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[kitz]

Posted in this thread because I do not want several threads where customers have issues with their connections taken off topic, by this debate.
This forum is to be constructive in the help of all users regardless of their ISP.

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My response to Roseway, if what you are attempting to perport was true then some of the basic laws of Physics would have to be re-written. The example I must site would be a line of 5 kilometers using your analagy would give a line attenuation of 20db per kilometer over say 5 kilometers the result 100db of line loss. You therefore will be able to supply a broadband signal of usable level to all peoples in all corners of the UK with little difficulty.
My figure gives approx 50db for a five (5) kilometer length of line attenuation which is the reason why broadband will function up to approx 65db and six(6) kilometers. QED!

I must take issue with your last post Kitz and state that the figure I a,m quoting is more than generous at 10db per kilometer and I can state that was obtained some years ago after extensive and refereed research across the specrum in use.

I still fail to see, nor have I ever seen, any evidence that 10dB per km is a generous figure.  I still stand by my statement that in the UK the average loop loss is around 15dB per km.  Actually perhaps I should have said 14dB.

Its one thing saying bt should give the users 10dB per km, but I fail to see how this is possible based on adsl technology and the fact that its carried over copper wire.  Attenuation isnt something that BT - or any telecom co -  can "dish out" to a magic number of 10.

I have however seen evidence that 14dB per km is about right. The evidence wasnt supplied by BT but its a world wide figure therefore there cant be any conspiracy theories that the figure has been cooked by BTw.  The survey was conducted about 2 years ago by Consultel in specific relation to adsl.

When I coded the max speed checker I based them on those figures, and once it was complete, I then spent the best part of a whole afternoon and evening checking every single line stat I could find against it to make sure it was as accurate as it could be in the UK.
I literally checked it against a few hundred line stats from various different sources.

I am not going to spend several days coding something then make a idiot of myself by putting it up on the main site if it was going to be wrong, without doing some research of my own first.

If you feel my figures are nonsense then you should also approach Mr_Saffron (who is one of the best adsl experts in the UK) and tell him that he's working on wrong figures too.

Both Andrew and myself spend a huge amount of time trying to help asdl users in the UK.
Im sorry that if you mistakenly feel that some of those that spend a huge amount of time trying to help adsl users, if they dont always agree with what youre saying must be in the pockets of BT.

I was quite shocked to hear a few weeks back that you perhaps class me in that category..  I can 100% assure you Im not. Anyone who knows me and my history of run-ins with BT would know just how ludicrous that statement is.
The biggest reason this site is here in the first place... and why I funded it myself and spent countless hours for so many years.. is because of the problems Ive had with BTw and therefore I wanted to try and help others too. 

I would like to think that I try if possible to give a balanced and factual view of things ...  rather than point fingers in the wrong direction and blame BT at every opportunity.

I am annoyed however that yet again a thread which is supposed to help a user went off topic.  You already know my thoughts on the only way that uk adsl is going to get decent speeds.. and that certainly isnt going to be possible without a huge investment and FTTC.

[kitz]

quote

I must also add that I stated yesterday a figure of 10db per kilometer I should have said 10db per mile as the maximum line attenuation that should be accepted. That is a figure that was accepted in addition up to the few honest staff in BT up until one year or so ago. All the acceptance tests in obtaining those figures were the result of refereed papers from such research. So I refute any critisism.

I just noticed that you are now saying per mile rather than km

1 kilometer = 0.6213 mile @ 10dB per mile

So therefore are you are now saying this report stated that attenuation should be no more than 6.213 dB per km?
I can honestly say Ive never seen a line recorded at such a low looploss !!


Heres my proof that loop loss is considered to be 7dB per 0.5km in relation to adsl

[guest]

You're wasting your time kitz. Ignore him as he doesn't have the first idea what he is on about and nor is he willing to correct his abysmal lack of knowledge by listening. Works for me

[Pwiggler]

......... and the last time i had a bt engineer out to my place he said 15db per km is what they work on ...........

[Ezzer]

looking back in my log book:
line lenght 1080m,   downstream loss 21  db
                  6440m                                43  db
                  3040m                                49.5 db
                  4306m                                53  db
                  2350m                                35.5  db
                  4180m                                57  db
                  3030m                                41  db
                    113m                                16  db
                  4480m                                55  db
                    263m                                10.5  db
                    893m                                19  db

as a genereralisation 14-15db/km seems about right, assuming all the wire is 0.5mm copper. some cables & routes have some variations 0.4-1.2mm copper and similar in aluminium, all will affect the overall result & is some times part of what an engineer may look into during a fault. I've got broadband working ok at 9.3km though this was mainly 0.63mm copper. I've even seen a modem sync at 11.5km (though only for 10-30 seconds at a time)

[soms]

With regards to the conductor size making a difference, is that sometimes why pairs are doubled up on very long lines?

Attached is a pic of the statistics from an ADSL circuit in an exchange building. It doesn't get much better than that.

[attachment deleted by admin]

[PhilT]

......... and the last time i had a bt engineer out to my place he said 15db per km is what they work on ...........

Early on they were using 10 dB/km so for example the 55 dB limit equated to 5.5 km which then extended to 60 dB / 6km. See for example http://www.bb4mk.org/ADSL%20extended%20reach.htm

I'm not sure everyone has a good handle on their actual line length, and a further question arises over the definition of attenuation - is this at 300 kHz or at a weighted average of the frequencies in use or.....

