Hugo Nebula wrote:

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?).

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.

Now, how to test that? The bits of kit I have available a 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 a
1) when plugged into the socket behind the faceplate, the results from
the DR Speedtouch log are Receive Attenuation=54dB & Receive
Margin=13dB;

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

2) when plugged into the socket on the faceplate and to the extension
in the study, Receive Attenuation=54dB & Receive Margin=11dB;

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.

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.

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.

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

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

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?

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


--
Cheers,

John.

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