC to DC to charge batteries, then DC to AC to power the external device, and then back to DC inside the powered device, some equipment accepts DC power directly and allows one or more conversion steps to be eliminated.

Many systems used in telecommunications use 48 volt DC power, because it is not considered a high-voltage by most electrical codes and is exempt from many safety regulations, such as being installed in conduit and junction boxes. DC has typically been the dominant power source for telecommunications, and AC has typically been the dominant source for computers and servers.

There has been much experimentation with 48v DC power for computer servers, in the hope of reducing the likelihood of failure and the cost of equipment. However, the amperage must increase to supply the same amount of power as a 120v or 240v circuit, and greater amperage requires larger conductors, and causes more energy to be lost as heat due to electrical resistance of the large conductors.

High voltage DC (380 volts) is finding use in some data center applications, and allows for small power conductors, but is subject to the more complex electrical code rules for safe containment of high voltages

Rotary UPS

A Rotary UPS uses the inertia of a high-mass spinning flywheel to provide short-term ride-through in the event of power loss. The flywheel also acts as a buffer against power spikes and sags, since such short-term power events are not able to appreciably affect the rotational speed of the high-mass flywheel. It is also one of the oldest designs, predating vacuum tubes and integrated circuits.

It can be considered to be online since it spins continuously under normal conditions. However, unlike an electronic double-conversion UPS, it is only capable of providing reserve power for a few seconds before the flywheel has slowed and the protection fails. It is traditionally used in conjunction with standby diesel generators, providing backup power only for the brief period of time the engine needs to start running and stabilize its output.

The Rotary UPS is generally reserved for applications needing more than 10,000 watts of protection, to justify the expense of an extremely large and heavy power system that can only be transported by forklift or crane. A larger flywheel or multiple flywheels operating in parallel will increase the reserve running time, but at greatly increasing cost due to the size and weight of the precision-balanced flywheels.

Because the flywheels are a mechanical power source, it is not necessary to use an electric motor or generator as an intermediary between it and a diesel engine designed to provide emergency power. By using a transmission gearbox, the rotational inertia of the flywheel can be used to directly start up a diesel engine, and once running, the diesel engine can be used to directly spin the flywheel. Multiple flywheels can likewise be connected in parallel through mechanical countershafts, without the need for separate motors and generators for each flywheel.

They are normally designed to provide very high amperage output compared to a purely electronic UPS, and are better able to provide inrush current for inductive loads such as motor startup or compressor loads, as well as medical MRI and cath lab equipment. It is also able to tolerate short-circuit conditions up 17 times larger than an electronic UPS, permitting one device to blow a fuse and fail while other devices still continue to be powered from the Rotary UPS.

Its life cycle is usually far greater than a purely electronic UPS, up to 30 years or more. But they do require periodic downtime for mechanical maintenance (ball bearing replacement), while solid-state designs, using batteries, do not require downtime if the batteries can be hot-swapped, which is usually the case for larger units.

Typically, the high-mass flywheel is used in conjunction with a motor-generator system. These units can be configured as:

• 1. A motor driving a mechanically connected generator,
• 2. A combined synchronous motor and generator wound in alternating slots of a single rotor and stator,
• 3. A Hybrid Rotary UPS, designed similar to an Online UPS, except that it uses the flywheel in place of batteries. The rectifier drives a motor to spin the flywheel, while a generator uses the flywheel to power the inverter.

In case #3 the motor generator can be synchronous/synchronous or induction/synchronous. The motor side of the unit in case #2 and #3 can be driven directly by an AC power source (typically when in inverter bypass), a 6-step double-conversion motor drive, or a 6 pulse inverter. Case #1 uses an integrated flywheel as a short-term energy source instead of batteries to allow time for external, electrically coupled gensets to start and be brought online. Case #2 and #3 can use batteries or a free-standing electrically coupled flywheel as the short-term energy source.

UPS Applications

The basic technology of UPS hardware can have many forms when applied for different purposes. Any of the technologies may be recombined as redundant systems or designed for special needs.

N+1 UPS

In large business environments where reliability is of great importance, a single huge UPS can also be a single point of failure that can disrupt many other systems. To provide greater reliability, multiple smaller UPS modules and batteries can be integrated together to provide redundant power protection equivalent to one very large UPS.

It is not normally possible to take the AC output of two separate UPS units and combine their output voltage, because the output waveform of one UPS inverter can be leading or lagging the other inverter, causing severe power fluctuations that can damage both the UPS units and the powered devices.

In an N+1 UPS, a special synchronization signal is shared amongst the inverter modules to assure that all are producing a sinewave output that is in synchrony, without leading or lagging waveforms. Additional monitoring circuits assure all inverters and batteries are operating correctly within tolerances.

