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BB snr

My line was activated last thursday. I was supposed to be connected to 1mbit (adsl - no cable available) but I have been put on 512kbit. What I want to know - is my line good enough for 1mbit?

I have been logging the connection stats as regularly as possible and get the following: Connection Speed up 576 kbps down 288 kbps

Downstream
Attenuation - always 48db
SNR margin - fluctuating between 28 and 16db

Upstream
Attenuation - always 15.5db
SNR margin - between 25 and 29db

I understand downstream attenuation should be as low as poss - 44-60db for 1mbit but what is the guidance for downstream snr margin?
If my snr margin is borderline should I ring my isp (aol) and try to get connected at 1mbit anyway?
 
BT consider a downstream attenuation of 60dB or less to be suitable for 1mbps, and 42dB or less to be suitable for 2 mbps. So it is not that bad.
AOL tried the same game on me, they are a pain in the arse.

SNR margin - fluctuating between 28 and 16db

Is this a Netgear dg834g by any chance?

On mine the SNR would drop very low in the evening, rebooting it in the evening when the SNR was at its worse cause the SNR to stablise near the higher level - I assume when the router tested the line at it's noisyest it made it drop some of the more noise prone channels (bins).



You'd need a minimum DS SNR of at least 6dB to have a reasonably reliable connectiona and preferrably 12dB+. If you have hard wired telephone extensions around the house, either disconnecting the ring wire at the master socket or something like a central faceplate filter can improve SNR and also decreases CRC errors. see http://yarwell.blogspot.com/2005_08_01_yarwell_archive.html
 
AOL tried the same game on me, they are a pain in the arse.

I saw your post - you have my commiserations - I can still cancel if they refuse to regrade ;)


Is this a Netgear dg834g by any chance?
Yep. I also have the Dynamode wired router - I have yet to give that a good trial.


On mine the SNR would drop very low in the evening, rebooting it in the evening when the SNR was at its worse cause the SNR to stablise near the higher level - I assume it made it drop some of the more noise prone channels (bins).
Yes the SNR margin drops in the evening to about 16db. I have not yet lost a connection (except once in a thunderstorm and snr dropped to 12db)


You'd need a minimum DS SNR of at least 6dB to have a reasonably reliable connectiona and preferrably 12dB+. If you have hard wired telephone extensions around the house, either disconnecting the ring wire at the master socket or something like a central faceplate filter can improve SNR and also decreases CRC errors.

Okay thanks. BTW the router is connected to the master socket (or what I believe is the master socket). The previous owner made some dodgy extensions. I tried removing the orange/white banded wire and it caused the snr to drop?! Also there is 6 wires?!
 
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BTW Mel did you stay with AOL or go to Eclipse?
If you are with AOL have you any tips to help coerce them into giving me a better deal or the 1mbit
 
Hmm, I hope he at least used proper twisted pair telephone cable to stop them picking up electrical interference. There's a reasonable guide to telephone wiring here:- http://www.wppltd.demon.co.uk/WPP/Wiring/UK_telephone/uk_telephone.html

If you've got the split front panel type master socket with the extension cables wired into the removable panel, try removing the lower half and connecting the router to the test socket it plugs into to see if you get a better SNR.

If you intend to have the router connected at the master socket, I would suggest connecting all of the extensions through a single filter such as the faceplate type filter shown on Yarwell's blog.

If you can convince aol to regrade the line to 1mbps, you will probably find your downstream attenuation will increase by 1-2 dB and the downstream SNR will fall by roughly 4dB
 
BTW Mel did you stay with AOL or go to Eclipse?
If you are with AOL have you any tips to help coerce them into giving me a better deal or the 1mbit

I'm still with AOL, but finally back on 1Mbps. My exchange is Tiscali LLU enabled which I understand Eclipse recently started using and I'd rather not be unbundled so I wouldn't even consider Eclipse now. I've also seen a fair few complaints about Eclipse recently, which is a real pity as they had such an excellent reputation.


Tips: use their freephone number (it still works) 0800 2796771 or else their national rate number 01179191100. If you are turned down flat, ring another rep, if all else fails while you've still got a few days of you cooling off period left ask for a MAC, they may suddenly decide you line is ok after all.

I eventually got my upgrade done by a rep. in their accounts department, I'd previously had 1mbps ADSL on the line (I even had a printed copy of the cease order which showed that I had a 1mbps connection) so I was able to give them a hard time when they insisted my line couldn't cope with it.

If you are a BT customer, you can check if they have actually ordered the regrade on BT's website and then chase them up if necessary.

Register on BT's website http://www2.bt.com/youraccount log into your acount, click "go" under "manage your BT accounts" and after the page loads open this link to get to the landline ordertracking page http://www2.bt.com/btPortal/applica...rnal.portlet.event&wfevent=link.ordertracking
 
Thanks for the advice.
I may be better remaining at 512 but I'll just have to see.

The extension was cut long ago because it was causing problems - but the wiring still remains so I'll take a look at it.
 
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I would expect your line to be ok a 1mbps, although I'd sort out the wiring first.

You can get some extra stats out of your netgear by telneting into it. Including the number of CRC & FEC errors and max attainable bit rate (at a guess a sustainable rate might be half of this if mine (8192kbps) is anything to go by)

First enable debug mode by opening this link http://192.168.0.1/setup.cgi?todo=debug

Open a windows CLI (console) window and enter: telnet 192.168.0.1

into the telnet window enter: cat /proc/avalanche/avsar_modem_stats
 
You can get some extra stats out of your netgear by telneting into it. Including the number of CRC & FEC errors and max attainable bit rate (at a guess a sustainable rate might be half of this if mine (8192kbps) is anything to go by)

Yes max attainable bitrate 4160kbps
 
AOL have agreed to try my line at 1mbit/s.

Here's some advice for anyone trying to get a regrade.

Make sure you are the primary billing contact - if not add yourself as secondary by going to https://bill.aol.com(ignore the $ signs).

Choose the option for customer service NOT tech support as they put you on hold for ages (me - 1h40m:eek: ) 08002796771 - thanks Mel it saved me a lot of money:D

In my experience the line is always "busy" and you will be waiting 10-12min to speak to a human! Set aside at least 20min for this.:hrmph:

Ask for a line regrade (they may be "confused" and ask if you want a package upgrade). They will put you on hold while they consult the BT checker - make sure the BT checker gives a good result or they will put you through to tech. (For my phone no it says 1mbit may be possible but require an engineer visit, upto 3.5mbit/s via MAX - customer support looks at the MAX figure even though it isn't max :rolleyes: )

- if you can't get a faster ds speed they will offer you a reduced price, and if they don't just redial
 
For the downstream line rate i would of thought the SNR would be higher than yours, however there is no set figure for a SNR margin untill you go onto a MaxDSL line then you will have problems with how much yours fluctuates, if you have a test socket try it from there to see if it does the same and what the figures are as that would show you the difference that the internal wiring is making.
 
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In case anyone is interested: I finally got around to checking the 'DIY extension'. After removal the ds snr margin is static 32.5db (using different router now) big increase from the average 25db! Seeing less crc errors as well
 
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