What Is ADSL? (Asymmetric Digital Subscriber Line)

Telecommunications service employs two different transmission speeds, with the downstream speed (from the provider to the user) usually being much higher than the upstream speed (from the user to the corporate host). ADSL can achieve downstream data rates up to 8 Mbps and upstream rates to 1 Mbps

How ADSL Works

It all starts with a telephone line, the wires that connect your home or small business to a telephone company are made of copper. These wires are wound around each other and are called twisted pair and the type of signal used for voice transfer is called an analog signal. To properly understand DSL, we first need to know what frequencies are, split a telephone wire lengthwise into sections, each section is a frequency, you can send information along this frequency in the form of a signal, the transmission of the signal is converted into cycles per second, each cycle being known as a Hertz. (For example, a megahertz (MHz) is one million cycles per second.) each hertz can carry a signal along its separate frequency, the total range of frequencies, expressed in Kilobits per second (Kbps) is called the bandwidth.

Human voices speaking in normal conversational tones, can be carried in a frequency range of 0 – 3,400 Hertz (a very small frequency), this is good news for DSL companies as they can use the large amount of space left on the lines to transmit digital signals.

There are two completely different competing standards for ADSL, the Discrete Multi-Tone (DMT) and the Carrier-less Amplitude/Phase (CAP) system, which was more easily implemented,