BROADBAND: A PRIMER ON TELECOMMUNICATIONS TECHNOLOGY.At the recent Annual Meeting, at the request of the Telecommunications Standing Committee, the Management Issues Committee recommended, and NRECA NRECA National Rural Electric Cooperative Association members approved, that the Resolution on Director, Management and Employee Training should include a directive to NRECA to "develop a primer that furthers the understanding of emerging telecommunications technology." This document attempts to respond to this resolution.
Americans shop, trade stocks, pay bills and search for information on-line. This ability to rapidly send or receive digitized information has transformed the global economy. Unfortunately, the technologies to provide this capability -- the technologies of broadband Internet See broadband. access- are not penetrating all areas of the country equally.
A recent article in the New York New York, state, United States
New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of Times was called "Life in the Slow Lane: Rural Residents are Frustrated by Sluggish Web Access." It described a real estate agent in Pryor, Oklahoma, who uses a dial-up modem to connect through her local Internet Service Provider Internet service provider (ISP)
Company that provides Internet connections and services to individuals and organizations. For a monthly fee, ISPs provide computer users with a connection to their site (see data transmission), as well as a log-in name and password. . According to according to
1. As stated or indicated by; on the authority of: according to historians.
2. In keeping with: according to instructions.
3. the article, "the connection is never very fast -- 33 kilobits per second (unit) kilobits per second - (kbps, kb/s) A unit of data rate where 1 kb/s = 1000 bits per second. This contrasts with units of storage where 1 Kb = 1024 bits (note upper case K). at most, although she has a 56K modem -- and at night it slows to a crawl." Like millions of others, she wants a faster Internet connection. But unlike urban and suburban Americans, she is stuck with slow dial-up service because there are no other choices in Pryor, Oklahoma, population 8,300.
This lady may have been inconvenienced, but the problem she faces in other circumstances could turn out to be a matter of life and death
"Matter of Life and Death" was the second episode of the first series of . . Many communities cannot support medical specialists, but journals are full of stories about how sick or injured people can be diagnosed from afar. Digital technology and advanced imaging systems allow doctors to diagnose and design treatments for people living thousands of miles away from hi-tech medical facilities. The technology for delivering a fine-grained signal must be precise, allowing doctors to peer with precision into a human body using a wire smaller than your little finger.
You may recall reading about Dr. Jerri Nielsen, a physician who served at the Amundsen-Scott South Pole South Pole, southern end of the earth's axis, lat. 90° S. It is distinguished from the south magnetic pole. The South Pole was reached by Roald Amundsen, a Norwegian explorer, in 1911. See Antarctica. Research Center at the South Pole. Dr. Nielsen found a lump in her breast. Worse, it was the Antarctic winter, and no planes could get in or out for a six-month period. Because of the Internet, she was able to e-mail photographs of slides of the tumor to doctors back home, and they were able to guide her through her initial treatment.
These examples show the obstacles to and the promise of broadband technology broadband technology
Telecommunications devices, lines, or technologies that allow communication over a wide band of frequencies, and especially over a range of frequencies divided into multiple independent channels for the simultaneous transmission of different signals. . Most urban Americans have fast, stable access to the Internet. The generic term for this is "broadband." It refers to the ability to transmit and receive large amounts of data to and from a computer.
The ability to transmit this data is determined by the size of the "pipe" through which it moves, referred to as bandwidth. As the Internet has become more graphical and interactive, the need for broadband has increased.
Numerous applications have been developed that require greater bandwidth to be used effectively. Broadband services include interactive purchasing, video-on-demand, remote interactive medical services, remote access to stored video materials, and two-way teleconferencing. As a result, government agencies, hospitals, and consumers all want broadband access See broadband and wireless broadband. .
Additionally, many electric cooperatives are investigating telecommunications technologies, and cooperative boards are being asked to invest in broadband infrastructure. But exactly what are these technologies, how do they work, and which have applications in rural America?
This Primer attempts to answer these questions. Its objective is to explain basic broadband technologies to non-technical readers. It will begin with a
brief explanation of the "bits" and "bytes" of the digital world, and then explain the role of the Internet Service Provider. Finally, it will review specific technologies that currently deliver Internet content to users, including 56K dial-up, satellite, Digital Subscriber Line See DSL.
(communications, protocol) Digital Subscriber Line - (DSL, or Digital Subscriber Loop, xDSL - see below) A family of digital telecommunications protocols designed to allow high speed data communication over the existing copper telephone lines between end-users and , ISDN ISDN
in full Integrated Services Digital Network
Digital telecommunications network that operates over standard copper telephone wires or other media. , terrestrial wireless, cable and fiber. A glossary of telecommunications phrases and concepts is included at the end of the Primer.
II. The Digital Divide Versus Broadband Access
About 60 percent of Americans have a home computer, and about 50% have logged on to the Internet. It has become a dramatic force in people's lives. Although the Internet is fairly new to the consumer market, it has already divided the nation into two camps: the 'technology haves' and 'have nots'. This division is commonly called the "Digital Divide," and primarily relates to the distinction between those who use or don't use the Internet. As we'll see below, Internet use correlates with socioeconomic status socioeconomic status,
n the position of an individual on a socio-economic scale that measures such factors as education, income, type of occupation, place of residence, and in some populations, ethnicity and religion. .
Broadband access is different. It relates not to the socioeconomic status of the user, but to the availability of technologies that provide high-speed access to the Internet. In many rural areas of the Untied States, those technological options are not now available.
Let's begin with the Digital Divide. Millions of Americans view the Internet the same way they view their telephone, car, or microwave: as an essential part of life. According to a AOL/Roper Starch Cyberstudy, 66% of Internet users would prefer a computer with Internet connection to a telephone or television if stranded on a desert island.
However, many Americans are not on-line and are not taking advantage of the resources found on the Internet. According to the White House, 45 percent of homes where at least one person has a college degree are connected to the Internet. This compares to 14 percent of homes where no one is a college graduate. Sixty percent of households with incomes above $75,000 have Internet access See how to access the Internet. while households with incomes in the $20,000-25,000 range only have a 14 percent on-line rate.
The trends of the Digital Divide are clear. Lower income consumers are at a disadvantage and run the risk of being left behind. This has important implications for rural America as it has historically experienced lower incomes than urban areas.
The Digital Divide is primarily a socioeconomic problem related to users. In contrast, broadband access is a business problem because of rural density. It is not about owning and using computers; it is about having access to a telecommunications infrastructure that allows users to take advantage of what the Internet has to offer. According to a major study produced jointly by the U.S. Department of Agriculture and the Department of Commerce, "...rural areas are currently lagging far behind urban areas in broadband availability.'' 1
This report claims that two broadband technologies are currently being deployed at a high rate in the United States United States, officially United States of America, republic (2005 est. pop. 295,734,000), 3,539,227 sq mi (9,166,598 sq km), North America. The United States is the world's third largest country in population and the fourth largest country in area. : cable modem cable modem
Modem used to convert analog data signals to digital form and vise versa, for transmission or receipt over cable television lines, especially for connecting to the Internet. and digital subscriber line (DSL DSL
in full Digital Subscriber Line
Broadband digital communications connection that operates over standard copper telephone wires. It requires a DSL modem, which splits transmissions into two frequency bands: the lower frequencies for voice (ordinary ). But each of these is being deployed primarily in urban areas. As shown in Exhibit 1, cable, the most used broadband technology in the United States, is available in more than 65% of cities with populations over 250,000, but is available in fewer than 5% of towns with populations less than 10,000.
DSL is the second most used broadband technology. As shown in Exhibit 2, more than 56%] of cities with populations exceeding 100,000 have DSL, but fewer than 5% of cities less than 10,000 have such service.
The reason for the slower deployment of broadband technologies in rural areas is economic. Just as with electric distribution, the cost to serve a consumer with a wireline carrier increases the greater the distance among customers. Cable and DSL are also limited because of physical limitations on how far their signals can be transmitted.
The government report notes that newer technologies are becoming available, and some, like satellite broadband service, have potential for rural areas because the geographic location of the consumer has virtually no effect on the cost of the service. Several broadband satellite services are now available, along with terrestrial wireless services, including multipoint multichannel Using two or more paths for transmission or processing. It can refer to a variety of architectures including (1) multiple I/O channels between the CPU and peripheral devices, (2) multiple wires in a cable, (3) multiple "logical" channels within a single wire or fiber or (4) multiple distribution systems (MMDS (Multichannel Multipoint Distribution Service or Microwave Multipoint Distribution Service) A digital wireless transmission system that works in the 2.2-2.4 GHz range. ) and local-multipoint distribution systems (LMDS (Local Multipoint Distribution Service) A digital wireless transmission system that works in the 28 GHz range in the U.S. and 24-40 GHz overseas. It requires line of sight between transmitter and receiving antenna, which can be from one to four miles apart ).
