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[AdrianH]

"There are certain areas here with large amounts of Aluminium cable (denied by the upper levels of BT but well known by the engineers on the ground)".

Urban myth, and untrue.

I was stating the fact that there are known areas with Ali cable within our region backed up by speaking to Openreach engineers. Poole is believed to be a good area to check and also parts of Christchurch if you want to check with any sources based down here. If I'm incorrect then why would OpenReach engineers lie to me?
Have I missed your point? It wouldn't be the first time 

There is Ali cable here in Wareham to some properties and street level junction boxes ( those grey cylindrical towers). I was talking to an engineer as he worked on one of these junctions a few yards from my house and he told me it was Ali cable, he even showed it to me.  Other engineeers deny absolutely that there is any Ali and say it hasn't been used for 20 years.
All I do know is a guy in Milton Keynes had copper replace by Ali and his ADSL Max synch dropped by 50%.

[Ottersnose]

I will speak to my contacts in OpenReach and see if I can acquire some pictorial evidence at least.

[AdrianH]

http://www.ispreview.co.uk/index.php/2012/03/ofcom-uk-publishes-more-detailed-broadband-availability-data-for-england.html

[Black Sheep]

"All I do know is a guy in Milton Keynes had copper replace by Ali and his ADSL Max synch dropped by 50%." 

Adrian H ..... you should rename yourself as 'Aesop'. Your fables are grand and puerile, yet sound feasible to the uneducated. I've personally never read as much tripe in all my life. You need to register under 'I love a conspircay . com' and trade your wares on a website that allows unfounded lies. TBB is one particular site.

Did you also know  .......  Anybody with a surname beginning with 'H', will win the 'National Lottery' before the cock crows three times before midnight on a month when Jupiter is in Mars, and the moon is made of cheese ?? That's gotta be true ?? Hasn't it

[asbokid]

It's an interesting question.. what bandwidth might we reasonably expect in the near future?

The Big Thinking is towards a fully packet-switched IP network (21CN). This will see the abandonment of traditional circuit-switched networking for voice calls (the PSTN and the ATM layer).

The buzz word of today is "Triple Play".  This means (1) voice telephony through VOIP,  (2) streamed video though IPTV, and (3) data - web, email, gaming, and pretty much everything else.

Of those three services, it is IPTV that consistently demands the greatest bandwidth. IPTV is also very sensitive to packet loss and delay.

We can use the transponder bandwidths for Freeview digital terrestrial broadcast TV to guess-timate the bandwidth requirements for IPTV over a copper (or fibre) local loop.

In the UK, high definition terrestrial TV is broadcast in DVB-T2 standard with MPEG4 video compression. The FreeView public service broadcast (PSB) transponders have a bandwidth of 40.2Mbps. This bandwidth is used to broadcast four HD TV channels (BBC1HD, ITV1HD, C4HD, and BBC HD). [1] 

For our rough estimate, it requires ~10Mbps bandwidth to broadcast one TV channel in high definition quality.

However, it is commonplace for householders to be watching several TVs at the same time, each channel demanding its own bandwidth of ~10Mbps. Unlike a broadcast scheme like DVB-T, FTTC cannot be used to deliver 100+ of video channels concurrently.

Conjuring up some ballpark figures..

If just three HD video channels are being simultaneously streamed into a household over an IPTV protocol, then the lowest downstream limit for IPTV bandwidth is ~30Mbps for the local loop.

Throw in a smattering of VOIP channels, an online video game or two, some peer-to-peer file sharing, as well as the upstream requirements to service all those channels, and the lowest bandwidth for "Triple Play" to the home is probably 40Mbps.

Without radical upgrade to the local loop infrastructure, Triple Play is never going to happen for many households in Blighty.

FTTC is basically an unsatisfactory Band Aid.  FTTC, in its current form, will never provide a 40Mbps service to many homes. The loops to those homes are simply in too poor condition to support it.  Triple Play is off-limits for those households.

Fibre-To-the-Premises is the only solution that is guaranteed to provide modern telecommunication services to every household. Since BT is too cash-strapped to fund a FTTP rollout itself, and the City has turned its back, such a project could only come about through major state investment.

