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Standard User aps2011
(newbie) Mon 25-Mar-13 14:42:17
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Can I get BT to alter modulation method?


[link to this post]
 
My telephone exchange upgraded to 21CN last October and I switched to BT Broadband in December 2012. I have now got a very stable connection (~7.3 Mbps with Line Attenuation (Down/Up): 40.6 dB / 22.5 dB ). The modulation is the old G.992.1 Annex A so the upload speed is just 448 kbps with a real-life throughput of 340 kbps.

Am I right in thinking that other modulation methods are possible and that I could get higher speed upload?

If that is the case, how do I best request BT do something about the modulation method? There are probably some key phrases that would help communicate the request (i.e. BT jargon.)

Many thanks.
Administrator MrSaffron
(staff) Mon 25-Mar-13 14:51:02
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Re: Can I get BT to alter modulation method?


[re: aps2011] [link to this post]
 
They may have connected you to the old hardware still, it is still in the exchange and will be being used.

If your IP profile is a now round figure, e.g 6500 then you are on the old hardware, if its a figure that is 88.2% of the current connection speed then the new hardware.

BT Retail tends to migrate people between the services en-masse as it is cheaper to do that, but you can I believe request a regrade individually, basically have you asked them to put you onto the ADSL2+ service?

Andrew Ferguson, andrew@thinkbroadband.com
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User 4M2
(fountain of knowledge) Mon 25-Mar-13 15:04:06
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Re: Can I get BT to alter modulation method?


[re: aps2011] [link to this post]
 
We really need to know your SNR margins as well - if the line is noisy then G.992.1 Annex A (ADSL1) may be the more stable option although this is unlikely since you are getting ~7.3Mbps

Actually with ADSL2+ you probably wouldn't gain any significant downstream sync speed but upstream sync speed would be more than double.

Just request the tech team at BT that you want ADSL2+ if the SNRM margin values are OK, i.e. 6dB downstream.


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Standard User RobertoS
(sensei) Mon 25-Mar-13 16:06:44
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Re: Can I get BT to alter modulation method?


[re: 4M2] [link to this post]
 
In reply to a post by 4M2:
Actually with ADSL2+ you probably wouldn't gain any significant downstream sync speed but upstream sync speed would be more than double.
Maybe 9Mbps+ sync? Compared to 7.3Mbps sync. And if it's stable the WBC DLM drops the noise margin to 3dB.

My broadband basic info/help site - www.robertos.me.uk | Domains,website and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync ~ 54.2/15.2Mbps @ 600m. - BQM

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Edited by RobertoS (Mon 25-Mar-13 16:08:01)

Standard User 4M2
(fountain of knowledge) Mon 25-Mar-13 16:26:31
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Re: Can I get BT to alter modulation method?


[re: RobertoS] [link to this post]
 
In reply to a post by RobertoS:
In reply to a post by 4M2:
Actually with ADSL2+ you probably wouldn't gain any significant downstream sync speed but upstream sync speed would be more than double.
Maybe 9Mbps+ sync? Compared to 7.3Mbps sync. And if it's stable the WBC DLM drops the noise margin to 3dB.


I was probably being a little conservative, i.e 6dB SNRM: used a 44dB ADSL2+ downstream attenuation in Kitz's "maximum adsl speed calculator" smile
Standard User aps2011
(newbie) Tue 26-Mar-13 15:01:36
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Re: Can I get BT to alter modulation method?


[re: MrSaffron] [link to this post]
 
Many thanks for the various posts providing information.
The downstream noise margin runs between about 3dB late evenings and and 6dB during day. The current stats are:

Line state: Connected ppp0_0
Connection time: 11 days, 21:24:01
Downstream: 7.281 Mbps
Upstream: 448 Kbps

VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.1 Annex A
Latency type: Interleaved
Noise margin (Down/Up): 6.0 dB / 27.0 dB
Line attenuation (Down/Up): 40.6 dB / 22.5 dB
Output power (Down/Up): 19.9 dBm / 12.5 dBm
FEC Events (Down/Up): 63690927 / 260
CRC Events (Down/Up): 52901 / 206
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
HEC Events (Down/Up): 391323 / 195
Error Seconds (Local/Remote): 5207 / 288

As I indicated, what I would like out of it is a faster upload speed and no worse download speed. The higher frequencies in ADSL2+ can presumably lead to higher attenuation (capacitive, inductive effects).

It looks like it is a matter of contacting BT, presumably via the web site or phone.
Thanks again.
Standard User burakkucat
(experienced) Tue 26-Mar-13 16:23:06
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Re: Can I get BT to alter modulation method?


[re: aps2011] [link to this post]
 
In reply to a post by aps2011:
As I indicated, what I would like out of it is a faster upload speed and no worse download speed.
Once you are migrated, so that you are using the 'new kit' in the exchange, your modem/router should be manually set to see if using ADSL2 mode (not ADSL2+) will give you the desired result.

100% Linux and, previously, Unix.
Standard User XRaySpeX
(eat-sleep-adslguide) Tue 26-Mar-13 16:26:11
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Re: Can I get BT to alter modulation method? - EDITED


[re: aps2011] [link to this post]
 
You might get slightly faster sync of 7.9 Meg on ADSL2+ (G.992.5).

However, if BT were to put you on WBC, you could then downgrade to ADSL2 (G.992.3) using your router and get syncs up to 9 Meg..

EDIT: In any case you would get higher Up syncs of 888K to 1.3 Meg.

1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC

Edited by XRaySpeX (Tue 26-Mar-13 16:28:00)

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