These broadband technologies will be explained later. First, however, we must address the "bits and bytes Bits and Bytes was the name for two Canadian television series, starring Billy Van, who teaches people the basics of how to use a computer. The first series debuted in 1983 and the second series, called Bits and Bytes 2, in 1991. " of digital language.
III. The Language of Digital Technology
Computers and microprocessors are driving the global economy, but how do these technologies really work? What is digital technology?
Signals are of two kinds: analog and digital. An analog signal An analog or analogue signal is any time continuous signal where some time varying feature of the signal is a representation of some other time varying quantity. It differs from a digital signal in that small fluctuations in the signal are meaningful. (Exhibit 3) is a representation of a continuous physical variable, like a sound wave. In contrast, digital signals (Exhibit 4) represent variables mathematically. Because of an essential feature of electricity, it is an ideal medium for sending digital information. It recognizes two possible states: OPEN or CLOSED. This fact about electricity is the foundation of all computer driven devices: the number "1" is used to represent a closed circuit, and the number "0" is used to represent an open circuit. Hence, electricity is more than just the energy used to make computers work. It is the medium that computers use to do their job. Rapid, tiny changes in voltage represent the ones and zeros that make up digital information. Since computer language has only two symbols, it is called a binary language. This accounts for the translation, storage and manipulation of all information within or between computers. Each 1 or 0 is a bit of information.
Bits can combined into 8-unit sequences called bytes. Consider the following sequence:
These numbers are the code through which information can be expressed digitally. Underneath each number is a one or a zero.
A one means that number is activated. A zero means that it is not. Imagine that we want to activate some mix of these numbers to achieve the number 72. Since it is not on the list, we must add two numbers: 64 plus 8 equals 72. Symbolically, this can be represented as:
We have presented this because computer engineers have agreed to follow the American Standard Code for Information Interchange American Standard Code for Information Interchange: see ASCII.
American Standard Code for Information Interchange - The basis of character sets used in almost all present-day computers. (ASCII ASCII or American Standard Code for Information Interchange, a set of codes used to represent letters, numbers, a few symbols, and control characters. Originally designed for teletype operations, it has found wide application in computers. ) and according to this code, 72 represents the capital letter H. (See Exhibit 5 for a list of ASCII conventions.)
According to the same ASCII convention, the small letter i is represented by 105, which is expressed by the following binary formula: 0-1-1-0-1-0-0-1.
If you add one more sequence and stream a total of 24 bits of information....
you have the computer language equivalent of "Hi!".
IV. Properties of Digital Communication
The Os and Is of digital data mean more than just "on and off". They also mean perfect copying. When information is translated into a digital format, it can be electronically manipulated, preserved and accessed perfectly every time. The millionth copy of a computer file is exactly the same as the original.
This makes computer storage of files an effective solution for saving documents. It also allows a user to e-mail a file to others and know that the file will arrive in the same format as it left, assuming both users have the same software and compatible computer systems. (See the sidebar for a discussion of the relation between files and digital bits.)
Contrast this with analog information, which is subject to distortion whenever it is amplified or repeated. Exhibit 6 contrasts the deterioration of analog versus digital information. As we will see later, communication technologies require "repeaters" to strengthen signals that must be sent over a distance. Every time analog information is sent through a repeater (1) A communications device that amplifies (analog) or regenerates (digital) the data signal in order to extend the transmission distance. Available for both electronic and optical signals, repeaters are used extensively in long distance transmission. , it deteriorates and loses some of its clarity. As is implied in the exhibit, digital signals do not deteriorate.
The 1s and 0s of digital communication cannot be transmitted to the Internet without being translated into a format that is used by the medium doing the transmission. In the example of a dial-up connection that uses a telephone line, the computer signal must be converted from the digital pulses of the computer to the audio frequencies that the telephone system can handle, and then back to digital pulses on the other end (Exhibit 7). This is done with a modulator/demodulator, known as a modem. Virtually all Internet access technologies (e.g., cable, DSL, ISDN, etc.) use some type of modem to send information from the sender to the receiver.
V. Speed on the Internet
Internet speed refers to the amount of data that can be transferred from one computer to another. This is measured in bits per second. Bit stands for Binary Digit See bit. . As we saw earlier, binary digits are the smallest elements of computer information: the ones and zeros that constitute the basic building blocks of all computer language.
The speed at which users send or receive messages over the Internet is measured in the number of bits that can be transferred either from the Internet (downstream) or back to the Internet (upstream) in a second. Typically the speed will be expressed in the thousands (1 kilobit (thousand bits). For technical specifications, it refers to 1,024 bits. In general usage, it typically refers to an even one thousand bits (see kilo). Also Kb, Kbit and K-bit. See space/time.
(unit) kilobit - 2^10 = 1024 bits of storage (1 Kb). is equal to 1,000 bits) or millions (1 megabit is equal to I million bits) of bits per second. (See Exhibit 8 for a conversion chart of data speeds.)
A 56K modem has a maximum bit transfer rate of 56,000 bits per second. Fifty-six thousand ones and zeros flow through every second. This may sound like a lot, but it takes several bits of information to compose a message digitally. For example, this document that you are reading now, including the exhibits, is made up of over 1,200,000 bits of information. Each letter, punctuation mark, and space requires at least 8 bits.
This factor becomes even more important when sending picture files or video images over the Internet. Such files can consist of several million bits of data. The greater the number of bits, the faster the speed and the greater the bandwidth required to achieve the benefit of the Internet2. A PowerPoint presentation with streaming video A one-way video transmission over a data network. It is widely used on the Web as well as company networks to play video clips and video broadcasts. Computers in home networks stream video to digital media hubs connected to a home theater. can be over 30,000,000 bits in size. With a 56K dial-up connection, it will take over one hour to receive the message, and that assumes it is in perfect working order and that there are no other bottlenecks within the system.
With a fiber optic broadband connection See broadband and wireless broadband. , the same file would take less than ten seconds3. Exhibit 9 presents the transfer times necessary to deliver a 10 megabyte One million bytes, or more precisely 1,048,576 bytes. Also MB, Mbyte and M-byte. See mega and space/time.
(unit) megabyte - (MB, colloquially "meg") 2^20 = 1,048,576 bytes = 1024 kilobytes. 1024 megabytes are one gigabyte. (10 million bit) file through a number of narrowband and broadband modems.
VI. The Role of the ISP (1) See in-system programmable.
(2) (Internet Service Provider) An organization that provides access to the Internet. Connection to the user is provided via dial-up, ISDN, cable, DSL and T1/T3 lines.
The Internet Service Provider (ISP) is an essential participant in providing access to users. The Internet has often been described as an "information superhighway." According to this analogy, the ISP is an on-ramp to the superhighway: it is the entry point where users have controlled access to the world's high-speed data networks. Because of this central role, it is important for policy makers to understand what ISPs do.
Exhibit 10 presents an image of an ISP. It houses a set of modems (to receive calls from consumers), servers (computers that store web sites and messages), and routers (computers that send messages to other ISPs, or back to consumers). To oversimplify o·ver·sim·pli·fy
v. o·ver·sim·pli·fied, o·ver·sim·pli·fy·ing, o·ver·sim·pli·fies
To simplify to the point of causing misrepresentation, misconception, or error.
v.intr. , the ISP moves IP packets to and from some National Backbone provider. We'll explain later what that means.
Exhibit 11 presents an image of the ISP in relation to the Internet. Several points are important. First, there are higher-order ISPs. A local ISP might serve a few thousand consumers. That ISP's routers send signals to a Regional ISP that serves several local ISPs. At the top of the ladder are approximately 10 national ISPs such as UUNet (a divison of MCIWorldcom), AT&T, and Sprint. These companies each have their own National Backbone, an ultra-high-speed fiber optic network that crosses the country. The exhibit shows just one of these National Backbone systems 
The major access points to the Internet are known as NAPs (Network Access Points). The NAPs connect Metropolitan Area Exchanges (MAE (1) (Metropolitan Area Exchange) Originally known as Metropolitan Area Ethernets, MAEs are junction points on the Internet where data is exchanged between carriers. See IXP and NAP. ). The original four MAEs were in New Jersey, Washington, D.C., Chicago, and San Francisco San Francisco (săn frănsĭs`kō), city (1990 pop. 723,959), coextensive with San Francisco co., W Calif., on the tip of a peninsula between the Pacific Ocean and San Francisco Bay, which are connected by the strait known as the Golden . Today there are 11 national NAPs and several regional NAPs formed by the national Internet Service Providers.
