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Diagnose ADSL connection

Was at the house of someone else in the village today and their broadband is basically unusable.

The line is about 2850m long. Line quality round here is terrible, but I'd have expected a little better than this - a neighbour to him manages 4 Meg on their line with errors being tossed all over the place.

ADSL Line Status
Connection Information
Line state: Connected
Connection time: 3 days, 03:37:27
Downstream: 1.122 Mbps
Upstream: 1.079 Mbps

ADSL Settings
VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.3 Annex A
Latency type: Interleaved
Noise margin (Down/Up): 10.1 dB / 6.5 dB
Line attenuation (Down/Up): 39.2 dB / 21.0 dB
Output power (Down/Up): 16.3 dBm / 12.5 dBm
FEC Events (Down/Up): 630934890 / 18873
CRC Events (Down/Up): 369 / 1120
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
HEC Events (Down/Up): 456 / 1356
Error Seconds (Local/Remote): 338 / 814

This might be all the line can do, but this doesn't look right to me. The noise margin is actually very good for this area, 15 is typical, but not only is the throughout nearly non existent but the connection repeatedly "goes away for a while".

Is anything wrong with this, and what should he say to BT when he calls them?

For voice the line does occasionally have noise (crackling) on it.
 
The Noise Margin is basically the wrong way around for a normal line. If it was normal then I'd expect upstream to be higher than downstream (maybe about double). A high margin on the downstream side thus does tend to suggest an issue with the voice line, perhaps a high resistance fault caused by corrosion in a joint or something. The upstream attenuation is similarly a bit mismatched.

I would suggests a line noise check.

Also, and correct me if I'm wrong since I might have it the wrong way around, but the modulation of G.992.3 Annex A is for basic ADSL2 and not the ADSL2+ (G.992.5) that a lot of ISPs use.
 
Mark2,

The first thing that needs to be resolved, before getting anything moved forward is those HEC errors. First thing, change the internal filters and RJ11 cable. You want to see those down at 0.

With the HEC errors gone, which normally highlights poor wiring, you may find the other bits of data start to fall back into line and at least give you a fighting chance.

Mark.J is right, the modulation has opted for ADSL2, rather than ADSL2+. Though at this stage I would force, via the router, to drop it back to g.DMT (ADSL1) whilst repairing the line. ADSL2+ will cause a line to drop far more often if in a poor state. More drops, worse the stats will end up.
 
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The noise margin is actually very good for this area, 15 is typical.

Can I just clear up this point for you. Areas don't have typical noise margins. It's line specific.

All BT lines have a target of 6dB (20CN) and 3dB (21CN), which the default setup. Any line that has increased, normally in steps of 3dB, away from this have resulted in the line being subject to noise or repeated dropped connections (rapid user router reboots will be classed as drops).

Al lines can have this figure reset by their ISP, however, the line needs to be stable. If a connection can hold a solid connection for 3 days (normally via good quality wiring/filters) you can normally engage with your ISP to reset this or lower it down. This will result in a high sync rate.

Therefore if your coming across higher than default figures, it's simply down to the above and not down to a regional problems/setups.
 
Are there/have there been trees that might be hitting the line???

I had weird stats on my old line - caused by thousands of micro-fractures in the cable.
 
Thanks - I have sent him an email to get him to check where the master socket is, if there is one (e.g. our house does not have one, it has a star setup, which may not be unusual in a village with a non transient population so the wiring never gets changed), otherwise the "first socket" e.g. the one nearest the dropwire, and move the modem so it plugs into that, while at the same time replacing the microfilter and cable from socket > modem. Then to give if a few hours, and then copy/paste the diagnostics into an email and send it back to me to compare.

When I say "15db is typical for the area" - I have stats for quite a few of the lines round here, and really, 15db is normal for the lines. There are only two which are lower which operate at 6db. There are also several lines where the noise is higher upstream than downstream and that isn't that unusual either (e.g. a 256kbps upstream sync). It's a small village of 240 houses ("the area").

The ones that have a 6db noise margin operate at the sync speed you might expect to see for the line length, all the others are more or less random, the line length and the performance do not correlate to each other at all. I had a guess this was down to aluminium circuits, knackered joint repairs, or all the DACS boxes pushing up the noise on the lines.
 
The house does have a master socket and the modem is plugged into that.

New filter and cable purchased, plugged in and new statistics as below:

ADSL Line Status
Connection Information
Line state: Connected
Connection time: 0 days, 14:44:52
Downstream: 1.122 Mbps
Upstream: 1.078 Mbps


ADSL Settings
VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.3 Annex A
Latency type: Interleaved
Noise margin (Down/Up): 10.7 dB / 6.5 dB
Line attenuation (Down/Up): 39.3 dB / 21.0 dB
Output power (Down/Up): 16.5 dBm / 12.6 dBm
FEC Events (Down/Up): 109483683 / 7327
CRC Events (Down/Up): 28 / 39
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
HEC Events (Down/Up): 10 / 11
Error Seconds (Local/Remote): 60 / 56

The modem was replaced a short while ago (new Homehub) which hasn't made any difference.
 
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Mark2,

It HAS made a massive difference, your just expecting instant results, which you won't get as the line noise margins have been fixed (maybe even a line banding added). The HEC errors have dropped by a huge amount which is the key.

The next stage is to keep the line stable (no reboots) for at least 72 hours. Once this has happened, then asked your service provider to lower the target noise margin (SNR). This will then result in an increased line sync.
 
Thanks Martin - will let him know.

To clarify, I meant that the change of the home hub didn't make any difference. But then it wouldn't have, since that doesn't appear to be the faulty component.

According to the Kitz website, attenuation of 39 = line length of 2800m so my guess wasn't far off.

That also says that the line "should" deliver an IP profile of 8.5Mbps which he'd be delighted with as it has been stuck at 1Mbps for two years.

A near neighbour syncs at 4Mbps with a similar array of errors on a (shorter) line length of about 2650m, a line about 2550m long - the fastest in the village by a long way - syncs at 7Mbps.

I think the Kitz stats are for 0.5mm copper lines, and I don't know that the lines are copper. But what would be realistic, so as to try to assess when this is "fixed"?
 
Here's how it looks now after a few days:

ADSL Line Status
Connection Information
Line state: Connected
Connection time: 6 days, 12:02:32
Downstream: 1.122 Mbps
Upstream: 1.083 Mbps


ADSL Settings
VPI/VCI: 0/38
Type: PPPoA
Modulation: Unknown or no mode configured
Latency type: Interleaved
Noise margin (Down/Up): 10.6 dB / 5.9 dB
Line attenuation (Down/Up): 39.3 dB / 21.0 dB
Output power (Down/Up): 16.4 dBm / 12.5 dBm
FEC Events (Down/Up): 1169816183 / 16082
CRC Events (Down/Up): 408 / 1237
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
HEC Events (Down/Up): 671 / 1749
Error Seconds (Local/Remote): 711 / 936
 
Right then. Have sent the "villager" an email summarising Martin's advice as above.

Apparently, in the meantime, the ISP has suggested sending someone around to replace the faceplate (2 years old, and the connection has always been this poor...) so I have recommended he reports back what he has done and tried, with the recommendation above.

And if all that doesn't get a resolution or some forward plan to achieve one, he changes ISP to someone who will actually deal with this long ongoing problem - and I'll recommend Aquiss to him. Martin, thank you.
 
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