ADSL2+ slight disappointment

Switched from ADSLMax to ADSL2+ today on TalkTalk LLU via XILO.

On ADSLMax i had an 8128 sync @ 6dB noise margin with a downstream line attenuation of 33dB (i am 2.4km from the exchange).
Prior to moving over i was hoping for 12-13mbps sync on ADSL2+ looking at the graphs and inputting my ADSLMax line details on a couple of websites.

Coming home tonight my sync was barely over 8128 @ 12dB noise margin (XILO default) but since that over 2 hours my noise margin had dropped ~3dB (monitored with Routerstats). Is that normal? On max it varied by 1dB maximum over a 24 hour period.

I've rebooted my router (Billion 7800N) and used its onboard SNR tweaking to reduce the target noise margin to 6dB. My new sync speed is 9770kbps, about 2000-3000kbps short of what i was reasonably expecting (websites and graph said expect anything up to 14000kbps).

Current stats:-
DMT Status No Defect
Operational Mode ADSL2+
Upstream 945
Downstream 9770
SNR Margin(Upstream) 12.4
SNR Margin(Downstream) 6.3
Line Attenuation(Upstream) 20.2
Line Attenuation(Downstream) 37.0

I'm using the latest 7800N firmware (1.06e) and have ADSL2+ and Annex L set only (did have G.DMT etc also selected but unticking them has made no difference).

I dont see how i can get anymore......am i either unlucky or are the ADSL graphs pretty inaccurate?
Or will a resync in the daytime give me another 2mbps...wishful thinking no doubt!!

(note:- I'm using a BT ADSL faceplate filter and ADSLNation Pro+ cable to the router, a few phone extensions are run from the front of the faceplate).

PS
Just went to post this and it dropped sync for a few minutes.....maybe i should of stuck with Max!!

Noise margin variation can be higher as you are pushing the line closer to its limits, and thus more variation is possible.

Your speeds are in the zone for ADSL2+ and the attenuation, 9400Kbps to 12800Kbps from www.farina1.com/adsl

Daytime resyncs may well give you more. I assume you have double checked the stats at the test socket, since with ADSL the ring wire was less of an issue, and with ADSL2+ it is more sensitive to wiring issues. VDSL2 is even more sensitive, hence the engineer installed faceplates on that product.

And just found out my landline and its not receiving incoming calls......(line is being taken over by TalkTalk/Xilo).

Edited by deleted (Tue 17-Jan-12 18:52:13)

Inputting my ADSLMax details ie 8128 sync, 6dB, and 33dB line attenuation i get from that link:-
Your ADSL2+ speeds are likely to be in the range 11500Kbps to 15000Kbps

I've tried my Netgear DG834GT in the filtered faceplate with the normal phone lines detached and its the same. I dont have any ringwire connected.

Tweaking the modem might confuse things.
What is the target margin if the modem has no tweaks applied? I'd usually prefer to let the ISP tweak things down.

So yes would expect better, but it is not at disaster levels. It is worth unplugging the filtered faceplate and checking at the test socket, just in case the extra connectors are making a difference, long shot though.

In reply to a post by InQ:

websites and graph said expect anything up to 14000kbps

Yes, for 33 dB attn., but attn. increases by about 3 with ADSL2+. So, I'd expect your line to hold about 11 Meg.

But the graphs and checkers say you cant check it when you actually have ADSL2+ as they take your ADSL line stats and tell you what to expect on ADSL2+.

Will be 12db with interleaving on a TTB service.

Matt

In reply to a post by uno:

Will be 12db with interleaving on a TTB service.

Matt

Yep Matt....i am impatient and running the SNR Tweak on 7800N.

Router Telnet stats:-

> adsl info --stats
adsl: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 8000
Max: Upstream rate = 944 Kbps, Downstream rate = 11656 Kbps
Path: 0, Upstream rate = 944 Kbps, Downstream rate = 9789 Kbps

Link Power State: L0
Mode: ADSL2+
TPS-TC: ATM Mode
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 6.5 12.3
Attn(dB): 37.0 20.2
Pwr(dBm): 0.0 13.0


Is the Max speed quoted at the top an achievable target? Whats this based on?

In reply to a post by XRaySpeX:

In reply to a post by InQ:

websites and graph said expect anything up to 14000kbps

Yes, for 33 dB attn., but attn. increases by about 3 with ADSL2+. So, I'd expect your line to hold about 11 Meg.

Mine line is 34db and during the summer it can hold 15Mb/s fairly reliably. Over the winter I've had to raise the target margin and it's been holding 12.8Mb/s for nearly two months now.

But yeah it depends on the particular line being considered.