SNR Target problems.

[#1]

Hi all,
It would seem my connection has changed its target from 9 db to 6db yesterday, however my connection has a tendency to fluctuate by 3 - 7 db which is now causing issues as my margin is regularly dropping below 0.0 db even showing negative on router stat page at times also showing an increase in errors etc and was wondering where the best place to request my margin to be fixed at 9db
current line stats are:

Modulation : ADSL2+
Annex Mode : Annex A/L
Line State : up
Lan Tx : 14104802
Lan Rx : 11715037
ADSL Tx : 1956799
ADSL Rx : 1907074
CRC Down : 0
CRC Up : 22184
FEC Down : 0
FEC Up : 16998
HEC Down : 15027
HEC Up : 0
SNR Up : 5.9
SNR Down : 0.2
Line Attenuation Up : 25.0
Line Attenuation Down : 46.0
Data Rate Up : 1048
Data Rate Down : 8396

This is after 3 hours of connection however last night i was having issues where i would get a period of no connectivity(where it drops below 0) and gettting 20,000 HEC errors  or more each time.
I'm unsure why this has changed so drastically in the last 2 days tried to reset it a few times last night after midnight to no avail.
Any help/suggestions would be greatly appreciated!
-D

[#2]

as a quick fix - when the noise margin drops to 3dB resync the router which should give you a stable speed

[#3]

It almost always drops to 3db shortly after connecting i disconnected a few minutes ago and resync'd at 6db
but now my current line stats after 5 minutes show

Modulation : ADSL2+
Annex Mode : Annex A/L
Line State : up
Lan Tx : 14380872
Lan Rx : 11968696
ADSL Tx : 45729
ADSL Rx : 55239
CRC Down : 0
CRC Up : 680
FEC Down : 0
FEC Up : 869
HEC Down : 283
HEC Up : 0
SNR Up : 5.8
SNR Down : 3.0
Line Attenuation Up : 24.9
Line Attenuation Down : 46.0
Data Rate Up : 1048
Data Rate Down : 7652

I tried the above last night and just appears to give me a similar speed to previous sync I'll try it in a few seconds since i'm at 3 now.

[#4]

30 seconds in: Modulation : ADSL2+ Annex Mode : Annex A/L Line State : up Lan Tx : 14428760 Lan Rx : 12008150 ADSL Tx : 9540 ADSL Rx : 13508110 CRC Down : 0 CRC Up : 9 FEC Down : 0 FEC Up : 20 HEC Down : 9 HEC Up : 053190 SNR Up : 6.1 SNR Down : 6.0 Line Attenuation Up : 24.9 Line Attenuation Down : 46.0 Data Rate Up : 1055 Data Rate Down : 7589

2 minutes in: Modulation : ADSL2+ Annex Mode : Annex A/L Line State : up Lan Tx : 14446927 Lan Rx : 12021882 ADSL Tx : 23092 ADSL Rx : 3152589 CRC Down : 0 CRC Up : 593 FEC Down : 0 FEC Up : 1143 HEC Down : 281 HEC Up : 0 SNR Up : 5.8 SNR Down : 4.1 Line Attenuation Up : 24.9 Line Attenuation Down : 46.0 Data Rate Up : 1055 Data Rate Down : 7589 Live video stream froze for 2 seconds then snr dropped to 4.1 from 6.0

20 mins: Modulation : ADSL2+ Annex Mode : Annex A/L Line State : up Lan Tx : 14656404 Lan Rx : 12202627 ADSL Tx : 199820 ADSL Rx : 239397 CRC Down : 0 CRC Up : 2665 FEC Down : 0 FEC Up : 6040 HEC Down : 1311 HEC Up : 0 SNR Up : 5.9 SNR Down : 2.0 Line Attenuation Up : 24.9 Line Attenuation Down : 46.0 Data Rate Up : 1055 Data Rate Down : 7589

[#5]

