Can I get BT to alter modulation method?

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.

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?

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.

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.

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

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"

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.

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.

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.

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