OT Unusual Broadband Problem

[cpvh]

Well, one i've not heard of before anyways.....

Friends in the next village (Broadbridge heath, West Sussex) have a Dell PC conncted to orange broadband via the USB ADSL modem supplied by Orange.

For about a week now they have been unable to use the connection except when they are using the phone for a voice call.

They have tried :

Plugging the modem directly into the master socket (well, via a filter) with all other exts unplugged.

Trying 3 different micofilters.

Spendijng ages on the phone to Orange Broadband at some extortionate cost checking and re-checking settings.

Getting BT to check the line (supposedly ok).

Anyone seen this before and know what the problem is?

[DIY]

How about trying another known working USB ADSL modem?

[Andy Cap]

You could try taking the faceplate off the master socket and plugging the filter into the BT part, that would eliminate any internal wiring.

Andy

[JohnW]

No... get rid of the USB Internet connection c**p completely and try a modem/router, such as

at around £20. Much better for your average home user, providing they have a 10/100 Ethernet port. It doesn't need the PC to work at controlling the ADSL "modem" using the dial-up networking software in a manner for which it wasn't designed and provides a good measure of protection from the Internet baddies.

It sounds like something in their computer driving the dial-up networking has got changed. This is a common occurrence if they have downloaded the ISP provided "let us help you fix your computer problems" revenue generation software. Typically, this can't see the difference between a USB modem used for ADSL and one used for normal dial-up. Change the hardware to a modem/router and tell the computer that the Internet is available via their new LAN.

[Bob Eager]

If you look back in the group, there are many instances of this. Usually due to a bad/dry joint somewhere on the line. Using the phone sticks some current down the line and temporarily makes the bad joint work a bit better.

BT need to do some more specialist work on the line, I guess. Good luck getting Orange to agree to ask them, though.

[Steve Walker]

Get them to re-check that every other extension really was unplugged, as the broadband only working when on a voicecall was exactly the symptom my sister-in-law had when she'd missed an extension in the kitchen.

[Newshound]

I just had something a bit similar; BT kept insisting the auto test showed the line OK even when it was almost too noisy to talk on. In my case I kept posting faults on the web site and, to be fair, a technical person (not a helpdesk) calls and talks you through faceplate removal, etc. They are a bit nervous about coming out to find the problem is "your" side and then either carrying the cost of the call-out, or having trouble getting you to pay for the repair.

In my case, having proved it was an "outside" (i.e. their) problem they came along and fixed it. It might be an inside problem though.

[Neil Williams]

Actually, yes. In the occasion I saw it it was a line fault - but it was difficult convincing BT of this.

I have heard of the same thing happening due to a faulty filter, though, so given that they only cost a couple of quid it might well be worth trying that first.

Neil

[The Natural Philosopher]

Remember that an on-hook telephone is IIRC a shorted phone. More or less. The point of the filter is not not make it shorted with respect to high frequencies.. if taking a phone off stats the broadband, the filter is not in the right place or not doing its job.

[Andy Wade]

YDNRC. An on-hook phone looks like a highish impedance, essentially the impedance of the bell or ringer. For a REN of 1 the impedance is about

4 kohm at ringing frequency. At DC an on-hook phone should appear an an open-circuit. But, as you imply, all this is irrelevant if the filtering is working OK.

Or, as already noted, the DC line current is 'wetting' an intermittent connection in the exchange line, reducing attenuation and/or intermodulation of the HF DSL signal.

[Dave Plowman (News)]

Hmm. My broadband works without any filter and with all the many phones on their rests. The filter(s) is/are to stop the ADSL carrier interfering with the phones - not the other way round.

[Huge]

OTOH, until we got a filtering master socket, my broadband didn't work at all. No matter what you did with the phones. Despite the fact that all the internal wiring was installed by BT.

[JohnW]

Filters work both ways. They do stop the ADSL signal affecting the phones and seeing the phones' variable load impedance. They also stop high frequency noise generated by the phone and its wiring being conducted back into the wires carrying the ADSL signal. Such noise is generated by taking the handset off the rest, for example, (step change in load = high frequency components) Also some DECT phones can get some part of their radio signal onto the line, due to the phone wire and aerial being adjacent.

Practically, I've had several cases where the noise level, as measured by the ADSL modem/router, has been improved by removing those (cheap) plug-in filters and replacing them with a good, single faceplate filter at the master socket. This prevents the ADSL part of the signal being sent over the unknown quantity that is the house wiring, where it can pick up noise from house sources such as fluorescents, thermostat contacts, switches, etc. There is an inbuilt filter in the modem/router that removes the signal below 4Khz in the POTS band but does nothing for noise components above this in the ADSL band (up to 1.1Mhz)

[Derek Geldard]

It's t' other way round. that's why you can measure the line voltage with a phone plugged in. If a phone represented a short you could never have extensions wired in parallel.

No it's to stop a loop disconnect phone shorting the line (at carrier frequency, it doesn't stop the DC) at 10 pps whilst it's dialling, causing the modem/router to retrain.

No doubt the adsl carrier is at a supersonic frequency but what effect it would have on an electronic phone is anybody's guess.

DG

[Derek Geldard]

That *has to be* a wiring error.

DG

[The Natural Philosopher]

That depends on what is inside the phone.

[Huge]

The matter is of no interest to me, especially since (i) it has been "fixed" by the fitment of a master socket filter, (ii) I would have to pay someone to investigate it.

[Derek Geldard]

If BT did the wiring they should fix it for free, or that is to say, for the expenditure of an *Infinite* amount of hassle on your part.

;-)

DG

[Dave Plowman (News)]

Well, there's a goodly selection on this line including an old one. Although of course it is filtered now with one at the master socket and a router fed directly off that. But when first playing with it my results were as above.

[Dave Liquorice]

ADSL carriers, plural. Upstream starts near 25 KHz up to around 138 kHz and the downstream from there right up to about 1.1MHz in 4 kHz (or there abouts) steps. This is for the now common 8 Mbps service. The 24 Mbps service doubles the top frequency to 2.2 MHz. Which is why it doesn't work any better than the 8 Mbps service once the local loop is about a mile long.

The filter is to stop phones shunting the low level RF carriers rather than them interfering with the POTS.