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Author Topic: Odd noise spikes causing speed issues and disconnections  (Read 26281 times)

duckson

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Re: Odd noise spikes causing speed issues and disconnections
« Reply #60 on: February 28, 2010, 11:28:33 AM »

I meant before that time, 20th Feb (1st one in the list) on here :- http://www.duckworth.myzen.co.uk/router/Netgear/Feb/

Yes the other time it resynced at 12db, i'm wondering if the resync occured due to BT changing me from a 9db to 12db profile.
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Cheers, Stu
Asus RT-AC68U (Merlin Fork 3.74 Update 5)
Netgear DG834GT (DGTeam firmware, modem mode)
XILO LLU

jeffbb

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Re: Odd noise spikes causing speed issues and disconnections
« Reply #61 on: February 28, 2010, 01:41:33 PM »

Hi
That first one showed the current(then) SNR margin of 12db,was that the original target or did the snr margin drop to that over a period of time ?? .A massive spike of about -12db caused a resynch(note*) to a lower synch rate with an SNR margin of ~15db ,this appears to indicate the target SNR margin to be 15db. Then several spikes of -3db or more (note*) at this level of SNR margin the line held .

note *: this illustrates exactly the effects of higher SNRM , a -3db noise spike at 15db is ~= to a -12db spike on a 12 db SNR margin.where you would expect to lose synch.(as it did)

Regards Jeff

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polymath

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Re: Odd noise spikes causing speed issues and disconnections
« Reply #62 on: August 17, 2010, 08:51:28 PM »

I am having similar problems. In fact I had this sort of problem back in late January 2010 through a good deal of February 2010. I raised a ticket with my ISP which eventually resulted in a BT engineer attending. The engineer did not do anything specific to fix the problem. I think the problem had 'fixed itself' before the engineer arrived. Prior to the problem I had been on 8128kbps, during the problem the downstream speed reduced to less than 5000kbps. After it fixed itself it went back to 8128kbps.

I have added this reply, because after several months of steady performance at 8128kbps 9dB SNRMargin, the connection started the same symptoms again last weekend (15 August 2010). I have Routerstat plots that look very similar to those of Duckson. This looks like the 'signature' of the problem. If it was steady interference surely the line would just sit at some high downstream SNR margin and lowish speed. What seems to be happening is more abrupt, almost like the connection is being switched off and on. Now obviously some electrical interference could casue that, something being switched on and off. I have checked within our property and there is no obvious on/off event anywhere in the property that coincides with the spikes. I have used a medium wave portable radio to check for noise, there is nothin continuous, but you would be lucky to catch a burst of noise if that is what is causing the drop outs.

By the way, at the downstream drop outs, the upstream goes down too, I guess that is going to happen as the re-synch will involve both. I have noticed the latest re-synch changed the upstream SNRMargin from around 12dB to 24dB with speed steady at 450kbps, at the same re-synch downstream went to 6336kbps and 15dB.

I have not provided the Routerstat graphs as they show such similar behaviour. In the 30 minutes I have been reading this thread and composing the reply, the downstream SNRMargin has gone to zero 4 times, with the speed also dropping to zero and then coming back up again (Netgear DG834GT by the way).

I know this thread is fairly old. Is this type of fault somethnig others have experienced?

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polymath

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Re: Odd noise spikes causing speed issues and disconnections
« Reply #63 on: January 30, 2012, 10:32:57 AM »

This is a reply to my own post, dated 17 August 2010. It has taken this long for me to be reasonably sure I have tracked down the problem with my ADSL conection.

In my last post I stated a BT engineer attended in February 2010 but did not do anything specific to fix the problem. Actually there were 2 BT engineer visits. The first did some checks but never made a report back to the ISP, so the ISP requested a second visit. The Second BT Openreach engineer did some checks and changed the connection block in the junction box attached to the outside wall of our house. By the way the phone line goes immediately underground from this outside junction box; as far as I know it is underground all the way to the exchange (other than going into the odd green cabinet en-route).

As noted in my last post none of the Openreach visits cured the intermittent problem. The problem came back in August / September 2010.

I have been suffering from this intermittent problem for literally years and have looked into many of the popular claimed reasons for bad connections (radio interference, domestic appliances, neon lights in power connector blocks). The frustration is, when the line is ok it is as good as it gets - 8128kbps downstream.

Something that has changed since early 2010 is I retired, and have had more time to fault trace and test what was going on.

In early 2011 I decided to go back to basics and start with the router (Netgear DG834GT) connected direct to the Master Socket 'test socket', without any phone equipment connected. In setting up the router in this way, I realised something I had not noticed before. In February 2010 the Openreach engineer had changed the Mater Socket inside the house, as well as the connection block in the junction box on the outside wall - BUT he had not changed the faceplate. The old Master Socket had the BT and "piper" logo in the top left corner (from 1993, when the house was built), the new Master Socket has the Openreach logo in the top left corner. But I realised the faceplate was the original from the original (1993) Master Socket.

In the past I had checked extensively the phone wiring in the house. And the wiring to the exchange is all underground and relatively new (and all copper according to the 2nd Openreach engineer). I began to wonder whether the problem was something to do with the faceplate itself. However I have thought I had found the cause of the problem before, only for it to return at a later date. So I needed to do some testing to check out the faceplate theory.

