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back to article ITU readies gigabit G.fast standard for copper's last wild ride

The International Telecommunications Union (ITU) has taken the first steps towards standardising G.fast, the next major DSL-based standard which vendors hope will provide a “fibre-like” experience without having to drag the glass all the way into homes. While it's touted by vendors as a gigabit-over-copper technology, the …

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Interference

As if we radio amateurs and short wave listeners don't have enough problems with powerline Ethernet adapters, cheap switch mode power supplies and some plasma TVs, this comes along to really bugger up our hobby.

If they're going to notch out the FM broadcast bands, I really hope they'll also notch out the shortwave broadcast bands and amateur bands, and think about harmonics too.

Yeah yeah, I know it's progress and I like fast Internet as much as the rest of you, but the HF to VHF RF spectrum still has its uses; commercial, military and hobbyist and should be protected.

Get of MY lawn!

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Anonymous Coward

Re: Interference

Knowing radio hams as well as I do, rolling out G.Fast as soon as possible would be a mercy.

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Facepalm

Re: Interference

Anyone who voted your post down is clearly uninterested in the benefits to society of having around a group of people who have the equipment and experience to assist in the sorts of disasters that clobber the phone network, either from damage to plant or massive call congestion.

If you've read about the sort of engineering that went into specifying Category 5 and higher cabling, then you can appreciate on the one hand the technical achievement of getting similar speeds down telephone copper, and on the other that it is a bloody awful medium for high speed comms. And yet, it's still better for large scale fixed deployments than wireless, which is what the telcos would really rather we were all paying through the nose for...

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Coat

Doomed...

I think we are heading to having only three services:

Mobile

Satellite

Wired (Coax, fibre, xDSL).

Nice and simple for Regulators and maximises the revenue. No technology that causes interference to Mobile will be approved. Any other Wireless Spectrum user is a 3rd class citizen. Satellite is a 2nd class citizen as they pay little or nothing to Ofcom, but tolerated as it will help get rid of pesky TV & Radio. According to the BBC, listeners to the Archers wanting the unique bits on 4Extra can use their TV to make up for poor DAB coverage, poor power consumption and lack of decent models and a minority of owners.

Soft Touch Regulation, the National Regulators and the "Market" are a failure at protecting vital infrastructure and the consumer.

Public Service broadcasters are now using spurious financial arguments to justify AM closures, IT outsourcing, program outsourcing.

We are doomed.

I'm reminded of the SciFi book where the character wakes up in ruins of the Hospital in the Future and discovers most modern tech is badly done fake. The car has "sound effects" to make it seem more powerful.

The Interplanetary spaceship tech is faked too but used as a prop on chilling "final solution" to overpopulation.

Today Bling on computer GUIs is more important than any real improvement in underlying performance, security or usability for the last 10 years.

Doomed I tell ye!

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Boffin

Vectoring, vectoring! Wherefor art thou vectoring?

F'shame. No mention of vectoring in that article. Boo!

Our hopes and dreams and some more information.

It's showing a lot of promise but without it higher speeds on copper are dead in the water for most practical purposes. How can you discuss G.Fast without talking about vectoring?

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Facepalm

Re: Vectoring, vectoring! Wherefor art thou vectoring?

Only a fleeting allusion to its (lac of) range too. A stop-gap for telcos which can't be arsed to run fibre beyond their cabinets perhaps but worse than VDSL2 over meaningful distances. So probably very little use *in the long run* ;-)

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Re: Vectoring, vectoring! Wherefor art thou vectoring?

What's the Vector Victor

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Re: Vectoring, vectoring! Wherefor art thou vectoring?

Roger, roger.

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Coat

Re: Vectoring, vectoring! Wherefor art thou vectoring?

We have clearance, Clarence.

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Re: Vectoring, vectoring! Wherefor art thou vectoring?

RCA Vector?

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So, it won't be here for at least another 2 years. And that's just for the kits to start being made, never mind actually being put in the home. In the mean time, even in Quebec, we're seeing fiber role outs pretty much everywhere, even less densely populated areas. I somehow doubt this will see any kind of use, ever.

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Trollface

It is probably an xDSL intermediate step for those telcos who don't want to deploy FTTH, especially in areas where there is a requirement to bury cables because that makes things expensive. In the UK for example they aren't allowed to put up new telephone poles and all new cabling should be buried/ducted. However for the millions of homes which don't have poles the incumbent telco doesn't always want to have the expense of installing new ducts when they can easily just extend FTTC. Most users don't need 200Mbit/sec anyway to look at cat pictures on the interwebs.

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M7S
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@ Bob H

"Most users don't need 200Mbit/sec anyway to look at cat pictures on the interwebs."

