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TD8816 - not sure I believe this!

PeeGee
Aspiring Pro
Posts: 1,098
Thanks: 51
Fixes: 3
Registered: 05-04-2009

TD8816 - not sure I believe this!

I had a TPLink TD8816 which developed a fault which appeared to affect processing of the higher frequency tones. Whilst awaiting a replacement, I used my TG585v7 which held a sync around 3.8Mbps/3dB down. I connected the TD8816 yesterday and, after eventually remembering to add "plusdsl.net" Embarrassed , got:
Quote
ADSL Firmware Version: FwVer:3.18.1.0_TC3087 HwVer:T14.F7_9.0
Modulation: ADSL2
Annex Mode: ANNEX_A
Downstream Upstream
SNR Margin: 0.1 17.2 db
Line Attenuation: 61.8 37.1 db
Data Rate: 4206 192 kbps
Max Rate: 8188 208 kbps
POWER: 0.0 12.3 dbm
CRC: 63 65401

Then, early this AM it changed to:
Quote
ADSL Firmware Version: FwVer:3.18.1.0_TC3087 HwVer:T14.F7_9.0
Modulation: ADSL2
Annex Mode: ANNEX_A
Downstream Upstream
SNR Margin: 0.1 6.7 db
Line Attenuation: 61.8 37.0 db
Data Rate: 4103 691 kbps
Max Rate: 8252 732 kbps
POWER: 0.0 12.3 dbm
CRC: 17621 65504

Surprisingly, it seems to be holding the connection at what seems a very high sync for the line and appears "more sprightly" than the TG585 connection Roll eyes
Obviously, the cold weather and a favourable following wind are allowing the higher frequencies (currently up to 170, usually <150) to give nonsensical "max rates" Shocked
Plusnet Fibre (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link TD-W9980 modem-router.
5 REPLIES
leight
Grafter
Posts: 29
Registered: 16-02-2013

Re: TD8816 - not sure I believe this!

I find it kind of hard to believe it's stable at that SNR (0.1 is like... you're sitting in the exchange). Lucky people can get stable connections at 3.0 +/- a little, but 0.1 just doesn't look right.
While it's not impossible to have great SNR and poor attenuation - your attenuation is pretty bad as it goes.
Pretty odd numbers in my opinion.
PeeGee
Aspiring Pro
Posts: 1,098
Thanks: 51
Fixes: 3
Registered: 05-04-2009

Re: TD8816 - not sure I believe this!

The attenuation matches the line length (4.5km+).
The SNR is weird, though. I think it's possibly a function of the frequencies used - 160 to 170, inclusive, have 3 at "3" and the rest at "0" so pull the SNR down (as it's based on usage). The TG585 used nothing above 155, so all (usable) frequencies were populated. At least, that's my understanding of the SNR calculations Undecided
Plusnet Fibre (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link TD-W9980 modem-router.
Community Veteran
Posts: 5,164
Thanks: 478
Fixes: 20
Registered: 10-06-2010

Re: TD8816 - not sure I believe this!

Presumably the difference is due to the Trendchip chipset in the TD8816 vs. the usual Broadcom.
It's also possible it reports the minimum SNR margin of all the used tones rather than an average (apparently that's what my DG834Gv3 does).
Plusnet Help Team
Plusnet Help Team
Posts: 13,479
Thanks: 246
Fixes: 68
Registered: 27-04-2007

Re: TD8816 - not sure I believe this!

Let us know how things go with the new router.
If this post resolved your issue please click the 'This fixed my problem' button
 Adam Walker
 Plusnet Help Team
PeeGee
Aspiring Pro
Posts: 1,098
Thanks: 51
Fixes: 3
Registered: 05-04-2009

Re: TD8816 - not sure I believe this!

OK, this TD8816 v7.1 was a warranty replacement - but I'm now thinking there may be a generic "fault" with this model as it is exhibiting the same SRNM instability as the previous unit.
After a day or so at 0.1dB, the connection dropped and came back at 3.6Mb/6dB down, 656kb up. After a while the SRNM started to jump between 6dB and 4dB before settling at 4dB. Due to the large number of "up" CRC errors, there was a resync and up had changed to 307kb and 9.5dB followed by a repeat of constant 6dB, then 6-4 jumps etc Cry This could be a combination of Trend chipset and 4.5km+ line, though the Broadbandbuyer spec has "max: 6km", unless it's a problem with the re-routed line - a repair using a length of cable installed from the house to the nearest "pit" and connected to a pair running back past the house to the cabinet; the original went directly toward the cabinet. The TD8816 was bought to confirm this outside fault rather than a router problem.
On the basis it was only a tenner (delivered) and "sort of" works (without RouterStats the SNRM variation wasn't noticeable), I'll keep it for emergencies and have reverted to the TG585v7 for normal use (currently at 3.7Mb/6.5dB and 757kb/6dB) Cheesy
I wouldn't recommend it for lines with 60dB attenuation from this experience.
Plusnet Fibre (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link TD-W9980 modem-router.