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Author Topic: Effect of power outage on S/N  (Read 1002 times)

sheddyian

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Effect of power outage on S/N
« on: August 30, 2018, 10:27:22 AM »

I had a letter the other day to notify me that I would lose mains power for 10 minutes on the 30th August, and I wondered what effect this might have on my broadband.

"It'll go off when the power is off, obviously"  :lol:

So I hurried to get the router and modem and monitoring setup moved over to the solar charged batteries.

The power outage, as it turned out, was brief, but if you look at the two graphs I've attached from DSLSTATS, I think you can tell when it was  :o

Ian
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tubaman

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Re: Effect of power outage on S/N
« Reply #1 on: August 30, 2018, 12:06:06 PM »

I wonder how much extra speed you could get if it wasn't for those pesky cross-talkers stealing your SNR!
 :no:
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re0

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Re: Effect of power outage on S/N
« Reply #2 on: August 30, 2018, 03:06:58 PM »

This reminded me of a time when I had a power outage back in the days of ADSL2+. I gained a whopping ~1.5 Mbps afterwards! From ~6.6 to ~8.1 Mbps if memory serves.

At the time, I am pretty sure I didn't realise that there had been a power outage. The celebration was soon postponed when the SNR Margin started dropping low levels (~1 dB), followed by a disconnect. At that point, I knew it was only a tease - I had been subject to a power outage. Something part of my wildest dreams left my grip as I slipped away with he rug of reality under my feet. Goodbye, extra 1.5 Mbps. ;D

Anyway, now I get the full 80/20 on FTTC (minus small G.INP overhead). I wonder what my attainable would be like after a power outage. :hmm: Depends on the amount of subscribers back online, but I do not think 100 Mbps attainable is out of reach. :)
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burakkucat

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Re: Effect of power outage on S/N
« Reply #3 on: August 30, 2018, 05:03:59 PM »

The power outage, as it turned out, was brief, but if you look at the two graphs I've attached from DSLSTATS, I think you can tell when it was  :o

Quite a dramatic change, albeit temporary!  :)
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sheddyian

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Re: Effect of power outage on S/N
« Reply #4 on: September 03, 2018, 01:51:58 PM »

I hadn't considered crosstalk, but of course that's likely to be the main thing here.  I had been imagining mains-borne interference along the way.  Probably because I've had problems with that in the past at my old place.

On a related note, the attached graph shows my SNR from the other day, and a very curious rise for a while, then it drops back down. 

Although my SNR fluctuates a little, it's usually only by 0.1 or 0.2 dB and it just wavers about a little. 

Any thoughts as to what might have happened here?  I can't relate it to anything in the house at the time.

"normal" SNR for me is around 8dB, so this jump to 9dB is an improvement, not a loss)

Ian
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j0hn

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Re: Effect of power outage on S/N
« Reply #5 on: September 03, 2018, 03:09:02 PM »

The dramatic improvement during the power outage is absent crosstalk.
All your neighbours power was off, that's probably only you connected to the DSLAM.

The smaller improved (the 1dB jump in SNRM) looks like a single neighbour/crosstalker turning their modem off for a few hours, then turning it back on again.

I can actually recognise a couple of my neighbours lines from the amount my SNRM varies.
When my neighbour to the left (my worse crosstalker) turns off their modem my SNRM jumps 3dB.
With my neighbour to the right it's about 0.5dB.
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burakkucat

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Re: Effect of power outage on S/N
« Reply #6 on: September 03, 2018, 10:04:00 PM »

I hadn't considered crosstalk, but of course that's likely to be the main thing here.  I had been imagining mains-borne interference along the way.  Probably because I've had problems with that in the past at my old place.

Both of the events, shown in your plots, are the products of the removal of crosstalk . . . exactly as j0hn describes.