In other words, FTTP requires a massive public works programme for technological advancement. A programme akin to Franklin Roosevelt's New Deal, funded entirely through a system of public credit. [2] 

Given the crooked "lugheads" we have in power today, and their subservience to the City of London, and their contempt for the General Public, such a programme seems very remote.

"Those lugheads..would do well to study the amazing achievements of Roosevelt in the dark days of the Depression...  FDR’s program included bankruptcy reorganization, banking regulation, farm and housing foreclosure protection, and massive job creation. In the first several months of his administration, the President..put 2 million Americans back to work in short-term construction and infrastructure jobs. The President also employed a further million unemployed, as long-term [Public Works] programs began their development. Later, Roosevelt created the Civil Works Administration. It unleashed a mammoth, but again, short-term public works program, that put over 4 million unemployed to work in four months.

CWA spent $1 billion, and its workforce built or improved over 500,000 miles of roads, and built or repaired 40,000 schools and 3,700 playgrounds. It restored all the city parks in New York; CWA laid 12 million feet of sewer pipe, and built 250,000 privies, while starting or upgrading 1,000 airports across the country—all in four months!

Compared to Roosevelt's achievements, a FTTP rollout is child's play!

Key manifesto pledge of the ASBO Party:  Vote for us and we promise to bring fibre to every home by 2015!

cheers, a

[1] http://www.ukfree.tv/fullstory.php?storyid=1107051920
[2] http://www.larouchepub.com/eiw/public/2011/eirv38n37-20110923/42-46_3837.pdf

[sevenlayermuddle]

Recent posts on thread have caught my interest as I always trusted the 'myth' that aluminium was bad news for adsl.  I've also tended to be open minded to the possibility that any advice from BT management was potentially BS in the extreme.  Though I hasten to add, I've immense respect for real BT engineering staff, and have several visits to Martlesham on which to base that opinion.

But after a quick google, hmmm... Is there really any scientific evidence that aluminium is bad?
 
The Maths behind any comparison would be highly complex, since adsl frequencies can be affected by 'skin effect', so you cannot just take the resistivity/conductivity of the medium at face value, in isolation.

I'll watch this thread with interest (let's keep it civil, though).

7LM

[asbokid]

But after a quick google, hmmm... Is there really any scientific evidence that aluminium is bad?

Aluminium, gauge for gauge, is certainly not as good as copper for use in high frequency transmission lines.

So far as I understand, the most important measurement for a HF transmission cable is its insertion loss as a function of frequency.   Insertion loss is just a logarithmic measure of line attenuation.  And for a given wire gauge, aluminium has a higher insertion loss than copper, particularly at higher frequencies.

However, many years ago, a Beatie engineer was explaining how aluminium itself is not the problem and how it would be better if the whole network was re-wired using it(!)    When used at an appropriate gauge, the insertion loss per kilometre of aluminium cable can be matched to that of copper, or even exceed it, across the spectrum used for xDSL.

BT has developed complex multi-parameter Cable Reference Models that can be used to derive insertion loss at any given frequency, for a given cable type.  These are known as the BT#x models.   Other telcos have their own models, but BT has somehow produced the most accepted Cable Reference Models. [1]

The Maths behind any comparison would be highly complex, since adsl frequencies can be affected by 'skin effect', so you cannot just take the resistivity/conductivity of the medium at face value, in isolation.

Indeed, and the BT Cable Reference Models are only accurate for brand new cabling.  Skin effect is no doubt affected by the extent of oxidisation in the cable conductors.  Aluminium is notorious for its rapid oxidisation in air.  That corrosion creates a second 'skin' that has its own signal propagation properties. 

There is a revised BT Cable Reference Model which captures the effects of a second skin, albeit from intentional cable cladding.  It gets ever more complex, the more you look at it!

The parameters needed to model the most common BT cable types are in the public domain, together with algorithms for the models. [2] However, I have never seen the parameters for typical aluminium cables found in the field.  Has anyone come across those?

There's also the effects of galvanic corrosion to factor in. How does the abutment of two different cable conductors - copper to aluminium - contribute to corrosion in the cable joint?

Cu and Al apparently have very different Anodic Indexes.  The more varied those indexes in a cable joint, the greater the potential for galvanic corrosion.  That corrosion creates a high resistance issue. This creates it own impedance mismatch to compound the mismatch from the different conductor materials and different gauging. The mismatch causes reflection losses, and ultimately a drop in bandwidth.

