SNR gone haywire again!!!

gingerjedi · May 03, 2008, 13:09:18

Top is SNR down, bottom is SNR up, what on earth could cause such a massive spike on the 'up' reading?

ADSL Link   Downstream   Upstream
Connection Speed   2272 kbps   288 kbps
Line Attenuation   47.0 db   25.5 db
Noise Margin   17.8 db   25.0 db

I've posted on here many times before with intermittent sync loss problems which seem exasperated when the phone is in use but again only intermittently? To save people the bother of replying with the obvious answers I'll list what has been tried over the last 12 months.

3 different routers
6 different filters
Rewired internal line
Ring wire removed
NT5 replaced by BT

I have tested at the NT5 with the front face removed which bypasses all my wiring and still the problem remains, the last time BT came via IDnet they replaced the NT5 which I thought had solved the problem but it came back occasionally after about 2 weeks which didn't bother me too much but now I am getting loss several times a day which is driving me mad.

Rik · May 03, 2008, 14:18:04

It looks to me like a line fault, possibly an elusive HR fault, or a poor joint on the cable somewhere. You shouldn't be on a 2Mbps service with that d/s attenuation so, I suspect that if you push too hard, BT will drop you to a 1Mbps service, which would well overcome the noise issue. Do you prefer speed or stability?

gingerjedi · May 03, 2008, 15:21:14

I know its not IDNET's fault but I begrudge paying for a premium service if 1meg is all I can reliably get, I wouldn't mind if I was in a rural location but I'm only 2km from the Weston-super-Mare exchange, BT themselves guess I should be able to get 4meg with their crude calculator.

What percentage of people can get >2meg? They can't all live within 1k of their local exchange can they??

Would a line fault or bad joint make my attenuation reading higher than normal?

Rik · May 03, 2008, 15:31:09

Potentially, any kind of fault, but especially a bad joint, will raise your attenuation. It will also increase with higher sync speeds (as hgiher frequencies are used, and these attenuate more.

Your attenuation suggests you have about 4.5km of cable between you and the exchange, which is about par for a 2km 'crow flies' distance. The quality of the line will also affect attenuation, eg thick copper, thin copper or aluminium. I'm on aluminium, but manage a stable 3520k connection, 3k profile. Those spikes are at the heart of your problem, so finding what's causing them is paramount. The issue is, will BT be prepared to investigate given that you are out of spec for the service you have. All you can do is ask support to get BT to take a look. Collect as many routerstats graphs (and logs) as you can, and let them have them as evidence.

Here's a typical graph for me...

[attachment deleted by admin]

gingerjedi · May 03, 2008, 17:43:23

I've been out and came home to this!!!

Why would my connection stay stable for weeks on end and now start acting up so badly? I've just checked my phone to hear for the usual crackle and digital noise that accompanies this and I heard a beep then the line went dead followed by a low pitch beep then crackle and the engaged tone came back.

I want BT to look at this via IDNET but I assume no-one will be about till Tuesday?

Thanks for the advice Rik.

Rik · May 03, 2008, 17:46:25

Dial 17070 and then select option 2. Can you hear noise on the line. If you can, repeat the test with everything but the phone disconnected. Is it still noisy? If so, report it as a voice fault via 151.

You're right, IDNet won't be around until Tuesday, neither, unfortunately, will BT.

It does sound like a line fault to me, so if the test shows up noise, you can get BT interested on the voice side (don't mention ADSL).

gingerjedi · May 03, 2008, 18:06:13

I've tried that and the noise always disappears as soon as the router is disconnected which initially made me think the router or filters were faulty but I've tried 3 routers with several different filters and the problem was still there, also if I ring my home number on my mobile I can't hear any noise on the mobile but I can on my home phone so it's only coming upstream.

Rik · May 03, 2008, 18:13:57

What else is connected to the line. What you describe is classic filter failure, but if you've tried multiple filters, you should have eliminated that possibility (have you tried an ADSL Nation xf-1e?). One thing you could try is double-filtering everything. Have you checked that your internal wiring is using a 'pair', assuming you have hard-wired extensions? Do you have an NTE5 master sockets, the type where the bottom part of the faceplate can be removed?

gingerjedi · May 03, 2008, 18:28:31

I have 2x ADSL nation xf1e filters bought on advice from here.

