Definition of DSL.

DSL stands for Digital Subscriber Line. DSL technology connects your computer to the Internet using the same copper lines that provide your phone service. Special equipment at the central telephone office and a DSL modem at your computer, modulate digital information and send it using previously unused frequencies in phone lines. For example, regular voice signals are transmitted across the line at frequencies ranging from 0 kHz to 4 kHz. Since a standard dialup modem uses the same frequencies as voice, the data transmission rates are limited. DSL on the other hand uses frequencies between 25 kHz and 1 MHz. That extra bandwidth means DSL can send more data using the same copper wire connection.

DSL and telephone call signals exist very comfortably on the same line. At each outlet used to make telephone calls, you install a DSL micro filter. Most DSL modem packages come with a supply of these small inline filters. If you need more, they're readily available at any electronics or computer store. The DSL filter takes care of any signals that your telephone might pick up and transmit to you as static.

DSL technology provides significant improvements in Internet speeds over standard dial-up modem connections. Plus, the DSL signal is always on regardless if your computer is or not. This means that you never have to dial up your Internet service provider every time you want to get on the Net. With most setups, you computer automatically connects each time you turn it on.

Like the name suggests, DSL is a dedicated connection between your computer and the central telephone office location. With other broadband technologies such as cable Internet access, you share the connection with everyone using the same. That means the bandwidth capacity is spread out between many different users. The more demand on the line the slower everyone's connection speed is. Not so with DSL.

There are several different varieties of DSL technology, but all achieve their high speeds in virtually the same way. On your end a DSL modem will connect to the network port on your computer. The DSL Modem modulates digital information from your computer and sends it along your phone line. When that signal gets to the nearest central office for the phone company, it is received by a Digital Subscriber Line Access Multiplexer (DSLAM). The DSLAM separates voice from data signals, and sends each signal in the appropriate direction.

DSL technology has one downside. Because of the frequencies DSL uses, the signal deteriorates the farther you are from the central office. This results in a slower DSL connection or none at all. The critical distance is based on the length of the lines to your computer. So it is possible to live within DSL range as the crow flies and not qualify due to an abnormal line length.

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