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Downstream vs Upstream Noise Margins

talkcomp
Grafter
Posts: 68
Registered: 10-03-2009

Downstream vs Upstream Noise Margins

Lately, my Upsteam Noise margins have rocketted from 4 db to 12.1 db and now stable at 5.6 db (but it keeps moving wildly - edit noticed it had rose to 6.1 db while writing the message) and my sync Upstream has decreased from 1056 kb at one point to 322 kb and now at 560 kb.
This has all happened over the least two weeks, when I had 16 syncs in one day (no fault found when tested 3 days afrer the event - cheers Plusnet!).
So with such variences and a stable Downstream, is this normal?

--- DSL Information ---
DSL Driver Version:  AnnexA version - A2pB022g.d20e
DSL VPI/VCI:        0/38
DSL Status:          ShowtimeRetrain Reason: 8000
DSL Mode:            ADSL2+
DSL Channel:        FAST
DSL Upstream Rate:  560 Kbps
DSL Downstream Rate: 8572 Kbps
                      Down        up   
DSL Noise Margin:    3.0 dB      6.1 dB
DSL Attenuation:    44.0 dB      24.0 dB
DSL Transmit Power:  0.0 dBm    12.9 dBm
45 REPLIES
scootie
Grafter
Posts: 4,799
Registered: 03-11-2007

Re: Downstream vs Upstream Noise Margins

well thats the problem with a varable upstream sync it acts the same as the downstream all thoe there is alot less things that mess up the upstream ferquency's as youve found out your probally one of the unlucky ones.
ive had my upstream noise margin target go to 10db for a week but the dlm sorted its self at same time as doing a rethink on my downstream nosie margin.
as your snr sounds like its going up and down wildly during a sync i would play close attention to anythin your switch on an off in the house and see if this is whats causing the added noise
what router do you have maybe try an run this and try and get it to plot the upstream snr to keep a close eye on it http://www.vwlowen.co.uk/internet/files.htm
talkcomp
Grafter
Posts: 68
Registered: 10-03-2009

Re: Downstream vs Upstream Noise Margins

ASBO, I am trying the software, but it seems to drop in and select the RX sometimes and then reverts back to the TX.
I have had a disconnect as well, which has made things worse.
talkcomp
Grafter
Posts: 68
Registered: 10-03-2009

Re: Downstream vs Upstream Noise Margins

Over the last few days, the Upstream has been running at approx 10dB with 550 Kbs Up.  Get a change tpday and it drops to 5.5 and sync upstream changes to 750 Kbs.  2 hours later on, I get another sync disconnect and it runs all the way up to 12.8 dB and I now get 511 Kbs.  The Downsteam has remained static at around 6 db and 7500 Kbs.
Has anyone any ideas?  Could it be my router?  Could it be the changing weather?  Coudl it be that my line into the house has become unstable? There si a published graph for downstream speeds, but is there one for Upstream Speeds?
Of course, when PlusNet tested (3 days after 12 syncs in one day), no fault was found.
Any ideas please or I'll be forced to leave the pilot.  Upstream means more to me than downstream (which may surprise a few of you).
scootie
Grafter
Posts: 4,799
Registered: 03-11-2007

Re: Downstream vs Upstream Noise Margins

if its possable then trying a diffrent router is all ways a good plan just to tick that one of the check list.
any extensions sockets running off the master? if so have you tried at the the test socket
An yep upstream is just as improtant to me.
Was you the max preminum offrering of adsl then?
I ask as the sync figures you have given so far for adsl2+ havent droped below 448kbps so its still better with a fault than adsl.
Best bet to me would be the router having a fit as i would think any source of intrefrence or weather playing its part on the copper would more likely show on the downstream as well  and looking at yours its fine.
talkcomp
Grafter
Posts: 68
Registered: 10-03-2009

