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[dejjones]

My current line stats are as below; they have been similar to this for some months now.
But the other day I noticed the downstream line attn. had reduced to about 15db; it stayed like this for a few days and then returned to around 40db after a re-connection.

I was under the impression that line attn. was a function of line length, and that with my line (about 2km), 40db was about the best I could expect.
I'd be grateful if anyone has an explanation for this.


Statistics          Downstream    Upstream    
Line Rate         5280 Kbps             448 Kbps    
Noise Margin       9.8 dB              21.0 dB    
Line Attenuation 40.0 dB           23.0 dB    
Output Power    19.7 dBm         11.8 dBm

[roseway]

It sounds like a router glitch. Those stats look perfectly reasonable in themselves. Assuming that the 2 km is the geographical distance and not the actual line length, then everything looks quite normal. You certainly wouldn't get an attenuation of 15 dB on that line.

[mr_chris]

the other day I noticed the downstream line attn. had reduced to about 15db

I'm sure I've seen someone else say the same thing, which is a bit odd - I'm sure it was down to 15dB too, for a while, then back up to the normal / expected value...

What router do you have? It might be a glitch in a particular router or firmware version, etc.

[jazz]

I have experienced similar  - my router is a Netgear DG834GT and my line attenuation is usually 51dB.  However on the odd occasion it shows 15dB for a few hours (though no other readings are affected and my speed does not change so I assume it is a false report from the router.)  I had always assumed that the 51 and 15 were just transpositions of the numbers - interesting that you get 15dB readings too

[dejjones]

Thanks for your comments,

My router is a Voyager 210, and the line length is from BT test.
I don't think the previous figure was exactly 15db, (15.something), so I don't think the digit reversal theory holds water.
I also noticed that my ISP broadband speed setting went up to 5500kbps, it normally sits at 4000 or 4500 and is now back to 4500.

[graevine1]

I can confirm that some BT Voyager routers will display 15 to 15.5db which is a false report for a true line attenuation of approx 46 to 49 db. I have to keep my powder dry for the moment. More will be disclosed in due course. BT are fully aware of this false reporting but like many other things they wish to fail to disclose the facts.

[graevine1]

I think I should now say that one must accept up to 10db line attenuation per kilometer of actual cable either "E" side thats to the CAB or "D" side from the CAB to the customers terminating socket.
Its high time that OFCOM and the Ombudsman start to regard a line as faulty and not up to standard if the line attewnuation at mean broadband is above the 10db loss per kilometer. Hope this assists. I am refering to actual cable (twisted pair) length and NOT line of sight or direct distance to exchange MDF termination.

[mr_chris]

Graevine, I'm interested in this BT voyager bug - do you have any more info about this?

Its high time that OFCOM and the Ombudsman start to regard a line as faulty and not up to standard if the line attewnuation at mean broadband is above the 10db loss per kilometer. Hope this assists.

Not really. Many lines I have seen examples of are higher than 10dB / km attenuation... where have you got this figure from, anyhow? As far as I know, it's always been regarded as an approximation of the rough length of a phone line... and has never been officially regarded as a target for what coinstitutes a 'good' line or not!

If you have information to the contrary regarding this I'd be extremely interested to see it.

[graevine1]

I will only speak about what I have measured or actually been present at and seen.
The work is in the course of being refereed.

I have only witnessed this 15.5db factor on Voyager routers and on two, it is well known to BT and another regular respected poster on thinkbroadband. There will be more on this later, but please you will have to wait. It could be the broadcom chipset but I am not prepared to confirm that at present, although I am in posession of two of the routers for further analasis.
Now on the matter of the 10db line attenuation that I believe is a generous figure that no line should exceed per kilometer.

In respect to services such as heavy power and your contract of payment the if the 240 voltage is out by say 6% then it is up to the provider to sort out the line plant. The same could be made to the supply of telercom cables, twisted pair.
I dont believe any court would accept a service being charged where the customer had a line loss of more than 10db per kilometer. Then we enter the SNR field and if crosstalk exists or noise then the supplier must I believe in the eyes of the court be able to be assured that that figure is not in any way service affecting.
Sorry I will not go further at present but. And I say so many people are having so much of their time wasted with "flat cables" and the courts must be asked to award substantial sums for actual financial loss in these cases, where it is not an "actual" then the courts have descretion to determine how it has affected the life of the customer and that construed as an "actual" loss.
I dont just feel but KNOW that the public is being taken for a gigantic ride due to their lack of tech ability, and ability to present the facts of the failure of the supplier. I am not hitting out at all the ISP's but I do feel they could do a lot more, especially with accepting substandard line plant and exchange termination equipment in many cases.

[soms]

I dont just feel but KNOW that the public is being taken for a gigantic ride due to their lack of tech ability, and ability to present the facts of the failure of the supplier. I am not hitting out at all the ISP's but I do feel they could do a lot more, especially with accepting substandard line plant and exchange termination equipment in many cases.

This is what privatisation achieves.

Ofcoms role is to mantain some fantasy equal market to provide you with a choice of suppliers who are not prejudiced by the fact that they own almost nothing.

