The Technical Story - What is DSL?

Digital Subscriber Line is a fairly new but very popular technology that delivers constant, high-speed access to the Internet via a standard telephone connection while still letting you make and receive calls uninterrupted.

The Broadband Access to the internet which PCUG can now offer members (PCUG DSL) uses the ADSL system. ADSL means Asynchronous Digital Subscriber Line, and is a technical protocol that allows data at speeds up to about 6MBps downstream and about 856 Kbps upstream to be transmitted over a single standard telephone line pair. It works by dividing the available spectrum on a telephone line into three information channels -- a high speed downstream channel, a medium speed duplex (in fact used mainly for upstream transmissions) channel, and a POTS (Plain Old Telephone Service).

Essentially ADSL works by processing the digital signal with very clever algorithms to make the computer see more than the telephone line is capable of providing. It also includes some very sophisticated error correction, again so the computer sees a good copy of the original signal, rather than the dreadfully distorted one that arrives at the modem.

ADSL services can only be provided if the subscriber's telephone exchange has the necessary equipment installed, called "enabled". Because the process is highly sophisticated, the service ADSL supplies depends very much on the quality of the line. It is claimed that ADSL services can work up to four kilometres from the exchange, however if the lines are in poor condition that distance can be shorter.

How fast is DSL?

There are different kinds of DSL service depending on the speed required and amount of data likely to be downloaded. Generally speaking, however, the slowest DSL service is still almost ten times faster than dial-up.

The most popular form of DSL is ADSL or "asymmetric" DSL which means that information you download, i.e data coming to you from the Internet, moves faster than the information you upload, or send to the Internet. ADSL is designed to reflect the fact that the Internet gives more information than it receives.

ADSL such as PCUG offers gives Internet speeds of between 256 kbps download / 64kbps upload right up to 1.5Mbps download/ 256Kbps upload.

The PCUG DSL Broadband Service

Broadband Access via PCUG DSL provides full, interactive, unlimited time, access to the Internet over an ADSL enabled telephone line. Subscribing to the PCUG DSL service also includes the benefits of both Limited Access and Full Access to the PCUG Internet Service, which means that you can dial-in if your ADSL service ever fails or if you are travelling away from home you can dial in from anywhere in the world. The ADSL service is available anywhere in the ACT and NSW (and later anywhere in Australia), where the telephone lines are suitable for ADSL.

Broadband over ADSL requires the member to have a working telephone line with any telephone company, which is capable of being upgraded to carry ADSL signals. Only one telephone service is required. Members will still need to pay for a telephone service in addition to the ADSL service.

The PCUG DSL service is available direct from PCUG. This service is different from the ADSL service provided by TransACT. PCUG members need to sign up for a twelve month contract, and pay a minimum of six months in advance in the first year (this is needed to cover our costs of setting up the service). All services must be paid in advance in accordance with the PCUG current policy on charges.