Rogue Sky Box

[tehidyman]

For a few years I have been trying to identify the causes and cures for the RF noise I experience on my broadband.  I eventually tracked it down to the bungalow opposite.  When he was away for a few days my margin shot up only to drop when he returned.  Using RouterStats I noted that there was often a big jump in margin around 10.30 to 11.00 in the evening.  I can readily see his TV now the light evenings mean we don't draw curtains till late. Yes, when he turns the TV off my margin goes up and when he turns it on it goes down.  Typically between 5-7db change.  I have established that he has Sky.  Searching the Internet I have found that a) it could be a faulty box (but it works fine), or b) nothing can be done about it, or c) he has not installed a filter.  As he is not technically minded what filter could I offer and where should it be fitted? Is this a likely cause/cure?  Has any one any other solution consistent with good neighbourly relations?.
All contributions gratefully received

[.Griff.]

You say there's a big jump in margin at around 10.30pm to 11.00pm when he's watching TV and you suspect it's a faulty Sky box but Sky boxes are generally on 24/7. Perhaps it's the TV itself at fault?

[Rik]

I agree, Griff. The only suggestion I can make, if he's amenable, is that you take a MW radio over there and explore the TV.

[tehidyman]

Thanks Griff and Rik for the input.  Having changed my search direction to TV interference it seems that neighbours' large plasma TVs are reported to cause the problem especially when connected to a Sky box.  However as the problem is a reduced sync and not a loss of service I assume from posted comment elsewhere that I may not get any help from my ISP (IDnet) unless I move to BT and then not sure if they would help.
From replicated observations of his TV and my RouterStats I am certain it is precisely correlated with his TV switching on and off so what progress could I make by proving it with a MW radio?

[Rik]

If you can establish that the set is producing noise, there's a greater chance of BT taking you seriously. Moving from IDNet wouldn't change the situation, btw, as this bit is down to Openreach.

[tehidyman]

Having involved IDNet support it would appear that nothing can be done for this problem and if BT attend then I will get the bill in any case.  Looks like a move to LLU is the only option.  Fibre to cabinet not scheduled  till March next year and as the problem is on the last 300m of copper I presume it will not make any difference.

[Glenn]

The LLU will use the same 'last mile' cabling too.

[tehidyman]

The LLU will use the same 'last mile' cabling too.

Agreed but will escaping the BT DLM enable my connection to cope better?  It seemed to before I moved to IDNet.

[Rik]

AFAIK, LLU operators still use DLM, just not profiles.

[tehidyman]

AFAIK, LLU operators still use DLM, just not profiles.

[MisterW]

If you're on 21CN it IS possible to get BT to hard-set your profile which effectively stops the DLM messing things up, you just need to get your ISP to badger them.
For instance mine is currently

BT have managed to hard-set your profile and it's showing as active in the exchange already: WBC 160K - 24M No delay (INP 0) 6dB Downstream, 448 No delay (INP 0) 6dB Upstream (ADSL2+)

effectively means my target SNR up&down is fixed at 6db, excessive errors (or a drop in SNR) will still cause my line to resynch BUT it (the DLM) won't ramp up the target SNR (or apply interleaving) in an attempt to stabilise.

[pctech]

That's interesting to note MisterW.

[.Griff.]

AFAIK, LLU operators still use DLM, just not profiles.

Be don't.

They allow the customer to select their own SNR profile (3dB, 6dB or 9dB) and allow the customer to select Interleaved or Fastpath.

They will only intervene and impose a lower sync if there's a justified reason for doing so.

[.Griff.]

If you're on 21CN it IS possible to get BT to hard-set your profile which effectively stops the DLM messing things up, you just need to get your ISP to badger them.
For instance mine is currently effectively means my target SNR up&down is fixed at 6db, excessive errors (or a drop in SNR) will still cause my line to resynch BUT it (the DLM) won't ramp up the target SNR (or apply interleaving) in an attempt to stabilise.