SNRM will naturally drift down 2-3 dB between dusk and dawn due to interference from MW transmissions.
When you restart the router, it will seek the best synch speed it can attain at the target SNRM given the then present background noise.  There after you will see SNRM fall if the noise increases or rise if it decreases.  If the noise increases enough, then you might loose connectivity altogether, after which the whole process starts again at the target SNRM.
If you are seeing a highly variable SNRM, then there is the possibility that there is a fault somewhere or something is generating electrical noise into your BB connection.  I would recommend obtaining RouterStats and dynamically plotting SNRM at 1 minute intervals so that you can visually see the variation in SNRM.  This might indicate if random electrical noise is present.
For your DS attenuation, your synch speed is quite good - if you are prepared to loose synch speed for greater stability, you could ask for your SNRM to be pinned to 9dB, but that would defeat the whole benefit of DLM operation.  Personally I would want to look for the source of the noise (could be in your home) and eliminate it, so that you can enjoy a faster synch speed.  That said, sometimes lowering the synch speed delivers a better throughput speed because there are less errors (retransmissions) to be handled.
If you want detailed info on this, look here - http://www.kitz.co.uk/adsl/linestats_explanation.htm
HTH,
Kevin

[#6]

Wasn't aware router stats worked for my DSL-N55U then saw it listed on router stats lite version
Got it running plotting margin now (-3 to +9 at 15sec intervals), as for my sync speed I've seen a deterioration in my connection over the last month after changing to the N55U only syncing at 4100ish at 9DB where as i typically see 6300-6800 at 9db hitting over 7000 is uncommon for my connection.
Needs to be more stable, can be playing a game or watching a live video feed and it will stop, then notice that I'm unable to access any internet but all the time still remain connected to the exchange and logged into plusnet most of the time the drop below 0db doesn't drop the connection but just causes issues on my end so I'm unsure if that will even show up on plus nets end. I'm currently
Thanks for the quick responses!

[#7]

If you are saying that the SNRM is varying between -3 and +9dB then something is seriously wrong here! ...or have I misunderstood your post?
I would be suspecting router or micro-filters.  Are you able to change both?  Do you have a PN supplier router?  RouterStats works particularly well with the TG582n.
It is also noteworthy that predominantly the errors are being reported on the UPSTREAM.
This needs more investigation - not got time to help right now though - sorry.  Have to checked out the fault finder guide at the top of this forum?

[#8]

Quote from: townman

If you are saying that the SNRM is varying between -3 and +9dB then something is seriously wrong here! ...or have I misunderstood your post?

No, i'm logging anything between those figures only, the micro filter is less than a month old but i can swap back to one of my old ones as for the router i had a Netgear DGND 37000v1 up until last month, but this one has problems i still have it though and i have an Asus DSL-N55U neither supplied by PN.
when i plugged the N55U in it achieved the same sync speed as previous modem but after alot of restarts(it seems to restart the router when you change WiFi settings?) the sync speed dropped to 4100 or so until 2 days ago.
Router stats been running while ive been out and the connection seems to be sitting between 0.4db and 1.9db.
I'm going to try swapping to the old filter right now and see if that helps.

[#9]

Quote from: dragona

when i plugged the N55U in it achieved the same sync speed as previous modem but after alot of restarts(it seems to restart the router when you change WiFi settings?) the sync speed dropped to 4100 or so until 2 days ago.

Opps and oh dear... that will have well and truly messed around with the DLM.  Over and above your other issues, it will now think that your line / connection is very flaky and will thus be slowing down your line.  It is important that you do a manual disconnect (through the router control screens) before making any changes that might cause a restart.  Otherwise the DLM will slow you down even more until it sees several days of an uninterrupted connection.  This might be the cause of the perceived slower synch post installing the N55U.
It might be worth you getting everything sorted with your N55U configuration, then ask PN to do a line test and then a line reset / remove any acquired profile and then LEAVE IT ALONE for 10 days and see what happens.  Keep the routerstats running, keep an eye on error counts - if there is then an underlying pattern it can be investigated.
Bouncing a router on a poor line is very bad news and will complicate the problem.

[#10]

Quote from: townman

It might be worth you getting everything sorted with your N55U configuration, then ask PN to do a line test and then a line reset / remove any acquired profile and then LEAVE IT ALONE for 10 days and see what happens.  Keep the routerstats running, keep an eye on error counts - if there is then an underlying pattern it can be investigated.

It's been left alone until the recent problem. configured ipv6 recently but did safe disconnects.
as for over nights stats it ran between 0.3 and 2.1 db fluctuating all night then note the attached pictures, at around 7am it increases to 6db, there are 2 disconnects in between the pictures uploaded but SNRM stays virtually constant. then just after one line quality degrades again. Multiple disconnects in a short space etc, I'm unsure if this is related to a thunder storm in area at the moment though.

