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[Dray]

Plenty of hits on Google, including https://www.itu.int/ITU-T/formal-language/itu-t/g/g774.1/2001/g774.1.html

[WWWombat]

From this sequence ...

From the link I posted

A Severely Errored Second is a one second period which contains 30% or more errored blocks OR several other events

and...

I'm not sure where that definition of a Severely Errored Second originates from, but for DSL, it's defined in G.997.1 as a second containing 18 or more CRC errors, or one of various other events.

and this link ...

Here http://www.kitz.co.uk/adsl/linestats_errors.htm

I gathered that, I was wondering where it came from originally.

May I offer an answer that could meet both statements?

From the link, we are told that ADSL modems generate 4000 frames per second, and that a superframe consists of 68 ADSL frames plus one synchronisation frame. That tells us there are 58 superframes every second.

I believe (and have for a long time, apparently) that the CRC check is performed per superframe - so the data being transmitted can result in 58 CRC errors per second.

18 CRC errors per second is pretty close to being 30% of the 58 blocks per second.

[licquorice]

Certainly in the SDH world (with which I'm much more familiar than DSL) a SES is a second in which contains 30% or greater errored blocks OR other severe events. Block size obviously dependant on the signal in question but proportional to the bit rate.  ITU G826 describes.

[MaximusPrime]

Guys,

Senior Engineer who knows everything about broadband was with me today.

He re-crimped my NTE, fixed up the junction box on the pole that was crooked and checked the diagnostics from that pole & my NTE.

He said my AC Balance was 66db at the pole but 56db at the NTE. He re-crimped the line in the attic & now the AC balance at my NTE is 59 db.

What's AC balance & how can it affect my line? Could it be the sole cause of my disconnections?

cheers

[William Grimsley]

Hopefully what the Openreach engineer has done has finally fixed your issue, I commend you for putting up with this.

[MaximusPrime]

@William Grimsley,

cheers, I think I'll be putting up with issues until FTTP is rolled out 

[William Grimsley]

A shame, you want to check out my recent thread, it's going to be an interesting evening seeing if we get any noise.

[MaximusPrime]

@William Grimsley,

I seen it, in comparison with me your speeds are great. As long as your line is reliable I think you should enjoy your broadband

[MaximusPrime]

Any1 know the answer to the AC Balance question above?

[William Grimsley]

@William Grimsley,

I seen it, in comparison with me your speeds are great. As long as your line is reliable I think you should enjoy your broadband

It's incredible isn't it, quite shocked to say how poor the line condition was nearly 2 years ago. I don't understand how being told to "power down the router for 30 minutes" is great advice when the line is stable.

Any1 know the answer to the AC Balance question above?

Unfortunately not, sorry.

[davinci8128]

You can think of AC balance as the ability of the line to repel interference/noise. The higher the value the less prone the line is to external interference. It is actually a negative number.

You want this to be above 60 db for a good circuit.

[MaximusPrime]

Thanks @davinci8128,

he said the AC Balance was 59+ at the NTE now, I think 59.6 I think, so nearly a good circuit.

I'm surprised at how just 1 connection can cause such a problem. There are so many connections, could have several problems 

Any of the graphs on DSL Stats show the AC Balance?

[MaximusPrime]

Disconnection this morning; went from 9.5Mb to 4.5Mb

There is a broken street right above the underground cable, 0.8km from the cabinet

Could it be the cause?

[MaximusPrime]

Got my Raspberry Pi & DSLStats set up!

Plus Fire Alarm

[attachment deleted by admin]

[burakkucat]

Got my Raspberry Pi & DSLStats set up!

Plus Fire Alarm