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[lemzip]

Any ideas? Tried multiple filters, routers, cables, faceplate filters, pro rj11 cables, test sockets...you name it.

Cannot find anything in my house that relates to it, also done the whole turn off power and tested.

Is this rein or crosstalk?

http://img.photobucket.com/albums/v228/Lemzip/help.jpg
http://img.photobucket.com/albums/v228/Lemzip/wedmorn2.jpg

It starts in the morning around 9-11am and continues all day until 11-12pm. I think obviously its a home users who is either turning his router on, however would this really be as bad as that with crosstalk or a user is turning on a device ie boiler etc that is causing this.

My best snr is during the night from 1am to 8am. then this happens and it just drops 3-4db snr.

Line stats (at present)

Noise Margin:     3.3   dB
Connection Rate:  14761 Kbps
Line Attenuation: 31.5  dB
Power:            0.0   dBm
Max Rate:         17260 Kbps
 
SuperFrames:      1367471
SF (CRC) Errors:  2179
Reed Solomon:     164096574
RS Corrected:     6488992
RS Un-Corrected:  25538
HEC:              1554
Errored Seconds:  3161
Severe ES:        43

Interleave Depth: 64
Bitswaps:         1307


Noise Margin:     11.5  dB
Connection Rate:  1020  Kbps
Line Attenuation: 15.4  dB
Power:            12.9  dBm
Max Rate:         1188  Kbps
 
SuperFrames:      1228834
SF (CRC) Errors:  0
Reed Solomon:     0
RS Corrected:     0
RS Un-Corrected:  0
HEC:              0
Errored Seconds:  0
Severe ES:        0

Interleave Depth: 1
Bitswaps:         5

Done the radio issue and cannot find much at 612kHz bar a french radio station at night.

DMT Screenshots

when the issue is happening
http://img.photobucket.com/albums/v228/Lemzip/bad.jpg

when things are good
http://img.photobucket.com/albums/v228/Lemzip/dmt20101126_0115.png

DMT missing tones

Gap1 474kHz-479kHz (Tone110)
Gap2 548kHz-552kHz (Tone127)
Gap3 811kHz-815kHz (Tone188)
Gap4 824kHz-828kHz (Tone191)
Gap5 1048kHz-1052kHz (Tone243)
Gap6 1255kHz-1259kHz (Tone291)
Gap7 1501kHz-1505kHz (Tone348)
Gap8 1686kHz-1690kHz (Tone391)
Gap9 1755kHz-1764kHz (Tone407-Tone408)
Gap10 1828kHz-1833kHz (Tone424)
Gap11 1898kHz-1906kHz (Tone440-Tone441)
Gap12 1971kHz-1979kHz (Tone457-Tone458)
Gap13 2005kHz-2014kHz (Tone465-Tone466)
Gap14 2044kHz-2048kHz (Tone474)


Any help would be appreciated, obviously my isp is not interested as i still sync okay for my attenuation.

[waltergmw]

Hi LemSip and welcome,

If you put your attenuation in here:-

http://www.kitz.co.uk/adsl/max_speed_calc.php

you will see that when in "good mode" your are exceeding Kitz's estimation quite significantly and even when in "bad mode" you are only slightly less.

It might be worth doing various speed tests e.g. http://www.thinkbroadband.com/speedtest.html

when in good and bad modes to see if your actual throughput varies very much.

It may well be that it's impossible to improve matters and you're certainly very lucky indeed to have those speeds compared to several I try to help.
If speed is vital it would be worth trying a Virgin Media service, always assuming that it's available in your area.

Kind regards,
Walter

[lemzip]

That is however based on a 6db snrm, mine is under that if i let it sync at 6db, only reason it is better is due to me running it at 3db

[geep]

Hi,
Looking at your error statistics you'll see on the "bad" screenshot that your CRCs are less than the "good" screenshot.
"Good" 1,009,377 CRCs over 1day 10:23:25 = 489 CRCs/minute
"Bad" 837,395 CRCs over 1day 22:52:52 = 297 CRCs/minute

My line with 9dB SNRM is currently running at 0.5 CRCs/minute. On bad days it approaches 10 CRCs/minute.
I've never seen any figures that detail how much throughput is lost due to retransmissions following a CRC error - maybe somebody else knows? To me, CRCs in 100s per minute seem high.

Sync speed isn't everything. If you can change your target SNRM, maybe try speedtests at 3, 6 and 9 dB and compare results. Note also the uptime and error statistics.

Cheers,
Peter 

[lemzip]

thanks for that but however those stats are taken during good/bad times aswell, ie its always in a cycle of good snr then bad snr its just a matter of when i resync so stats will just continue from the past 24 hours of whenever and i always have the cycle so it will have a bad snr time and a good snr time.

[geep]

Ah - I thought you were selecting either a 3dB or 6dB SNRM.
A variation of 3dB over a 24 hour cycle isn't unusual. My line drops about 3dB in the evening - 16h00 to 20h00 at present.
If you can monitor using RouterStats http://www.vwlowen.co.uk/internet/files.htm then you can see the SNRM graphed directly, and maybe pinpoint more precisely when changes to SNRM happen.
Cheers,
Peter

[lemzip]

Hi
thanks for taking time to reply.

My first post shows some screenshots in the two first links from Routerstats. As you can see, this shows a very large drop very suddenly so cannot be the usual fluctuation from nighttime snr drop.

Im really struggling to find what it is. It one of two things, crosstalk or rein however my line has no noise on it and i dont have any issues with the voice side or REIN however my radio struggles to find anything bar a constant noise at 612kHz or at night, a french lady talking.

