ADSL microfilters

Ladies & Gentlemen, I give you, Microsoft Windows!

AIUI there is now no limit on line length, the limit is now just what a particular line will support (and what you want to pay for). Before if your line was >6km then they wouldn't even come out to try.

unsatisfactorally

Just to add to this a bit more, the facia plate splitter from Clarity has a nice feature: As well as two sockets out - one filtered for the phone and one clean unfiltered for the ADSL, it has two extra terminals on the punch down block inside (marked A and B) so that you can neatly run a few metres of cable with the clean unfiltered signal for ADSL to another extension socket, and then plug your ADSL modem in there.

My line is LLU and I use UKonline as an ISP . Using this technique, my line speed has gone from 3.6 Mbps (when using micro-filters) to 5.2 Mbps, so the facia plate splitter makes a significant difference. Not bad for 3.5 Km from the exchange on a line that BT said would be luck to get 2M.

cheers, Mike

And a load of noise on the phone?

And possibly a lower than normal upstream data rate (not that BT exactly push the technology to its limit in this direction). Also if you use an old bell type phone the ADSL is almost killed dead by some internal diodes.

ADSL signals start at 1MHz. You should not be able to hear anything on the line without the filters. If you do hear anything its not the ADSL.

The filters are there to stop the ADSL being interrupted by impedance changes when you pick the phone up. These changes in line impedance cause retraining of the line and a break in access.

I assume you mean stops. Upstream runs from 32kHz to about 100kHz. Downstream from about 120kHz to 1.1MHz.

You will because any diodes in the telephone rectify the incoming signal in the same manner as a crystal set and you hear the modulation of the ADSL signal - which sounds remarkably like noise.

Well they do smooth these out a bit. The original BT active splitter was excellent for this but people didn't like having another wall-wart.

Retraining only occurs if the modem cannot carry on from its current sync timing after a noise impulse - be it a line change, lightning or whatever. Thus for most noise you only lose about 2mS worth of data. If the modem has to retrain it will take several seconds min, up to 30 seconds theorectical worse case.

All I can report is what happened when my mum went ADSL. Before I installed the (central) filter, if you picked up a phone to make a call you could quite clearly hear a kind of white noise. You could make a call as normal, but the white noise made it a little difficult to hear what was going on, though after a while said noise would cease. Co-incidentally (or not) at the same time as the noise ceased, the ADSL modem would go offline, and wouldn't reconnect until you had finished your phonecall.

There's no way my ears can hear 1MHz so I suspect that something a *lot* lower was on the line :-)

Hwyl!

M.

I have detected that sort of noise on about one handset in ten (without a filter)... most don't pickup any noise, but the ones that do can get it quite bad!

(That is why some exchanges will disable the ADSL signal until after a ADSL modem is detected as being connected for the first time)

In message , Martin Angove writes

Well I report my experience, as ever it seems the opposite :-)

I just recently gone ADSL, the ADSL was activated earlier than expected and the filters etc. weren't fitted (I'm using the dangly plug in filters until I figure out the wiring in this place, and get suitable round tuit)

I could notice nothing different when picking up the phone. I don't know how it would have affected the ADSL connection though. I guess it depends on the phone itself ?

Often the case in my experiance (installing several ADSL setups a month typically)

The voice usually has no effect - the picking up and/or replacing the handset however often drops the ADSL carrier for a period (the duration being dependent on how quick the modem/router gets its act together and reconnects)

Shoving high level carrier into a cordless phone base station might end up with any result. Same, I'd guess, with ordinary phones. I got noise on mine - and so have others I know.