ADSL Line impedance (was DSL lead pinout)

>>
>> Are all router modems using the same dsl lead (pins) and if so which
>> carry the 2 wire signal. My stock lead has all 6 wires terminated
>> both end so I can't see. I want to break in to the dsl feed by
>> building an rj11 socket to plug filter and plug this into my router.
>>
>> Much obliged.
>
>It uses the middle 2 pins of the 6.
>--
>Cheers,
>Tim
>______

All good stuff thanks, I've now split my adsl lead on it's way to the
router/modem - indeed, an rj12 (6p) with centre is feed.

Next question, I'm having difficulty with is; what is the line impedance of
the b/b modems - after the filter plate to modem(router). I assumed 600ohm
but I'm wrong. Is there a standard/spec they work to, has someone
determined it all works better is xxkohm and what would that be (I need this
to design my filter properly).

Getting there ...

On Sat, 18 Jun 2005 09:29:15 GMT, "317" <(E-Mail Removed)> wrote:

>Next question, I'm having difficulty with is; what is the line impedance of
>the b/b modems - after the filter plate to modem(router). I assumed 600ohm
>but I'm wrong. Is there a standard/spec they work to, has someone
>determined it all works better is xxkohm and what would that be (I need this
>to design my filter properly).

you are designing a filter ?

try the BT SIN 346 at http://www.sinet.bt.com/
pages 12 and 13 are full of impedances and the like.

It talks of 100 ohm sources, complex impedances and the like.

Bea rin mind the modem isn't filtered at all, so is it not more a
question of the impedance fo the telephones ?

Phil
--
Tiscali - dialup speeds at Broadband prices, see
http://bbs.adslguide.org.uk/postlist...&Board=tiscali

AOL - the unlimited ISP of choice for heavy downloaders.

> All good stuff thanks, I've now split my adsl lead on it's way to the
> router/modem - indeed, an rj12 (6p) with centre is feed.
>
> Next question, I'm having difficulty with is; what is the line impedance
> of
> the b/b modems - after the filter plate to modem(router). I assumed
> 600ohm
> but I'm wrong. Is there a standard/spec they work to, has someone
> determined it all works better is xxkohm and what would that be (I need
> this
> to design my filter properly).


Whilst I admire you technical adventuretwo things occur. Firstly, AFAIK,
you are not allowed to connect unapproved kit to a BT line. Secondly good
quality prebuilt filters are available for less than a tenner. Maybe I have
missed the point!

Peter Crosland

>
> you are designing a filter ?
>
> try the BT SIN 346 at http://www.sinet.bt.com/
> pages 12 and 13 are full of impedances and the like.
>
> It talks of 100 ohm sources, complex impedances and the like.
>
> Bea rin mind the modem isn't filtered at all, so is it not more a
> question of the impedance fo the telephones ?
>
> Phil
> --
Yup, but not quite all my own work - I do have some software tools to help a
little.
But I have gone the wrong way if it is that low. I'll nose about the site
linked above.
I'm hoping mine will be filtered before too long - but for a very good
reason as I'm getting an interfering signal on the line at my end that
sometimes reduces the s/s+n ratio too low to maintain sync.
Sorry Peter, can't see your post!
Thanks.

317 wrote:
>> you are designing a filter ?
>>
>> try the BT SIN 346 at http://www.sinet.bt.com/
>> pages 12 and 13 are full of impedances and the like.
>>
>> It talks of 100 ohm sources, complex impedances and the like.
>>
>> Bea rin mind the modem isn't filtered at all, so is it not more a
>> question of the impedance fo the telephones ?
>>
>> Phil
>> --
> Yup, but not quite all my own work - I do have some software tools to
> help a little.
> But I have gone the wrong way if it is that low. I'll nose about the
> site linked above.
> I'm hoping mine will be filtered before too long - but for a very good
> reason as I'm getting an interfering signal on the line at my end that
> sometimes reduces the s/s+n ratio too low to maintain sync.
> Sorry Peter, can't see your post!

Just adapt the feed to the burglar alar (?) so's that it goes thru an over
the counter filer, or even buy one, remove the casing & then just solder the
connections to the appropiate tags...

Why invent the wheel when it has been adequately done already...