By dividing the approximately 1MHz bandwidth afforded by the copper twisted pair already connected to your premises into a large number of sub-channels, ADSL can provide downstream (central office to your premises) data transmission rates upto 6.144Mbps and upstream (your premises to central office) transmission rates of around 600kbps, depending on how the connection is configured.

Obviously, this will provide internet access at extraordinary speed (approximately 200 times the rate at which a V.34 modem can operate), but, as with most things there is a quid pro quo, in that the upstream channel operates at a fraction of the speed at which data will be received.

Now, this isn't a problem for normal web surfing, where the data received vastly exceeds the amount of data transmitted to the internet.

For example, Windows 95 users can check this right now by positioning the mouse pointer over the modem lights in the tray at the bottom right of the display. Wait a moment and the session statistics will be displayed.

Unfortunately, data transmission performance reduces with increases in the distance over which the information is transmitted.

In short, this means that only subscribers close to the telephone exchange (central office) will receive data at rates sufficient to carry MPEG-1 or 2 video, but almost every subscriber will be able to obtain data transmission rates of 1.536Mbps, which I'm sure you will agree affords excellent internet performance.

So, enough of the reasons why you should read further.

Examining the connection between your computer and the telephone exchange...

As you can see from the diagram above, installation of ADSL technology is simple for the network operator and the subscriber.

All the network operator has to do is link the subcriber line circuit (already terminated at the main distribution frame (MDF)) to the exchange equipment via the POTS splitter (separation filter) and attach the ADSL modem with its control and audio/visual data terminations and all their work is complete.

For subscribers, the task is even simpler.

All that is needed is for the existing telephone(s) to be disconnected from the wall socket for a few moments while the POTS splitter is attached to the socket in its place.

Then, connect the telephone(s) into the back of the POTS splitter, along with the ADSL modem and as soon as the ADSL modem's power is applied a broadband connection is established!

The ADSL modem will be supplied in a variety of flavours, from set top box through PC card to Network adapter.

Finally, it must be noted that subscribers served by pair-gain systems such as WB900 or DACS will not be able to use ADSL.

NOTE:WB900 and DACS are used to provide service to customers sharing a single copper loop.