Impulse Noise Protection

[jezuk1]

Hi all,

The Billion 7800N supports this feature called Impulse Noise Protection which according to one website: "provides a significant improvement in residual bit error rate (BER) as well as resistance against impulsive noise, resulting in a vastly improved user experience for subscribers" etc etc...

Does anybody know much about it and whether the equipment at the other end need to support it too?

Cheers

[Rik]

No, but I'm sure someone will be along who does.

[Steve]

As I understand it this is associated with PhyR which has been mentioned on this forum. It relates to a particular feature of the Broadcom chipset but I think the dslam has also got to be compatible.

http://www.broadcom.com/press/release.php?id=1202932

http://www.idnetters.co.uk/forums/index.php/topic,26467.0.html

[jezuk1]

Thanks Steve - so I imagine turning this on will have no effect at all (unless BT have added support)  
That's correct, it's called PhyR in the web interface and can be enabled for Downstream and/or Upstream channels.

[Rik]

Come on, BT - you're joking.

[jezuk1]

My SNR margin is quite high (13db Downstream) at the moment, so I suspect my line suffers from this kind of impulse noise.. I would be great to see this feature in operation but as you said Rik it's a slim chance BT will support it    To be honest I'm not even sure if it's worth restarting the router to try, I'd be so surprised!!

[Rik]

How long has your margin been that high?

[john]

Sounds like something from Star Trek

[jezuk1]

Well it was sitting quite happily around 7db for months and then recently it ticked up to 13db and I lost about 3000kbps on the sync speed.
For my relatively low attenuation I get quite a low sync speed, it's never been great - I'm sure I have a bit of a lemon of a phoneline

DMT Status   No Defect
Operational Mode   ADSL2+
Upstream   444
Downstream   12157
SNR Margin(Upstream)   19.5
SNR Margin(Downstream)   12.9
Line Attenuation(Upstream)   11.2
Line Attenuation(Downstream)   21.5

[Rik]

Sounds like something from Star Trek

Warp speed!

[Rik]

Well it was sitting quite happily around 7db for months and then recently it ticked up to 13db and I lost about 3000kbps on the sync speed.
For my relatively low attenuation I get quite a low sync speed, it's never been great - I'm sure I have a bit of a lemon of a phoneline

Have you done a quiet line test on the voice side?

If your margin has been high for 2 weeks or more with no resyncs, then it would be worth turning it on and forcing a resync, as DLM may have cut your target noise margin.

[jezuk1]

Have you done a quiet line test on the voice side?

Instructions please 

If your margin has been high for 2 weeks or more with no resyncs

It last resync'd 18 hours ago.. It used to be happy and sit for months without a resync but lately it's resync'ing every few days..

[Rik]

Dial 17070, select option 2 and listen. You should hear just a background hiss or hum. If there's any crackles, report it as a voice line fault to the line provider.

If it's resyncing that much, you definitely need to be exploring the possibility of noise on the line.

[jezuk1]

Next question - do I do all this with the ADSL connected?

[Rik]

Yes. If you hear noise, disconnect it and see if it stops. If it does, it suggests a faulty filter (unless you have a DECT phone, where you'd also have to consider the base unit might be interacting with the router.

[jezuk1]

Yes I can hear crackles on the line, every 30 seconds or so.. Started more after a while
Trying with ADSL offline/disconnected.. Reporting back soon

[Rik]

Call in a voice fault, don't mention ADSL.

[jezuk1]

"Whatever you do, Don't mention the war.. I mean the ADSL"
Understood 

[Rik]

 

[jezuk1]

The kind lady did some tests and phoned me back to reveal a groundbreaking discovery that there are no faults detected

[Rik]

Well, I am surprised. I take it you got no crackles during the call?

[jezuk1]

There were one or two while I was on the call to her and I explained that they seem to come and go so her tests might not reveal anything exciting. I can hear the crackles while doing that quiet test - although they are usually quite faint. It's definitely not a continual hiss, there are audible crackes in the background bubbling away albeit not loud enough to the point where you have to talk over them.

On the plus side - the test caused the DSL to resync and I have gained 2 kbps on my upstream sync speed.
Love it

[Rik]

Line tests often do that.