It sounds like the Homeplugs are putting so much 0-30MHz RF into the BT modem that it simply can't cope.

I believe Homeplugs are a vile technology, putting RF energy onto cabling that is neither a differential twisted pair nor co-ax. This will give you two separate problems:

• your mains wiring will radiate that RF energy (in exactly the same frequency band as that used by DSL), which can be picked up directly by other equipment or can get in via cables (including the phone cabling)
• the RF energy can get directly into an affected device via its mains power supply

The usual way to figure out which one of these two problems you have is to power the affected device from batteries, which eliminates the second problem temporarily - but that is non-trivial for the BT modem which is not designed to be battery powered. You really can't blame the BT modem - Homeplug noise is often far over that specified in EMC immunity tests.

If you are determined to debug this, I'd wind a ferrite ring (following the diagram I've previously linked to carefully) on the BT modem's power lead as close as possible to the modem. That should minimise the second problem. If you're still getting problems, put another ferrite ring on the phone lead as close as possible to the modem, ideally changing that lead for a twisted pair one.


For optimal DSL speed you want to minimise the noise on DSL frequencies. A Homeplug is about the best source of noise you can get. If possible, put the Homeplugs in your nearest e-waste collection (vile things that they are) and install a cable in their place. A competent tradesperson should be able to run 5m of cable neatly for you if you don't feel confident in doing this yourself.

I'm going to look at purchasing some ferrite rings today, i'm looking on ebay, does it matter what size they are? as there's a vast variety of rings/beads on there

edit: what do you think about this bead?
http://goo.gl/qmBeL

Edited by deleted (Fri 18-Jan-13 08:57:32)

what about good old long ethernet cables? the proper way.

I actually think homeplugs need to be banned they seem very high interference. If they affect 0-30mhz How do I not know one of my neighbours are using any and affecting my vdsl?

also would a belkin filtered extension cable work?

Even then the noise will be picked up on te phone line which cannot be mitigated.


As for vile technology - I totally agree.

I found (after a comment by someone else on the BT forum) that my Homeplugs work better when the homeplug is not plugged into to a twin socket with all my other computer things plugged off the other side of the socket.

All my other computer things in this case are connected off a surge protected extension, and include computer, printer, gigabit switch and a few other bits. The modem and router are in a different place.

I knew not to connect the powerline into a surge protected extension; but was surprised how big a difference plugging it into the twin made. The powerline wasn't that close to any of the other equipment. Keeping it in the same place, but plugging into a longish mains extension itself plugged into another socket on the same ring improved speeds quite a bit. (I know a longish mains extension isn't a good idea either, but that was what was practicable in the short term.)

Text

1 23 45 67 89 1011 1213 1415 1617 1819 2021

signal ~~~~~modem-->router----/long ethernet cable/-----> switch --> powerline1 --/different ring/----> powerline2 --> computer2                                                   |                                                  ' ---> computer1    power~~~~~      twin  ----> surge protected extension --> switch    socket                              |----> computer1               |                                 '----> etc      '-> powerline1                                             <<<<<<<< BAD         twin  ----> surge protected extension --> switch    socket                              |----> computer1                                                 '----> etc      separate --/mains extension/--> powerline1                   <<<<<<< BETTER                                              socket

Well, in the end, i realised i could keep my network doing everything i wanted to, using standard wireless and a wireless bridge, so the home plugs will go on ebay shortly, thanks for the replys guys, feels great using my infinity at the speed i was expecting!