[#11]

Gonna see if i can get the router swapped out, tried the DGND3700 it holds a stable SNR but am experiencing issues with data transfer through lan/wifi which is why it was replaced in the first place.

[#12]

Great graphs - I think they tell a clear story - you've got a nose problem!
Over night is reasonably as might be expected, MW transmission interference. Come dawn this decreases and the back ground SNRM rises to 6dB.  However there are some nasty spikes which look like something switching on an off - possibly a room stat on your central heating system?
Later is settles down to a rock steady 6dB, after 13:00 all hell breaks loose.  What happened at 13:00?  Central heating switched on again?  Plasma TV?
You are moving in the right direction.  You need to keep this plotting going for a few days to see if there is a time pattern to this interference.  There are a number of potential solutions to this issue.
1. Negate the phone line's susceptibility to the noise - first check out your own internal wiring.  See the Kiz website I referenced before.  If you have extension wring from the master socket, only terminals 2 & 5 should be used.  There should e no star connections.  Check out filters.  After that it would be down to determining if there is a problem with the line (copper test) and having BTOR improve the line.
2. Find the source of the interference and eliminate it.
3. Accept a raised SNRM and slow synch rate to over come the error rate caused by the interferance
1 is ideal / 2. Might not be attainable / 3. Is what you might get stuck with!

[#13]

I don't suppose this would also cause interference with WiFi also?
I get decent SNR on my DGND3700 and it doesn't drop like the N55U, however the WiFi problem i mentioned occurs whenever someone comes home, (like the other issue.) there is a Plasma within about 10 ft of the router but the problem continues if its turned off.
First image shows my DGND keeping a stable noise margin since 23:30 last night as soon as someone comes home the wifi starts dropping randomly. I'ts definately the wifi as opposed to SNR because when streaming across the LAN over wifi video freezes for a moment then catches up when reviewing router stats moments later results similar to the graph are posted below.
I'll hold off opening the new N55U for now an do some tests with the DGND tomorrow since im off (i can get bit tones with this too) not sure if i can with N55U.

[#14]

I've been monitoring the connection and have tried to establish any cause within my home I've tried with everything but my laptop and router running and still get the drops during the times they have been noticed. Today however i noticed a change we received drops from 13:45 - 16:00 then we had nothing until the neighbors got home at 20:20, then this occurred i got a drop on my WiFi connection for a few seconds and found the internet unusable by all devices with ping time outs etc another interesting thing that i noticed was we get interference on our Freeview TV signal (squares) when this initial spike happened.
I'll carry on logging and try and get times where they come home and see if they match up with interference, unfortunately they are usually home well before me.
Going to take a look at internal wiring tomorrow

[#15]

Every picture tells a story... Great graphs, what s the latest tool you are using?
The -8dB spikes are really nasty - they suggest that with a target SNRM less than 9dB (and its associated higher synch speed) you are going to be at risk of frequent loss of synch and aggressive DLM action.  You need to correlate these spikes with something in the home (or eliminate such correlation).  You suggested that this started after arriving home - did you switch the central heating on?  Look for correlation with the boiler firing up or the room thermostat clicking on and off.
If the interference is broad enough spectrum then it could interfere with the WiFi - there are a lot of modern gadgets using the 2.5 GHz channel, from DECT phones through to cordless door bells.  Have you also looked at the WiFi channel spectrum?  Get inSSIDer if you do not already have it.
The plasma TV though switched off is it still in standbŷ?  Try turning it off at he socket - if that makes a difference, then it points to a problem with its PSU. Note that switch mode PSU issues are not usually responsible for spike noise - they tend to generate a gradual increase of noise (as they get warm).
Checking out the phone line extensions is a good strategy - start at the master socket - trace all of the wires - only terminals 2 (blue + white ) and 5 (white + blue) should be connected.  Eliminate any extensions not required.  Indeed consider getting a multi handset DECT phone system.  Plug the base station and router into the master socket and disconnect all extensions if practical.
Whilst you suspect local noise, i think there is little point in considering a line fault investigation - you run the risk of NFF and picking up a charge from BTOR.
Will keep a watch on your progress!