The gel-filled crimps (the CWI8A) - the most common type of splice connector used by BT probably contribute to the problem, too. The tech specifications for those connectors are somewhat opaque.  The composition of the gel is unspecified and the BT tests performed on the gel are performed over a very short period.  So long as the gel doesn't 'phase separate' over 24 hours, or crack or dry over 7 days (under controlled lab conditions) the connector pretty much passes the BT tests.  [3]

Yet some of those 'jellies' have been in the field for decades, exposed to the extremes of the British climate.  It would be astonishing if the gel is still performing to spec under those conditions.  And once that gel has failed, it very likely triggers another HR fault, through conductor oxidisation and/or galvanic corrosion.

Given the inclement British weather, its contribution to cable and joint failure, coupled with penny-pinching at the telcos through inadequate cable gauge, etc, etc, the rollout of fibre to the premises is long overdue!

cheers, a

[1] http://ftp.tiaonline.org/TR-30/TR-30.3/Public/0206%20Columbia/ETSI%20Documents/970p02r3%20ETSI%20Cable%20Reference%20Models.pdf
[2] http://www.mathworks.com/matlabcentral/fileexchange/3834
[3] http://www.dexgreen.com/documents/%5B3210%5D%20Discrete%20Connectors%20(DexCrimp%20CWI8A)%20TECH.pdf

[AdrianH]

"All I do know is a guy in Milton Keynes had copper replace by Ali and his ADSL Max synch dropped by 50%." 

Adrian H ..... you should rename yourself as 'Aesop'. Your fables are grand and puerile, yet sound feasible to the uneducated. I've personally never read as much tripe in all my life. You need to register under 'I love a conspircay . com' and trade your wares on a website that allows unfounded lies. TBB is one particular site.

Did you also know  .......  Anybody with a surname beginning with 'H', will win the 'National Lottery' before the cock crows three times before midnight on a month when Jupiter is in Mars, and the moon is made of cheese ?? That's gotta be true ?? Hasn't it

Wrong, I know the guy personally and know the problems he suffered after the backhaul was changed, you may laugh all you like , to me it is just is yet again another demonstration of the deplorable attitude displayed by the staff and managers at Bangalor Telecomm.
Interesting also that you choose to slate TBB when the place is full of BT engineers and managers that answer peoples queries............. do remember the other acronym for BS  .  Strange also that you ask for facts to back statements yet when links are provided , even to Ofcom data you sidestep that and make comments  like this?

[waltergmw]

@ Everybody,

BS's burlesquian defence of his employer is perhaps to be mildly applauded.

I would not doubt that the measurements his Martlesham Heath colleagues have made are beyond question.
I would also expect that there is another paper measuring the effects of both age-hardened and corroded bi-metal joints but the marketing departments will probably be less enthusiastic to publish that data.

Equally, I would not doubt the veracity of Adrian H's descriptions.
It follows that there must be a practical explanation for the inconsistant statements made and which almost certainly have been influenced by human error(s) of some sort.

I have listed some possibilities below but perhaps others can postulate other explanations ?

1.  Given that BT have three-way crimp connectors, it would be easy for a telephone engineer (not a trained broadband one) to "improve the connection" by double-jumpering two twisted pairs in parallel.

2.  The engineer making the connections inadvertently crossed two pairs (as I believe has been reported elsewhere quite recently).

3.  Either the modem reported, or the observer recorded, inaccurate data.

4.  There are other significant noise sources on the unshielded twisted pair(s) in question.

kind regards,
Walter

EDIT

PS The following link gives some interesting comments upon the commissioning of a PlusNet FTTC service including some aluminium cabling.

http://community.plus.net/forum/index.php/topic,90502.0.html

[Black Sheep]

"There are certain areas here with large amounts of Aluminium cable (denied by the upper levels of BT but well known by the engineers on the ground)".

Urban myth, and untrue.

I was stating the fact that there are known areas with Ali cable within our region backed up by speaking to Openreach engineers. Poole is believed to be a good area to check and also parts of Christchurch if you want to check with any sources based down here. If I'm incorrect then why would OpenReach engineers lie to me?
Have I missed your point? It wouldn't be the first time 

Yup, you've completely missed my point. I've never, ever, known the upper echelon state there is no Ali cables in our network. They've sometimes wrongly stated there was no lead/paper cable left on the UG infrastructure, but never Ali !!

