PN line speed reset needed?

[#1]

I suspect an external RFI source.

[#2]

Changes in max attainable rate do tend to follow changes in the current SNRM.

Also, perhaps all the disconnections are making it difficult to see any changes in SNRM because each time the DSL re-connects, it will connect at the target SNRM.

You also said earlier today that the SNRM went up from 5.1 in the middle of the night to 6 at about 2pm in the afternoon.

Mardler at 24-03-2017 1:46 PM@  wrote:

Whilst the SNR went up from 5.1 to 6.1 (now) in the last 14 hours the "Attainable rate" also increased a bit from 18788 to 19380. Sync remained at 17467.

[#3]

Back home.

Connection stable since I went out.

SNR 4.9, other stats not unreasonable.

Night time anomalies ruled out.

[#4]

This (above) is a good result.

For whatever reason, connection stability is good.

Just turned the (plasma) TV on: nothing.

SNR just gone from 4.9 to 4.1 - this is nuts and definitely is nothing to do with the ionosphere!

[#5]

Outage 01.05: reconnect at SNR 5.9.

So, where does this leave proponents of snake oil remedies now? The SNR fluctuates wildly all day but can't do because it must decrease at night: gimme a break.

Is there anyone here who understands what might be happening?

Oh dear, SNR now 6: kicks bonkers ideas of night time SNR reductions into the long grass.

D/l speed reduced to c.14. Sync is 17198. PN line speed reduced to 15.4.

Is there no-one here who has real knowledge of what might be going on?

[#6]

So, I'm monitoring SNR and Attainable Rate.

As SNR decreases AR does likewise. As SNR rises so does AR. Common belief is the opposite.

This is counter to popular theory so does anyone have a clue?

Please, no snake oil.

[#7]

Oh and sync is always at least 2mbps lower than Att Rate: why? It used not to be.

I repeat: in Aug/Sept 2016 after 18 months of lousy BB we had a rock solid connection for two months at d/l 21.5 on SNR c.6.8. Now, we get continual outages.

Today, the connection is flaky even at SNR 6db.

PN: thoughts from you guys preferred.

[#8]

---

@Mardler wrote:
So, I'm monitoring SNR and Attainable Rate.

As SNR decreases AR does likewise. As SNR rises so does AR. Common belief is the opposite.

This is counter to popular theory so does anyone have a clue?

Please, no snake oil.

---

No, it is not counter to popular theory. Perhaps you were confusing the current SNRM with the target SNRM.

With a lower target SNRM, you'd get a higher speed, and with a higher target SNRM, you'd get a lower speed.

As the current SNRM changes to reflect the current noise level, an increase in the noise level would result in a lower SNRM figure and a lower max attainable rate. A decrease in the noise level would result in a higher SNRM and a higher max attainable rate.

[#9]

I'll grant you this, ejs, whilst it's not huge monitoring SNRM on this Billion router it is clear that it's reducing at night.

Target SNRM was set by me at 5.1. During the day SNRM is c. 6.1. Right now (20.57) it's 5.3. 

I understand the possibilities (I'm ex IT, build PCs, built radios & amps etc. as a kid, interested in propagation over long distances etc.) and am seeing the night time reduction in SNRM for the first time.

OTOH, it often happens in daytime!

Connection up for 19hrs so far. 

[#10]

Re SNRM and a different tack. Target was set to 5 but no way of knowing what DLM has done, if anything. The value notified by the router hovers around 6. It has dropped a bit in the evening but nowhere near every evening - in fact right now (00.09 on March 27) it's 6.1.

Anyway that isn't the reason for this post so read on.

Baxkground:- Until our exchange was upgraded to ADSL2+ we never had a problem with BB disconnects - it never happened and IIRC SNR was 6-ish, down attenuation about 9.

Mulling over RFI/REIN etc. I had a thought. Several years ago, after two years of complaints, we managed to get our mains electricity supply improved so that we get 230v (actually closer to 240) instead of the 190v that was usual here. The solution was a transformer placed right outside the house.

Now ADSL2+ arrived in early October 2015 and sync & d/l speed went, as with ADSL, to close to the theoretical maximum. In December 2015 the entire village centre lost BB completely; it came back in dribs & drabs but our connection was at greatly lower sync etc with far higher attenuation and near constant outages (and not a few days when sync was ❤️ or 4!).