As also shown in Exhibit 11, consumers can send signals to a local ISP through several possible communication "pipes": 56K, DSL, wireless, cable, satellite, or fiber. This "pipe" is always narrower than the pipes that move from the local ISP to the regional ISP, or from there to the national ISPs. Signal capacity must increase as one moves from the residence to the Internet backbone (communications, networking) Internet backbone - High-speed networks that carry Internet traffic.
These communications networks are provided by companies such as AT&T, GTE, IBM, MCI, Netcom, Sprint, UUNET and consist of high-speed links in the T1, T3, OC1 and OC3 ranges. . Anything less would produce bottlenecks and delays.
Another way to put this is to say that the Internet is only as fast as its slowest link. Many observers call the final connection from the local ISP to the home "the last mile." For most residential consumers, this is why Internet access is slow, and why broadband needs to be brought to rural America. (It is also worth noting that the Internet can slow down anywhere in the system. If the Internet is a superhighway, experiencing it at different times can be like the difference between riding at high speed on an open road and being on the Washington beltway during "rush" hour. The latter is not high speed.)
The user's modem sends data to modems at the ISP. ISPs appear to have one modem for about every 7-12 customers. This decreases the chance that the consumer will get a busy signal when dialing up. That message is routed up the Internet chain until the final destination is reached. It can be transmitted over one of several Internet backbone systems.
This communication is done through the use of Internet Protocol See Internet and TCP/IP.
(networking) Internet Protocol - (IP) The network layer for the TCP/IP protocol suite widely used on Ethernet networks, defined in STD 5, RFC 791. IP is a connectionless, best-effort packet switching protocol. numbers. These IP numbers are assigned to every computer on the Internet. When users dial into an ISP, they are randomly assigned a ten-digit number. For example, 123.456.789.0 may be the number identifying your computer the next time you log on.
When a user sends an e-mail, the message can take an almost infinite number infinite number
a number so large as to be uncountable. Represented by 8, frequently obtained by 'dividing' by zero. of routes to the receiver. For example, a user in New York sends a photo of her new baby to her parents in Houston. The e-mail leaves the user's computer in hundreds of pieces. These are known as "packets". To send the e-mail as one block would be too much for the Internet to handle. The packets are created by the modem. The packets arrive at the ISP. From there, each packet is sent onto the Internet. Each packet finds its way to the recipient by looking for Looking for
In the context of general equities, this describing a buy interest in which a dealer is asked to offer stock, often involving a capital commitment. Antithesis of in touch with. the SMTP (Simple Mail Transfer Protocol) The standard e-mail protocol on the Internet and part of the TCP/IP protocol suite, as defined by IETF RFC 2821. SMTP defines the message format and the message transfer agent (MTA), which stores and forwards the mail. address. SMTP, or Simple Mail Transfer Protocol See SMTP.
(messaging) Simple Mail Transfer Protocol - (SMTP) A protocol defined in STD 10, RFC 821, used to transfer electronic mail between computers, usually over Ethernet. It is a server to server protocol, so other protocols are used to access the messages. , is the language used by ISP servers and routers to designate where e-mail is to be sent. Each ISP has a unique SMTP address and each ISP customer has a unique e-mail address See Internet address.
e-mail address - electronic mail address on that SMTP server.
It is impossible to tell where the packets go as they make their way to the receiver because the packets take the path of least resistance Noun 1. path of least resistance - the easiest way; "In marrying him she simply took the path of least resistance"
line of least resistance
fashion - characteristic or habitual practice . If there is a great deal of Internet traffic Internet traffic is the flow of data around the Internet. It includes web traffic, which is the amount of that data that is related to the World Wide Web, along with the traffic from other major uses of the Internet, such as electronic mail and peer-to-peer networks. in the Washington D.C. area. the packets will avoid it and find alternate routes. Each packet could take its own unique route to the receiver. Eventually, the packets arrive at the ISP of the grandparents grandparents npl → abuelos mpl
grandparents grand npl → grands-parents mpl
grandparents grand npl in Houston where they are reassembled and can be downloaded the next time the e-mail is checked. The entire process can take as little as a few seconds or as long as a day. Typically, it takes less than five minutes.
The ISP also plays an important customer service role. The ISP should have a staff that is able to answer questions from the most basic ("How do I save the Internet to a floppy disk?") to more advanced ("Flow can I configure my Eudora Pro e-mail software to have more than one account?").
VII. Dial-UP Access hot Dial-up access is a form of Internet access via telephone line. The client uses a modem connected to a computer and a telephone line to dial into an Internet service provider's (ISP) node to establish a modem-to-modem link, which is then routed to the Internet.
Dial-up service is the most basic way to access the Internet. It involves calling an ISP using a 56K (or slower) modem, and sending the signal over ordinary telephone lines. The modem converts the digital pulses of the computer to the audio frequencies that the telephone system can handle, and then back to digital pulses. The modem is also used to dial the telephone number of the consumer's ISP. The ISP can be a large nationa1 provider such as America Online See AOL. or Mindspring or one of hundreds of local companies.
The dial-up system relies on the same copper telephone lines that carry voice traffic. The wires are known as twisted pair A thin-diameter wire (22 to 26 gauge) commonly used for telephone and network cabling. The wires are twisted around each other to minimize interference from other twisted pairs in the cable (Alexander Graham Bell invented this and was awarded a patent for it in 1881). . One wire is the ground and the other is the live wire carrying voice or data. Users in remote areas may suffer from slower speeds because the telephone system, often referred to as POTS, (plain old telephone system), is not capable of handling the increased traffic. Some wires are older and have deteriorated over time.
Most computers today come with a modem pre-installed to access the Internet using a dial-up connection. Basic modems vary in speed from 14.4K (14,400 bits per second) to 56K (56,000 Bps). In the past 2 years, 56K modems have become standard, but many older computers have slower modems.
Dial-up service through an ISP is available in most parts of the country. In some areas, users may be required to dial a toll number and incur long distance charges to use the Internet. A toll charged is incurred when the ISP does not have a local Point of Presence (POP) in the caller's area. The Point of Presence is the telephone number that users dial in order to gain access to the ISP. The POP does not have to be in the same building or even the same city as the ISP's servers, routers and other hardware. Large ISPs can have dozens or hundreds of POPs that relay calls to the ISP's servers.
A person using dial-up can access any web page on the Internet. However, because dial-up operates at levels that allow data to be transferred at speeds no greater than 56,000 bits per second, many Internet applications cannot be used efficiently, or at all. For example, to watch live video of the U.S. Senate at http://www.c-span.org/watch/ over a 56K modern, you likely would receive a choppy chop·py 1
adj. chop·pi·er, chop·pi·est
Having many small waves; rough: choppy seas.
[From chop1. video picture and poor audio. The same signal with any of the broadband connections will show a dramatic improvement.
The cost of dial-up access through an ISP ranges from approximately $15 - $30 per month.  Typically, ISPs offer users unlimited access to the Internet. (In the early days of the Internet, many ISPs charged by the hour.) Consumers generally receive at least one e-mail address and sometimes they receive space on the ISP's web server (a computer that contains a web site's files and makes them available to web users who wish to see them) to make their own web sites.
VIII. Broadband Technologies
Broadband is an ambiguous term with no official meaning. According to the Federal Communication Commission, it is any connection that allows 200,000 bits per second (200K) of information to be sent to a users computer from the Internet Service Provider (referred to as "downstream") or from the user's computer to the consumer's Internet Service Provider (referred to as "upstream.")
For the purposes of this Primer, "broadband" refers to any technology that allows a user to connect to the Internet at speeds faster than a 56K modem and can be connected to the Internet 24 hours a day without prolonged interruptions.  Although 56K is not available in every part of the country, we assume that it represents basic Internet access, and that broadband is anything faster.
There are seven broadband technologies that we will review. They are shown in Exhibit 12, with downstream access Downstream access (DSA) is the term used to describe mail which has been collected and distributed by a competitor, but is handed over to Royal Mail for delivery (the final mile). speeds. While these technologies make the same general promise-- faster and more reliable access to the Internet-- they vary in the method and speed at which this is accomplished. Overall, there are two approaches to broadband access:
* Technologies that augment or enhance existing 56K access, such as DSL or ISDN. These technologies "enhance" dial-up access lines and allow users to send and receive data at higher speeds than 56K.
* Alternative technologies that bypass traditional 56K telephone lines. These alternatives include geo-synchronous satellites paired with earth-bound uplinking and downlinking technologies, low earth orbit (communications) low earth orbit - (LEO) The kind of orbit used by communications satellites that will offer high bandwidth for video on demand, television, and Internet communications. satellites, terrestrial wireless microwave systems (e.g., MMDS, LMDS), T-Carriers, cable, and fiber optic.
These broadband technologies are described below.
