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Author Topic: Noise spikes on line, SNR Margin drops, REIN issue?  (Read 10621 times)

Adamantium

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #15 on: July 22, 2011, 07:25:18 PM »

July 22nd 2011 - Update from BT; "I and my colleague have carried out thorough investigations on this line and the neighbouring lines.

I have checked other circuits on the DP and all have been running very similar to your customerís with the SNR of 0dB which has only recently dropped. It is running similar at times to the other lines on the DP with regards to speed etc but then the SNR just dips to 0dB on this one circuit.

All the lines are long which Iím sure you already knew, and their speeds are not the best.

So from what I am seeing all lines have been running similar but your customerís has the dips to 0dB. The times it does this are random with no pattern whatsoever The line is also dropping now and then but the majority of the issue is this dip to 0dB. The dips are more than likely caused at the end user end (BT network side, not end users equipment) as other circuits are not experiencing these dips. The broadband is fit for purpose but this customerís is probably being pushed to the limit if it is being used for gaming etc

I think we have no option but to send another engineer to see if the line can be improved anymore.

If you can advise of customer availability I will arrange an appointment to get this investigated further.

I was considering a TPM but donít want to jeopardise the working circuit as it could end up having a detrimental affect and the issues do seem to point to the network as opposed to the port."


The words "fit for purpose" in their update worry me tremendously... :no:
As that smells to me like they're going to push to have the issue closed off if they're unable to find the source of the fault after their next engineer visit  >:(
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burakkucat

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #16 on: July 22, 2011, 08:03:52 PM »

Quote
The line is also dropping now and then but the majority of the issue is this dip to 0dB. The dips are more than likely caused at the end user end (BT network side, not end users equipment) as other circuits are not experiencing these dips. The broadband is fit for purpose but this customerís is probably being pushed to the limit if it is being used for gaming etc

Looking at the above paragraph, it seems that the OR engineer is suspicious of your line from the DP to the NTE5/A. To eliminate that completely, I would expect a new cable run and an NTE5/A with filtered faceplate to be fitted.

The definition of "broadband is fit for purpose" is the achievement of a (chronically) low download sync -- I can't recall the exact figure but I believe it is 512Kbps. :(  However, with regular drop-outs (loss of sync) I would dispute the "fit for purpose". Care must be taken here, for OR is entitled to say that it is a satisfactory POTS line but it is unable to support an ADSL broadband service -- so "tough". :'(

Perhaps RP will drop in later on this evening and give his updated (remote professional) opinion on the situation.

If I were in your position, I would search eBay for a 2Wire 2700HGV (a.k.a. a BT Business Hub) and spend up to £30 in purchasing one -- brand new, factory sealed in box. For long lines, they are really the modem/router of choice. And OR will approve of the device. ;)
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Adamantium

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #17 on: July 23, 2011, 12:51:21 PM »

Care must be taken here, for OR is entitled to say that it is a satisfactory POTS line but it is unable to support an ADSL broadband service -- so "tough". :'(

My issue with that statement is that I had perfectly working broadband service on this line for 6 months before this problem arose, so it's not as if the line has always had a problem...
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waltergmw

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #18 on: July 23, 2011, 06:58:56 PM »

@ Adam M,

Which is why I keep records of line performance from the moment anybody asks for my help.

Do try to gather whatever evidence you have of past performance.

Kind Regards,
Walter
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Adamantium

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #19 on: July 25, 2011, 01:18:27 PM »

July 25th 2011 - Update from BT when trying to book the engineer to come out to investigate further;

"I have raised a trouble report but ironically the line test failed showing a dial tone fault. A DT fault is either customer end or PSTN related. This type of fault is a ďnext availableĒ and not appointed as it will be a line engineer that needs to go out to look at this.

Once this has been actioned we will reassess to see if this has had any bearing or improvement to the broadband and decide if we need to book a broadband engineer after this time.

There should be no need for the customer to be available for this particular visit.
"

I think i'd be over-optimistic if i were to think that this has been the problem all along, and will fix the underlying issue..
The pessimist in me just thinks that this will be another delay in getting my actual issue resolved..  ???
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Adamantium

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #20 on: August 03, 2011, 01:36:48 PM »

July 26th 2011 - Update from Zen;

"Hi Adam,

The openreach engineer did not find any DT faults on the line.
BT are requesting an engineer to come to site to do a complete end to end test.
We have provisionally booked the appointment for tomorrow 27th pm slot.
Can you let us know if that is ok for you, or let us know when you are available.

