In reply to a post by systemx:

Yes sorry I did mean you. The two filters impose a lot of attenuation if.

(1) First filter is pluged in to the telephone socket as normal.

(2) Second filter is pluged into the phone socket of the first filter.

(3) the router is connected to the router socket of second filter.

They wouldn't be much of a filter if that worked. Explain how a line can be "too short"

It is not intended to be a filter, but to add atenuation to a line as a test to see if the router would sync. Its uncommon as most routers will deal with the line attenuation during the sync with the dislam, but it is possible that the line is just too short so the router syncs at a low speed. its much more common on fixed speed services, but always worth a try if you get a low speed with a very low attenuation.

Edited by deleted (Sun 31-Jan-10 17:08:41)

In reply to a post by systemx:

It is not intended to be a filter, but to add atenuation to a line as a test to see if the router would sync. Its uncommon as most routers will deal with the line attenuation during the sync with the dislam, but it is possible that the line is just too short so the router syncs at a low speed. its much more common on fixed speed services, but always worth a try if you get a low speed with a very low attenuation.

This sounds like an entry in the BT book of excuses.

Fair enough, have it your own way. Its not intended to a cure, as the filter would add a hell of a lot of attenuation, and if the router did sync, would indicate a problem which would need further investagation.

Edited by deleted (Sun 31-Jan-10 17:56:36)

One factor that might be acting non-intuitively is that the phone line is, basically, a tuned circuit akin to an antenna. It might be possible to have certain critical lengths which are in tune (resonance) with some local interference... changing the length of the line - in either direction - could detune it, thereby attenuating the "rogue" frequency.




[Dear BT, can I have a job on your excuses panel :) ]


John.

Hi systemx,
I'm still not sure that's right! Can you try it and report the attenuation figures?

I would do if my line was that short, but at a guess it would add 30dB to the attenuation.

But wouldn't it (your suggestion) change your attenuation whatever your line length?

Yes but on my line it would no sync at all.

This should only be tried on very short lines (less than 10dB) and then only if there is a problem. Most routers will cope with very short lines and give the results you would expect, full sync and a large SNRM, but if the router does not, or as in this case syncs at a higher speed when using an extension, with a very short line, then its something that can be tried.

Jus to back you up on this, seeing as you know more about it than the rest of us put together, in the time I've been using these forums I have seen something like two or three reports of people moving very close to an axchange and finding their broadband gets lousy speeds on very low attenuation.

IIRC one solution is to reduce the output power? Though from the opening post that is already happening.

Edited by RobertoS (Mon 01-Feb-10 16:49:16)