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Router stats query

maranello
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Router stats query


I thought I was begining to understand this........
On Saturday morning I had to reboot my router as I could not connect to any sites beyond my router interface. I checked my router stats, which showed that I had had a resync 44 hours previously,  and line speed was ~1400kbps (prior to this I had achieved 2176kbps). The downstream noise margin was reported to be 6.3dB, and I rebooted expecting very little improvement in speed as my target SNRM is 6dB. Immediately after rebooting, the line speed had increased to 2144kbps and the noise margin had increased to 6.8dB. Clearly there are other factors apart from line length and noise levels which impact on the line speed, can anyone enlighten me or point me in the right direction to do some research?
My other car isn't a Ferrari
14 REPLIES
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Re: Router stats query

Bit of an off the wall guess, maybe what caused the resync wiped out a load of tone bins, which became available again later but you weren't able to use until you resyncedHuh
maranello
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Re: Router stats query

Thanks Chris.
So if I understand correctly, the frequency bands that are used in my connection stays fixed for as long as sync is maintained. The noise margin reported by my router is an average across all of the bands. Some frequencies could experience more noise than others, but a reboot could utilise different frequencies (or more bands). This effectively changes the relationship between noise margin and achievable sync rate.
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itsme
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Re: Router stats query

If you go here you will see a practical example what happen. Basically at night when the noise is at the greatest Bins are completely lost.. These Bins will only become available again with a resync when the noise is not present.
Neilski
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Re: Router stats query

Any idea why noise gets worse at night (or indeed why it gets better in the daytime Smiley)?
itsme
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Re: Router stats query

Street lighting and P2P crosstalk are my suggestions.
198kHz
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Re: Router stats query

In the case of a defective light or cable, perhaps.
Commonest cause is the natural increase in medium-wave radio being picked up by the line - especially overhead sections - from sunset to sunrise.
Remember you are unique - just like everyone else
itsme
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Re: Router stats query

My 20 foot of overhead cable is picking up more than it's fair share of this noise.  Grin
Community Veteran
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Re: Router stats query

Chop it down Grin
Yes, MW propogation is usually the predominant culprit. Monitoring your line with RouterStats and looking at the patterns generally gives the best idea.
Any slight imbalance in the line will make matters worse.
Neilski
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Re: Router stats query

Quote from: Anotherone
Any slight imbalance in the line will make matters worse.
What sort of imbalance do you mean?
Community Veteran
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Re: Router stats query

Telephone lines are supposed to be balanced - ie each leg is the same impedance to ground. Cable/insulation problems or exchange equipment faults or maybe even dodgy EU equipment can upset that.
maranello
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Re: Router stats query

Quote from: 4Candles
Commonest cause is the natural increase in medium-wave radio being picked up by the line - especially overhead sections - from sunset to sunrise.

So why is MW radio pick-up worse from sunset to sunrise?
I had a power failure at home yesterday, and powered router back up at 6:30pm. The best sync I could manage was 832kbps, tried twice to increase it as the noise margin was above the 6dB target, but it wouldn't sync any higher. Same lack of success this morning at 6:30am. I want my 2Mbps back. It would be great if I could reboot about now, but I'm 8 miles away, and I still haven't found any way of remotely accessing my router.
I've got an Openreach filtered faceplate, the bell wire is disconnected. There is no obvious noise on the voice line, and no REIN detected using a MW radio. I'm not sure I believe all this radio interference nonsense, it's a myth spread by BTw to divert blame away from their abysmal infrastructure. Either that or someone must have stolen half of the frequency bins. Maybe its the same person who steals the lids from the recycling boxes. Maybe I just need a holiday.
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198kHz
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Re: Router stats query

Quote from: maranello
So why is MW radio pick-up worse from sunset to sunrise?

The 'D' region of the earth's atmosphere is ionised by the sun during the day, and acts like a sponge, absorbing MW frequencies. After sunset, the ionisation gradually declines, allowing the signals to reach the 'F' layer, where they are reflected back to earth. A MW receiver will therefore be receiving 'sky waves', as they're known, from the UK and abroad, as well as the normal 'ground waves' received in the day.
It's just unfortunate that MW is from about 530 - 1600kHz, while ADSL downstream is 138 - 1104kHz, so there's quite a bit of overlap. Make a note of what you can hear on MW during the day, and then compare with what it's like at night.
Remember you are unique - just like everyone else
maranello
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Re: Router stats query


A clear, simple and easily understood explanation - thanks
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pierre_pierre
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Re: Router stats query

and it is also affected by Sun Spot activity, going back to AM CB Days, normal range 30 mile, on a good day with "Skip", I got a clear converation with Aberdeen from Sibble Hedingham in Essex, get a good Radio Ham Magazine and they give a chart of Sun spot predictions