SNR Drops - Errors Skyrocket! HELP!

The SNR on my line will suddenly drop to a low value and as a result the errors will skyrocket. I have attatched a RouterStats plot to show this.

I am on ADSL Max and my providor is Vivaciti, I have an open ticket with them at the moment but they haven't responded yet.

http://img824.imageshack.us/img824/3975/rxnoisemargi...

(Please note: I realise that the SNR is low (3dB) but this happens even if the SNR is at 15dB.)

Any help will be very much appreciated.

Thank you.

Edited by deleted (Sun 18-Mar-12 09:22:17)

Just to add: the drops don't seem to relate to a particular time of day.

Is there any pattern, for instance every hour and a half?

At the moment I'd assume something electrical in your house or close by is being used or switched on at the time of the SNR drop. Can you think of any candidates?

Thank you for responding so quickly.

The SNR dropped at 5:50PM last night (as shown in the graph posted above) and it started dropping at about 9:00AM today so I don't see any pattern at the moment. I'll keep monitoring to see if a pattern does emerge, however.

I have suspected the boiler, but after turning it off and turning it back on, it doesn't seem to have any effect. The router is next to a PC, but after turning it off, there is no change. Is there anything else you could suggest?

Thank you.

Things like microwaves, anything powered by mains with one of those transformer blocks, anything electrical I'm afraid. As a quickish check you could operate every piece of electrical kit for a minute or so and see if anything triggered a drop. A boiler kicking in does seem a likely candidate, even though you seem to have ruled it out.

In reply to a post by arobertson545:

The SNR dropped at 5:50PM last night (as shown in the graph posted above) and it started dropping at about 9:00AM today

Did it go back up between those 2?

In reply to a post by BatBoy:

In reply to a post by arobertson545:

The SNR dropped at 5:50PM last night (as shown in the graph posted above) and it started dropping at about 9:00AM today

Did it go back up between those 2?

Yes it did.

I have just finished some re-organisation of cables by the router. I doubt this will make any difference, but it is worth a try.

I have now restarted the router and I am on the default 6dB target noise margin with no tweaks. I will keep RouterStats on the whole day and I will post any drops in the SNR.

Edited by deleted (Sun 18-Mar-12 10:40:24)

Current stats:

adsl: ADSL driver and PHY status
Status: Showtime Channel: INTR, Upstream rate = 448 Kbps, Downstream rate = 6304 Kbps
Link Power State: L0
Mode: G.DMT
Channel: Interleave
Trellis: OFF
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 6.3 24.0
Attn(dB): 41.0 24.0
Pwr(dBm): 19.6 11.9
Max(Kbps): 6848 1100
Rate (Kbps): 6304 448
G.dmt framing
K: 198(0) 15
R: 14 16
S: 1 8
D: 0 0
ADSL2 framing
MSGc: 1 1
B: 198 15
M: 1 8
T: 1 1
R: 14 16
S: 1.0703 9.0000
L: 1592 128
D: 0 0
Counters
SF: 92216 92214
SFErr: 2 0
RS: 6270734 783819
RSCorr: 817 0
RSUnCorr: 16 0

HEC: 2 0
OCD: 0 0
LCD: 0 0
Total Cells: 23308519 0
Data Cells: 1991642 0
Drop Cells: 0
Bit Errors: 0 0

ES: 1 0
SES: 0 0
UAS: 14 0
Total time = 26 min 32 sec
SF = 92216
CRC = 2
LOS = 0
LOF = 0
ES = 1
Latest 1 day time = 26 min 32 sec
SF = 92216
CRC = 2
LOS = 0
LOF = 0
ES = 1
Latest 15 minutes time = 11 min 32 sec
SF = 40710
CRC = 2
LOS = 0
LOF = 0
ES = 1
Previous 15 minutes time = 15 min 0 sec
SF = 51506
CRC = 0
LOS = 0
LOF = 0
ES = 0
Previous 1 day time = 0 sec
SF = 0
CRC = 0
LOS = 0
LOF = 0
ES = 0

An average line with 41dB downstream attenuation might get a bit closer to the maximum interleaved sync of 7616kbps.

If you have a test socket within your BT master socket it may be worthwhile to get stats from there at some stage. Has the bell wire been removed if it has been fitted?

See http://www.dslzoneuk.net/socket.php?type=html

In reply to a post by john2007:

If you have a test socket within your BT master socket it may be worthwhile to get stats from there at some stage. Has the bell wire been removed if it has been fitted?

I use a BT ADSL v1.0 faceplate. The bell wire has also been removed.

Now the errors start to increase:

http://img690.imageshack.us/img690/700/rxeslatest15m...

Not too bad:

http://img843.imageshack.us/img843/3975/rxnoisemargi...

The spikes which caused your loss of sync were pretty dramatic. You have a bit of a waiting game I'm afraid. If you are lucky it is something inside your house. If outside you may never pinpoint the problem (and even if you do there may be nothing you can do about it).

It has been fine all day:

http://img831.imageshack.us/img831/3975/rxnoisemargi...

Hopefully this is a good sign!

Touch wood. You can see a slight downward drift as you would expect as day turns to night and radio intererference increases.

As expected, the SNR is dropping, but there haven't been any large blips (yet):

http://img835.imageshack.us/img835/3975/rxnoisemargi...

Dropped to 5dB where it was previously at 6dB about 10 minutes ago:

Noise Margin: 5.3 dB
Connection Rate: 6304 Kbps
Line Attenuation: 41.0 dB
Power: 19.6 dBm
Max Rate: 6848 Kbps

I assume the sudden drops are quite recent. Any changes you can think of around the time they started?

Happened twice today:

http://img259.imageshack.us/img259/2382/rxnoisemargi...