If longer lines have fatter copper to compensate (on voice) then the dB/km will be lower in any case, I've seen numbers like 62 dB over 10 km on a thick overhead line.

Phil

[graevine1]

Thank you Phil,
I believe there are certain individuals on this site acting like "barrack room lawyers" in the sense of being "pretend competent engineers" sadly misleading those seeking advice. Where I pay credit to the wealth of information that is available on this site. No one can condone quoting figures that they are neither competent or with the facilities to measure. Phil the facts you quote are absolutley correct. In fact the work was originally per mile. We must I believe consider accepting the figures these days per kilometer.
Now with reference to the brightly coloured graph in this thread it I believe has little practical relevance to the practical situation in the Uk but is an interesting guide to the overall picture and is of course drawn up by whatever means by a group in Australia. So please in future quote from work with the credibility of the IERE or IEE in the UK.
I shall stick to and believe customers should expect a figure of 10db loss per kilometer to be an acceptable line or the provider should be held responsible for bringing such line up to an acceptable service standard. To start accepting 15 or 20db loss per kilometer is to enter the slippery slope of those customers paying for a service which they would not be receiving. Therefore a line indicating 15 or even 20db loss per kilometer is clearly one which requires rapid maintenance or a cable "uplift".

[roseway]

Ignoring your offensive remarks about 'barrack room lawyers' and 'pretend competent engineers', the facts still are that a loop loss of around 15 dB/km is typical. It isn't the best which can be achieved, fairly obviously, but lower loss would require more expensive cable. This discussion isn't about what you would like (and presumably are prepared to pay for) but about what IS.

If you choose to believe that anything over 10 dB/km is unacceptable, that's your prerogative, but all considerations of this nature are about what's achievable at a price the customer is prepared to pay. Anyone can grab a figure out of the air and say that's what they want, but here we live in the real world.

[graevine1]

I am not plucking a figure from the air and I am living in the real world. 10db per kilometer is what the network should provide anything less is NOT what the customer is paying for. We also must insure that the network is maintained with the standard of cable used that is appropriate for its length, if that is not the case then those responsible must be called "to book". If you wish to go to the garage and purchase a gallon of petrol and go away with 4 pints or even 7 1/2 pint I bet you would be one of the first to call in trading standards. Im not in this world to "sell the customer short" as it would appear some would appear to condone.

[soms]

The customer is not paying to for 10dB per km. Most customers are only after the cheapest monthly tariff they can get from ANY broadband supplier. Obviously BT foots the bill for anything to do with the access network and in the present climate of Ofcom driving market competition there is absolutely no way such infrastructure upgrades are going to happen. Since the majority of customers are oblivious to the term attenuation, I don't think they are going to get to upset by the difference between 10dB/km and 15dB/km.

[graevine1]

Hi Soms. Thanks for that we shall have to see what comes from the Ombusman and OFCOM in the near future. BT do have a responsibility to maintain the network to an acceptable standard and as Yarwell has brought out a document that is in the public domain we shall have to see what penalties are brought to bear, where there are service failures

Its sad but for anyone to take advantage of the public as you say not being aware is for those apointed responsible bodies to take care of the public. If cables that are not up to standard for the job have been laid then it must be corrected.

it is not for anyone here or anywhere else to condone a substandard network or suggest to customers that they put up with 15db or 20db, they should point out that the customer has statutory rights and for those to be upheld and if necessary competent and qualified persons who are independent to be called in to report and correct.

[roseway]

Your views on BT are well known, but they are simply your opinion. Kitz has done extensive research which shows clearly that ~15 dB/km is quite typical, not only in the UK, but around the world. We're not here to defend BT or anyone else, but unless you can actually produce some facts to support your opinions this discussion is a waste of time. Describing the BT network as substandard is just so much hot air unless you can justify it with properly researched information. You've been asked to do this several times, but have failed to do so.

[graevine1]

Roseway, you simply must start to understand basics and stop using work and figures not substantiated or carried out under any form of control. "Yarwell" by putting up the link that he has, has spoken for the public. I repeat,
"Early on they (BT)were using 10 dB/km so for example the 55 dB limit equated to 5.5 km which then extended to 60 dB / 6km. See for example http://www.bb4mk.org/ADSL%20extended%20reach.htm.
Taking the attitude that you are taking can leave me and others with the only view that you are clearly in support of a degrading network, one must therefore question your motive and I believe it will leave the public at large with a clear view of how your view will benefit you. I am not the owner of the rights to the research and testing so am not in a position to place such on this site. So I and those other qualified professionals will continue to state that any line loss greater than 10db per kilometer is more than that which should be acceptable to any customer. "Ezzer" in this string has shown quite clearly how poor the quality control of this network in fact is, however, he does not state and this is not a criticism of that which he has published, how and what if any calibrated test equipment was used.

[roseway]

You know, I'm beginning to get more than a little irritated by your patronising remarks, and your repeated vague references to unidentified sources. Who are these 'qualified professionals' who you associate yourself with? Where is the link to yarwell's posting to which you refer, so that we can read it for ourselves and not have to rely on your translation of it?