Believe they mean this faceplate http://www.run-it-direct.co.uk/btvdslfaceplate.html

Filtering requirements are the same for ADSL/ADSL2+ and VDSL

Have you put a typical ASDL and VDSL filter on a spectrum analyser? A colleague has and the performance of the ADSL filters above about 5 or 7 MHz was abysmal. It is not just teh requirement to keep the lower frequencies off the audio band but needs to ensure there is no significant attenuation or phase change at the higher frequencies.

I did actually post some comments on it soon after he had tested them.

http://www1.btwebworld.com/sinet/498v4p1.pdf
and this leads to
http://www.etsi.org/deliver/etsi_ts/101900_101999/10...

A lot depends on the components and values - might have to rip a few apart to see what value components are used.

Have a close look at the specs from page 41 onwards and there are different complex impedances listed. Cross talk on an ADSL filter is only defined up to 1.1MHz whereas on a VDSL2 it is 30MHz ... Above F_H the attenuation is undefined - for an ADSL filter that is 2.208MHz and thus it could be quite high which would adversely affect VDSL

Tables A4 & A5 show significant differences for the frequencies specified on ADSL/VDSL.

Edited by MHC (Fri 14-Dec-12 22:24:35)

I'm old .. so perhaps using the wrong term. He took the extension cable and the cable from the outside world and joined them together in the box. What happened is that the extension cable hadn't lost the plastic covering so wasn't making a connection.

As below, I thought that the top was 'straight through' and the bottom / extension were pre-filtered. Up until this point I had to have filters on all the extensions.

In reply to a post by boxst:

I'm old .. so perhaps using the wrong term. He took the extension cable and the cable from the outside world and joined them together in the box. What happened is that the extension cable hadn't lost the plastic covering so wasn't making a connection.

As below, I thought that the top was 'straight through' and the bottom / extension were pre-filtered. Up until this point I had to have filters on all the extensions.

Are you sure?

The cable from the outside world should be terminated on the A & B screw terminals. The extension should be on the filtered output and the plastic covering should remain in place - the IDC jaws just cut through the insulation to make contact. the should NOT be joined together inside the box!.


Can you get a picture with the lower half of the face plate removed?

Not 100% sure. I will take off the faceplate later and have a look.

If that is the case, I wonder if I will get better speeds by rewiring it. Estimate was 80/20 and getting 75/18.

In reply to a post by boxst:

getting 75/18.

That is full speed, the 80/20 is without the required overheads.

Picture here: http://www.sadandlonely.com/btfttc.JPG

Two wires from the outside world behind the main plate, then the extension attached as in the picture (with 'joins').

COWBOY ...

And why? is the wire from the extension not long enough? If so, it is one way to extend it but even then he should have used appropriate CW1308 cable and ensured the colour coding was "normal" and not used what looks to be jumper wire.


edit to add:

Just for reference, the picture shows the location of the straight through VDSL extension connection at the top left. Useful if you want to hardwire to a remote location for the modem.

Edited by MHC (Mon 17-Dec-12 12:12:58)