MisterW where is that quote from? Someone at Idnet support?

I plan on calling them and asking about hard setting my profile so it would be useful to know who you spoke to.

[.Griff.]

Forget the above.

I spoke to James and although it's possible to hard-set profiles on 21CN it's not possible on fibre connection. Damn..

[pctech]

If you're on 21CN it IS possible to get BT to hard-set your profile which effectively stops the DLM messing things up, you just need to get your ISP to badger them.
For instance mine is currently effectively means my target SNR up&down is fixed at 6db, excessive errors (or a drop in SNR) will still cause my line to resynch BUT it (the DLM) won't ramp up the target SNR (or apply interleaving) in an attempt to stabilise.

Do you know if this applies only to ADSL2+ or can it be applied to lines provisioned as ADSL Max but delivered over 21CN?

[Rik]

AFAIK, Mitch, only true ADSL2+.

[pctech]

Will have to talk to Zen.

[Lance]

Just to be clear, is this hard setting the actual profile, or the SNR target?

[Rik]

In my case, it was the SNR target and interleaving, Lance.

[MisterW]

MisterW where is that quote from? Someone at Idnet support?

Nope, PlusNet support, I'm with them.

Do you know if this applies only to ADSL2+ or can it be applied to lines provisioned as ADSL Max but delivered over 21CN?

Not sure if its just ADSL2+, might be.

Just to be clear, is this hard setting the actual profile, or the SNR target?

Its hard setting the SNR target and the Interleaving depth.

[pctech]

I wonder if that option is available to all BT Wholesale ISP customers or just BT Retail which Plusnet is a division of as we know how fair BT can be  

No offence MsiterW.

[Rik]

It was available on trial to IDNet, which is how my line got set. I haven't heard that it's been rolled out since, though.

[pctech]

I do think that BT have their preferred customers (probably those that spend the most on circuits per month or of course, divisions of the mothership)

[Rik]

I'm sure you're right, Mitch, but Ofcom don't seem to have noticed.

[pctech]

I'm in the process of sending a mail to Zen as I transferred the line rental of the ADSL line to them which went through today so that if I have any bother, they can do all the necessary (main house line is still with IDNET).

I'd definitely like a bit more speed so this maybe just the ticket.

[Rik]

I think you need fibre, Mitch, not a ticket.

[Lona]

Maybe the next door neighbour has access to your wireless connection so your sharing with him and when he's not online you have it all to yourself.

[Rik]

It has been known...

[pctech]

I did have a mail from the fibre product Manager at Zen inviting me to take part in the FTTP trial as I'd expressed an interest.

I declined because neither they nor A&A (who are also participating) could give me an idea of the cost post trial (I think A&A are too pricey anyway)

He did say that I could have it removed at the end if it was too expensive but I doubt I'd go back to ADSL after having it.

And my pay cut hits in August.

[Rik]

That's the trouble, isn't it, going back.

[pctech]

We have one machine in the office with a dial up modem which we use if the BT ADSL goes down for testing external access.

Had to use it the other day as someone had disconnected the modem (a 2700 as it happens) from the switch that feeds our ports.

It was painful.

[Rik]

I can imagine.

[MisterW]

I wonder if that option is available to all BT Wholesale ISP customers or just BT Retail which Plusnet is a division of as we know how fair BT can be

AFAIK its available to all BTW customers.

It was available on trial to IDNet, which is how my line got set. I haven't heard that it's been rolled out since, though.