I can remember you searching, a year or more ago, for the source of the mains-borne interference. Was it ever resolved?  :-\
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sheddyian

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Re: Effect of power outage on S/N
« Reply #7 on: September 04, 2018, 08:57:48 PM »

Both of the events, shown in your plots, are the products of the removal of crosstalk . . . exactly as j0hn describes.

I can remember you searching, a year or more ago, for the source of the mains-borne interference. Was it ever resolved?  :-\

Thanks j0hn and burakkucat for the clarification.  I'd got quite obsessed with combatting mains-borne interference - when I first moved here and was on slow ADSL, I was chasing around the house with a medium wave radio to see if there was anything especially noisy that I could switch off and maybe get a fraction more signal dB to use  :-\

As to my previous noise problem, it was a good few years ago now - 2014 ish?  It was at my previous house, and I didn't ever get it resolved, though it just went away after many months. 

I reckoned it was someone with an occasionally used spare TV or somesuch, that got switched on occasionally.  The interference would last around an hour, could be heard swamping the MW radio band in my house and for some distance up and down the road, and made my ADSL lose 4 or 5 mb of capacity.  I tried switching my electricity off at the fuse box but the noise continued, so was sure it wasn't from me, but despite walking up and down the road with a radio buzzing away, I wasn't able to find the source of the noise, only (roughly) determine the bounds of the signal.

Ian
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burakkucat

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Re: Effect of power outage on S/N
« Reply #8 on: September 04, 2018, 09:35:46 PM »

As to my previous noise problem, it was a good few years ago now - 2014 ish?  It was at my previous house, and I didn't ever get it resolved, though it just went away after many months.


It was as long ago as that?  :o  I can remember you attempting to trace the source and one of your neighbours (the church organist?) allowing your to test by turning off their incoming mains supply.
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sheddyian

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Re: Effect of power outage on S/N
« Reply #9 on: September 04, 2018, 10:01:12 PM »



It was as long ago as that?  :o  I can remember you attempting to trace the source and one of your neighbours (the church organist?) allowing your to test by turning off their incoming mains supply.

I'd have to look back at my posts to be sure, but it was a while ago!

I'd forgotten that I got my neighbours to turn their power off as well  :-[  The noise on my radio was particularly strong near where the mains cable entered their house, so I wondered if they were also the source.  They weren't. 

The noise stretched from neighbour on other side (it got weaker there) to 5 or 6 houses up the road, but also was easily detectable whilst walking behind the row of our houses, so could have been from a side street.  Much weaker on the opposite side of the road though.

I noticed that, when the interference wasn't present, I could hear the hiss of DSL by holding my radio near the "Post Office" inspection cover in the pavement.  When the interference was present, doing the same would get a loud buzzing sound from the radio  :no:

Happy / frustrating memories  :D

Ian

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burakkucat

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Re: Effect of power outage on S/N
« Reply #10 on: September 04, 2018, 11:38:06 PM »

Looking around for a possible pointer to the appropriate thread, I came across a link to a certain YouTube video.



And here be the thread, started in February 2013, with a length of six pages in total -- Serious interference around 700Khz.

Your sketch-map is attached to Reply #49.
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johnson

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Re: Effect of power outage on S/N
« Reply #11 on: September 05, 2018, 01:47:08 AM »

I hope you have cut your damn fingernails since!  ;D
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sheddyian

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Re: Effect of power outage on S/N
« Reply #12 on: September 05, 2018, 09:55:08 AM »

Looking around for a possible pointer to the appropriate thread, I came across a link to a certain YouTube video.



And here be the thread, started in February 2013, with a length of six pages in total -- Serious interference around 700Khz.

Your sketch-map is attached to Reply #49.

Hah, fantastic!  I think I later found the noise to extend further to the left in my drawing, as I remember walking up and down the road and being surprised at how far up it went.

It got me tuning the car radio to low end MW when I was out and about, mostly just quiet hiss there but now and again I'd get a very loud buzzing - near a TV repair shop for one.

*looks at nails* hmm.
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