Regards,
"


July 27th 2011 - I had two Openreach engineers turn up briefly.
One of them said he'd been round the village looking at various sources of REIN that he'd found (he confirmed he wasn't a REIN engineer, but nevertheless had been round with an AM radio to look for sources).
He said he'd found 3 sources of REIN at different locations throughout the village, although he didn't elaborate what or where they were. He said this issue was affecting a number of households in the village - all with outstanding broadband problems.
He did say that he'd tried "suppressing" some of the sources (again, how this was done i don't know) and he thought that it may have fixed the problem. He added that the equipment he was using to detect the REIN had now broken, so he couldn't do any further testing.
At the time they arrived (approx 3:20pm) the stability of my connection was better than i'd seen it for a long time - with minimal SNR margin dips and errored seconds on the router (although i'm not ever generally home during the day to test it - so at the time i couldn't say whether this was due to the work they'd done, or if it was just due to the time of day).
The second engineer then plugged her device into the phoneline and performed some sort of test which seemingly came back fine.
So at this point it was looking like they had indeed resolved the problem.

However within an hour of them leaving, the connection was back to normal (i.e. 0.0dB dips constantly).
Both Openreach engineers were still in the area as they had been looking at a neighbours' issue. I went out and spoke to them again to confirm the problem was still apparent.
The engineer that had been performing the REIN "tests" said he would go up the road and do a few more checks and then write up his report.

I informed Zen of all the above and asked them to pass back to BT..


July 28th 2011 - Update from BT;

"I have spoken to the REIN Team, the REIN issue has been identified and closed off this morning.

The engineer went out yesterday and this morning and has liaised with several people in the village. He had identified 3 sources of REIN and has addressed them by suppressing them with a RF3 filter.

The issue should be resolved, if you can check with your customer as to any improvements.
"

I re-affirmed my previous update to Zen that the issue is no different.
I also swapped my router back over to my NETGEAR model which is compatible with Routerstats so I could capture the SNR margin drops..


July 29th 2011 - Update from Zen;

"BT have advised that the next step is to carry out a Tie Pair Modification.

This will move you on to a completely new line card and DSLAM at the exchange and will result in some downtime as they have to physically move your connection.

This rules out an issue with the port on the line card and any issues that may be caused by the line card and DSLAM

If you are happy for this to be done, then let us know and we will get this actioned with BT as quickly as possible.

Regards
"

I confirm I am happy for this to happen ASAP.


August 1st 2011 - Update from BT;

"TPM is done and customer is in sync on the new CBUK.

Please retest.

Thanks
"

No change - everything still exactly the same. Asked Zen to pass back to BT.


August 3rd 2011 - Update from BT;

"I have tested the circuit this morning and can see errors on the upstream. It looks like we are going to have to arrange another engineer visit to look at both the network and the REIN issue. Whilst installing filters will go some way to screening interference it wonít eradicate it altogether.

The customer does need to be aware though that REIN isnít BTís responsibility and is only investigated as a gesture of goodwill because it is affecting the broadband. There are very few REIN trained engineers and those that are REIN trained canít always get hold of the specialist equipment needed. They sometimes have to travel several miles to attend a job so to manage the customerís expectations it could turn out to be a lengthy investigation.

You say that the customerís neighbours have reported issues with their CPís but there are no other faults reported whatsoever on the NCIF this customer is on. There are 306 circuits but only this one fault. It could be that the other circuits are on a different NCIF.

So, if once again I can ask you for the customerís availability I will arrange the appointment.

Kind regards
"

REIN is mentioned as i have been running routerstats on my line 24/7 for the past week. This has shown that the drops to 0.0dB generally show a trend towards being present more early in the morning and then late afternoon onwards until about 2-3am. Between these times there are periods where i get little or no drops at all. However this isn't always the case.
I have advised BT of this, which is why REIN is again back on the radar.
I will post up some of the graphs when i get home to illustrate the loose patterns i'm talking about..

In the meantime, I have asked that a new cable run from the pole to my house is done when they come out - along with a NTE5/A with filtered faceplate as burakkucat suggested previously..

So I await their next visit.....
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waltergmw

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #21 on: August 03, 2011, 02:57:49 PM »

@ Ezzer & RP,

Have you ever tried earthing the catenary wires in a drop cable to see if that might just help REIN Issues ?

Kind regards,
Walter
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burakkucat

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #22 on: August 03, 2011, 05:22:31 PM »

@ Walter,

My inventive mind promptly wanders off to consider the use of a screened (as co-axial) twisted pair (think low-impedance balanced microphone input) but comes back to the fact that the aerial drop wire is probably not where the majority of RFI or REIN is picked up. From my limited understanding of the propagation of REIN, more often than not it is injected into the multi-pair cables bundles via the pair from the premise of the REIN generating source.
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waltergmw

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #23 on: August 03, 2011, 06:04:14 PM »

@ BKC,

IMHO there are two sources of RFI but they can't be easily defined precisely. The horrible mess that we loosely call REIN and the licensed spectrum users. I know of one (now removed) source which was a faulty first generation analogue cordless phone which just produced serious cross talk up the bundle whenever and only when a phone call was made.
For the second type for E.g. how many bit loading diagrams have you seen with Radio 4 missing ?

Except for the precedent problem, I cannot understand why (seemingly) BT don't use a foil wrapped cable whenever new or replacement cables are being installed.