My thought and question therefore is this: could something in the mains transformer have deteriorated and started generating sufficient interference to mess with ADSL? I'm sceptical but all thoughts welcomed.

I'll have a wander around with an AM radio tuned to 612KHz tomorrow. 

[#11]

Well that was interesting!

I donned the headphones with the portable AM radio plugged in and tuned to c.612KHz and heard a French station.

Before going outside I "surveyed" the computer room. The router is next to the monitor with both power cables and phone lines running up to them on the desk.

There was a loud high pitched hash so I turned off the monitor and it disappeared but there was no change in router SNRM as observed on another device.

I then noticed another, lower frequency, noise. I crawled under the desk and found that the router transformer is making a huge noise.

Now, the BB problems started in Dec 15 so two routers back and the same monitor so I'm not sure what this means if anything. Remember, for 19 years prior to Dec 15 there were zero connection problems. Maybe, though, the Billion router might work better with a linear tx?

Next: outside.

[#12]

Before going outside I checked the rest of the house. The plasma TV was horrendous but it was bought in Feb '13 and BB was fine until Dec 15 so I rule that out. Short of covering the back (telephone cable is behind and above it outside) there's nothing that can be done about it and anyway it makes no difference to SNRM.

An outside check found nothing untoward and the adjacent mains transformer is silent.

By chance, a guy stopped to ask what I was doing. He was on his way to a neighbour about 400 metres away and he told me that that guy has terrible BB.

I'll do another check after dark.

ITM, any thoughts?

[#13]

Just noticed that the TV knocks c.0.6 off the SNRM (range 0.3 to 0.7).

Am thinking of a Faraday cage for the router wall wart TX but that might be difficult for the TV!

[#14]

Does PlusNET provide your phone service?

Are you plotting CURRENT SNRM using something like DLstats or RouterStats?  If not set up one or the other and leave things alone.  Current SNRM will vary constantly.  Watch the graphs for marked changes to see if they correlate with use of equipment.  Turn stuff off at the mains switch - things left in standby still have their power supply units left on.  By 2015, something bought in 2013 could have a switched current PSU which has gone squiffy enough to emit RFI but not enough to not function.

You are chasing shadows here, you have no clear profile of the problem.  All that PlusNET can do is to set the TARGET SNRM, after which the CURRENT SNRM (and AR) will vary due to line conditions, including poor joints and RFI from whatever source, including night time AM propergation.

If there is a copper path way issue, that needs to be addressed by your phone service provider as a voice fault.

[#15]

Hi Townman, thanks for chipping in.

PN is not my phone line sp, BT is.

I'm not using RouterStats but am thinking about it.

I'm fully aware of and conversant with everything else you say especially chasing shadows: five BT engineers, one private telecoms guy, myself (ex IT) haven't located the problem. (The BT/OR guys also replaced internal cable to and replaced the master socket and checked all of the internal cabling, socket and filter to the router as AOK.) The most clued up BT/OR guy was certain that there's an underground copper line fault: he said he'd raise a fault notification with his supervisor but nothing happened.

In case you aren't aware, ditching the 582n router for my old DG834v2 stabilised the outage problem a lot and the Billion now in use is not dissimilar to that (Broadcom chip in the Billion).

At the moment, the connection seems stable at the target SNRM of 5 that I set: we shall see. 

The problem is that the line will not provide the sync and d/l speed at the same SNRM (6 or higher) that it did. The increase in down attenuation from 9 to 15.5 is a clue to an external line fault: engineers found four bad connections and one exchange fault (an unbalanced line) since the Dec 15 general local BB loss.

Another clue is my neighbour with a slightly longer line has sync at 20220 with no target SNRM tweak and down attenuation of 10.9. Other neighbours achieve d/l of c.19 (BT, TT isps).

A BT argument runs: what is it that you can't do at 12-14 d/l that you could at 18-21? I say, be comfortable that there is a good margin for line deterioration.

Yesterday I discovered that a guy no more than 300 metres further away from the exchange, on our "spur", can hardly get BB at all. (We're c.0.85km from the exchange.)

Do PN cap d/l speed at 17, btw? I read a PN ad that said this and my neighbour went to a new PN tariff and her d/l slowed from 18+ to <17.

I'll investigate RouterStats and try to put a Faraday cage round the router TX!