[billy171]

I'm wondering how long you have had the connection for .... that's to say, how long it has been "established".
The reason I mention this, is because a while ago I managed to get hold of a presentation file outlining certain aspects of the 21CN line algorithm, and in there it described a situation whereby certain connections with either limited line history or those that had seen previous instability .... were "studied" by the associated msan.
This can happen on a daily basis apparently, until the msan is "satisfied" the correct solution is applied to the connection to give maximum stable line speed and throughput. Adjustments to noise margin can change on the fly, according to error count (I presume.) Perhaps it may be the case and in fact the connection is fine.
I have seen numerous people with low levels of SNRm, and 3db is not uncommon, even though DLM's default target is 6db. And as you rightly point out, it is a distinct step in margin level, rather than the usual night-time gradual erosion.  Just a thought.  Perhaps the passing of time (and increase in line history) will see it disappear.

[lemzip]

Line is on LLU ans i have been assured they have ran all test possible to find a fault remotely and they have all come back fine. I have had LLU and ADSL2+ setup on the line for 2 years now this Jan.

The set is very quick in the lose of SNRM. i am unsure if this can be blamed on crosstalk or REIN. IE new years eve, around 8pm my snrm jumped up to usual levels arouns 8pm and stayed that way (dropping around 1db in night time erosion until around 5pm on new years day and then things went back down again. I have done everything i can my side, the only other options is crosstalk or REIN but trying to track it down is hard. Now for instance, my SNRM is sitting at 2.2db however my snr will get better tonight going up to around 3-4db

[kitz]

>> The set is very quick in the lose of SNRM.

Doesnt look like crosstalk, if anything looks like some sort of  EMI.  Variations of 3dB SNR would be considered 'normal', but the quick drop would seem to indicate something being switched on.

[lemzip]

thanks Kitz for responding

Here is the latest screenshot

http://img.photobucket.com/albums/v228/Lemzip/routerstats07012011.jpg

I am tempted to get a BT SFI Engineer out who is REIN trained however not sure if i will be able to get a REIN trained engineer for the first visit. I am 100% certain it is nothing in my property, the only other option is neighbours but i struggle to pick up any noise with a radio.

Also this morning at 9:30 it dropped back down

Fri 07 Jan 2011  09:29:32   92.25.122.222   Rx-Noise=10.1   Tx-Noise=11.9   Rx-Sync=12393   Tx-Sync=1020   
Fri 07 Jan 2011  09:29:35   92.25.122.222   Rx-Noise=10.1   Tx-Noise=11.9   Rx-Sync=12393   Tx-Sync=1020   
Fri 07 Jan 2011  09:29:38   92.25.122.222   Rx-Noise=10.1   Tx-Noise=11.9   Rx-Sync=12393   Tx-Sync=1020   
Fri 07 Jan 2011  09:29:41   92.25.122.222   Rx-Noise=10.1   Tx-Noise=11.9   Rx-Sync=12393   Tx-Sync=1020   
Fri 07 Jan 2011  09:29:44   92.25.122.222   Rx-Noise=9.1   Tx-Noise=11.9   Rx-Sync=12393   Tx-Sync=1020   
Fri 07 Jan 2011  09:29:47   92.25.122.222   Rx-Noise=9.1   Tx-Noise=11.9   Rx-Sync=12393   Tx-Sync=1020   
Fri 07 Jan 2011  09:29:50   92.25.122.222   Rx-Noise=7.5   Tx-Noise=12.0   Rx-Sync=12393   Tx-Sync=1020   
Fri 07 Jan 2011  09:29:53   92.25.122.222   Rx-Noise=7.6   Tx-Noise=11.9   Rx-Sync=12393   Tx-Sync=1020   
Fri 07 Jan 2011  09:29:56   92.25.122.222   Rx-Noise=7.6   Tx-Noise=11.9   Rx-Sync=12393   Tx-Sync=1020   
Fri 07 Jan 2011  09:30:00   92.25.122.222   Rx-Noise=7.3   Tx-Noise=12.0   Rx-Sync=12393   Tx-Sync=1020

As  you can see im checking routerstats every 3 seconds, so somethingg is turning off at night, then back on in the morning however this does not happen like this every day

[waltergmw]

Hi Lemsip,

When I need comparative data from several broadband connections I have a couple of old laptops I leave connected in the target houses.
I then access them remotely from my home using LogMeIn which allows me to access the modem interface to collect the stats or routerstats etc.
I have to be careful with speed tests as I'm flying blind and don't usually know whether the end user is involved in heavy downloads at that time.

This is quite a good way of finding if there has been an equipment outage if I lose all the remote services.

Kind regards,
Walter

[geep]

I now remember I used to suffer from sudden SNRM drops a bit like yours. It stopped when the fridge-freezer was replaced due to dodgy thermostat.

Had suffered from resyncs most mornings, and at random other times too. I reckon that opening the fridge to get milk for the morning cuppa made the thermostat switch the fridge on with a lot EMI causing the morning resync.

Cheers,
Peter

[lemzip]

had everything in the house turned off today from the main trip switch bar the router and battery powered laptop, no change in the issue. I have agreed for BT to come round on Monday so hopefully i will find out more.

£100 if no fault found but we will see.

[orainsear]

my radio struggles to find anything bar a constant noise at 612kHz or at night, a french lady talking.

What kind of noise do you hear during the day when you are experiencing the reduced SNR margin?

Have you gone outside with it?  If not try tuning the radio to 612 kHz and walk away from the houses, noting if there is any change in the noise.  Remember to turn the radio through 90 degrees and back in your hand while you are walking.