Engineer Never Arrived.

[#1]

15.2 is the BT IP profile from http://speedtest.btwholesale.com/ current sync is 17.224.

Quote

Modulation : ADSL2+ Annex Mode : Annex A/L Line State : up Lan Tx : 70419025 Lan Rx : 38305371 ADSL Tx : 183740 ADSL Rx : 329011 CRC Down : 0 CRC Up : 39 FEC Down : 0 FEC Up : 112 HEC Down : 94 HEC Up : 0 SNR Up : 6.4 SNR Down : 6.0 Line Attenuation Up : 14.0 Line Attenuation Down : 21.0 Data Rate Up : 1115 Data Rate Down : 17224

Highest sync I have seen was shortly after the upgrade to 21CN back in December. 19.075 @3db SNR.
Speedtest results are currently only 9.6Mbps because the Plusnet profile is 10.1.
Cheers,
Wo0x.

[#2]

It looks as though the script ran and updated your profile for you. Having looked at your line, it's looking much, much better than it was.

[#3]

Hi,
I have routerstats lite running and have noticed that the SNR drops by 2db at seemingly random times. I'm attaching the screenshot of when these were most frequent. Is this normal/anything to be concerned about? I hadn't been able to monitor this previously, but had observed when checking the router that the SNR would fluctuate frequently (any time I hit refresh it would change) by around 0.5 above the target and 1.9 below. Since yesterday's work it is staying right on target bar these 2db drops and has yet to go over.
I haven't had ay disconnections yet and have my fingers crossed the SNR doesn't change overnight tonight - this is when it would change after previous resets.
Cheers,
Wo0x.

[#4]

I wouldn't worry too much about that, it's much improved, but it's one of those things where we need to see how the line performs over the next few days (the weekend should suffice). When we come back on Monday, shall we review with a few more graphs (if possible) and see how you've got on?

[#5]

Thanks, Chris. Keeping routersts lite running means leaving my laptop on so it's not something I'd be comfortable with 24/7, but just for the weekend is fine 

[#6]

Hi,
These graphs are interesting.  What is your concern about running your computer 24x7?  Constant RSL monitoring can be very useful - after the event.  Mine runs line that all of the time with nothing untoward.
2dB dips is strange, undesirable but as Chris suggests not an undue concern when the "back ground" SNRM is 6dB.  If it were more or the background was 3dB you might be at risk of the line dropping.  What is the sample interval?  I use 10 seconds with 720 plots per graph, which gives 2hours per graph.
Though the modem's SNRM resolution is 0.1, the quantum changes in the SNRM plot suggest that the sample frequency is missing detail of the SNRM shifts.  This line is somewhat too smooth for dark hours SNRM.  This looks like electrical switching interference, which if is manifest for prolonged durations will have an impact on your DATA speeds and could be responsible for a reduced synch speed.
Kevin

[#7]

Disconnection overnight with a 3db rise  

Quote from: Townman

Hi, What is your concern about running your computer 24x7?

Hi, I guess I'm just a little old fashioned and like to turn things off if I'm not using them. The laptop can get a little hot if left on for long periods too.

Quote from: Townman

What is the sample interval?  I use 10 seconds with 720 plots per graph, which gives 2hours per graph.

5 and 250... I will change this to how you have yours.

Quote from: Townman

This looks like electrical switching interference, which if is manifest for prolonged durations will have an impact on your DATA speeds and could be responsible for a reduced synch speed.

Is this why the highest sync I have had at 6db is 17Mbps when everyone keeps telling my attenuation should be good for 20+?

Gaming since the last reset has been awful, as it has been after every reset. This is the most obvious thing to me, but isn't something I can demonstrate to you. Whatever is causing the SNR to rise is impacting the gaming. At 15db the gaming isn't great, but it's far better than at 6db or anywhere in between. This is why I do not want the SNR pinned.
Here are a few graphs that seem to be the most relevant....
This one shows last night's disconnect and subsequent SNR increase

This one is indicative of the other graphs after...

Finally, this one is the one that stands out from the others after the disconnect...

Two final pictures showing the errors in my router...