1. Digital Subscriber Line (DSL)
DSL is one of the two most commonly used broadband technologies, and it is the primary technology for enhancing existing 56K telephone lines. It is offered as a service by many (but not all) local telephone companies.
DSL uses a coding system Noun 1. coding system - a system of signals used to represent letters or numbers in transmitting messages
code - a coding system used for transmitting messages requiring brevity or secrecy to transform ordinary phone lines into high-speed digital lines by compressing signals, allowing them to be transmitted at a significantly higher speed than dial-up. It does this without interfering with regular phone service. Users can simultaneously talk on the phone while surfing the net. It is estimated that there are about 2 million DSL subscribers, almost all of them in urban areas who live or work in close proximity to a telephone "central office."
The local telephone provider must install a DSL Access Multiplexor In communications, a device that merges several low-speed signals into one high-speed transmission and vice versa. See multiplexing and inverse multiplexor.
multiplexor - multiplexing (DSLAM (DSL Access Multiplexor) A central office (CO) device for ADSL service that intermixes voice traffic and DSL traffic onto a customer's DSL line. It also separates incoming phone and data signals and directs them onto the appropriate carrier's network. See DSL. ). The "central office" is a switching station, not necessarily the administrative office of the phone company. It is the facility that bridges the consumer lines with those that go to the national network. The DSLAM allows the phone line to carry voice and data at the same time. It allows data traffic to be carried at download speeds of up to 1,500,000 bits per second (1.5 Mbps), and it can transmit data at 500,000 bits per second (500 Kbps). 
DSL uses a telephone line to access the Internet in much the same way as a traditional analog modem A common device that converts the computer's digital pulses to tones that can be carried over analog telephone lines. See modem. . Unlike the analog modem, DSL is a constant connection to the Internet. It is always on, so users don't need to dial any numbers to connect to the Net. And unlike cable modems, a DSL line establishes a connection to the Net that is the user's alone and isn't affected by how many other people are using the wire.
A problem with DSL is that its signal can extend only 18,000 feet (about 3.5 miles) from the central office. This is a significant impediment in many rural areas. Also, according to some observers (including the Wall Street Journal), many phone companies have problems in installing and maintaining the lines, which require special procedures. It can also be expensive and tricky to set up DSL service for multiple PCs in a home or business.
Consumers of DSL can expect to pay an up-front charge of approximately $100 - $200. This includes the DSL modem ADSL modem or DSL modem is a device used to connect a single computer or router to a DSL phone line, in order to use an ADSL service. The acronym NTBBA (network termination broad band adapter, network termination broad band access) is also common in various countries. and installation. Monthly charges range from approximately $40 to $200 depending on the desired Internet speed. (DSL comes in different varieties: ADSL See DSL.
ADSL - Asymmetric Digital Subscriber Line , RADSL See DSL. and IDSL See DSL. . See the related sidebar for a description of DSL types.).
2. Integrated Service Digital Network (ISDN)
ISDN is another technology that can be used to augment existing 56K telephone wires. Like DSL, it is a complicated technology that augments dial-up service in order to provide high-speed digital transmission of both voice and data. An ISDN network integrates voice (analog) data with digital data from the Internet over the same network by creating two channels over a single twisted pair telephone line. One channel carries data, voice, fax, or video signals, and the other is used by the phone company to identify whether the information being sent over the wire is data or voice. Channels can be combined to provide a high-speed connection to the Internet or to support video conferencing See videoconferencing.
(communications) video conferencing - A discussion between two or more groups of people who are in different places but can see and hear each other using electronic communications. applications. ISDN is capable of transferring information from the Internet at speeds ranging from 126,000 bits per second (126 Kbps), for the basic service, to 1,472,000 bits per second (1,472 Kbps) for advanced ISDN services.
Business consumers make up the bulk of ISDN subscribers. Connecting ISDN to a personal computer requires a network terminator and an ISDN terminal adapter A device that adapts a computer to a digital ISDN line. Like a modem, it plugs into the serial port of the computer or into an expansion slot. Some terminal adapters use the parallel port for higher speed. . The network terminator is where the line from the ISDN provider enters the consumer s computer. From there, the wire is sent to the terminal adapter See ISDN terminal adapter.
terminal adapter - Terminal Adaptor , which is the modem in this installation. The terminal adapter is also the device that allows the same wire to be used to receive telephone calls or faxes.
ISDN service is offered by many local telephone companies. The telephone company achieves high rates of data transfer over copper wire by combining wires to act in unison. Wires are "bonded" together in order for many different wires to act as one. When two wires (or channels as they are called in an ISDN installation) are combined, speeds increase to 128,000 bits per second. ISDN can support a maximum of 23 channels being combined to form a system that can operate at a maximum speed of 1,472,000 bits per second.
3. Cable Modem
The most widely used broadband technology involves accessing the Internet via the same wires that bring cable television into the homes of consumers. The signal travels over coaxial cable, which is capable of carrying more data than telephone lines. Coaxial cable is a high-capacity cable used in communications and video. It contains an insulated solid or stranded wire A metal wire that is made up of several smaller wires twisted together. Stranded wire is more flexible than wire with a solid core. surrounded by a solid or braided braid·ed
a. Produced by or as if by braiding.
b. Having braids.
2. Decorated with braid.
3. metallic shield, wrapped in a plastic cover.
The cable was originally designed for one-way communication. New routers and other equipment installed by cable companies allow two-way communication Two-way communication is a form of transmission in which both parties involved transmit information. Common forms of two-way communication are:
Currently, local cable companies are the only providers of this service. Nationally, there are two major cable ISPs: Excite@Home and RoadRunner roadrunner
or chaparral cock
Either of two species of terrestrial cuckoo, especially Geococcyx californianus (family Cuculidae), of Mexican and southwestern U.S. deserts. About 22 in. . Local cable operators partner with one of the two companies to bring the service to consumers. Both systems use their own browsers and offer unique content that non-users cannot access.
The coaxial wire that cable uses can hold tremendous amounts of information, but only over short distances without significant signal loss. Cable systems that have been upgraded to provide broadband service can only do it for about 2,000 feet from the node without losing television signal quality. (Compare this with DSL, which can send signals about 18,000 feet from the central office.)
The node is the point at which the cable operator's main lines enter a neighborhood and branch off into coaxial cable. Typically, a node serves from about two-hundred to one-thousand households. To ensure signal. integrity, cable operators install amplifiers every 2,000 feet. However, after eight amplifiers, television signals begin to become fuzzy due to interference from the amplifiers. That gives cable a maximum range of about 16,000 feet from the node.
Cable's other weakness relates to its ability to carry data. While it is one of the fastest services currently available with possible download speeds of 27,000,000 bits per second (27 Mbps), it suffers from a feature that other technologies do not. The more people using the service, the slower it becomes. Coaxial wire can only hold a limited amount of data. When that limit is reached and additional people attempt to use the Internet, they will all experience slower service. For that reason, individual cable operators have installed "virtual speed bumps" that limit the speed at which users can download and transmit data. Typically, download speeds range from 1,000,000 to 2,000,000 bits per second (1 to 2 Megabits per second (unit) megabits per second - (Mbps, Mb/s) Millions of bits per second. A unit of data rate. 1 Mb/s = 1,000,000 bits per second (not 1,048,576).
E.g. Ethernet can carry 10 Mbps. ) downstream and less than 1,000,000 bits per second (1 Mbps) upstream.
The monthly and up-front costs for cable Internet Internet access via the cable companies. There are two kinds of service. One uses a cable modem to connect to a computer, and the other uses an enhanced cable box that provides Internet access directly at the TV. access are higher than that of dial-up service. Typically, a consumer can expect to pay approximately $200-400 for installation of the cable modem and equipment. Most systems appear to have proprietary modems that must be purchased from the cable provider. Monthly costs are approximately $40-50 for the home user.
4. Satellite Service
Consumers today can receive high-speed Internet See broadband. service via satellite. The consumer must have downlinking equipment that is pointed to a specific satellite that is in geostationary orbit geostationary orbit
A circular orbit positioned approximately 35,900 km (22,258 mi) above Earth's equator and having a period of the same duration and direction as the rotation of the Earth. approximately 22,000 miles above the earth. Such satellites have a constant 'footprint'' and remain in the same relative position to the earth.
The satellite sends data to the user's satellite dish satellite dish
A dish antenna used to receive and transmit signals relayed by satellite.
A parabolic antenna used to receive signals relayed by satellite. at a download speed of approximately 350,000 bits per second (350 kilobits per second), more than 6 times faster than dial-up service. To send information from the user s computer, users must use dial-up service since direct satellite uplinking technologies are not yet generally available on a commercial basis (but they may become available soon). (See Exhibit 13 for an image of how this works.) Hence, satellite-based Internet service bypasses dialup service when moving downstream from the satellite to the user, but uses dial-up service to send signals to the Internet. About 100,000 Americans access the Internet through this technology today.
