cancel
Showing results for 
Search instead for 
Did you mean: 
JonnyF73
Newbie
2,484 Views
Message 1 of 14

BT Home Hub 5 Type B - SNR Margin

Go to solution

Hi,

 

I have recently swapped from a Type A to Type B HH5 Router as I believe the type B has a superior chipset that fully supports G.INP etc. (Broadcom?)

 

As a result my line speed has improved marginally.

 

Previously on the type A I was at a SNR margin of 3.5Db with a sync of ~69500

 

On the Type B, my SNR is 6.2 with a sync of ~70500

 

This is great because it means my line should now be capable of possibly the full 76000 sync at the 3db Margin.

 

My question is, will my SNR be automatically reduced to 3Db (it hasnt done in 3 days connected) or is the standard Margin different between Type A and B HH's?

 

Thanks in advance,

 

Jon.

0 Ratings
Reply
13 REPLIES 13
Distinguished Sage
Distinguished Sage
2,467 Views
Message 2 of 14

Re: BT Home Hub 5 Type B - SNR Margin

Go to solution
Standard margin is 6dB, it doesn't matter what router you have
0 Ratings
Reply
Distinguished Guru
2,453 Views
Message 3 of 14

Re: BT Home Hub 5 Type B - SNR Margin

Go to solution
The SNR margin shown in the stats can vary throughout the day as noise varies. What determines your fixed speed is the exact SNR margin applied at sync time and the noise conditions at that time. This is recorded in the Troubleshooting > Event Log > WAN category.

Your line profile parameters include a target SNR margin which influences the actual value applied at sync time. The normal sync time target SNR margin is 6dB. You would therefore expect a value around that to be shown in the log at each re-sync.
0 Ratings
Reply
Distinguished Guru
2,447 Views
Message 4 of 14

Re: BT Home Hub 5 Type B - SNR Margin

Go to solution
On ADSL the standard target is 6dB but can be set to 3dB on good lines.

On VDSL the standard target is also 6dB.
Note: It has been reported that Openreach have been doing limited trials of the effect of possibly using 3dB on good lines in future.
0 Ratings
Reply
JonnyF73
Newbie
2,354 Views
Message 5 of 14

Re: BT Home Hub 5 Type B - SNR Margin

Go to solution

Hi,

 

Thanks for the replies.

 

However, on my Type A the SNR margin was ALWAYS 3.5db.

 

It's only risen to 6db since I swapped to a Type B.

 

Ideally I want 3db on the Type B to acheive the maximum possible sync rate.

 

Is there any explanation for this behaviour - or why I was synced to 3.5db on the type A (it was like this for 12 months+, or as long as I can remember, also after every reboot of the router!)

 

Jon.

0 Ratings
Reply
Distinguished Sage
2,349 Views
Message 6 of 14

Re: BT Home Hub 5 Type B - SNR Margin

Go to solution
6db is the norm on FTTC. It's possible your line has been on the trial of 3db noise margins but has since been removed.

You're actually getting a better sync rate at 6db with the 5b than you were with a 3.5db margin on the 5a.

You won't be able to tell the difference between 70 and 75meg.
If you want to say thanks for a helpful answer,please click on the Ratings star on the left-hand side If the the reply answers your question then please mark as ’Mark as Accepted Solution’
0 Ratings
Reply
Distinguished Guru
2,314 Views
Message 7 of 14

Re: BT Home Hub 5 Type B - SNR Margin

Go to solution
0 Ratings
Reply
Distinguished Guru
2,309 Views
Message 8 of 14

Re: BT Home Hub 5 Type B - SNR Margin

Go to solution
Though actually reading it again it seems to be talking about 3dB on ADSL2/2+ which seems confusing as BT already do that in certain circumstances. My ADSL2+ line has a down target SNR margin of 3dB.

Not sure now about 3dB with FTTC-VDSL2 trials?
0 Ratings
Reply
Distinguished Sage
2,300 Views
Message 9 of 14

Re: BT Home Hub 5 Type B - SNR Margin

Go to solution
The trials have been on FTTC.

Openreach have nothing to do with ADSL MSANS so it isn't related to ADSL2/2+ Although the reporting on that article seems to be a bit muddy. BT retail (using BT Wholesale kit) can put an ADSL line onto 3db already and have been able to for some time.
If you want to say thanks for a helpful answer,please click on the Ratings star on the left-hand side If the the reply answers your question then please mark as ’Mark as Accepted Solution’
0 Ratings
Reply
Distinguished Guru
2,291 Views
Message 10 of 14

Re: BT Home Hub 5 Type B - SNR Margin

Go to solution
Also to me the author of that article doesn't seem to understand the difference between SNR and SNR Margin.
It's the Target SNR Margin that is 6 or 3.