Adding a filtered faceplate to an NTE5 master socket

[John Rumm]

Yup that's generally true, however there is an exception...

To cut down noise introduction on more "difficult" lines, its often advised to not run the bell wire in the domestic wiring - since this is unbalanced. Just run a pair for pins 2 and 5 on all secondary sockets. This does however mean that some phones won't ring, and one of the solutions is to use a plug in filter for these, since that will regenerate the ring line locally.

(the better alternatives are to use PABX master sockets for all the extensions (has the ring cap like a master, but not the surge arrestor and test resister), or simply fit a bipolar 10uF electrolytic cap between pins 2 and 3 on the back of a normal extension socket)

[dennis]

There are filter plates that have idc connections for the unfiltered ("ADSL") side and the filtered POTS side. So it is possible to run extensions that still need filters after the plate. It probably isn't common but Murphy says you will find one after you have tried everything else.

[tony sayer]

Well how is it then that we have a lot of installs over CAT 5 and no problems whatsoever?. One carrying ISDN 30 the others ISDN2e and the others POTS services as well as APPL's ?..

Well if thats the case then there must have been something wrong with that pair, more then likely a short to another pair and if you see some of the blokes who pull these into ducts you'll understand when in a 200 pair sometimes they can only get 75 % of them to work the others are beyond redemption;!.

Was the cable connected properly?. The correct "pair" colours?..

[tony sayer]

Umm ... thats supposed to be like that..

[tony sayer]

Got much of that up on poles then?..

Well its a wonder that it works as well as it does Dave, but until something better comes along then yer stuck with it..

Here in civilisation we have a co-ax cable;)...

[tony sayer]

In article , Frank Erskine scribeth thus

Quite!. Just consider it like this.

In your incoming phone like there are two component AC signals. One the voice part around 300 to 3500 Hz. Above that the ADSL part on Radio frequency carriers around one MHz or so.

The filter just separates them out. Voice one way, ADSL carriers the other way.

Once they are separated then thats it, they don't need any further separation..

Best way is,

ADSL signal off to modem/router. / Incoming line --- filtered faceplate -- \ Voice signals to phones

You can of course plug just the one phone into the filtered faceplate, and then extend any other phones off the terminals in the faceplate provided for that purpose these are already filtered, they don't contain any ADSL components..

[tony sayer]

In article , dennis@home scribeth thus

Thats because its poorly understood like it seems you've interpreted the filtered faceplate;!...

[Mathew Newton]

Hi Tony,

Are you sure that's right? I always thought that only the voice branch is filtered (low pass) and that the ADSL branch is actually left completely unfiltered i.e. it still contains both ADSL *and* voice carriers - the high-pass filtering is performed inside the ADSL modem.

Mathew

[John Rumm]

A popular misconception I fear. Many filters only apply a low pass filter to the audio side, and none at all to the broadband side. That's enough to prevent any DC switching on the audio circuit from creating transients in the ADSL frequency range. (and also prevent any "hiss" being detected in the occasional clunky phone that would otherwise manage to demodulate some of the ADSL signal). The modem usually does not care about any audio frequency signals below its normal operating band.

[dennis]

I have not misinterpreted the face plate, just pointed out that they are not all the same.

Going by some of your comments I don't think you understand it very well.

The filters are low pass and are there to stop phones and such like interfering with the line characteristics for the ADSL signal. There is no requirement to filter the ADSL signal from the phone, phones have to reject RF noise anyway. The ADSL modems digital filters reject the audio signal on the line the same as they reject any other interference.

[John Weston]

Tony, I think you misunderstand me. The OP was considering _not_ using a filtered faceplate at the master. This would leave the phone socket on the master, plus any downstairs phone sockets connected to the master, carrying the combined signal. If someone in future plugged a phone into the master's unfiltered faceplate socket socket it would severely reduce of kill the ADSL performance. If it can happen, it will.

I'm advising that all the "BT-style" sockets come from the filtered side of a fixed master or slave socket filter - no temporary plug-in filters that can get removed and lost. All the combined, unfiltered signals going to the one (there can only be one) DSL modem appears on "modem-style" RJ11 sockets only.

[Mike Clarke]

Yup, that's the way we're going to go. A mix of one phone socket needing a plug in filter and the rest not needing one would only lead to confusion and problems in the future.

[tony sayer]

Yes correct as such .. the -need- is to keep the ADSL signals away from the phone which will load them and do other undesirables, but in view of the confusion already over "ADSL" filters this was intended to simplify the concept;!....

[tony sayer]

Which the above comment related to!..

OK..

Yes a "correct" method;)..

[tony sayer]

In article , dennis@home scribeth thus

What different ones are available then?..

Correct..

Think about that statement...

[tony sayer]

In article , dennis@home scribeth thus

Got a BT part reference number for that anywhere?..

[tony sayer]

As mentioned in the other post John, for simplicity of the concept;!...

[Dave Liquorice]

signal

Only the last 50m. Out of the ground, up the pole, across the road down the front of the house through the window frame, master socket, filter and ADLS modem on the window cill.

Quite agree, when the BT bods come here to fix faults they normally express some surprise that I get as good as ADSL as I do. A mile further on down in the village it's down to 1Mbps or less.

Coax, pah! We *might* have FTTP within the next couple of years.

[Mathew Newton]

I don't think there are any BT-supplied filter plates like that, however popular aftermarket ones such as the ADSL Nation XTE-2005 and Clarity plates do. Incidentally, the latter I believe are factory modified 'BT' units with the hardwirable unfiltered connections added.

Mathew

[Andy Wade]

The program might take seven-and-a-half-million years to run...