What Happend

Had BT round today regarding my loosing sync problem, unfortunatly I was at work but the Mrs was in. I left a note regarding the varying SNR been as low as 6 and as high as 15 on a DG 834 V2 router.

I spoke with the engineer on the phone and he told me basically the line was fine but the NTE5 socket was corroded on the inside, seen as that was their equipment I would not be charged, Fine I thought. After speaking with the enginer who told me my line was now syncing at 2000 and downstream SNR was 50db great I thought

So armed with my shiney new DG 834 V4 which turned up today and with a freshly repaired line I thought I may get my speed back. Wrong the V4 is reporting SNR at 55db and sync rate of 928, I'm a bit miffed to say the least.

Does the v4 report attenuation differently to the v2 or is my line still borked or do i need to leave it a bit to retrain so to speak?

Sven

Doubt the SNR is as high as that, maybe the attenuation.
Tried the V2 if you still have it?

Yeah the Downstream,

My stats now are
Connection Speed 928 kbps 448 kbps
Line Attenuation 55.0 db 31.5 db
Noise Margin 16.1 db 16.0 db

and yesterday before BT came they were
Connection Speed 1152 kbps 448 kbps
Line Attenuation 50 db 15.5 db
Noise Margin 12 db 17 db

and on the 24th of last month they were
Connection Speed 1312 kbps 448 kbps
Line Attenuation 54 db 15.5 db
Noise Margin 11 db 17 db


Can this be explained easyly? I dont under stand this?

the low synch is probably explainable by the increase in snr margin. It appears you was on a 12db target snrm and this has now been changed to a 15db target snrm which will reduce the synch speed.

I cannot explain the increase in attenuation tho and why the engineer said he got a 2mbit synch.

Your synch speed does seem low anyway, on a 50db line the last time I was on a 15db profile I was getting about 3 and half mbit up to about 4mbit depending on what time of day I synched.

Edited by Chrysalis (Sat 07-Mar-09 01:59:36)

There is no set standard for reporing attenuation. Attenuation varies throughout the wide frequency range used by ADSL and different firmwares use different formulae for the calculation. The V2 and V4 use different chipsets so the formula used may well be different and quite obviously is.

The fall in sync is down to the increase in margin. Probably that was earned by the engineer fiddling with the wiring while the router was still connected or possibly because he just pulled it out rather than turning it off.

Which socket is the router connected to and how (master hard wired extension plug in extension).

The bad news is that your target margin seems to have increased. The good news is that if the line is stable it will drop back and possibly back to 6dB which should see you syncing quite a bit faster. Unfortunately that will take quite a time - 3dB drop in target per 14 days of stability. If you are lucky. Factors that will help in that is the new router and new master socket which with any luck will have an inbuilt ringwire filter.

I did plug the modem into the new socket that the engineer fitted, but then I removed the front plate and tried it in the test socket which it is in now. I did try the extension upstairs but that is reporting the same as the test socket. I did notice that the engineer did not re connect ring wire though. He alsos mentione that he fitted a filterd RF socket what ever that is? looks like a NTE5 socket with openreach in the top LH corner

The openreach faceplate includes an RF3 filter that can help - occassionaly.

Your issue is a high target noise margin, until the line is stable i.e. no varying sync speeds and very few errors this wont drop.

The rise in attenuation, appears to be offset by a rise in noise margin. It is possible that the bins used to carry the signal have changed resulting in a different attenuation calculation result.

So its just a case of suck it and see then.I think Maybe its best not to run DMT tool and bring the SNR down thru that untill the line stabilises ?

Or could i contact Zen and ask them to ask BT to reset the line?

Sven

Just noticed, after the fix, SNR is sat at 15 but when I make a phone call it jumps upto 20 and beyond. Have I still got a problem?

All the filters are new, DECT phone 2 floors below the router.
Current Stats are:-

Connection Speed 1472 kbps 448 kbps
Line Attenuation 55.0 db 31.5 db
Noise Margin 15.3 db 16.0 db