One large satellite ISP is DirecPC. This is a subsidiary of Hughes Network Systems Hughes Network Systems, LLC (HNS), is a provider of broadband satellite network products for businesses and consumers. HNS pioneered the development of high-speed satellite Internet access services and IP-based networks with its original DirecPC service but which it now markets , the company that provides DirecTV service. The same dish can be used to access both services at the same time. For DirecTV consumers, start-up costs are about $200 for the modem, and about $30-40 per month for the subscriber fee. The satellite dish can be purchased from a number of retailers.
T-Carriers are a family of technologies that require the use of a dedicated digital communications Transmitting text, voice and video in binary form. See communications. line and specialized computer equipment at both the user's site and at the site of the company that provides the service. T-Carrier service may be provided either by local or long distance telephone companies or by the Internet Service Provider. The user must have a dedicated computer to manage the flow of data coming in and to route it to other computers for processing. Basic T-Carrier service is called T-1, and faster applications are called T-2 and T-3.
DSL and ISDN use standard 56K twisted pair lines and specialized equipment to send signals at higher frequencies. They are "party line'' technologies in the old sense of that phrase. In contrast, T-Carriers use dedicated lines that can be either twisted pair (in some TI applications), or fiber (for T2 and T3 applications).
For the system to be reliable, a SONET ring The architecture used in SONET technology. SONET rings, known as "self-healing rings," use two or more transmission paths between network nodes, which are typically digital cross-connects (DCSs) or add/drop multiplexers (ADMs). must be installed. SONET (Synchronous Optical Network (networking) Synchronous Optical NETwork - (SONET) A broadband networking standard based on point-to-point optical fibre networks. SONET will provide a high-bandwidth "pipe" to support ATM-based services. ) is a universal computer system that all high-speed digital traffic uses. SONET provides a standard interface so that all systems are able to connect to one another. For example, without SONET technology the Internet backbone system of AT&T could not transfer data to the backbone through and through; thoroughly; entirely.
- Lord Lytton.
See also: Backbone of MCIWorldcom, or vice versa VICE VERSA. On the contrary; on opposite sides. . The SONET ring is composed of several of these systems that act as redundancies in case of failure. This ensures that the Internet Backbone is never disabled.
All of this technology is needed for the T-Carrier lines due to the amount of data that they are capable of carrying. Many ISPs use T-Carrier lines to provide access to the Internet for their consumers. While the ISP may not offer a T-carrier as an option for consumers, the ISP uses it to transfer their customers signals to a regional ISP.
A T1 line uses four twisted pair wires that contain 24 channels capable of transferring data at 64,000 bits per second (64 Kbps). These channels may be combined to increase the speed of information transfer. If all 24 channels are used together, a T1 line can transfer data at 1,544,000 bits per second (1.544 Mbps).
A T2 line increases the amount of channels to 96. This gives the T2 a maximum data transfer rate of 6,312,000 bits per second (6.312 Mbps). T2 connections and higher must use a fiber optic cable Noun 1. fiber optic cable - a cable made of optical fibers that can transmit large amounts of information at the speed of light
fibre optic cable
transmission line, cable, line - a conductor for transmitting electrical or optical signals or electric power in order to operate at these high rates of data transfer.
T3 is the fastest T-carrier line and often used for Internet access. It contains 672 channels and has a maximum data transfer rate of 44,736,000 bits per second (44.736 Mbps).
The cost of a T-Carrier line depends on the distance the line must travel. Unlike dial-up access, cable or DSL, a T-Carrier is not just a plug-in technology. Switches, bridges and routers are required to configure the channels, to transfer data from the T-Carrier line to the computer network and to direct the data to the right destination. All of this equipment takes a specialized staff to ensure that the system works as designed.
6. MMDS/LMDS Terrestrial Wireless Service
Terrestrial wireless is an important technology that allows users to send and receive Internet signals using a land-based system similar to that used by cellular telephones. All versions of wireless service work on the same principal. Signals are sent from a transmitting tower to an antenna on the recipient's home for a fixed wireless system. (This compares with mobile wireless systems that send signals to the recipient's cell phone or laptop, which is discussed in the sidebar). Two technologies capable of delivering broadband are known as Multipoint Multichannel Distribution System (MMDS) and Local Multipoint Distribution System (wireless) Local Multipoint Distribution System - (LMDS) A broadband wireless technology. (LMDS). Both systems use microwave towers that were originally designed to deliver television signals to consumers.
For MMDS to work, consumers must have a line-of-sight path to the tower, and signals can be effectively received within a radius of approximately 20 miles in any direction. Factors limiting the distance include the curvature of the Earth, height of the tower, hills and tall buildings.
Users need not only a modem but also a digital transceiver, which is the antenna that receives the signal. MMDS is faster than DSL. Current downstream speeds are near 5,000,000 bits per second (5 Mbps) and upstream transmissions are rated at 256,000 bits per second (256 Kbps).
LMDS is another fixed wireless system and works in much the same way as MMDS. It operates at higher radio frequencies, which allow for very clear signals and an ability to handle millions of bits of data. LMDS can transfer 150,000,000 bits (150 Mbps) of data per second into and from a user's computer. However, operating at these frequencies diminishes the effective range of the signal. A user can be no more than approximately four miles from the transmitter tower. This limits application to denser urban areas.
7. Fiber Optic Cable
Fiber optic cable uses light waves sent through small glass tubes to carry information from one point to another. It currently represents the ultimate in high-speed Internet access. Devices located at each end of the cable convert the digital signal into light and then back to digital. Information can be anything from TV signals, voice, live teleconferences, data, or Internet web sites.
Fiber optic cable was developed to carry signals hundreds of miles without the need for signal boosters and without loss of signal strength or integrity. This is why the long distance telephone network relies almost exclusively on fiber optic cable to transmit calls.
In the last few years, Regional Bell Operating Companies The Regional Bell Operating Companies (RBOC) are the result of the U.S. Department of Justice antitrust suit against American Telephone & Telegraph. History (RBOCs) and other telecommunication companies have begun to install fiber on the local level. In addition, the national network of wires that carry cable television signals use fiber optic cable. It is not until the signal reaches the neighborhood level that the signal is transferred to coaxial cable to be delivered to consumers.
Fiber optic cable can transmit information to and from the Internet at speeds measured in millions of kilobits per second. The national fiber optic network has almost an unlimited supply of capacity.
Fiber may be used in two ways on the local level. The first is known as "fiber to curb." This occurs when the local company installing the cable runs the fiber within 1,000 feet of a home. The wire from the curb to the home and inside the home is the traditional twisted pair copper wire. Tests of this installation method have shown that the fiber could carry data at 52,000,000 bits per second (52 Mbps). That is fast enough to view any type of video over the Internet, download any file found on the Internet almost instantaneously, and receive telephone and cable television service.
"Fiber to home" is a system in which the fiber optic cable is extended into the home and is used as the telecommunication wiring throughout the structure. In this installation, there is no need for twisted pair or coaxial cable. With a 100% fiber installation, Internet transfer rates jump to millions of kilobits per second.
The connectors which attach fiber cable to transmitters, receivers, and other fiber must provide a near-perfect interface, with little room for error. To a light wave traveling along the cable, a gap the size of a human hair at a connector is a major obstacle. Fiber optic cable is wrapped in five layers of protective material to prevent damage from weather or abuse. This adds to the cost and time it takes to deploy the cable.
Although initially expensive, many cooperatives are installing fiber optic cable or participating in local projects with other providers. Some cooperatives are connecting their headquarters, district offices and substations with a fiber link to improve utility operations and communications. For example, a fiber link could allow every district office to have ultra-high speed access to a single customer database. The same link could then be used for other e-commerce applications. Some of this investment can be recovered by selling excess capacity (which is almost unlimited) to local businesses.
We have reviewed a number of technologies that may be utilized to deliver broadband access to rural America, including to electric cooperatives. These technologies either augment existing twisted pair lines (like DSL or ISDN), or bypass lines by using other technologies, such as cable, satellite, or MMDS. Each of these technologies has strengths and drawbacks.
We anticipate that cooperatives will continue to investigate all of these technologies, and others that may yet be developed. As noted above, many cooperatives are already involved in important projects involving fiber, MMDS, DSL, and others. We also anticipate the increased use of satellite applications.
There may be no single broadband technology that will be ideal in all situations. As shown in Exhibit 14, cooperatives may install (or be involved with) a number of different broadband technologies. What ultimately matters is that cooperatives are able to connect all of these approaches, and that consumers have high-speed Internet access.
X. Conclusion: The Value of the Cooperative Network
There is one other broadband issue to discuss. Electric cooperatives serve over 30,000,000 Americans in 46 states. Collectively, they represent the largest electric utility network in the United States.