Possibly not but it's that kind of patronising attitude, often from the utilities and authorities, that results in large swathes of the country (and not just the countryside, although I am in the latter) being palmed off with a poorer infrastructure which in turn can inhibit economic growth, amongst other things.

I recall being told many years ago when I used to bitch about the slow rollout of broadband (rather than the current rollout of slow broadband) that dial up was perfectly fine for internet access. Not, I think, an era that many of us would willingly opt to go back to now.

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Is FM interference a real issue?

Just how much leakage of signal will there be? After all, phone lines use twisted pair cables. If they didn't, then existing DSL wouldn't travel very far at all due to signal loss and interference (especially cross-talk). Indeed voice frequencies wouldn't travel that far either - something the Victorians picked up on fairly rapidly. The whole point of transmission lines, like the humble twisted-pair phone cable, is that it is simultaneously designed to minimise signal loss and susceptibility to EMI (even if DSL pushes things way beyond what the original designers ever anticipated).

As it is, existing ADSL frequencies overlap AM bands without, apparently, causing significant problems (albeit AM is a minority interest these days). That's despite the fact that ADSL is often carried into domestic extensions which often don't use twisted pair. With VDSL (and beyond) frequencies, the termination point is at the point of entry to the house (where its filtered), and it doesn't travel down domestic extension wiring. VDSL overlaps shortwave frequencies, and again nobody seems to be complaining of interference in the real world.

For those that think this is anything like the issue of pumping high frequency data carrying signals down mains wiring, forget it. Mains wiring is almost designed for propagating EMF. Telephone wiring is not.

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It's not all twisted pair…

@Steven Jones: existing Telco line plant has low quality pairs between exchange and PCCP (cabinet) and then PCCP and DP (distribution point). From the DP (telephone pole or distribution box) then the pairs to the customer are, generally, non-twisted pairs designed a very long time ago for audio performance only. The modern CAT5/6/7 cables used for data networking have much tighter specifications than the old CAT3 cable used for telephone applications (all of thses use twisted pair technology). If one has a pole feed, or a feed from a distribution box, then the cable involved will not be balanced. Whilst not as leaky as mains wiring, flat pair is still a leaky medium.

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Re: It's not all twisted pair…

I know that the distribution cable isn't as highly specified as highly as modern data cables of course. It's a fairly loose twist. It is therefore, of course, not as resistant to EMI (and, therefore will also "leak" more signal), but this has to be kept in perspective - if it can be considered and antenna, then it's an incredibly inefficient one. The biggest problem is with cross-talk within multi-pair cables, and I've yet to see any evidence that external EMI is a significant issue to other communications with existing DSL (which, after all, goes up to 30Mhz). As people will know, lower frequency radio waves (in general), travel further with less attenuation than higher, so I'd expect frequencies up to 100Mhz to propogate even less.

As far as the sub-loop is concerned (the bit from the "green cabinets" to the household), then the ANFP-S for VDSL (only currently carried over the sub-loop) certainly refers to this is a twisted pair network.

http://www.ofcom.org.uk/static/archive/oftel/ind_groups/nicc/Public/interconnectstandards/dsltg_spec/nd1605_2001_10_issue1.pdf

"it is applicable to all sub-loops in the BT access network provided using unscreened twisted metallic pairs." It goes on to specifically exclude fibre provision (which is not relevant of course). Maybe there are non-twisted sub-loops (but I'd be surprised), then they aren't going to be suitable for vdsl (and, of course, g.fast) too.

All BT local access loop cables have a specification as regards the balance to earth, mutual capacitance and so on. The main standards are CW 1128 & CW 1128/1179.

http://www.caledonian-cables.co.uk/Telephone/Outdoor/CW1128-2.htm

There are other suppliers with single and dual pair cables to the same spec.

There's also a well-known spec for extension cabling (and there are external and armored versions available). This is also twisted pair and is known as CW1308, albeit I don't think it is used as part of the sub-loop itself.

The standard for "drop wire" is CW1411/CW1417, and whilst these may not be twisted par as such, they still included relevant specifications for balance to earth, mutual capacitance and so on.

In general, the cables are designed to have considerable rejection of interference and, by dint of this, make very poor antennas.

From what I can find, egress interference from VDSL signals to amateur bands is not usually much of an issue due to relatively low VDSL power densities. Indeed the reverse ingress interference is more of an issue due to the much higher power densities of amateur transmitters.

In general, I can't find much in the way of actual, rather than theoretical, egress interference from existing DSL services despite the fact they overlap a considerable number of bands up to 30Mhz. In other words, is this really a problem in practice (unlike powerline transmission).

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Bronze badge

-- And, of course, even if they're underground, the copper plant provides a long antenna. That means any emission from the cables is going to destroy FM radio transmissions. --

Interfering didn't seem to worry PLC floggers (BPL over here) -- but they're not making enough to stay in business. Something about an open door working both ways . . .

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