Kind regards,
Walter
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burakkucat

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #24 on: August 03, 2011, 07:24:54 PM »

Quote
Except for the precedent problem, I cannot understand why (seemingly) BT don't use a foil wrapped cable whenever new or replacement cables are being installed.

I suspect there would be a two fold response: (1) It would involve a deviation from the "norm", thus a rewriting of the standards. (2) Cost. ::)
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razpag

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #25 on: August 03, 2011, 08:10:47 PM »

As regulars will be aware, I'm a relative novice when it comes down to REIN and it's many guises, but have been in attendance on quite a few jobs, and been 100% succesful in the 2 issued to me since completing my training (big whoopee eh ?? ;D).

So, on the back of that, Walter ..... no, I've never 'earthed' the "Catenary" wires as you mentioned. By catenary, do you mean the steel strengtheners that are in the dropwire 10/12/14 ???

Again, from my limited experience, the higher percentage of REIN faults I've been involved in has seen the source begin at the EU's premises and 'track' back up the dropwire to the DP, and then (depending on the strength of the interference), into some or all of the other dropwires fed from that DP. In a recent case, it actually then went down the UG cable feeding the DP, and into another UG cable running parrallel to it in an underground box. This caused another DP and it's EU's to be affected.

I identified the source of the REIN, informed and proved it to the occupant of the house it was emmiting from, and then informed the REIN team. 'We' (Openreach) have no powers at all thus far to make the occupant switch off, or remove the offending item. 'We' feed back the information to the SP of where the REIN is coming from and it is down to them to liase with the occupant and try and reach some kind of compromise.

B*Cat is also correct (and covered by myself in another thread months ago) in that any change to 'flying wires' whether they be multi-core or otherwise, would need stringent load bearing tests/aerodynamic effects. We have  'certain' maximum distances we can erect different types of OH cables, and any further weight gain given to those cables may drastically affect this distance. I'm not sure how many poles we have nationwide, but the costing would be astronomical if major parameter changes were implemented.

We know REIN is more prevalent of late than in years gone by, due to much higher frequencies susceptible to noise, being pumped down our cables. Also, the comment below about access to REIN testing equipment was correct, but in-roads are being made to purchase more 444b testers. I can verify this to be fact, as I have filled in the neccessaries to get one myself just a few weeks ago and our Level 2 manager agreed to the price of it.

I reiterate, REIN is a problem, but as yet not directly under the juradstiction of Openreach, as we perform the location of it as a 'Goodwill gesture' only . 'We' are however  training lots more engineers in REIN fault-finding. HTH  ;D

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Adamantium

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #26 on: August 04, 2011, 03:34:02 PM »

August 4th 2011 - Update from BT;

"Hi,

I have just cooped with the engineer who has been on site all morning. There is no fault on the line, they have checked all joints and cable, most of it has been renewed anyway. The engineer saw the dips but they are not caused by any line faults. The REIN engineer has been out with the SFI this morning and any REIN issues they were able to detect were actioned last week. There is no more that Openreach can do. The wiring has all been replaced, e and d side and there is nothing faulty for him to replace in any case. The port has been changed also so we have eliminated that.

The speed the customer is achieving is more than acceptable for this length of line and db loss, as for the dips there is nothing on the Openrach network causing this.

We have reached a stalemate with this as there is nothing else we can do, everything possible has been done for this customer. The line just goes and then comes back with no other reason other than being a completely random SHINE (single high impulse noise event).

We will not be able to resolve this, we do not have engineers that can find this.

The only thing I can suggest is that the router PSU be changed and maybe investigate any other electrical equipment with a power brick which might be on its way out but other than that we will not be able to help any further.

It would appear that this is down to the environment but there is no actual fault causing this.

Kind regards"


 :no: :'( :no: :'( :no: :'( :no: :'( :no: :'( :no: :'( :no: :(

P.S. Here's a screenshot of my routerstats capture for a period of 3 hours this morning...
« Last Edit: August 04, 2011, 03:40:03 PM by Adamantium »
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cookieuk

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #27 on: August 09, 2011, 02:53:55 PM »

August 9th 2011 - Get a life!
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roseway

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #28 on: August 09, 2011, 03:10:48 PM »

I'm not sure what you mean by that, cookieuk, but if you have nothing to contribute to the discussion it's probably best to say nothing.
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waltergmw

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Re: Noise spikes on line, SNR Margin drops, REIN issue?
« Reply #29 on: August 09, 2011, 04:14:32 PM »

@ adamA,

The statements made by the support staff are clearly not logical. Given that, in electronic terms, there are really quite long periods of reasonable stability around 07:00 onwards where the trace stays much more at a reasonable operating level. There is definitely an external influence destroying most of your throughput for much of the night. I wonder if you might investigate, at least externally, visible lighting sources probably from discharge lamps such as street lighting or possibly PIR controlled building lighting? Also look for overhead phone lines running close to electricity cables.

It would be worth trying to trace possible RF Noise causes before continuing the battle.

Kind regards,
Walter
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