Electric cooperatives have long constituted a network in the sense that they have cooperated and worked together to achieve common goals, Co-ops are famous for providing mutual aid when one or more suffers a storm or comes under attack from a predator utility. Comparably, co-ops have worked together for legislative or regulatory solutions that are best for the network and end-use consumers collectively.
The issue of broadband now brings this discussion to a higher level. The network can become networked. Through broadband technologies, co-ops will not only be able to work together, they will be able to communicate and share information instantaneously. They will be able to coordinate purchasing activity and immediately lower the total amount spent on materials and supplies. They will able to achieve cost economies by handling medical, retirement and personnel information electronically. In fact, cooperative.com is being developed as a business telecommunications platform that will help make these things "These Things" is an EP by She Wants Revenge, released in 2005 by Perfect Kiss, a subsidiary of Geffen Records. Music Video
The music video stars Shirley Manson, lead singer of the band Garbage. Track Listing
1. "These Things [Radio Edit]" - 3:17
Broadband technologies may soon allow for digital meetings and eliminate the need for some travel. Web-based training is clearly on the horizon. Broadband may have applications that enable co-ops to respond to the increasing volatility in the wholesale electricity market. The opportunities, like broadband's own capacity, are almost unlimited. There are still obstacles to bringing broadband to rural America, but those obstacles will be overcome.
Greg Boudreaux is NRECA's Senior Adviser to the CEO (1) (Chief Executive Officer) The highest individual in command of an organization. Typically the president of the company, the CEO reports to the Chairman of the Board. for Member Eduction e·duce
tr.v. e·duced, e·duc·ing, e·duc·es
1. To draw or bring out; elicit. See Synonyms at evoke.
2. To assume or work out from given facts; deduce. . Prior to joining NRECA, Greg was an assistant dean of the graduate school at the University of Maryland University of Maryland can refer to:
An academic degree conferred by a college or university upon those who complete at least one year of prescribed study beyond the bachelor's degree.
Noun 1. from LSU LSU Louisiana State University
LSU Large Subunit
LSU La Salle University (Philadelphia, PA)
LSU La Sierra University
LSU Link State Update (OSPF)
LSU Learning Support Unit and a doctorate from Duke University.
Brian Sloboda is a Research Associate in the Education & Training Department at NRECA. Brian is a 1997 graduate of Fairmont State College with a degree in Speech Communication and in Political Science.
(1.) "Advanced Telecommunications in Rural America: The Challenge of Bringing Broadband Service to All Americans," April, 2000.
(2.) In everyday use, factors such as distance from telephone switching Telephone switching
Moving one's assets from one mutual fund or variable annuity to another by telephone.
The movement of an investor's funds from one mutual fund to another mutual fund on the basis of an order given via stations, time of day, line quality, and others affect Internet speed.
(3.) When discussing the size of a computer file such as a picture or Word document, the term byte is used to refer to file size. When referring to Internet speed the word bit is used. They refer to files that are the same size. A file that is 56 kilobytes in size would take 1 second to transfer via a 56 kilobit per second “KBPS” redirects here. For the AM radio station in Portland, Oregon, see KBPS (radio station).
A kilobit per second (kbit/s or kb/s or kbps) is a unit of data transfer rate equal to 1,000 bits per second. modem. The reason for the difference is that different groups wrote the standards for computer storage and for the Internet. Otherwise, they refer to the same thing.
(4.) For a complete list of National Backbone providers and ISPs in the United States visit www.boardwatch.com.
(5.) All ISP and broadband costs identified in this Primer are approximate at best. And as evidenced by other technical areas, they are also likely to change quickly in response to competitive forces or new technologies that enter the market.
(6.) Many traditional Internet Service Providers do not allow dial-up customers to remain constantly connected to the service without data being transmitted back and forth. The reason is that if all of the ISP's consumers did this, there would not be enough lines for everyone to use. An ISP may have 5,000 consumers but have the capacity for only 1,000 to be on-line at any one time.
(7.) These speed measures are ideal. DSL providers appear to install electronic "speedbumps" to manage their systems. As a result, actual DSL download speeds are in the 100,000-200,000 bits per second range, and typical uploads speeds are in the range of 64,000-250,000 bits per second.
FILES VS. BITS
Computers exchange bits. Users exchange files- actual documents, pictures, charts, videos, songs, and other complex combinations of data that have meaning for humans. Because so many files are exchanged over the Internet, a new "file language" has developed to show how such exchanges are actually performed.
Any file on a computer can be e-mailed to or downloaded from a web site. The most common file types to download or send via e-mail are application files, executable files, picture files, and zip files.
Application files are items such as Word Documents or Excel spreadsheets. They are the documents that most computer users create with software packages such as Microsoft Office Microsoft's primary desktop applications for Windows and Mac. Depending on the package, it includes some combination of Word, Excel, PowerPoint, Access and Outlook along with various Internet and other utilities. .
Application files do not operate on their own. Instead, they need a piece of software known as an executable file to open, edit and view it. Executable files are the actual programs that a computer uses to do things such as install software or make application files. For example, when a user opens Microsoft Word A full-featured word processing program for Windows and the Macintosh from Microsoft. Included in the Microsoft application suite, it is a sophisticated program with rudimentary desktop publishing capabilities that has become the most widely used word processing application on the market. , he or she is actually opening a file named "world.exe." The ".exe" extension on a file identifies it as an executable file.
Picture files sent via e-mail are in either .jpg, .gif, .tif, or .bmp format. The formats deal with the quality of the picture, size of the file, and what can be done with the picture. Each format has its own pluses and minuses. Typically, a .tif file A file extension used for TIFF files; for example, image1.tif. See TIFF and extension. will be larger in size and more detailed, and are only used when a high resolution picture is needed. The higher the resolution, the better the clarity.
Formats commonly found on web pages are .jpg and .gif. These are smaller in size and consequently take less time to download. The quality is acceptable for most uses. A .bmp or bitmap is a file type not commonly used on web pages as they tend to be larger in size to the .jpgs or .gifs. Any picture on a web site can be saved to a user's computer by right clicking and choosing "save picture as."
Zip files are files that have been compressed to decrease file size. They can install software onto a user's computer or can be used to send several documents in one easy-to-use package. A zip file is like a suitcase. You can stuff many items into it and when it comes time to close it, everything is compressed. To open or create a zip file a user must have a zip utility such as Winzip or PKZip.
SPEED CONVERSION CHART
1 bit is a single digit of a binary number. Either 1 or 0.
1,000 bits = 1 Kilobit = 1K
1,000 Kilobits = 1 Megabit = 1M = 1,000 K
1,000 Megabits = 1 Gigabit = 1G = 1,000 M
1,000 Gigabits = 1 Terabit = 1T= 1,000 G
DSL types can be categorized as Asymmetric or Symmetric. Asymmetric DSL features a fast rate transfer from the Internet but a slow speed when sending out data. Symmetric DSL See DSL. has the same rate transfer speeds upstream and downstream.
ADSL- Asymentric DSL allows voice and data to share the same line at the same time. This is accomplished by sending data at a higher frequency than the voice communication. A device called a splitter is installed at the user's end. The splitter separates the two frequencies and allows voice traffic to go to the phone or fax and data traffic to the computer. Versions of ADSL known as "lite" allow residential users to use a filter instead of the expensive splitter to separate the signals. Consumers must be no more than 18,000 feet from the provider's central office.
RADSL- Rate Adaptive DSL works in the same manner as DSL. However, it is able to adjust speed based upon signal quality. This helps to optimize the capabilities of the network. Users can be up to 25,000 feet from the central office.
VDSL- Very High Bit Rate DSL is the fastest of all DSL technologies with a downstream rate of ranging from 13 Mbps, when within 5,000 feet of the central office, to 52 Mbps, when 1,000 feet from the central office.
HDSL- High Bit Rate DSL is a symmetric version of DSL. This gives it the advantage of having the same rate of data transfer upstream and downstream. The user must be within 12,000 feet of the central office instead of 18,000 feet for ADSL.
SDSL- Symmetric DSL is a variation of HDSL See DSL.
HDSL - High bit-rate Digital Subscriber Line that adjusts speeds based upon line quality.
IDSL- ISDN DSL is the slowest of all technologies at a transfer rate of only 144 Kbps but does allow the user to be 26,000 feet from the central office.
LOW EARTH ORBIT SATELLITE SYSTEMS
Although not currently available, reference should be made to a new technology known as low earth orbit. As the name implies, these satellites will fly lower than geostationary Aligned with the earth. Refers to satellites (GEOs) that travel at the same rotational speed as the earth (they are geosynchronous) and are always the same distance from the earth. See GEO. satellites at approximately 930 miles above the earth. Because of the lower orbit, they are not geostationary, which means that there must be a larger set of orbiting satellites which are networked together to provide continuous service. Any single satellite is in view (i.e., maintains a specific "footprint") for only a few minutes. In order to maintain continuous communications, several satellites must be used.
