Absolute Beginners Guide to Upgrading and Fixing Your PC
| Unlike connecting to the Internet via your old analog phone line, a broadband connection is an end-to-end digital connection. When you don't have to modulate and demodulate the data from digital to analog (and back again), the all-digital data can travel much faster from your computer to other points on the Web. There are five types of digital broadband connections available today. When you want to speed up your connection, you can choose from:
Of these broadband options, three are in widespread use today: DSL, digital cable, and digital satellite. ISDN is an older technology no longer widely used; broadband wireless, at this point in time, appears to be a failed experiment with few providers and even fewer subscribers. Choosing a Broadband Technology
Which of these broadband technologies are the best for your particular needs? You need to consider availability (not all types of broadband are available in all areas); ease of installation (you can install a cable modem yourself; DSL and satellite connections require professional installation); and speed (cable is fastest although the more people in your neighborhood with cable modems, the slower your connection will be). Table 16.1 compares the basic features of the three major broadband technologies: DSL, cable, and satellite broadband.
DSL
DSL is a phone line-based technology that doesn't require a dedicated telephone line. Most providers offer DSL service for a flat fee of $35 $50 per month, which includes standard ISP service. This gives you a high-speed broadband connection for about what you'd pay for a second phone line and a subscription to a traditional ISP. DSL service piggybacks onto your existing phone line, turning it into a high-speed digital connection. DSL technology splits your existing phone line into three frequency bands one for standard voice communications, one for downstream data flow, and one for upstream data flow. There are actually several different types of DSL, each using a variation of the basic DSL technology, and each with its own acronym. The DSL technology offered to most households and small businesses today is called ADSL (asymmetric digital subscriber line) Lite. With ADSL Lite you have a maximum downstream speed of 1.5Mbps, and a typical upstream speed of 384Kbps. To get DSL, you have to be within 15,000 feet or so of a phone company's switch facility (called a central office, or CO). DSL access is spreading, however, so if you can't get DSL today, wait a bit it will be in your neighborhood soon. note
Digital Cable
The most popular type of broadband connection today is available from your local cable company if your local cable company offers digital cable service, that is. If you can get it, broadband cable access is a great deal, offering a high-speed Internet connection for between $20 $50 per month. It's also the easiest of all broadband installations, involving nothing more than connecting a cable modem between your cable line and your PC. Where DSL piggybacks over your telephone lines, cable broadband occupies a defined space (called a tunnel) within the signal that travels through the cable company's coaxial or fiber-optic cable. Most cable companies assign Internet signals to a 6MHz slot within the cable signal, which enables downstream speeds as high as 5Mbps. (This theoretical maximum is seldom achieved; speeds in the 500Kbps to 2Mbps range are more common.) Upstream signals are assigned to a subset of the total data tunnel, which produces slower upstream rates typically in the 128Kbps to 384Kbps range. The data signals are extracted from the cable line via a cable modem, which feeds directly into your computer. The modem also serves to pack your computer's data signals back into the cable signal for upstream transmission. Digital Satellite
If neither DSL nor cable broadband is available in your area, you have another option connecting to the Internet via satellite. Any household or business with a clear line of sight to the southern sky can receive digital data signals from a geosynchronous satellite at a downstream speed of 400Kbps. Newer two-way systems also transmit data back via satellite, at upstream rates of 128Kbps 256Kbps. Although this is slower than digital cable, it's about what you'd expect from a moderate DSL connection. The largest provider of satellite Internet access is Hughes Network Systems. (Hughes also developed and markets the popular DIRECTV digital satellite system.) Hughes' DIRECWAY system (www.direcway.com) enables you to receive Internet signals via an 18-inch round dish that you mount outside your house or on your roof. The installation package (including dish and modem card) will set you back around $500 (before any specials), with monthly subscription fees in the $60 $100 range, depending on which usage plan you pick. note
Internet service via satellite works by beaming Internet data off an orbiting satellite down to a satellite dish that is connected to your PC. It's the same digital data you get via DSL or cable, it just has to travel a lot farther to get to you in the neighborhood of 44,000 miles, from transmission point to your PC! When you access a Web page, the request to view that page travels (via phone line in one-way systems, or via the satellite in two-way systems) to DIRECWAY's Network Operations Center (NOC) in Maryland. The NOC sends a request to the Web page's server, and the data that makes up that page is then sent from that server back to DIRECWAY's NOC. The NOC then beams the data for the Web page up to the DIRECWAY satellite (22,000 miles up); the signal bounces off the satellite back down to your DIRECWAY dish (22,000 miles down), at 400Kbps. The signal then travels from your dish to a broadband modem in your PC. caution
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