Blowing Thought Bubbles Like A Preschooler With Bubblegum

Vectored DSL Falloff

Vectored DSL improvements over top 1%-worst-case & 50%-worst-case lines. Remember, distance is in foot not metres.

Uhoh, he’s at it again. Malcolm Turnbull’s latest thought bubble has been blown & now it’s all about VECTORING (ABC Radio National this morning – MP3)! I’m guessing one of his staffers has been reading Whirlpool recently & seen the buzz from Liberal party voters on there about how Turnbull could introduce vectoring (aka Dynamic Spectrum Management) to bump speeds up on FTTN.

I’m not going to go on about how stupid this idea is, because as people know by now, everything Turnbull says, tweets, writes, is a load of garbage designed to appease Murdoch & hobble Australia’s telecommunications. Vectoring may work, but only over short distances, only with already pristine copper, & only with one provider. Guess who that provider will be? Yeh, Telstra.



NEXT (Near End Crosstalk) & FEXT (Far End Crosstalk). Only FEXT is solved by vectoring.

The technology is quite simple. Stick an encoder & modulator on the exchange end that takes into account crosstalk of the copper pairs around it. It does improve speeds, & you might get close to 100Mbps in a <300m loop (cable length), but the further away from the exchange you are, the less the improvement will be.

Vectoring only solves one problem, crosstalk. Crosstalk comes from copper pairs being bundled together affecting each other. This is common with xDSL (Digital Subscriber Line) services & causes upper limits to be placed on existing technology, vectoring utilises algorithms to offset crosstalk & create pre-modulated signals that don’t create crosstalk at all. One major downside is that the forces all copper in a cable bundle (10, 20, 50 or 100 pair cable) to be run by one provider.

Another downside is that non-crosstalk interference (foreign battery, induction, corrosion, etc) will not be effected by vectoring, in fact, research shows that some of these faults become more noticeable when vectoring is applied to the line. Some can be mitigated by changing algorithms, most, however, cannot.

Then there’s the vectoring falloff, which, as with all xDSL, is quite rapid. The higher the peak speed, the quicker the falloff, with vectoring showing no benefit over about 1.2km, meaning that this is a lot of expense for no real benefit.


Even as far back as 2003, Telstra were planning on ripping up their copper as ADSL was “the “last sweat” of revenue Telstra could wring out of the 100-year-old copper wire network”. It makes me wonder why Turnbull is attempting to apply every possible life support mechanism on copper (no matter the expense, & it will be expensive) while ignoring technologies that are the future of communications.

It seems a week doesn’t go by without Turnbull blowing a thought bubble, only to have it popped by ICT experts, tech writers, & even economists. One would think that by now, after countless permutations, he would accept that fibre optics is the best way to upgrade Australia’s communications. Having seen Turnbull’s arguments shift from wireless, to HFC, to FTTN, & now to vectored FTTN, I can see the clutching at straws will continue, & there will be no policy released, just rough outlines of what might be deployed.

Josh Taylor of ZDNet Australia tweeted me yesterday that there’s rumours of Turnbull releasing a policy within the next two weeks, I am highly cynical of this & have heard it all before. Josh may be right, but I’ll believe it when I see it. Apparently Turnbull has had said document ready since August last year, yet there was no mention of vectoring or leaving HFC serviced areas to rot back then, leading me to believe the policy document is non-existent, let alone costed.

Over the coming months we’ll see more outlandish claims from Turnbull on broadband, becoming more shrill & more unbelievable the closer to an election we get. The main thing to do people is to double check with technical experts & websites that what Turnbull is saying is true, or just another bald faced lie designed to create doubt about the need for fibre optic services.

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  • MWS

    Telstra “committed” to repairing my current copper line by 6/3. Today (7/3) they rescheduled the repair to 14/3 due to “peak workload.” Looks like the copper network around here is already well past its use-by-date.

    Can’t wait for the NBN!

  • Jason Ozolins

    Good points; couple of ways this article could be easier to grok:
    – Label the “vectoring improvement” graph vertical axis…
    – attribute the apparent “last sweat” quote
    – bit more explanation about NEXT/FEXT and why it matters that vectoring only helps reduce FEXT

    interesting quote from WP VDSL2 page:
    “Although technically feasible at the moment vectoring is incompatible with local-loop unbundling but future standard amendments could bring a solution.”

    Even better! Vectoring delivers Telstra an unassailable sinecure even if there were a way to deploy other operator’s equipment in the cabinets!