Teledesic Corporation has developed a system that it claims will use 288 satellites in low earth orbit. This would give them complete coverage of the globe. According to the Teledesic web site (www.te1edesic.com) "customers will obtain two--way, broadband access to the Teledesic Network through compact user equipment mounted on the roof of their office, home or school. No ground-based infrastructure is necessary, so Teledesic is a last-mile/kilometer (or first-mile/kilometer) solution that can work anywhere in the world." The combined signal could carry 30,880,000,000 bits of data per second. The project is projected to be operational in 2004 at a cost of $9 billion.
If this system performs as promised, it could be a viable solution to the lack of broadband access in rural areas. Electric Cooperatives should follow the development of this and other technologies. Notice also that Teledesic is promising broadband speeds that dwarf other technologies, with the exception of fiber.
MOBILE WIRELESS PCS
Mobile, wireless Personal Communications Systems are currently being promoted, but technically speaking are not broadband technologies, and do not currently bring the full. capabilities of the Internet to users. (Some have called this service "Internet-lite.")
The required infrastructure includes a tower placed on top of a tall building or hillside. Fixed (e.g, MMDS, LMDS) and mobile (PCS) systems vary in the speed at which they deliver Internet content. Mobile wireless technology eliminates the need for special cables, routers or amplifiers. One of the first wireless technologies was Cellular/PCS dial-up. This non-broadband technology uses the same system that cell phones use to send and receive signals.
Typical uses are for laptop computers and for so-called Personal Digital Assistants such as the Palm Pilot. Cellular dial-up transfers data at 9,600 bits per second (9.6 Kbps). This is five times slower than a 56K dial-up connection, which is why in its current applications, PCS can only deliver basic data (e.g., sports scores, movie times) and not the colorful graphics or detailed information available over the Internet through broadband applications.
GLOSSARY OF TECHNOLOGY TERMS
analog: Not digital. Analog describes a way to transmit or measure data in terms of continuously varying physical qualities--as with the shifting hands of a grandfather clock.
ASCII (American Standard Code for Information Interchange): The standard, unformatted (1) A hard disk, rewritable optical disc or floppy disk that has not been initialized and is completely blank. See format program.
(2) Without a structure. For example, an e-mail message that contains only text without any style attributes and no graphics is 128-character set of letters and numbers that can be represented by a seven-digit binary number between 0000000 and 1111111.
Baby Bells The nickname given to the regional Bell operating companies after Divestiture in 1984. See Bell System and RBOC. : Sometimes referred to as regional Bell operating companies or RBOCs, the Baby Bells were created by the breakup of Ma Bell in 1984.
backbone: The main conduit of a computer network, to which all other users and networks connect. There are only a handful of major backbones today, and the top two--MCI Worldcom and SprintLink--handle close to 75 percent of Internet traffic.
bandwidth: the maximum rate at which information can be pushed through a network. Most modems run at 56Kbps; ISDN lines run at 128Kbps; a T1 line provides 1.5Mbps of bandwidth. Bandwidth is also an internal computer issue, as in the speed at which a processor can talk to memory.
baud baud (bôd, bōd), measure of the rate at which signals are transmitted over a telecommunications link. It is equivalent to the number of elements or pulses transmitted in one second, e.g. : A speed of data transmission, pronounced "bod."
binary: The essential adjective of the 0 or 1, on or off, black or white world of computing. A binary or base-two number system represents data in 0s or is. Computers are electrical machines and recognize only the existence or nonexistence non·ex·is·tence
1. The condition of not existing.
2. Something that does not exist.
non of electric current. Charge, no charge. One, zero.
bit: The smallest unit of digital information; a binary digit, either 1 or 0. Generally used to describe transmission speed.
byte: A collection of bits, usually 8 bits in length. Bytes, therefore, range from 0 to 255. Generally used to describe storage capacity.
bps (bits per second): This measurement of the speed at which data is transferred is the mph of the Internet. Variants include Kbps (kilobits per second) and Mbps (megabits per second).
broadband: An adjective that comes from the telephone world, where it refers to wider bandwidth than a standard telephone line. In the popular press, broadband is a synonym synonym (sĭn`ənĭm) [Gr.,=having the same name], word having a meaning that is the same as or very similar to the meaning of another word of the same language. Some are alike in some meanings only, as live and dwell. for high bandwidth.
cable: Wire that dwarfs the capacity of copper. Installed originally to deliver cable TV, cable is often used as a synonym for that service.
CLEC (Competitive Local Exchange Carrier) An organization offering local telephone service that is not one of the traditional telephone companies. The Telecommunications Act of 1996 allowed competition to the incumbent telcos (ILECs), enabling new companies (CLECs) (competitive local-exchange carrier): Pronounced "sea-leck." After years of market dominance Market dominance is a measure of the strength of a brand, product, service, or firm, relative to competitive offerings. There is often a geographic element to the competitive landscape. , the ILECs--incumbent local-exchange carriers like regional telcos SBC (1) (SBC Communications Inc., San Antonio, TX, www.sbc.com) A large, national telecommunications company that grew from a multitude of local and regional companies, including Southwestern Bell, Pacific Bell and Nevada Bell, into a single, unified brand by 2002. and Bell Atlantic-- are under pressure from upstarts entering the market with advanced data and broadband services.
client/server: An adjective describing the network architecture in which a powerful, central computer (server) accepts requests for resources and services from many individual PCs (clients).
coax: Short for coaxial cable, the standard cable TV wiring.
common carrier: A private company that offers telecommunications services to the public.
compression: A method to store text, data, sound, or images in fewer bits. Rather than store every pixel of a blue square, the computer might store one blue pixel and the dimensions of the square. Compression is carried Out by any one of many compression standards: AU, GIF, JBIG JBIG - Joint Bi-level Image Experts Group , JPEG JPEG
in full Joint Photographic Experts Group
Standard computer file format for storing graphic images in a compressed form for general use. JPEG images are compressed using a mathematical algorithm. , MPEG (Moving Pictures Experts Group) An ISO/ITU standard for compressing digital video. Pronounced "em-peg," it is the universal standard for digital terrestrial, cable and satellite TV, DVDs and digital video recorders (DVRs). , MP3, PICT, SIT, TIFF, ZIP.
cookie: A unique identifier With reference to a given (possibly implicit) set of objects, a unique identifier is any identifier which is guaranteed to be unique among all identifiers used for those objects and for a specific purpose. sent to your computer by a Web server and stored on your hard disk. As a verb, the term refers to tagging users' browsers in order to monitor their browsing.
digital: A description of data which is stored or transmitted as a sequence of discrete symbols from a finite set In mathematics, a set is called finite if there is a bijection between the set and some set of the form where n is a natural number. (The value n = 0 is allowed; that is, the empty set is finite.) An infinite set is a set which is not finite. . Most commonly this means binary data binary data - binary file that is represented using electronic or electromagnetic signals. The opposite of digitalis digitalis (dĭj'ĭtăl`ĭs), any of several chemically similar drugs used primarily to increase the force and rate of heart contractions, especially in damaged heart muscle. The effects of the drug were known as early as 1500 B.C. analog.
Digital Subscriber Line (DSL): Also known as Digital Subscriber Loop Digital Subscriber Loop - Digital Subscriber Line . A family of digital telecommunications protocols designed to allow high-speed data communications data communications, application of telecommunications technology to the problem of transmitting data, especially to, from, or between computers. In popular usage, it is said that data communications make it possible for one computer to "talk" with another. over the existing copper telephone lines between end-users and telephone companies. The first technology based on DSL was ISDN, although ISDN is not often recognized as such nowadays. Since then, a large number of other protocols have been developed, collectively referred to as xDSL, including HDSL, SDSL See DSL.
SDSL - Single-line Digital Subscriber Line , ADSL, and VDSL See DSL.
VDSL - Very high bit-rate Digital Subscriber Line .
FCC (1) (Federal Communications Commission, Washington, DC, www.fcc.gov) The U.S. government agency that regulates interstate and international communications including wire, cable, radio, TV and satellite. The FCC was created under the U.S. (Federal Communications Commission Federal Communications Commission (FCC), independent executive agency of the U.S. government established in 1934 to regulate interstate and foreign communications in the public interest. ): The FCC was created by the Communications Act The establishment of the Federal Communications Commission (FCC) in 1934, the regulatory body for interstate and foreign telecommunications. Its mission is to provide high-quality services at reasonable cost to everyone in the U.S. on a nondiscriminatory basis. of 1934 to police the airwaves.
fiber optics fiber optics, transmission of digitized messages or information by light pulses along hair-thin glass fibers. Each fiber is surrounded by a cladding having a high index of refractance so that the light is internally reflected and travels the length of the fiber : A communications technology Noun 1. communications technology - the activity of designing and constructing and maintaining communication systems
engineering, technology - the practical application of science to commerce or industry that sends electromagnetic signals down cables made of glass or plastic fibers.