Tbh I don't think it would be fair for any further regulations committing to service levels for broadband performance.
A large proportion of UK lines must be more than 10dB per Km and typically BT would bear the cost.

Of course FTTC or FTTP would be a nice future development, but again BT would make the investment and have to allow other CPs to make use of it, what nonsense. I dont see Virgin Media being forced to allow other CPs to have the benefit of its cable network.

[graevine1]

Soms. Well you have used the words
"Ofcoms role is to mantain some fantasy equal market " we are not in the world of fantasy markets but I or we live in the real world !!!! We all pay more than enough to receive across the country a twisted pair service that is maintaned up to scratch by competent 'engineers'. Not a service that is crumbling unless you can spit at the exchange, and, there are even some who dont get it within a few hundred meters.
Now
"I don't think it would be fair for any further regulations committing to service levels for broadband performance." Why on earth NOT. you dont buy a gallon of petrol and go away wih 6 pints. You dont go to the restaurant and expect half a meal or one that you cant eat half of do you.
Its time we had a solid standard, industry has had long enough to maintain the line plant up to scratch and to responsibly replace line plant termination cards in say 24 hours not two months or more.
I will now deal with ;-
"A large proportion of UK lines must be more than 10dB per Km" they may be getting into that bracket now but that is down to lack of management of resources if it is the fact that you state.

[kitz]

>> Now on the matter of the 10db line attenuation that I believe is a generous figure that no line should exceed per kilometer.

I'm afraid I disagree with that - Most lines I know exceed the 10dB per km - including my own.
10dB per km is only a very rough ballpark figure used to try and give some backwards indication of line length based on your attenuation.  It shouldnt be seen as anything more.

So for eg you may have a line thats showing 12dB and in reality the actual line length (not distance) is say 600m.
Therefore that line would actually be 20dB per km.  This sort of thing is not untypical. 
Whilst I understand where you are coming from on this..  the 10dB per km is way too harsh and would probably affect the vast majority of lines in the UK.

Who would fork out the expense for this?  Should it be BTw?  If so why should they when the ISP may be an LLU provider and BTw get little return (if any) for their investment?
Copper is an expensive resource, hence the use of aluminium a few decades ago.
The cost of bringing each line in the UK into the 10dB per km range would be extortionate.


On top of that all adsl routers likely report different attenuation figures

For example on my own line

7dB - BT voyager 2100
8dB - Speedtouch
9dB - SAR110 (VIK-2.1.040311a)
12dB - Netgear DG834G
21dB - Solwise SAR110 (original firmware)

I'm actually <200m from the exchange. Actual line length is 600m.  Therefore which router is reporting the correct attenuation?

adsl routers report guide figures - they are not expensive therefore cannot be relied on to show the exact figures as a substitute for equipment that would normally costs £1000's.

[soms]

Sure it would be nice to see standards and we would all benefit, it just seems impractical as things stand.

Trying to establish and maintain such service standards be a huge undertaking, and just something else BT has to try and do because Ofcom says so.

The cost would be huge, mainly due to the amount of labour and the cost of the copper used in hundreds-of-pair cables.

BT is already committed to 21CN, which is self-funded and we hope after that there might be investment in fibre in the access network.

My view is that this should have happened sooner, perhaps when broadband was first taking off. With the number of broadband enabled lines we have now, and with no many ISPs simply renting the use of the network in question, it just doesn't seem right.

[kitz]

This is what privatisation achieves.

Ofcoms role is to mantain some fantasy equal market to provide you with a choice of suppliers who are not prejudiced by the fact that they own almost nothing.

Tbh I don't think it would be fair for any further regulations committing to service levels for broadband performance.
A large proportion of UK lines must be more than 10dB per Km and typically BT would bear the cost.

Of course FTTC or FTTP would be a nice future development, but again BT would make the investment and have to allow other CPs to make use of it, what nonsense. I dont see Virgin Media being forced to allow other CPs to have the benefit of its cable network.

Totally agree with that statement.
De-regularisation has actually left the consumer worse off in some instances.  Whilst I do have some issues with BTw..  I am perfectly able to see the other side of this. Why the hell should BTw invest billions of pounds for something which other telecom providers are going to reap the rewards?

The 10dB figure is a "pluck out of the air" figure and bases no reality on the true situation of the vast majority of lines in the UK - without even making any allowance for connections with aluminium on the lines. :/

Deregularisation forced BT to open up the exchanges - therefore the LLU providers reap the rewards and cherry pick.   I dont see any other telecom provider putting as much effort into getting the UK fully broadband enabled as what BTw are doing.
Should VM be made to open up their backhaul network for other providers?   and why hasnt the old NTL/Blueyonder/cable network been expanded for many many years.  I dont see them making much investment... nor trying to bring an alternative method of provision into the UK.

[graevine1]

Your last post produces the question, Who are you wishing to represnt BT or the poor customer who wants what they believe they are paying for.

it is also interesting to discover how and who funds OFCOM and the way OFCOM is under control of those with an interest in profit.

Government have a duty to protect the public and especially to protect the public from scams and ensure that "trading standards" are able to be upheld.