Investigating telephone extension

[Hugo Nebula]

Please bear with me: My ADSL router is connected via an extension from the BT master socket in the hall. The distance to the exchange is high and I've never got a particularly good connection, but it's been acceptable at 1Mbps. I'm with UKOnline/Easynet LLU.

Over the last few days the speed and the stability have dropped markedly. It happened between 6:00pm and 8:00pm on Wednesday. On phoning my ISP, they said that it could be my internal wiring (well, they would, wouldn't they?).

Now, how to test that? The bits of kit I have available are: a screwdriver for removing the faceplate's screws, a USB DSL modem, DR Speedtouch, and a Netgear router. So far, the only results I've been able to establish with any certainty are:

1) when plugged into the socket behind the faceplate, the results from the DR Speedtouch log are Receive Attenuation=54dB & Receive Margin=13dB; 2) when plugged into the socket on the faceplate and to the extension in the study, Receive Attenuation=54dB & Receive Margin=11dB; 3) currently, according to the router, Line Attenuation Downstream=58dB & Noise Margin Downstream=wobbling around 12 to 14dB; 4) Connection Speed according to the router=1152kbps, speed test results currently 965kbps.

The current connection is OK, but I had to re-boot the router this morning to get it.

The difference between the logs' margins of 11 and 13 doesn't seem that great, and AIUI anything greater than 10 shouldn't be detrimental. Does this indicate that the problem is likely to be on the BT/LLU side of things? If not, how can I test the quality of my internal wiring?

[The Natural Philosopher]

Well before you go fussing and fiddling, bear with ME.

In my new install drearily documented in anther thread, I have seen noise levels and connection speeds dropping at precisely the same times of day ..my conclusion is that the cold weather is affecting either the lines, or the amount of electrical noise..from a reliable synch at 4800 a few days ago, post last night the best I can get is 3600..

Its probably loads of CH thermostats arcing and clicking in your neighbourhood.

Sounds about right.

Slightly better, but not much.

that should be OK for reliability..it looks like your line is subject to burst noise tho, as normally you will synch at 6-8dB SDNR.

Looks like BT has (rightly by the sound of it) adjusted you for a high noise margin. Or if it's LLU then easynet have.

Its a bit warmer today ;-)

I think that in reality there is nothing you can do.

The attenuation and noise sounds like you are several miles from the exchange, and basically there isn't much you can do about it:

Everyone blames microfilters blah blah blah, but the reality is that long lines are noisy and lossy and that's that.

I am running reliably at the moment at 45DB attenuation and 7.5dB margin..that means that my noise spike trigger level is equivalent to

52.5dB 'noise floor' for 3.6Mbps.

You are connecting at a third that speed, so given similar noise floors you should be able to hit 5dB more..57.5dB..In fact you are operating at

70dB..frankly I am amazed you can get THAT much.

Obviously its worthwhile scraping what you can with top quality filters, but don't expect miracles.

You noise margin is high, which the ISP can (get?) lowered for you,but you may end up trading speed for unrelaibility. The longer the line the higher the margin needs to be.

How far from the exchange are you? Attenuation suggests maybe 5 miles or so..?

[Simon]

OK up to now.

That's because it's peak time when loads of people switch on and try to use the Internet. The company you are paying can't keep up with demand so everyone has their transfer speeds lowered. What do you do with your internal wiring each night between those times! That's just on their "get shut of the caller" scripts they have.

It's nothing to do with your wiring, outside temperature, rain, full moon or buses going past - it is the ISP unable to cope with demand in peak times. Simple as that. Look for a different ISP.

[Hugo Nebula]

On Sat, 17 Nov 2007 12:11:59 +0000, a particular chimpanzee, The Natural Philosopher randomly hit the keyboard and produced:

When I first signed up, it was for 2Mb. That worked well enough for a couple of months, but I started having problems, and UKOnline lowered my line's speed to 1Mb in February 2006. It's been fine until three days ago. IIRC, the figures were around 56db & 15dB.

About two as the crow flies. Probably 3 miles if the cables follow the main roads. All I know is I'm at the edge of my exchange's area.

[Bob Eager]

How would that affect stability?

[John Rumm]

We had a recent case where speed started dropping. This was shortly followed by loss of voice quality and finally loss of all voice - the ADSL hung on though. BT were called out and replaced the cable from the pole (and commented that they had not seen a cable that old for ages!). Apparently one leg had eventually gone open circuit (hence loss of voice).

So don't rule out the possibility of a line fault. Its getting damper this time of year, so any external line junctions are vulnerable.

Quite high attenuation, but a decent margin. (I get 32/7 at 448/8128 bps).

That suggests the noise immunity of your internal wiring (or possibly your microfilter) is not that good. How long is the cable run? What type of wire?

