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Author Topic: Daily DS SNRM Drops  (Read 311 times)

g3uiss

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Daily DS SNRM Drops
« on: October 01, 2018, 05:03:49 PM »

Strange problem arisen over last few weeks.

Most mornings at 0919 my DS SNRM fall to nearly zero on my ADSL line, there is a corresponding drop on my VDSL line but only to about 4db. Until today, the ADSL held sync, but today it fell so much it lost sync. I guess its a big bust of noise at a frequency in the ASDL range.

Strangely it doesn't happen every day but more than others, and more strangely it happens less days on the VDSL .

I have put some current stats at :-

www.west-lodge.com/adsl/index.htm - ADSL line

www.west-lodge.com/vdsl/index.htm VDSL line (Regretfully no snapshots uploaded recently )

There is nothing in the house with a timer or device that triggers at 0919. I suspect it must be external. It was happening when I was away and the house unoccupied and nothing running ?
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kitz

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Re: Daily DS SNRM Drops
« Reply #1 on: October 02, 2018, 10:30:07 AM »

I also have a noise burst which happens each morning that I've never been able to get to the bottom of and has been ongoing for a few years now.
 
It will cause my line to generate quite a few errors - as per the attached you can see throughout most of the day I only get 1 CRC, but the whatever it is will cause a sudden burst to around 2800-3000 which will last for about a minute. 

That spike is the reason why I have to monitor my line, because sometimes the errors will stick until I reboot my modem. If I don't then DLM will penalise me..  which is a PITA because by the time DLM catches up, the errors will have already stopped about 18hrs ago, but will take weeks to recover.  :/
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How to get your router line stats :: ADSL Exchange Checker

g3uiss

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Re: Daily DS SNRM Drops
« Reply #2 on: October 02, 2018, 02:24:15 PM »

Interesting. Very similar, I get about 3000 CRC on my ADSL2 when it happens at 0919, I did at first think it might be a new electric train. The cable from my UG DP goes over the railway bridge which you will know was recently electrified, but firstly there is nothing going under the bridge at 0919 and I guess it couldn't just be 1 train. (However Northern cancel more than run  ;D )

I'm going to have to live with it, like you unless it gets so bad that the line syncs every day. This morning the CRC was less and the SNRM dipped to just above 0 so it stayed in sync.

Do you get a similar SNRM drop to match and is the time constant ? Interesting if it is as its just a bit later than me ???

Have sent you a personal PM also

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kitz

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Re: Daily DS SNRM Drops
« Reply #3 on: October 02, 2018, 05:58:19 PM »

No corresponding dip in SNRm which is strange considering the amount of errors.  The only thing I can think of for that is there is a micro-second dip that dsl stats doesnt catch as it only records every 1 min.   In that instance CRCs would still show as they are based on accumulated errors rather than real time.

However that would not account for the fact that the CRC/ErrSec spike will usually last over 2 recordings.  I suppose there could be a couple of spikes, but you would have thought that because it happens daily and has been happening for years, that DSLstats would have caught it at least once.

>>> firstly there is nothing going under the bridge at 0919

Mine isn't always at exactly the same time.  It will usually be between 9.15 to 10:15 but can also happen any time between 8 - 11:30.  Today's was at 10:24 & 10:25.

I have seen similar on a few other lines just not as noticeable and I have in the past wondered if it is something at the DSLAM side.
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Weaver

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Re: Daily DS SNRM Drops
« Reply #4 on: October 06, 2018, 04:33:08 AM »

The question is, what happens at that time. Something getting switched off, or switched on? Heating turned off, or an oven turned on? (By neighbour) if so, something needs interference suppression.

Is there any chance that a mains filter might help? (No, because it is RF, going straight into the DSL line, not coming in by mains.)
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