Broadband over Powerlines (BPL)

Broadband Over Power Lines (BPL) is a technology for distributing broadband internet over the high voltage electricity lines. It seeks to exploit the established network of powerlines for broadband distribution - avoiding the need to lay new or upgrade existing telecom cabling.

Broadband over Powerlines faces various challenges due to the noise created by high voltage power and the blocking effect of trasnformers.

Broadband over Powerlines should not be confused with HomePlug technology where network signals are distributed throughout domestic wiring in s house.

The effect of internal wiring on ADSL and faceplate splitters

To get a good, high speed ADSL connection you want to minimise the line loss between your ADSL modem and the telephone exchange where the DSLAM (the exchange based broadband controller) is located.

The loss of signal is measured in decibels and you really want to keep the loss below about 60dB to pretty much be guaranteed to have a good ADSL signal. It is possible to get a connection with higher losses but is rare and the connection is likely to be slow and/or unstable.

Most of the factors that affect line loss (line length, the quality of the cable used by BT, whether the cable is underground or up poles) are outside of your control. One area that you can change that does impact line loss is the internal wiring and the devices you have connected to the internal wiring.

Most recent BT installations should have a master socket and possibly several extension sockets. The extension sockets are smaller and don't have a removable bottom half to the front panel. The wiring from the exchange to the back of the master socket belong to BT and you mustn't monkey about with it.

You can remove the bottom of the master socket faceplate and you will see it just plugs into a telephone socket (known as the test socket) in the back of the master socket. The wiring from the master socket, including the bottom half of the faceplate you are allowed to monkey about with.

If you are plugging your ADSL modem into an extension socket then you are obviously on a longer total line length than if you simply plugged into the master socket - this will increase line loss. If the wiring is poor or is complicated in layout then the line loss may be even greater.

There is anecdotal evidence that plugging too many devices or certain 'poor quality' devices into your phone sockets can also increase the loss. I have specifically heard that DECT phones can have quite an impact.

The good news is you can test all of this quite easily and you have a good chance to rectify the problems. You should learn how to read the synchronisation speed of your modem and hopefully the line characteristics (including the line loss). You will need to refer to the documentation for your ADSL device to find this information. You can also run a speed test by following the instructions here. Whenever you make a change force your modem to renegotiate the connection (which will make it connect at the best available speed) by switching it off for a few moments and then restarting it.

Your first step should always be to ensure every non-ADSL device plugged into your phone line is plugged into an ADSL filter.

Then try removing everything connected to you telephone wiring except the broadband device. If this results in a much better connection plug the devices back in one at a time, rebooting each time and see if one of the devices causes a significant degradation in signal - consider replacing this device or simply using less devices.

Try plugging your broadband modem directly into the master socket. If this improves the signal you should consider improving the internal wiring or fitting a faceplate filter (see later).

Finally try removing the bottom of the master socket and plugging your broadband device directly into the test socket behind the faceplate. At this stage none of your telephone extensions should be connected to the phone circuit and you have the best possible connection without BT making any adjustments.

If this final step results in a much better signal then you need to either review the internal wiring for replacement or re-routing or better still fit a faceplate filter. A faceplate filter separates the ADSL signal from the phone signal at the point it enters the domestic wiring. Telephone extensions can then be connected without the possibility of them interfering with the ADSL signal.

Unfortunately the master socket may not be located in the best position for you to connect your broadband device and PC. In this instance you may want to consider using a broadband router to handle the ADSL connection and create a home network, which is not as complicated as it might sound.

You could create an Ethernet network around the home using network cable and sockets (which is probably the most reliable), you could install a wireless broadband router and then use wireless adapters to connect your PCs to the broadband connection or you could use powerline networking to run the broadband network over the power sockets in your house. I will cover some of these options in a later article.

Solwise have a good article about filtering and home networking.