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tifosi_29
join:2010-10-14
Los Altos, CA

tifosi_29

Member

U-Verse (ADSL2+) 12mbps Line Issue

Hi, I just upgraded hre in Pasadena, CA from "std" 6.0Mbps "DSL" to 12.0Mbps "U-Verse (ADSL2+) which was the maximum that the att.com website said I could receive.

Installed the Motorola NVG510 as part of the self-install, and then out of nowhere, got a call from a Field Tech 2 hrs before my activation time saying that he was here to install my system. Surprised since I had ordered a self-install, but hey, always enjoy talking to the techs.

Now my previous DSL (non-Uverse/ADSL) service was plagued with issues where it would often drop-out of sync time and time again. Here were statistics from before, though my understanding is that both the SNR & Line Attenuation are not terrible...and I had never pinpointed the problem even though I new something was up.
----------------
Broadband Link – Statistics
ATM Statistics
IP Statistics
DSL Down Up
Current Rate: 6016 kbs 768 kbs
Max Rate: 8228 kbs 1016 kbs
Current Connection:
Current Noise Margin: 14.0 dB 14.0 dB
Current Attenuation: 39.1 dB 24.0 dB
Current Output Power: 19.7 dBm 11.9 dBm
ATM Cells Errors %
Transmit: 18284 0 0
Receive: 0 0 0
----------------

Before the tech had arrived I had actually connected the new Motorola NVG510 RG, and had the following stats (even though service wasn't working since it was still provisioned for 6.0Mbps using the non-Uverse/ADSL.

----------------
Downstream Sync Rate (kbps) 6016
Upstream Sync Rate (kbps) 768
Modulation ADSL
Data Path Fast
Current Rate: 6016 kbs 768 kbs
Current Noise Margin: 14.0 dB 14.0 dB
Current Attenuation: 39.1 dB 24.0 dB
Current Output Power: 19.7 dBm 11.9 dBm
Downstream Upstream
SN Margin (dB) 13.7 13.0
Line Attenuation (dB) 36.5 24.0
Output Power(dBm) 19.8 11.9
----------------

Once the Field Tech showed up and was line testing the demarcation point, I mentioned the historical issues I had...and right as I finished saying this...he mentioned that he was seeing issues between the CO and the DP (I believe that the line was only able to get about 10Mbps for 12Mbps service, and that he was seeing it as 7,500ft)...that it looked like there was an issue we has going to have to issue an internal maintenance ticket against.

He mentioned something about my setup here in Pasadena, that instead of my DP going direct the the CO, it instead went to a Satellite office closer, if I understood correctly.

He then said we would still swap the provisioning over to 12.0Mbps ADSL2+ (my new service), and we could test the service anyway, so that by chance I could get some service for the time being even if it was 12.0Mbps or cut out occasionally due to interference. Once this was complete, the Field Tech re-did the DP to CO stats and got:

DL 12956(max) 11795(cap) 6.1dB(SNR)
UL 1225(max) 1021(cap) 13.1dB(SNR)

I then went upstairs to my appartment and looked at the performance stats on the Mot NVG510 and they were as follows:

----------------
Downstream Sync Rate (kbps) 11795
Upstream Sync Rate (kbps) 1021
Modulation ADSL2+
Data Path Fast
Downstream Upstream
SN Margin (dB) 6.1 11.8
Line Attenuation (dB) 41.0 20.6
Output Power(dBm) 19.2 12.0
----------------

At the end of it all...I am getting 12.0Mbps service, though the tech mentioned I'm at 91% cap, and typically they would like to have us at 75% for headroom.

The questions I have are:

1. Does the drop from 14.0dB SNR down to 6.1dB SNR make sense when moving from 6.0Mbps to 12.0Mbps service? I know there is supposed to be degradation as you use higher bandwidth and get closer to the noise floor, but I wasnt sure what the rate of degradation was.

2. I know 6dB is getting dangerously close to losing sync, any ideas what the Field Tech could have been seeing between the DP and the CO...and is there anything AT&T can do to resolve this (or make it better)?

3. What can explain my line attenuation going down from 6.0Mbps to 12.0Mbps? Does the modulation bandwidth increase have the inverse effect on Line Attentuation? I thought that was simply a factor of Loop Length & Line Resistance?

4. The Field Tech's initial thoughts were at my distance (he said 7,500ft) he expected I should be able to see something around 15-16Mbps DL, but prob not the next tier, 18.0Mbps, which is why I couldnt purchase it. If that is the case, is it possible to get AT&T to provision it, understanding that I would never actually get 18.0Mbps service?

5. Is there a test I can have AT&T run from either my DP or the CO, to confirm if in fact there is an issue with there line...as opposed to the line within my apartment building?

6. I have just DSL, and no phone service...but always am suspect of apartment wiring. By using the DSL filter at my phone jack, am I ensuring the cleanest signal? Or am I unnecessarily degrading the line if there are really no phones connected to the system?

Regards,
Tifosi