I have 3 phones 1x wired 2x wireless DECT but I've tried unplugging these individually (took the handsets to the bottom of the garden!) and the problem remains, my skybox isn't connected.

I agree everything points to a filter problem but I have exhausted every avenue on that front including double filtering, I've tried plugging a filter into the socket behind the front plate of the NTE5 box and then connecting a router and landline and still the problem remains.

Rik · May 03, 2008, 18:40:52

TBH, then, you've done everything I can think of in DIY terms. If you're happy that the wires on your face plate are a pair, eg blue/white and white/blue, that they're connected on terminal 2 & 5, and that no other wires are in use, then I think you have to push IDNet to get BT out to look at the line. I'd just caution that BT might choose to solve the problem by dropping your connection to 1Mbps, given your d/s attenuation is greater than 43db.

AAMOI, do you have any idea of the route the cable takes back to the exchange? Does it run near any industrial plant or overhead electricity supplies, including trains? Can you check with any neighbours what sort of speeds and stats they get?

gingerjedi · May 03, 2008, 19:01:16

There is one long main road between me and the exchange which is mostly residential with only a few retail outlets along the way, no rail or power lines as far as I can tell, I can only assume it follows this route?

Asking my neighbours is next on my list, I'm convinced there's a bad joint that's causing a problem or possibly the line between my house and the pole is damaged in some way?

I'll be ringing IDNET on Tuesday to log a call, I've rang before and they've had BT out for me but the last 2 times my wife had to explain the problem, I'm off for a few weeks so at least I can give the engineer more detail this time.

Thanks Rik, enjoy the rest of the weekend.

Rik · May 03, 2008, 19:03:41

And you.

Sorry we can't solve anything, but at least we've covered everything that could possibly be an issue on your side of the test socket, so you shouldn't need to worry about any charges from BT. It would be good if you could run Routerstats 24/7 for 24-48 hours, as that might give the engineer a clue.

Sebby · May 03, 2008, 20:19:42

I can only agree that this looks to be like a line fault, but as Rik says, BT have been known to take the easy way out and just downgrade products, rather than looking for the issue.

I'd be extremely surprised if the problem was at your end; there really is nothing it could be! I think it's worth getting BT involved, especially given that the problem exists when using the test socket.

Wingco1 · May 04, 2008, 13:52:26

Can I make a suggestion. It may sound silly but you have nothing to lose. Remove the faceplate of the NTE 5 spray some WD-40 onto a phone plug and work it in and out of the test socket a few times. Daft as it may sound it cleans the terminals, and gave me a higher sync at an extension socket

Sebby · May 04, 2008, 13:53:25

I've never heard that one before. Interesting...

The only thing is that the OP has had a new NTE5, so you'd think things wouldn't have gone downhill so quickly. Still, it's worth a try.

Wingco1 · May 04, 2008, 13:57:20

Quote from: Sebby on May 04, 2008, 13:53:25
I've never heard that one before. Interesting...

The only thing is that the OP has had a new NTE5, so you'd think things wouldn't have gone downhill so quickly. Still, it's worth a try.

Missed that.

gingerjedi · May 04, 2008, 16:54:04

Even though I have a new NTE5 I have wiped the socket terminals with an alcohol wipe wrapped round a screwdriver already.

I've had routerstats running all night and since yesterday it hasn't dropped once and my SNR has been a steady and almost completely flat 18dB... don't you just love intermittent faults??!!

This got me thinking, as it's a bank holiday weekend it would be interesting if it remained flat today and tomorrow and then started playing up again on Tuesday, maybe something industrial is causing interference? I'm going to set up my laptop with routerstats and leave it running for the next 2 days.

Rik · May 04, 2008, 16:58:18

That's a pattern I see, though nowhere near the extent you do. Over the Xmas shutdown, my margin increased by 1db, when January 2 arrived, it dropped back again. If you do see it reappear on Tuesday, then those graphs will be indisputable evidence - BT need to put an SFI team along your line and possibly fit RFI filters.