I've never seen anything like this number of errors before, certainly not after only 50 minutes. A couple hundred after 24hrs had been usual for me at 6db.
You can see in this pic that after a further 12 hours they haven't increased at the same rate.

Cheers,
Wo0x.

[#8]

Well your line appears to have shifted its target SNRM to 9dB so the DLM is not happy with your line.
You are going to need to keep monitoring this; I recommend elevating your laptop off any flat surface - two 1"x1" pieces of wood - to provide a better air flow underneath to help keep the temperature down.
I suspect you've got REIN so on going RSL plotting will be very useful.

[#9]

Ok, thank you, I will continue to monitor. 

[#10]

Another disconnect and 3db SNR increase this morning (shown in the second image.)



Thanks, Townman for the information about how you capture your graphs. They're much better like this and result in fewer saved images.
I've only posted a few of what I think are the more interesting, but have 100+ images if you want to see them all. Attachment limit seems to be 9, though.

[#11]

This is really useful stuff - you now need to do some analysis...
There are potentially a number of issues here.  From what you've posted, there are some marked transients resulting in line drops and resynchs.  There are other events giving rise to 1dB SNRM shifts.  Away from resynchs, SNRM rising indicates the removal of noise, it falling represents the start of noise.
Can you look through your graphs and see if you can relate the step changes in SNRM to something being switched on / off / in coming / out going phone calls.  Clearly something is not right with the line, which DCT should pick up tomorrow.
Cheers,
Kevin

[#12]

Quote from: Townman

Can you look through your graphs and see if you can relate the step changes in SNRM to something being switched on / off / in coming / out going phone calls.  Clearly something is not right with the line, which DCT should pick up tomorrow.

I'm struggling to think of anything that coincides with the times that the graphs show changes. It dropped this evening at 19:35 and has stayed like it for now. I can say with certainty that nothing was switched on or off at this time. Same goes for some other times that it changes, sometimes it's in the middle of the night. I don't use the telephone and there hasn't been an incoming call since the 5th so it's not that either. 
I'm guessing Plusnet can see if other customers have had their SNR increase to 15db too, but that's assuming there are other Plusnet customers on the exchange.
Cheers,
Wo0x.

[#13]

...it could be outside of your property, your neighbour, local take away (extraction fans) or in my case electric trains.
If you are on good terms with the neighbours, try asking them...

[#14]

Hi,
My neighbours don't seem to be able to think of anything that may be causing this. I've asked them to find out their SNR figures or current speed test results and I'm now waiting for them to get back to me.
Today the line dropped, then my fault ticket was updated. My line dropped again after I replied. Assuming these were due to Plusnet running tests (I usually have a line drop before the ticket gets updated,) I have a question. If something is causing the SNR to drop from 15db to 13.8db, why does the SNR go back up after a disconnection? It seems unlikely to me that the source of the noise would just happen to go away at the same time as the line disconnects. If the drops were not due to tests then disregard.

Another question I have is, the changes on the graphs occur at the same time for both upstream and downstream, so why does DLM only adjust the downstream SNR?
Cheers,
Wo0x.
*edit* Well that was fast, I have another engineer coming tomorrow. I'll let you know how that goes.

[#15]

Hi Wo0x,
Some really good questions here - I hope the following answers will be clear enough to explain what you are seeing.

Quote from: Wo0x

If something is causing the SNR to drop from 15db to 13.8db, why does the SNR go back up after a disconnection? It seems unlikely to me that the source of the noise would just happen to go away at the same time as the line disconnects.

SNRM is not a static parameter.  It changes all of the time, however the TARGET SNRM is at any given time a static value.  This is how ADSL works.  When the modem synchs with the exchange it negotiates a synch speed which "delivers" the TARGET SNRM set by the DLM over the current background noise.  Then during normal operation, if noise occurs, the CURRENT SNRM decreases, if it goes away, the CURRENT SNRM rises.  In complete answer to your example, you'll find that the resynch at 15dB was at a slower speed.

Quote from: Wo0x

Another question I have is, the changes on the graphs occur at the same time for both upstream and downstream, so why does DLM only adjust the downstream SNR?

Good question, to which I'm not sure I have a clear answer.  I do not believe the US SNRM is set by the DLM, it simply is what it is.
Kevin