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[kitz]

>> a higher noise margin is better as this is the difference between the noise on the line and the data signal,

Yep correct.   Although with the rate adaptive products - more SNR = higher speeds..  but the higher the speed you sync at then this will obviously take up some of your SNR Margin.
Each 3dB of SNRM = anything from 400 -1200 kbps of speed depending on your bit loading.

>> if my router attenuation is 52dB shouldn't my upstream be the same?

No - Upstream subchannels use lower frequencies, and therefore often arent as attenuated at the higher frequencies used by the downstream. See DMT.

[pTang]

So Kitz, following on from your comment on another thread, my CRC/Header error blizzards are my router really struggling to see any signal.

As these seem to happen randromly (R in the month, I turned left after walking through the frontdoor, black cat on way home etc) is thisanother indication that either the line is shonky as hell or the DSLAM port has an issue?

'tang.

[kitz]

>> CRC/Header error blizzards are my router really struggling to see any signal.

Yes they are an 'early warning system' that the signal is struggling through increase noise

>> is thisanother indication that either the line is shonky as hell or the DSLAM port has an issue?

More likely to be EMI/REIN.  If it was anything at the dslam then youd expect it to be more or less continuous.

[pTang]

Good news - well, ok, better news. Bulldog are going to run remote line tests tomorrow! woohoo! - just hope I get the chance to talk to the engineer at some point.

Also, I aquired an ADSL2+ router for the night (it may have come from the office but I'm not saying) and I've got marginally better stats:

Downstream: Sync: 5020kbps, Margin 4dB, Power 17dBm, Attenuation 48dB - Margin is very low - between 1dB and 8dB
Upstream: Sync 575kbps, Margin 16dB, Power 12dBm, Attenuation 26dB

But on the flipside, I've got a RS EC counter that looks like the Jackpot totaliser in Vegas - but I get only the odd CRC/Header error.

As to the blizzard CRC/Header counters, I've tried to link them to something nearby that would EMF the hell out of the signal but there's nothing around the router/line at all. I've been right by the unit when it has gone nuts twice today and there was nothing happening in the house at all... no TV, dishwasher etc...

Hopefully the enigneer will agree that the line is barely hanging in there and will get that physically checked - and I may see if they can move me on to another port/card just in case.

Have a good evening all...

'tang

[kitz]

Hope the engineer visit went well

[pTang]

I'd like to say it went well - but it seems the person who scheduled the job didn't realise that yesterday was Good Friday. I got a call in the evening to say that the test didn't happen and it would be rescheduled on Tuesday. Yet another reason for UK based call centres.

Since starting this thread my line is getting progressively worse almost inline with the weather - or maybe it's linked to the economy?

[kitz]

it seems the person who scheduled the job didn't realise that yesterday was Good Friday. I got a call in the evening to say that the test didn't happen and it would be rescheduled on Tuesday. Yet another reason for UK based call centres.

 

[Weaver]

Shouldn't interleaving be on? I would have thought this needs to be turned on urgently (may be set to "auto"?)

I'm assuming that you've also checked for un-microfiltered extension sockets, gone straight into the BT test socket, changed microfilter models (good quality microfilters are of course essential) - usual stuff with recommendations for h/w to be found in my earlier posts on this site and elsewhere.

[pTang]

Well I got the call from Bulldog to say "We've fixed your line". Or at least I think that's what they said over the hiss on the line and the fact the call was from somewhere in Asia.

And how has that helped my stats? Occassionally I can get almost 6M downstream but more often than not it's with a 1dB margin and doesn't last for long. The attenuation has remained the same (~52dB still 12dB higher than before this all started). I did manage to find out that the engineer did "something" at the exchange. When I asked what exactly I was told "Thank you for using Pipe.... erm... Bulldog." <click>

So I'm going to open another call and dig my heals in until I speak to the UK engineers.

In the meantime I'm going to trawl round the house with a radio to see if there's anything here that just might be causing me to get a low margin - like a PSU on its way out or something.

Hope you all make the most of the sun this evening....

JB.

[kitz]

>> Or at least I think that's what they said over the hiss on the line

oh dear :/   Is it still noisy when making calls elsewhere?


>> Occassionally I can get almost 6M downstream but more often than not it's with a 1dB margin and doesn't last for long. The attenuation has remained the same (~52dB still 12dB higher than before this all started).

Doesnt seem to have made much difference - a line with 1dB isnt going to stand much chance of remaining connected. :/


>> I did manage to find out that the engineer did "something" at the exchange.

Obviously I dont know for sure, but that would seem more like they have been tweaking the adsl side of things.   The hiss and increase in attenuation is more likely to be related on the physical wire.


>> So I'm going to open another call and dig my heals in until I speak to the UK engineers.

I would do..  then you can explain that you think the problem is with the voice part of the line rather than just the adsl.


>> I'm going to trawl round the house with a radio

wont harm, but I still think the main problem is likely to be something like a rusty joint or worn cable.

[pTang]

Well there's no oddities on the AM band - all nice an DSLy.

I'm suprised I can even send this as current I have a -1.5dB noise margin! (with 49dB attenuation).

I had a look in the outside grey BT junction box on the side of the house and all the connectors look ok - if maybe a bit damp thanks to the heavy rain.

I'm still waiting for the engineers to get back to me.... ho hum.

[kitz]

>> I'm still waiting for the engineers to get back to me.... ho hum.

If  youve not heard anything soon then it may be worth giving your ISP a poke to see if theyve heard something :/

[pTang]

While I'm waiting for someone/anyone at Bulldog in the UK to ring me about the jump in attenuation and the noisy line, I thought I'd share my stat graphs for fun....

Should I be worried?

Oh, does anyone really exist that works for Bulldog or are they a construct of my warped imagination?

'tang

From 0600 on the 17th through to 1500 on the 18th (Left to right)

[kitz]

Those swings in attenuation just should not be happening.

Whilst the one that occurred at 10pm gave an expected result of drop in SNRM and sync speed, I find the shift in output power at 4am curious... but it is possible that a spike could have occurred that soon recovered... meaning that your sync speed was then a bit lower than what could have been handled if you'd performed a reboot.

Im presuming you did a manual reboot at 8am ish?  If so that makes the power output and SNRM behave as normal... although I wouldnt expect a resync to cause yet another change in attenuation.

The line definitely needs looking at since all the signs are that theres a fault somewhere on the physical line.