Downstream SNR varying wildly
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- Re: Downstream SNR varying wildly
Re: Downstream SNR varying wildly
22-01-2016 8:56 PM
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Here are some of my graphs: http://community.plus.net/forum/index.php?action=dlattach;topic=138230.0;attach=63644
Re: Downstream SNR varying wildly
22-01-2016 8:58 PM
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The first big dip, at about tone 46, that goes down to 6 bits, will be due to BBC Radio 4 on Long Wave 198 kHz.
It does look a bit of a mess after about 110, but some of the gaps down to zero might be deliberate gaps set by the DSLAM, and another normal dip is the pilot tone, which usually has 2 bits allocated to it on ADSL2/2+, and may be in a different place each time you connect.
Re: Downstream SNR varying wildly
24-01-2016 11:56 AM
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The bits per tone files, I have a file to analyse. Quick eyeball, and over 10 hours yesterday, the bips per tone only varied by a few bits; so expect to look like graph plotted the other day. I'll check.
My script for doing bits pet tone, doesn't grab the Thomson adsl stats - so I can't see if the the router saw noise in the afternoon. I'll add that, if I can work out command to get useful info from the Thomson router.
ANyway, from the TP-Link router, here is 1 weeks with of down steam noise margin.
Re: Downstream SNR varying wildly
24-01-2016 1:17 PM
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Seems almost no change in the bits per tone.
So yes looks like I'll have to add the adsl wider parameteres to the log file, as I can see last night, if there was noise on the line.
Re: Downstream SNR varying wildly
26-01-2016 7:25 AM
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You've suggested the possibility of street lighting which would be the obvious choice I would have thought of - but does your local street lighting fit this time pattern? - If not, it may be some other form of lighting or associated equipment that operates on a similar time slot. It will not be storage heating, that does not come on and go off at those times. Try and spot what comes on and goes off at exactly those times.
As far as tracking with a radio, if around 1.6Mhz is the strongest source of the interference noise - be certain that it comes on and goes off exactly with the interference otherwise you have the wrong noise. As ejs mentioned make sure that you aren't listening on a frequency with a radio station and the source may change by a couple of kHz each time it comes on. The primary trick is to identify the pattern of noise you need to listen for. It doesn't matter if the precise frequency you listen on has bit loading, it's merely a means of tracking the interference source.
Use the directional properties of the radio ferrite rod antenna to try and triangulate the potential source. I wouldn't get too concerned with that cable, the interference is probably being radiated from it as well as elsewhere. The problem with this type of interference is it can have multiple harmonics and can be picked up and re-radiated by various cables, as well as transmitted along them. Because of the multiple harmonics it can appear to have a fairly broad spectrum and can cause a general depression in bit loading across multiple tones. This won't be easy to spot on a graph because of the general AM/MW interference that appears from dusk to dawn, but won't really prevent tracking with the radio.
I know all that makes it sound easier than it will be in practise, but I hope it'll be of some help. Getting a list together of potential sources and then eliminating as many as possible is a good way to start.
Re: Downstream SNR varying wildly
26-01-2016 10:19 PM
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. Maybe it my network printer, plugged into the TP-Link router, and in a very similar place. The Thomson router is futher away. Easy to check.
. Maybe the owner of the house with the cable, noticed me leaning against the wall with a radio, last weekend; he came out of the house before 3:41. Anyway if he has recieved complaints in the past, maybe he just switched the noise off.
Anyway a few more days of collecting stats, then I'll plot some graphs, and then home in on the noise. Hassle for me is only real time I can dig into the noise out in the field, is at weekends - just don't get time in weekday evenings ...
Re: Downstream SNR varying wildly
29-01-2016 9:12 PM
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Anyway last few days of logging with the Thomson - Noise margin has been very constant. 15.5-16dB in day time, decreasing to 14.5-15dB at night. Attenuation has dropped to 39.5dB.
So Thomson isn't seeing the noise, and has less attenuation, than the TP-Link. This doesn't make much sense. I'll try switching back to the TP-Link over the weekend - and see if the noise comes back. That will help identify the source ...
Re: Downstream SNR varying wildly
30-01-2016 11:43 AM
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Maybe the noise has gone?
I know nothing about linux but there is program IPcop? with an addon "Adslmonitor for IPCop v.0.2 " which looks abit like routerstats for linux
have you looked at those.
Re: Downstream SNR varying wildly
30-01-2016 3:10 PM
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Anyway now flipped back to the TP-Link to see if the noise has gone there as well ...
Re: Downstream SNR varying wildly
05-02-2016 6:44 PM
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So 28/1/16 is from the Thomson
All in febuary are from the TP-Link.
So clearly on both the noise has gone. Notice how the noise margin is shown smaller on the TP-Link
So all I can do is keep the TP-Link and NAS watching.
But also should raise a plusnet ticket to reset noise margin, as clear now I can live with less than the 12-14 db it is set to ....
... hmmm how does one raise tickets with plusnet, don't seem to be able to find the link ...
Re: Downstream SNR varying wildly
05-02-2016 8:48 PM
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Live chat might be the quickest way.
Re: Downstream SNR varying wildly
06-02-2016 2:55 PM
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Re: Downstream SNR varying wildly
06-02-2016 4:10 PM
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Eventually found out how to post a ticket again - forgot how hidden it was on the plusnet site. Ticket seemed easiest - as then I post the graphs, that give the whole story. Ticket is still wiating a staff reply, so currently have also 15dB of noise margin! In case any PN staff are reading - its ticket 119451935; should just be a simple reset ...
Re: Downstream SNR varying wildly
08-02-2016 3:01 PM
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Re: Downstream SNR varying wildly
08-02-2016 4:23 PM
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- Re: Downstream SNR varying wildly