A decent face plate "whole house" filter as the master socket, with the router connected there ought to get you the best results. Rather than routing the ADSL over too much internal cable, its better to take the ethernet (via home plug or wireless if needs be) through the house.

You would expect the sync speed to be a little over the true data speed since the ISP will have to throttle the data into the ATM network at

*typically) a little under your sync speed.

Having to reboot on the odd occasion (i.e. once every few weeks) is not that uncommon even with the best of installations.

It seems like you have already tested it reasonably well. There is obviously scope for improvement - but not drastically.

[Dave Liquorice]

Ah, sounds like a crap lossy line then. Our line length is similar but with 43dB loss, SNR 15dB day 7dB night and stable sync speeds are in the low 5,000's. Is voice clear and noise free?

3 miles is not the "edge of an exchnage area" at least not in a rural area. Long lines are 10 miles+ and struggle for voice to work let alone ADSL...

The LLU may well add to the problem as well, yet another reason for the involved companies (BT Openreach (the wire), BT Wholesale (the backhaul), UKOnline/Easynet) to bounce the problem between themselves.

[newshound]

Agree with all that. Performance does vary with time. External line quality regularly drops following heavy rain even though BT insist is is "fine". I have a wireless router in the middle of a large-ish rubble stone house for convenience, with wired ethernet to the main computers. Certainly got an improvement in performance by running a better quality ADSL lead from the RedFishShop direct to the master socket instead of to an extension.

[Hugo Nebula]

On Sat, 17 Nov 2007 14:25:33 +0000 (GMT), a particular chimpanzee, "Dave Liquorice" randomly hit the keyboard and produced:

Yes.

I'm in a city suburb, and a few roads away the houses have different codes and are served by a different exchange (according to Samknows).

Is that a euphemism for passing the buck?

[Dave Liquorice]

Yes.

That's a bugger, as getting BT Openreach to sort out a noisy line is damn site easier (even with LLU) than getting them to trace a problem with ADSL.

Ah, lines in built up areas can go, literally, around the houses on their way back to the exchange, taking really circuitous routes. Unless you know you only have a 3 mile line by talking to a BT engineer fixing it, (he'll know from his reflectrometer) there could be a couple of miles spent wandering off in strange directions.

If you like, yes.

[Hugo Nebula]

On Sat, 17 Nov 2007 11:34:44 +0000, a particular chimpanzee, Hugo Nebula randomly hit the keyboard and produced:

Have just done a good couple of hours plugging routers, USBs, filters, etc in all kinds of holes in all possible permutations. The conclusion is this; the problem is somewhere between the test socket and the socket on the faceplate.

I get the full 1Mbps speed test when connected via a USB or router, with or without filter into the test socket, but anything plugged into the faceplate socket drops to ~850kbps, and out of the 8 speed tests, four timed out and the remainder got between 400-600kbps.

Can I replace part of this master socket? If BT do it, will they charge (and roughly how much)? Do I go through my ISP or BT?

[John Rumm]

Replace the whole socket and try again:

better still, replace the faceplate with a ADSL-NTEFACE:

will filter all the house in one hit, and also has ADSL outputs on both the back and front (so you can do a wired ADSL extension without needing to use the RJ11 on the front of the filter)

[The Natural Philosopher]

Yes, and the recieved wisdom is that a filtering faceplate is the best of all.

Try some contact spray on what you have first as well.

[Dave Liquorice]

But isn't the case here. Bought an XTE2006 on the basis that it got good reviews and would neaten up the wiring. On my line with my router (ZyXEL) it was worse by a consistent and significant amount than the plug in BT badged MF50 microfilter.

As with a lot of things related to ADSL it's suck it and see...

Unless you are going to use that highly expensive contact stuff(*) you may as manually clean the contacts (if they are visibly mucky) or just plug things in and out a few times. Phone and RJ45 contacts wipe very well when insterted/withdrawn thus keeping the mating surfaces pretty clean.

(*) Stabilant 22. Though I have my doubts that it's cost justifies its routine use on decent connectors.

[shaq]

Even better, use DeoxIT. Works better, easier to apply, lasts longer and is much less expensive.

Mike

[Dave Liquorice]

Rival product with some legal battle in the present or past IIRC, or if not legal a lot of FUD from both companies. Both are still rather close to the serpentine for my liking.

[shaqtopz]

Want something that works better than stabilant, try Deoxit and DeoxIT GOLD. Chemically improves the connections, last a long time, many convenient applicators and most important, works on moving as well as stationary connections (under vibration). It is more of a very thin liquid, then a grease, so it moves with the connection. You do not even have to apply if to both plugs and sockets. If you can not apply it to one of them (which is sometimes imposible), it will migrate to the other metal surface and treat it also. Stuff is amazing AND very cost effective. Not dirt cheap, but worth every pennie. Been using it for over 10 years and it sometimes amazes me how well it works. Go to

for info. Mike