DSL has its roots in telephone lines

To understand how DSL works, you need to have a general understanding of how telephone lines work. Telephone lines work by sending signals through copper wires. These wires run from your home to the road. There, they are packed into a thick cable and bundled with over 100 other wires. The cable either runs directly to the phone company’s switch board or to a box on the side of the road which acts as a digital concentrator. From there, the signal can be directed anywhere in the world.

So what does this have to do with DSL?

Telephones only transmit voice signals over the copper wires. Voice frequencies typically range from 0 to 3,400 Hertz (cycles per second), however the copper wires are capable of handling much more bandwidth then is used by regular telephone lines.

This is where DSL comes in. DSL takes advantage of the extra space available on these wires. By using different frequencies (high frequency for DSL and low frequency for normal telephone) DSL is able to transmit data through the phone lines without interrupting your regular telephone service. This is achieved using a device called a POTS (Plain Old Telephone Service) splitter. Telephone frequencies are routed one way while the DSL frequencies are routed the other way.

Of course, historically, it makes sense for phone companies not to use this extra space because it allows them to have a higher capacity of phone lines in a smaller space. However, modern technology uses digital signals instead of analog signals so DSL can safely use much more of the telephone line’s capacity without interrupting the signal.

Advantages of DSL

Because of these advancements in technology, DSL comes with many advantages. First of all, it allows you to keep your internet connection open and talk on the phone at the same time. Before DSL, unless you had a separate phone line for the internet, you couldn’t talk on the phone at the same time you were on the internet. Additionally, the connection speed is much greater than a regular modem which allows pages to load faster and for faster download speeds.

Since DSL works directly with your existing phone lines, it doesn’t require any new wiring. Unless your house hasn’t been renovated since 1875, you can use your existing phone line to connect to the internet. Also companies that provide DSL also usually provide a modem to go with your connection as part of the installation. DSL is so easy to install that some companies will simply send you the hardware and you can install it yourself. This saves you both time and money.

By: Saleh Tousi