56Kbps (56 kilobits per second): The data capacity of a normal single-channel digital telephone channel in North America North America, third largest continent (1990 est. pop. 365,000,000), c.9,400,000 sq mi (24,346,000 sq km), the northern of the two continents of the Western Hemisphere. . The figure is derived from the bandwidth of 4kHz allocated for such a channel and the 16-bit encoding (4000 x 16 = 64000) used to change analog signals to digital, minus 8000 bit/s used for signaling and supervision.
gateway: A translator machine or router that links networks speaking different protocols.
GIF (graphic interchange format): A compression format used for images.
host: A computer on a network. This is almost a synonym for "node," but it generally implies that the machine is a normal computer (most commonly a server) and not an infrastructure device (such as a hub or firewall).
in full HyperText Markup Language
Markup language derived from SGML that is used to prepare hypertext documents. Relatively easy for nonprogrammers to master, HTML is the language used for documents on the World Wide Web. (hypertext markup language (hypertext, World-Wide Web, standard) Hypertext Markup Language - (HTML) A hypertext document format used on the World-Wide Web. HTML is built on top of SGML. "Tags" are embedded in the text. A tag consists of a "<", a "directive" (in lower case), zero or more parameters and a ">". ): The formatting lingo Lingo - An animation scripting language.
[MacroMind Director V3.0 Interactivity Manual, MacroMind 1991]. of the Web, HTML lets humans talk to Web servers and browsers. HTML is spoken in tags--short commands such as [less than]HI[greater than] that surround pertinent text like quotation marks quotation marks
the punctuation marks used to begin and end a quotation, either `` and '' or ` and '
quotation marks npl → comillas fpl
HTTP (hypertext transfer protocol See HTTP.
(protocol) Hypertext Transfer Protocol - (HTTP) The client-server TCP/IP protocol used on the World-Wide Web for the exchange of HTML documents. It conventionally uses port 80.
Latest version: HTTP 1.1, defined in RFC 2068, as of May 1997. ): The original communications protocol Hardware and software standards that govern data transmission between computers. The term "protocol" is very generic and is used for hundreds of different communications methods. A protocol may define the packet structure of the data transmitted or the control commands that manage the of the Web. Browsers use HTTP to connect to Web servers and servers use HTTP to talk amongst themselves.
hypertext: A system of linking electronic documents.
Integrated Services Digital Network Integrated services digital network (ISDN)
A generic term referring to the integration of communications services transported over digital facilities such as wire pairs, coaxial cables, optical fibers, microwave radio, and satellites. (ISDN): A set of digital telecommunications standards allowing a single wire or optical fiber to transmit voice, digital network services, and video data up to 128 Kbps.
interface: The physical piece of hardware which does the actual transmitting and receiving of network data.
modem: A piece of hardware that allows computers to talk to each other by transmitting digital information into analog signals that can be sent over regular phone lines and redigitized at the receiving end.
node: A device on a network. Nodes can be personal computers, servers, printers, modems, or infrastructure elements (routers, switches, etc). In essence, a node is any machine that can actively participate in the exchange of information on the network (cables, for example, are not nodes).
operating system operating system (OS)
Software that controls the operation of a computer, directs the input and output of data, keeps track of files, and controls the processing of computer programs. : The underlying software that give a computer its look and feel and upon which all other applications and hardware depend.
optical fiber: A plastic or glass (silicon dioxide silicon dioxide: see silica.
(SiO2) A hard, glassy mineral found in such materials as rock, quartz, sand and opal. In MOS chip fabrication, it is used to create the insulation layer between the metal gates of the top layer and the silicon elements below. ) fiber no thicker than a human hair used to transmit information using infra-red or even visible light as the carrier (usually a laser). Optical fiber is less susceptible to external noise than other transmission media, and is cheaper to make than copper wire, but it is much more difficult to connect. Optical fibers are difficult to tamper To meddle, alter, or improperly interfere with something; to make changes or corrupt, as in tampering with the evidence. with (to monitor or inject data in the middle of a connection), making them appropriate for secure communications. The light beams do not escape from the medium because the material used provides total internal reflection. A single fiber can transmit 200 million telephone conversations simultaneously.
packet: A small stream of information, including the information necessary for delivering it. In the TCP/IP TCP/IP
in full Transmission Control Protocol/Internet Protocol
Standard Internet communications protocols that allow digital computers to communicate over long distances. world, a packet includes the datalink address of the device which issued it, a source network address, a destination network address, the datalink address of the device to which it is headed next, a service number, and the payload data.
pixel: The shortened form short·ened form
An abbreviated form of a polysyllabic word, as auto for automobile. of picture element, for dots that make up an image or character on a computer or TV screen. The more pixels, the better the resolution.
POP (point of presence): Informal jargon for local access to a network or telecom service.
portal: The welcome mats of the Web. These vast sites lead the way to the Net for millions who use the proprietary interface, channels, and search technologies to find news, entertainment, or other information. The largest portals include Yahoo!, Excite, Lycos, AOL (A division of Time Warner, Inc., New York, NY, www.aol.com) The world's largest online information service with access to the Internet, e-mail, chat rooms and a variety of databases and services. , and MSN (1) (MicroSoft Network) A family of Internet-based services from Microsoft, which includes a search engine, e-mail (Hotmail), instant messaging (Windows Live Messaging) and a general-purpose portal with news, information and shopping (MSN Directory). .
protocol: Protocols such as HTTP, IP, PP, and TCP (1) (Transmission Control Protocol) The reliable transport protocol within the TCP/IP protocol suite. TCP ensures that all data arrive accurately and 100% intact at the other end. are sets of rules governing the exchange of information. Computers use these rules to communicate with other computers, printers, and modems. Protocols are used to control when a node on a network can transmit, the format of transmissions, addressing rules, methods of data delivery, and virtually every other aspect of computer communications.
Public Switched Telephone Network (PSTN (Public Switched Telephone Network) The worldwide voice telephone network. Once only an analog system, the heart of most telephone networks today is all digital. In the U.S. ): The collection of interconnected systems operated by the various telephone companies and administrations. Also known as the Plain Old Telephone System (POTS) in contrast to xDSL and ISDN.
router: A machine that forwards packets between different networks on the basis of source and destination addresses. Routers maintain lists of paths to networks (called "routing tables"); these often include a "default route," to be used when a more specific route is not available. Considered the traffic cop of networking.
search engines: Search engines help Net users target information by keyword or concept. Unlike database searches such as Lexis-Nexis and Dialog, search engines are free as long as you have Web access.
server: A computer or workstation that "serves' stored data and files or processing power to other machines--or "clients"--on a network.
SMTP (simple mail transfer protocol): The language computers must speak to send and receive email on the Internet. SMTP is used in conjunction with another protocol that downloads incoming messages or stores them on the server.
spider: Search engine technology. A simple program that scans the Web, crawling from link to link in search of new sites and recording the URLs.
T-1: A digital carrier facility used to transmit a DSI (Dynamic Systems Initiative) An umbrella term for a suite of Microsoft products that help manage the Windows environment in large enterprises. DSI was introduced in 2003. formatted digital signal at 1.544 megabits per second. Although some consider T-1 signaling obsolete, much equipment operates at the "T-l" rate and such signals are either combined for transmission via faster circuits, or demultiplexed into 64 kilobit per second circuits for distribution to individual subscribers. T-1 signals can be transported on unsheilded twisted pair telephone lines. A T-l circuit requires two twisted Two Twisted is an Australian TV mystery drama which premiered on the Nine Network on 14 August, 2006. Narrated by Bryan Brown, who also produced the series' predecessor, Twisted Tales pair lines, one for each direction. Originally a backbone technology, T1s now carry data and voice for most medium-sized businesses. The T-1 designation refers to the signaling speed rather than the medium of the network (copper, fiber).
uplink: To transmit a signal from a ground station to a satellite.
upload: To transfer a file from a PC to a server, on a network or on the Net.
in full Uniform Resource Locator
Address of a resource on the Internet. The resource can be any type of file stored on a server, such as a Web page, a text file, a graphics file, or an application program. (uniform resource locator See URL.
(World-Wide Web) Uniform Resource Locator - (URL, previously "Universal") A standard way of specifying the location of an object, typically a web page, on the Internet. Other types of object are described below. ): The address of a page on the Web.