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Author Topic: Netgear DG834G Sync speed dropped suddenly  (Read 5360 times)

BadWolf

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Netgear DG834G Sync speed dropped suddenly
« on: July 24, 2007, 09:56:34 PM »

I have had had a stable max DSL service that line syncs at 2.6 to 2.8 Meg
(long rural line) for 9 months, the noise figure was typically 1 to 6dB with
the occasional drop.
Yesterday all changed, I found the line sync at about 1.8 Meg (currently
1888kbs @12dB noise) and the noise margin varying from 1 to 12dB, The line is stable.
My big problem is this has reduced my profile from 2 Meg to 1.5 Meg.

The line has NO audible noise of any kind, once in the past I had some line
crackling (which was fixed) and this only reduced my sync speed a few
hundred kb.

Equipment:
Netgear DG834G Router
Line attenuation reports 62 to 63dB (as before) I think the router does not
show more than 63db but I think I am just on the limit since it flicks 62 to
63dB.
I have not added or changed any pc or phone hardware or software or upgraded
anything.
I have cycled the router power and disconnected/reconnected the router.

Any ideas?
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roseway

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Re: Netgear DG834G Sync speed dropped suddenly
« Reply #1 on: July 25, 2007, 07:42:56 AM »

Hi and welcome.

Your noise margin is varying quite a lot, which suggests some intermittent noise problem. What's very possibly happened is that the occasional drops have become more frequent recently, and this has resulted in your target noise margin being raised to 12 dB. This would make your connection more stable, but with a lower connection speed.

Really, the only thing you can do is to make sure that your own internal wiring arrangements are as good as they can be. There's some useful advice at http://www.kitz.co.uk/adsl/lowSNR.htm . With a 63 dB attenuation you're stretching the technology, and you're very vulnerable to any changes in interference sources nearby, and to small deteriorations in the line quality. :(
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  Eric

BadWolf

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Re: Netgear DG834G Sync speed dropped suddenly
« Reply #2 on: July 25, 2007, 09:01:25 PM »

Roseway I think you may have got my problem, as I said I had some line noise on my phone that took BT a couple of weeks to trace and fix. Dropouts were a problem during this. i assume the system has logged this and has reacted to it even though it ts away now!
I believe my target noise margin was 6dB previously since this was the figure at every reboot now it is 12dB at every reboot!
I found this whilst searching other sources:

"If you find your line is unstable and reconnecting frequently then BT's systems should after a while set the target SNR margin to a higher value. This starts at 6 dB then steps up to 9,12, 15 dB giving reduced speeds but hopefully better stability and less errors. If a line improves the target margin should come down after perhaps 2 weeks of stability."

If my line remains stable maybe my noise target will reset to 6dB or is there anything I can do about it to speed up this process?

Also my internal wiring/filter setup is OPTIMISED, I put some effort into this some time ago.
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soms

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Re: Netgear DG834G Sync speed dropped suddenly
« Reply #3 on: July 25, 2007, 10:21:52 PM »

Quote
If my line remains stable maybe my noise target will reset to 6dB or is there anything I can do about it to speed up this process?

Unfortunately from experience I haven't seen this happen. I would bet our line has held sync for over 2 weeks previously but the target margin has not ever reduced from 9dB back to 6dB.

Whether others here have seen any time triggered change or not? From what I have seen on these forums it seems the target margins are raised automatically and stay that way.

soms.
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kitz

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Re: Netgear DG834G Sync speed dropped suddenly
« Reply #4 on: July 27, 2007, 02:40:05 AM »

I've not seen it occur in a 2 week time frame either.   I have seen a few reports after a month..  and it seems to go down in stages rather than one jump.

Ive also seen other reports of people waiting months and nothing happen at all. 
 
AFAIK theres nothing set in stone from BT about when the DLM will reduce the target SNR.  With a lot of lines the target SNR has been increased for a purpose to keep the line stable, if it was automatically reduced every 2 weeks then there would be a lot of lines that could suddenly become unstable every other week.

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BadWolf

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Re: Netgear DG834G Sync speed dropped suddenly
« Reply #5 on: July 29, 2007, 12:18:15 AM »


I had a word with my ISP last night, but I am not sure that the gentlemen I spoke to understood properly what I was trying to say even though I was very clear.
On my first call the guy was able to confirm my connection rate and noise figures but could not get any historical information to compare it with and kept referring to his 'supervisor', he said call back later as he would try to get more information. Because my broadband was working he seemed very apprehensive to query anything with BT, he suggested I should speak to them but I said there was no point since my voice line was now fine and I wasn't allowed to speak to BT Wholesale, he then dropped this line of conversation.
I rang back after a couple of hours and spoke to someone else who didnt seem to have and extra information and agreed my speed was low and i should turn off my router for 15 mins and he would 'reset' my session as expected this made no difference.
Am I wasting my time trying to get anything done, can BT intervene and put my Target Noise Margin down or will I have to wait and see if anything happens automatically, or if I change my ISP in the future would this put my connection back to the default settings.
I must do a bit more research,  I will keep you posted if I make any progress but any ideas would still be appreciated.
For information since my router was reset  over 24 hrs ago I have been connected at 1856 kbps with the noise margin varying from 6 -12 dB.
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roseway

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Re: Netgear DG834G Sync speed dropped suddenly
« Reply #6 on: July 29, 2007, 07:21:05 AM »

Your ISP can't reset the target noise margin, they can only request BT Wholesale to do this. If the ISP doesn't even understand the question it will be a bit of an uphill struggle.

I rather tend to think that a stable 1500 profile with a bit of spare noise margin is the better option. As you said in your first message, even at this speed the noise margin sometimes drops close to zero, so unless a fault can be identified and eliminated you're not going to gain anything.
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  Eric
 

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