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JandRoo
Beginner
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Message 1 of 16

New BT customer, unexpectedly low sync speed.

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I recently switched to BT on the 4th Feb, I'm aware that it can take some time for things to settle down, but my sync speed after 5 days has not changed from 1152, I'm on a rural BT exchange which is still fully bundled up so was hoping that switching provider would not seriously impact on speed.

 

Being on a fairly long EO line, I spent a lot of time when I moved in getting the internal wiring sorted etc and managed to coax speeds up from mid 5000s sync to reliably over 7000, settling to 7616 almost all the time.  Given it's an EO line to a BT only exchange, I assume i'm still on the same copper as before...

 

The BT wholesale speedtester does not yet recognise my details, tried both firefox and IE,  no joy.

 

The below line stats are after 24hrs uptime, prior to that I had 5 days solid uptime, disconnect was me messing with the router.

 

Hoping someone can help, many thanks in advance.

 

 

Modulation : G.Dmt
Annex Mode : Annex A/L
Line State : up
Lan Tx : 13668322
Lan Rx : 12463470
ADSL Tx : 1687638
ADSL Rx : 1853970
CRC Down : 8
CRC Up : 0
FEC Down : 0
FEC Up : 0
HEC Down : 0
HEC Up : 3
SNR Up : 26.0
SNR Down : 30.5
Line Attenuation Up : 24.0
Line Attenuation Down : 47.5
Data Rate Up : 288
Data Rate Down : 1152

 

 

 

 

avail check.jpg

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Distinguished Sage
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Message 2 of 16

Re: New BT customer, unexpectedly low sync speed.

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You're somehow on a fixed rate 1meg service (upload speed is an indiciator) but the modulation type is g.dmt which is basic adsl.

Hopefully a moderator will be along soon and will offer some assistance.
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Distinguished Sage
Distinguished Sage
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Message 3 of 16

Re: New BT customer, unexpectedly low sync speed.

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This is the second post very recently where wholesale have put on 1mb fixed and BT don't sell that product anymore

 

mods will post contact us link and help you get moved. 





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After completing the email NOT PM then you join a queue of other customers waiting for mod help. The mods will get back to you in 3/5 working days either by phone or email



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Moderator
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Message 4 of 16

Re: New BT customer, unexpectedly low sync speed.

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@JandRoo I'm sorry to see you're having issues with your BT Broadband. Your SNR down is very high and most likely this is the reason why the speed is very low. Have you reported a fault to the helpdesk yet? 

 

If you would prefer that the mod team takes a look at this please use the contact the mods link which can be found in by clicking on my username. Please be aware that we are very busy at the moment and we are working through a backlog so calling may get you a speedier resolution. Smiley Wink

 

Thanks

Neil

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Distinguished Sage
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Message 5 of 16

Re: New BT customer, unexpectedly low sync speed.

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Neil,

The connection is on a fixed rate 1meg service as opposed to ADSL MAX. The upload speed of 288kbps confirms this.

As the connection has a sync rate of 1152 or nothing, the SNR will be high to give as much protection to the line as possible.

With it not being on a rate adaptive product, there would be no benefit of having an SNR of say 6db as it wouldn't increase the sync speed, only leave the connection more vulnerable to potential noise issues.

An order for ADSL Max needs to be submitted to BT Wholesale. The line is not in a fault state.

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JandRoo
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Message 6 of 16

Re: New BT customer, unexpectedly low sync speed.

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Neil, thanks I have sent an email.


Webby,  I'd concur with you, and just to add that a quiet line test is virtually silent.

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Distinguished Guru
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Message 7 of 16

Re: New BT customer, unexpectedly low sync speed.

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@Webby wrote:


As the connection has a sync rate of 1152 or nothing, the SNR will be high to give as much protection to the line as possible.

With it not being on a rate adaptive product, there would be no benefit of having an SNR of say 6db as it wouldn't increase the sync speed, only leave the connection more vulnerable to potential noise issues. 


 

Isn't the SNR margin just the difference between the SNR the line is capable of and the required SNR for the selected connection speed? 

 

So the system hasn't even selected a high SNR margin for extra protection, it is just what it is given the line capability and that connection speed. The system couldn't have reduced it to a target of 6dB at connection time even if it wanted to. Well that's how I see it.

 

I agree that the line needs changing to ADSL Max.

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Distinguished Sage
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Message 8 of 16

Re: New BT customer, unexpectedly low sync speed.

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Yes that's exactly what the SNR margin is. I was refering to the SNR 🙂

The higher your SNR is at a given connection rate, the more stable your connection will remain.

If this was adslmax and the line isn't able to sync at the max rate of 8128 then a target of 6 would used to get the most out of the line. If you were within a few hundred metres of the dslam and syncing at 8218 then your SNR would likely way high.
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Distinguished Guru
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Message 9 of 16

Re: New BT customer, unexpectedly low sync speed.

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The target of 6dB is referring to SNR Margin, not SNR.

The simple example that Kitz uses is that if the line is capable of an SNR of 40dB, and a target SNR Margin of 6dB is applied, then a connection speed supported by an SNR of 34dB would be selected.

In the case of the OP the SNR Margin is way above 6dB because the connection speed is fixed at a very low speed requiring only a low SNR to support it.
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Distinguished Guru
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Message 10 of 16

Re: New BT customer, unexpectedly low sync speed.

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Modems often don't actually show SNR figures, only the SNR Margin.
This is all the HomeHubs show, calling it noise margin.
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