25.2 Digital Subscriber Line (DSL)
DSL (often ADSL) uses the existing twisted pair line from your home (etc.) to the local telephone office. This can be used if your telephone line can accept significantly higher speeds than an ordinary modem would use. It replaces the analog-to-digital converter at the local telephone office with one which can accept a much faster flow of data (in a different format of course). The spectrum of the twisted pair line is divided up into various channels. Each channel uses QAM modulation like ordinary modems do. Data is sent over multiple channels. The device which converts the digital signals from your computer to the analog signal used to represent digital data on what was once an ordinary telephone line, is a DSL modem.
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