There are two 'spur' phone lines in the house, leading from the Master Socket. By the way, over the (literally) years I have had this intermittent problem, these two spur lines have been connected:

1. both plugged into the front socket of the faceplate (using a doubler plug);

2. One connected to the IDC connectors on the back of the faceplate, the second plugged into the front socket of the faceplate.

When the Openreach engineer attended, the two spurs were connected as in 2 above; maybe that is why he did not touch it - but that is beside the point.

I did about 2 months of testing with the faceplate out of the connection path. I will not go into details about what that involved but it was all legal, I did not touch the Master Socket itself. I concluded it is somewhere in the circuit board in the faceplate leading to the 'plug' on the back of the faceplate, or a fault in the faceplate 'plug' connectors.

Having convinced myself it was something to do with an intermittent connectivity or connection issue in the faceplate, in March 2011 I went to Maplin and bought a standard NTE5A Master Socket. I took the faceplate from the Maplin Master Socket and put it on the Openreach Master Socket. This new faceplate does not have any microfilter, it is a standard faceplate. The two spur lines are connected to the new faceplate using method 2 above (one on the IDC connectors, the other plugged into the front).

From the time I started my testing in February 2011 to now (end January 2012), the intermittent connection problem has not occurred, most of that time has been with the new faceplate. Of course there has been the odd issue with power cuts causing re-syncs. As of today, since last re-sync, the ADSL connection has been running for 40 days (downstream: speed 8128kbps, attenuation 22dB, noise margin 8.3dB - RCO 86%, 9440kbps) and the total CRC errors are 77 in 77 error seconds, with no Severe Error Seconds. The CRC errors seem to occur mostly when there is an incoming call and so a ring in event. Sometimes an incoming call does not cause and CRC erros, and somtimes they seem to occur with no obvious reason. I noticed this happens even when the router alone is connected direct to the test socket. But as this level of CRC errors does not cause any problems, I have not tried to sort it.

Since changing the faceplate, the longest continuous run has been 100 days (8128kbps downstream speed) - in Autumn 2011. That ended when I realised that although the downstream speed was 8128kbps, and my ISP showed the current speed as 7150kbps (correct IP profile number for the speed of 8128), the bRAS had somehow become stuck at 2000kbps. It took over 2 weeks of ticket tennis with my ISP to get BT to reset the bRAS.

For me, the circumstantial evidence is my intermittent ADSL connection issue was a simple continuity / connectivity issue in some part of the original Master Socket faceplate. The faceplate was certainly not changed when the rest of the Master Socket was changed in early 2010. Since changing the faceplate for a new one the intermittent problem has not recurred.
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duckson

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Re: Odd noise spikes causing speed issues and disconnections
« Reply #64 on: January 30, 2012, 12:06:30 PM »

Thanks.

I havent really looked into mine properly since those previous postings, although i got Zen to get BT to reset my target noise margin from 15dB to 6dB back in October 2011. It went back up to 15dB after 3-4 weeks though but i didnt really monitor it.
A fwe weeks ago we finally got an LLU provider in my exchange and so i'm now on TalkTalk LLU through a reseller called XILO....no more profiling and automatic upping of the target noise margin! hurrah! I've been messing about with 3 routers and had a power cut to boot so i havent spend more than a few days connected but will leave it since my last reboot which was sometime at the weekend to see how it goes.
One thing though I have done is change the cable between the RF3 filter (where the external drop wire terminates) and the master socket as the existing item was split open in a couple of places as it was run under carpets infront of doorways so was always stood on....now while not allowed i have left the existing cable in there so could reconnect it up at any time.

Can you clarify to me which part you have replaced?
There is the bottom half faceplate which you can remove to get to the test socket and there is the main master socket plate which the wiring from BT terminates at...which did you replace?
(Note i have removed the bottom half and use a filtered face plate, tried 2 different types, one BT gave me and an ADSLNation one).
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Cheers, Stu
Asus RT-AC68U (Merlin Fork 3.74 Update 5)
Netgear DG834GT (DGTeam firmware, modem mode)
XILO LLU

polymath

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Re: Odd noise spikes causing speed issues and disconnections
« Reply #65 on: January 31, 2012, 09:47:46 PM »

I replaced the bottom half faceplate on the front of the Master Socket.

I have not looked at changing to an LLU provider, though at least one is available on our exchange, on the basis that my problem has always been somewhere in the wires between our router and the exchange. I have always doubted that changing the hardware in the exchange would have any benefit. I just wish cable was an option.

Now I think I have fixed my problem, I could be in a position to change. However our exchange is due to go onto ADSL2+ soon. Be interesting to see how that works. My overall conclusion from my years of problems is whether it is Century 20 or 21 hardware at each end, the ends are connected by Century 19 type wiring and that is the weak link.
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burakkucat

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Re: Odd noise spikes causing speed issues and disconnections
« Reply #66 on: February 01, 2012, 02:32:08 AM »

Quote
My overall conclusion from my years of problems is whether it is Century 20 or 21 hardware at each end, the ends are connected by Century 19 type wiring and that is the weak link.

A very succinct statement!  :)
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:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

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