FYI .... my patch is roughly 25 miles from one side to the other. There is just ONE lead/paper cable length (400 mtrs) that we know of, in this entire area.

To reiterate, it is urban myth that BT deny Ali exists in our network.

[Black Sheep]

"All I do know is a guy in Milton Keynes had copper replace by Ali and his ADSL Max synch dropped by 50%." 

Adrian H ..... you should rename yourself as 'Aesop'. Your fables are grand and puerile, yet sound feasible to the uneducated. I've personally never read as much tripe in all my life. You need to register under 'I love a conspircay . com' and trade your wares on a website that allows unfounded lies. TBB is one particular site.

Did you also know  .......  Anybody with a surname beginning with 'H', will win the 'National Lottery' before the cock crows three times before midnight on a month when Jupiter is in Mars, and the moon is made of cheese ?? That's gotta be true ?? Hasn't it

Wrong, I know the guy personally and know the problems he suffered after the backhaul was changed, you may laugh all you like , to me it is just is yet again another demonstration of the deplorable attitude displayed by the staff and managers at Bangalor Telecomm.
Interesting also that you choose to slate TBB when the place is full of BT engineers and managers that answer peoples queries............. do remember the other acronym for BS  .  Strange also that you ask for facts to back statements yet when links are provided , even to Ofcom data you sidestep that and make comments  like this?

Again, you've lost me !! The 'backhaul' as far as I'm aware, is completely made up of Fibre cable, and always has ??!!! Are you making this up as you go along

[Ottersnose]

"There are certain areas here with large amounts of Aluminium cable (denied by the upper levels of BT but well known by the engineers on the ground)".

Urban myth, and untrue.

I was stating the fact that there are known areas with Ali cable within our region backed up by speaking to Openreach engineers. Poole is believed to be a good area to check and also parts of Christchurch if you want to check with any sources based down here. If I'm incorrect then why would OpenReach engineers lie to me?
Have I missed your point? It wouldn't be the first time 

Yup, you've completely missed my point. I've never, ever, known the upper echelon state there is no Ali cables in our network. They've sometimes wrongly stated there was no lead/paper cable left on the UG infrastructure, but never Ali !!

FYI .... my patch is roughly 25 miles from one side to the other. There is just ONE lead/paper cable length (400 mtrs) that we know of, in this entire area.

To reiterate, it is urban myth that BT deny Ali exists in our network.

Ahh I see. I was suggesting that they deny the AMOUNT of Ali thats in the Network and not that there is Ali.

Crossed wires!

[Black Sheep]

No worries bud.

There's a lot of urban myth, (more commonly known as lies), about BT, their ethics and their customer commitment. Believe me, having worked for them for over a quarter of a century, I'm only too aware of their sometimes faux-pas'. But they're not as bad as some would have you believe.

If you think 'we' don't give a stuff, just ambling through the day telling lies to our EU's, then I would guess you as an individual has had a bad experience. It happens it all businesses, especially international conglomorates akin to a company of our size. For every bad experience, there's a thousand or more good ones on a daily basis. Unfortunately, people very rarely take the time to comment on these.

Back OT though and I can't comment on individual areas, as to the actual presence of Ali cable, but as I and others have mooted, it was put in place approx 50yrs ago for fiscal reasons. Broadband was just another name for a cummerbund back then.  Who would dare to dream that one day we'd be pumping up to 30Mhz frequencies over said cable ??

 

[asbokid]

Leaving the aluminium wars aside..

No doubt this forum unanimously agrees that it is honoured to have its very own expert OpenReach engineer. And one who generously imparts the plentiful wisdom acquired over a quarter century of public service.  Much appreciated 

[Bald_Eagle1]

Leaving the aluminium wars aside..

No doubt this forum unanimously agrees that it is honoured to have its very own expert OpenReach engineer. And one who generously imparts the plentiful wisdom acquired over a quarter century of public service.  Much appreciated 

I can't find the "I second that opinion" icon, but I for one do second it.

This particular OR engineer helped me to reach the stage I'm at now, with his detailed descriptions of HR faults etc. etc. etc.

(So you can all blame him for the length of my other "epic" FTTC thread)