How ADSL achieves faster throughput with the Pair Gain System (PGS)

Starting approximately six months ago Skyway West has been allowed to resell ADSL (DSL) services over 6 Mb to our business customers. At that time we were capped at 15 Mb and then, two months ago 25 Mb came available (location depending). Before these higher speeds opened up to us Telus made some significant changes to how they would allow these speeds to be sold. The biggest of these changes was that ADSL service speeds over 6 Mb would be sold as PGS (Pair Gains System), services. For this reason I thought you might be interested in what PGS is and does. Before doing so however I think it would be prudent to look at how Skyway delivered ADSL prior to the addition of PGS on the higher speed services.

On a standard ADSL line you have three basic elements: The Telus port, the ADSL router at the customer end and the cable in between (granted there is other equipment in the mix but for our purposes here they need not be mentioned). So let’s say you send a request to a search engine to look for the best pricing of your favorite widget. The packet information is sent from your computer to your ADSL router, converted into an electrical signal, fed over a twisted pair copper cable, received by the Telus port, converted back into data and sent to the Internet. When the server hosting the search engine site receives your request they reply back with the details you asked for and the process just described is reversed until the data reaches you. That’s standard ADSL.

In the case of 15 and 25 Mb services the above scenario still essentially describes what happens. Data is sent over the twisted pair, received and sent back. There is one difference though, and apparently it makes all the difference. Devices called “multiplexers” have been added to the system. Multiplexers take the data and create multiple connections for that data to pass, allowing more data to flow at the same time and at the same speed. So effectively, instead of making the data pipe bigger, they have just made more pipes available. You can sort of think of it as a bonding of services without the physical requirement and expense that bonding needs to achieve faster speeds. Despite the speed increases, the one thing that hasn’t changed is ADSL performance is still dependent on location. The closer you are to a central office the better the speed you can expect to get over your Internet service.

And there you have it. I hope you found this little introduction to PGS interesting and informative. If you want to read more on the subject you can Google “Pair Gain System” and/or have a look at the Wikipedia article below.

Wikipedia article: Pair Gain System

Got a question or an idea for a topic you would like to see covered in one of my upcoming blogs? Write to and sound off. I’ll do what I can to address your questions or concerns either personally in a reply email or on the blog. Until next month, take care.