Generally an N+1 UPS is designed to supply more power than is actually required by the load, so that in the event of a fault, at least one of inverter or battery modules can be disabled and removed from powering the load. An internal crossbar bus can permit any battery module to be connected to any different inverter module, to bypass potential failures.

An N+1 UPS can permit easy, centralized expansion of enterprise load capacity. In contrast, by purchasing small separate UPS units, eventually the server room fills with a collection of many different UPS models with many different batteries all aging at different rates and needing lots of care and monitoring. Buying a single huge UPS means wasted capacity until it is full, and then another huge UPS must be added which again has wasted capacity. With the N+1 UPS, as capacity grows, expansion just requires purchasing additional inverter modules and battery modules, and adding them to the N+1 chassis.

Multiple, Redundant UPS

Many computer servers offer the option of redundant power supplies, so that in the event of one power supply failing, one or more other power supplies are able to power the load.

While it is common to plug each of these individual power supplies into one single UPS, redundant protection can be extended further yet by connecting each power supply to its own UPS. This provides double protection from both a power supply failure and a UPS failure, so that continued operation is assured.

These additional layers of protection also add complexity and cost to the design of an enterprise server room environment. It also requires handling only by experienced professionals, since the multiple redundant cabling can appear confusing and unnecessary to an untrained person.

Outdoor UPS

When a UPS system is placed outdoors, it should have some specific features that guarantee that it can tolerate weather with a ‘minimal to none’ effect on performance. Factors such as temperature, humidity, rain, and snow among others should have been considered by the manufacturer when designing an outdoor UPS system. Operating temperature ranges for outdoor UPS systems could be around -40°C to +55º C.

A small outdoor UPS system.

An outdoor UPS system is normally made of several components designed for this particular task:

• Outdoor enclosure: provides protection against the elements to all the components placed within. Quality outdoor enclosures are powder coat finished for corrosion resistance and long life. Outdoor enclosures are normally NEMA 3R compliant

• Power Module: is the UPS itself. The boards of this power module should be conformal coated to avoid humidity damage. This UPS unit is normally based on Line Interactive or Double Conversion topology. Some manufacturers prefer Line Interactive because it provides a better Mean Time Between Failures (MTBF), and that is a critical part of an outdoor UPS system.

• Batteries: The batteries used in outdoor UPS systems must operate in a wide temperature range, usually from -40°C to +60°C. Batteries normally used in outdoor UPS systems are Gel Cell Batteries. The outdoor UPS’s Power Module should provide a temperature compensated battery charging mechanism to optimize the life of the batteries.

A proper outdoor UPS system requires that all its components are designed for this environment. As seen from the features of the components above, an outdoor UPS system is not an indoor UPS inside an outdoor enclosure.

Outdoor UPS systems can be pole, ground (pedestal), or host mounted. Outdoor environment could mean extreme cold, in which case the outdoor UPS system should include a battery heater mat, or extreme heat, in which case the outdoor UPS system should include a fan system or an air conditioning system.

Outdoor UPS systems are ideal for protection of WiFi/GSM/CDMA/satellite base stations, wireless communications/perimeter surveillance and security/gate control systems, LED traffic light/roadway display systems and remote terminal units (RTUs).

Internal-PC UPS

Internal UPS are a group of uninterruptible power supplies (UPS) designed to be placed inside computer chassis. There are two types of Internal UPS. First type is miniaturized regular UPS that are made small enough to fit into a 5.25” CD-ROM slot bay of a regular computer chassis. The other type is re-engineered switching power supplies that utilize dual power sources of AC and/or DC as power inputs and have an AC/DC built-in switching management control units.

The first type often requires extra connection wires between the internal UPS and computer’s power supply. Some internal UPS of this group output high voltage (110 V – 220 V) direct current (DC) and some output nine-step table wave AC. Neither design is safe or energy efficient. As of 2006, there are only a couple of companies still selling this type of internal UPS in Australia, Asia and some part of Europe

The second group of internal UPS replaces the regular switching power supplies. There are three main design mechanisms:

1. Optic-coupling that imitates AC during AC outages. This mechanism was first introduced by American Advanced Power of USA and Magnum Power of UK in 1997, as well as Apollo Power of Taiwan in 1998. This design provides a low-cost solution but its efficiency is low and it has a very low overall wattage limit (<300 W).
2. An analog-circuitry-controlled AC/DC switching mechanism. This design also provides a low-cost solution. However, because of the bulky component circuit board, little space is available for increasing wattage output. Plus, the final products are very sensitive to factors such as local heat and causing frequent operational errors. Nevertheless, because of its low cost, it is still popular in China. Most Asian internal UPS manufacturers belong to this category.
3. A CPU controlled AC/DC switching mechanism. This design was first introduced by American Advanced Power Inc. of USA and Amsdell of Canada. It provides error-free switching control and a complicated communication protocol between the power supply and computer.

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