Yes, Rik's right there was a trial last year which most of the BTW customers took part in and there was rumours about when/if it was going to be rolled out. From what I can ascertain the facility exists for ISP's to request hard-setting of profiles but there has been little publicity as I guess the ISP's and BTW don't really want a flood of people requesting it. It seems to be a matter of getting sufficient enthusiasm from your ISP support to request it.
My hard setting came about when my line was upgraded to 21CN without warning, having previously declined an upgrade. On 20CN my line was rock solid 8Mb and since I use voip I didn't want it getting messed up by the DLM. When it got upgraded, initially it was ok at about 13Mb for a couple of days and then the DLM (bless it!) decided to try a 3db target SNR. Well,as you can expect, it was up&down like the proverbial for the next day and I could foresee the DLM applying Interleaving and increasing the target...
So I posted on the PlusNet forums asking if the No DLM option (ala trial) was available and if so could my target be set back to 6db with no interleaving to stabilise it so as not to affect my voip. One of the support people spotted it and offered the hard-setting option, 30 mins later it was done!
Maybe they thought they owed me one for upgrading my line without warning

[Rik]

 

It would be nice to think so.

[pctech]

Forget the e-mail, I'll give support a call when I get in tomorrow evening and try to persuade them, they've always been terrific so I don't think it'll be a problem.

[pctech]

Put a mail in this morning, here's hoping.

[pctech]

Had a response back.

They don't recommend an ADSL 2+ move nor forcing SNR lower in case it causes an intermittent line

Here's the data they say they've seen from their end

Downstream
Sync Speed: 2880 Kbps
SNR Margin: 6 dB
Loop Loss: 57 dB
Errored Seconds: 5
HEC Errors:
Cell Count: 99317

Upstream
Sync Speed: 448 Kbps
SNR Margin: 13.7 dB
Loop Loss: 34 dB
Errored Seconds: 0
HEC Errors: 0
Cell Count: 19960

BIP Interface Data
FTR: 2272
MSR: 2272
BRAS Profile: 2000
Interleaving: A

I adjusted MTU to 1400 last night on the router which raised the sync from 2752 but lost a little throughput (presumably that will rise if line is seen as stable)

Do I go for broke, request the re-modulation and then request the fixing as they've not said no or shall I wait and see if my own tweaks have done anything.

[MisterW]

I would tend to agree with them on the ADSL2+ move. With an attenuation of 57db you are unlikely to achieve an improvement in synch going to ADSL2+ ( see graph here http://www.internode.on.net/residential/adsl_broadband/easy_broadband/performance/ ). Your target SNR looks like its already at 6db and dropping it to 3db to attempt to synch faster is going to push up the error rate significantly.

[pctech]

Thanks for your opinion MisterW, you've pretty much echoed what they've said in their e-mail.

When I moved back to Zen in June last year the migration was ordered as ADSL2+ (they always order it configured that way now) and for the first few months it was great.

But then it started going down, regraded back but still was getting a slow speed, rang Zen and they were terrific. sorted it out within the hour by doing a bit of tweaking their end on the BRAS.

Even though the speed would be nice I'd rather have a stable connection, we'll see what the DLM does now.

[Rik]

OTOH, I had an attenuation of 57db on Max, sync around 2.4-2.6mb and a target NM of 6db. Switching to ADSL2+, my attenuation went up to 62.8, my sync to 4-4.4Mb and my target NM is still 6db. Other than a couple of brief spells of external noise forcing the sync lower, I've maintained those speeds for 16 months.

[jameshurrell]

I think you have a gold plated pair of wires coming into your house Rik...

I manage a 20CN line with attn. of 59 that manages a sync of about 2.2MB (good old 2700HGV) - this gives a profile of 2000... But I'm in no rush whatsoever to move that line to ADSL2+!!

[Rik]

I do have a good pair, if I can phrase it thus.  I was an early adopter, so the BT engineer found me the best pair he could. My neighbours have speeds varying from 512k to 3M, but I'm not letting on.

[pctech]

Think the 2700 said I was on the inner pair.

[pctech]

speed is on the up, BT test says about 1844 but TBB put it at 1931

[pctech]

I'm back up to just under 2.4 

[Simon]

[pctech]

Now just wondering if speed is good enough for Xbox live.