Re: Downstream vs Upstream Noise Margins

Right - during lunch (I Know TMI). Disconnected all phones. No change 12.2 db..
I do not have an ADSL filter on the master socket as I have the original Dual Socket, with one port for phone and one for ADSL.  Undid the socket and inserted the ADSL filter and cable into the master port. Immediate lowering to 6.1 dB.  Waited ten minutes and now change.  Replaced everything as original and has become 6.0 (and is now at 5.6db). The router has not been rebooted during this time.
So it cannot be anything in the house as it is all back as was.
Will monitor and see what happens.  Speed now at 771 Kbs.
Asbo - thanks for your help and to answer your question I was on ADSL MAx prior and 844 Upstream, prior to 21CN cross over. 
scootie
Grafter
Posts: 4,799
Registered: 03-11-2007

Re: Downstream vs Upstream Noise Margins

if you have play between setups again in the future could all so take capture of the bits v tones graph if this avalable to you on the telnet tab of routerstats
talkcomp
Grafter
Posts: 68
Registered: 10-03-2009

Re: Downstream vs Upstream Noise Margins

Now -
DSL Noise Margin:    Up 6.4 dB      Down  4.1 dB
Soemthing very odd. a drop of 8.2 dB in just over an hour?
Asbo. Sorry - I do not understand the last comment.
scootie
Grafter
Posts: 4,799
Registered: 03-11-2007

Re: Downstream vs Upstream Noise Margins

yeah sry.
what am wanting to see is if the is any tones on the upstream are not being used or very under used which would more point to interfrence than the DLM alone using noise margin targets to reduce the sync.
as a little compare ive added my upstream snr capture
talkcomp
Grafter
Posts: 68
Registered: 10-03-2009

Re: Downstream vs Upstream Noise Margins

Sorry cannot: There is no CLI access via telnet on the WAG160N.
talkcomp
Grafter
Posts: 68
Registered: 10-03-2009

Re: Downstream vs Upstream Noise Margins

Really freaky one, but think I have it sussed (ish).
I was looking at the SNR screen, just to check what was happening, when the home phone rang.  Upstream SNR started rising rapidly (up 6,500 dB) and then sync failure.  Sync came back fairly quickly.  So I thought, ring out. Sync failed. Unplugged cordless phones and tried standard corded phone. Dialled out and sync failed. Unplugged all phones that are normally used and pluggged in my phone that is used on another (business) line and dialed.  On answering the call, sync failed.  Unpluged router, which is always on the master socket and switched to the engineer point.  Two different routers, two different filters and two different cables led to the same conclusion.  Inbound and Outbound calls, on answering, drop sync.
Call has been logged with PlusNet, but I feel it maybe a BT special this one.
James
Grafter
Posts: 21,036
Registered: 04-04-2007

Re: Downstream vs Upstream Noise Margins

Do you get static on the phone line when doing a quiet line test?
It's more likely to be a voice fault than a broadband one.
talkcomp
Grafter
Posts: 68
Registered: 10-03-2009

Re: Downstream vs Upstream Noise Margins

James, Sorry for the delay.
The call had been returned to me last week, but I was out of the UK, to play BT lotto. i.e. "Do you feel Lucky, Punk; do I want to charge you £144+VAT?"
I have re-tested and lost sync while the phone was dialing 17070.  Now tested with two phones, two adsl filters, both in the engineers socket.
I've given the nod to the BOT to play BT Lotto.  May find out in about a week or two what is wrong..
James
Grafter
Posts: 21,036
Registered: 04-04-2007

Re: Downstream vs Upstream Noise Margins

Thanks for the update.
Let me know how the engineer visit goes.
talkcomp
Grafter
Posts: 68
Registered: 10-03-2009

Re: Downstream vs Upstream Noise Margins

Requested BT visit. Had to provide 3 time slots last week. So, I chose Thursday am, Thursday pm and Monday (today) am.
So guess when they are coming? Yes, you guessed it Monday (today) PM.