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SNR Fluctuations

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SNR Fluctuations

The SNR on my connection is normally 12.5, but every now and again, it drops down to 8.0. This drop is gradual over a period of a few days. A few days later, it's back to 12.5 again.

Any ideas why this could be happening? Is it worth getting PN/BT to investigate?
19 REPLIES
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SNR Fluctuations

Mine is very similar. But rather than over a few days its all day long. It goes from 26 to as low as 16. No idea why it does, I have tried everything bar building my own exchange lol.

There is not much you can do, and BT dont see it as a major issue because if its not losing connection (less than 6dB) then its not classed as a problem. You could try using better filters, a NTE5 face plate or removing the ring-wire.

Here is more information:
http://portal.plus.net/central/forums/viewtopic.php?t=41671

It could be that your router just needs a reboot every so often, if so the cheapest way to do this is with one of these:

http://www.diytools.co.uk/diy/Main/Product.asp?iProductID=2304

Other than that I dont think BT or PN will be able to help as they probably wont see it as an issue until you lose your connection completely heh.
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SNR Fluctuations

hi
it could just be down to the weather or you could try changing your filter at the phone socket

try that and see how that goes
Plusnet Staff
Plusnet Staff
Posts: 12,169
Thanks: 18
Fixes: 1
Registered: 04-04-2007

SNR Fluctuations

Hi,

Unless it's causing the connection to drop then I'd say it's nothing to worry about and is probably normal. I've seen a lot of people saying similar things, SNR does fluctuate over time and can be anything from temperature and the weather, to random interference, to probably birds sat on the line.
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SNR Fluctuations

I live practically on top of my exchange, but since I got my max upgrade I sometimes see it flicker down to -1dB :lol:
It doesn't lose connection at that point though.
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SNR Fluctuations

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I sometimes see it flicker down to -1dB :lol:
It doesn't lose connection at that point though.


Damn man! Can I come and live with you? :lol:
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SNR Fluctuations

am I seriously mistaken in thinking that surely you want SNR to be a really high decibel rating, suggesting that there is a lot more signal than noise, so 20db >> 10db for SNR..


Attenutation however, I would assume a low number would be what is wanted there, so 10 db >> 20db for that.
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SNR Fluctuations

The higher the better for SNR, the opposite for attenuation. My post was a little misleading, what I meant was that he is close to the exchange which I am most definatly not lol

The closer you are to the exchange obviously means the better connection. The fact that his SNR can drop so low without disconnecting means he would be able to get a pretty fast connection and still hold it with sub 0 SNR ratings.

That sounds good to me lol
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SNR Fluctuations

That would be very good, holding a connection where the noise is greater than the signal, thanks for clearing that up for me though.
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SNR Fluctuations

I have a slightly different problem that someone can maybe shed some light on.

Upstream Attenuation never moves from 31.6
Upstream SNR Margin never moves from 30

Downstream Attenuation never moves from 35.5
Downstream SNR Margin continuously fluctuates second by second between a max of 27 and a min of 23.

I am using a XF-1e filter.

Why would just one of the values be so continuously changing ?

Ray
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SNR Fluctuations

Your problem is the same as the thread starters and mine, the downstream SNR is fluctuating. Its just a common thing when you are far from your exchange, or when contention at your local exchange is at peak times. Weather can also effect it, or machinery.

Its very hard to pin-point one cause. It could be something as simple as a phone being too near to your router, or a computer. Best thing to do is when it starts happening look around in/outside you house for signs of anything that has just come alive and could cause the issue.

For example, if your line passes close to a street light this can cause it.
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SNR Fluctuations

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Damn man! Can I come and live with you? :lol:

I also happen to live practically on top of old trafford, not the best place to be on a match day :x
Luckily my exchange is a tiny little one, with very few BB users from what I can tell. Maybe just enough to keep the thing upgraded but not enough to be hit by LLU yet.

Anyway, back to SNR. Today my SNR is 10dB and 25dB, attenuation is 25.6dB and 14dB for down and up. I've just noticed some worrying figures though, 1950 "errored seconds" on my downstream, whatever that means. only 51 on upstream.
4922 CRC errors on downstream.
Anyone know if this is normal after 15 hours of uptime?
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SNR Fluctuations

What modem/router are you using?
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SNR Fluctuations

Well my BT/efficient networks 5861 is currently acting as a bridge to the router near my phone as it's ridiculously slow and unstable since the Max upgrade. Figured a bridge over Cat5 is better than an extension cable on the line.
Currently I'm on using a Mentor MR4C to do the connection. It's a piece of junk and I'm looking to replace it soon. Just wondering if the errors are on the router or the line. The 5861 doesn't list CRC errors or "errored seconds".
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SNR Fluctuations

Its the Mentor causing the errors, I have one here that I bought for £9 as a back-up device only. When I try it, its starts pumping errors out like a Microsoft Beta Operating System.

I suggest a US Robotics 9003 if you want an none-wireless router cheap. You can get them on eBay for less than £10 sometimes and they are pretty damn good, most things USR are good though.

I wouldnt use a Mentor for MaxDSL, lets put it that way. If I was you I would ditch it quick.

I read your other post, your other router had issues with MaxDSL? Can I ask what router it was?