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Author Topic: No longer able to overide target SNR  (Read 3930 times)

timh

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No longer able to overide target SNR
« on: October 17, 2007, 11:15:45 PM »

Hello All,

Until recently I've had a stable connection for nearly a year on MAX ADSL, synching at approx 3100 kbps with a target SNR of 6db, which gave me a solid profile of 2500.  A  couple of months ago however my wifes sewing machine blew the noise suppression capacitor in the foot pedal and as a result the target snr set by BT shot up to 15db.  I left it for a week or so to see if it would drop, but it didnt.  My ISP said BT wont reset the snr, so I consequently purchased a netgear dg834gt and used the ubergt f/w to override the target snr back to approx 6db, which was successful and allowed my to sync again at 3000+ .  A few weeks ago however, my router resynched one evening and the target snr shot up again, even with the overide set on the router.  Ever since I have been unable to get it below 10db, even using a snr percentage of 1%.

Does anyone have any idea why my overide on the target snr is now only able to get down to 10db, and why the target snr doesn't lower again over time (I've had over 10 days solid connection as I write this, but no drop in target snr)?
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kitz

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Re: No longer able to overide target SNR
« Reply #1 on: October 18, 2007, 12:03:39 PM »

There is a maximum % range that you can adjust the target SNR, normally you can at least get down to the next stage using DMT..  it depends on the router.

As regards to lower over time - this does seem to be a hit and miss affair, Ive seen reports of it happening in a couple of weeks yet in other cases it can take months.  It certainly isnt a strict  10 days as Ive seen one ISP Help Desk report. AFAIK no-one has yet found a complete strict  pattern to what the DLM system does.

In the case of "One Offs" your ISP should be able to get BTw to reduce the target SNR, I believe it should be processed by them under the "faults system" interface.   

Interleaving and Target SNR are supposed to be the 2 configurable attributes that can be changed, so if youre not having any joy with DMT tool, then it will have to be persistence with your ISP Im afraid. :/

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timh

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Re: No longer able to overide target SNR
« Reply #2 on: October 18, 2007, 01:14:56 PM »

Thanks Kitz.

I guess I'll have to push the ISP to get BT to lower the snr margin.

P.S.  Will it cause issues if I am still running a 'tweaked' snr, with respect to BT lowering it ?  It's just that if I let it run at default snr, I dont get much above 1Mbps ?
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mr_chris

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Re: No longer able to overide target SNR
« Reply #3 on: October 18, 2007, 01:28:54 PM »

The only danger is that if they DO suddenly lower it, then your DMT tweak may tweak it too low, causing resyncs and thus causing your SNR to automatically fly up again - I haven't heard of that happening, but I imagine it might.

Some exchanges seem a LOT more sensitive than others to what causes target SNR changes. Mine seems horrendous. My SNRM was 6dB for months and months... and then suddenly I think I caused about 3 or 4 resyncs and it flew up to 9dB. Then something else caused it to fly up to 12dB.

So my 7.5 - 8Mb line is now suddenly a 4Mb line, because my Netgear DG834Gv2 doesn't support DMT, and I don't like the Speedtouch 576 that I got cheap. I think it's actually got a fault. Oh well. I am seriously considering moving to Be or UKO.
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Chris

timh

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Re: No longer able to overide target SNR
« Reply #4 on: October 19, 2007, 11:04:32 AM »

I managed to get my new dg834gt for £18.

Basically the sky routers (or the recent ones at least) are dg834gt models and there are loads of them on ebay.  A simple recovery routine (detailed on netgear support site) and you then have yourself a netgear dg834gt at a fraction of the retail price.
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kitz

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Re: No longer able to overide target SNR
« Reply #5 on: October 21, 2007, 03:20:24 PM »

Yes if youre prepared to do that then you can pick up a bargain.

Theres something on my main about flashing the sky Netgear..  but sometimes its not what your average bod feels they are capable of.
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