[LINK] NBN and Batteries

Richard Chirgwin rchirgwin at ozemail.com.au
Thu Feb 24 07:32:38 AEDT 2011

On 23/02/11 9:39 PM, Bernard Robertson-Dunn wrote:
> This battery thing suggests to me that the original NBN solution didn't
> think it all the way through.
> My view is that every solution creates new problems. In this case it
> looks to me as though they (a range of people, not just the NBN) are
> trying to modify the NBN to replicate the system being replaced, not
> look at is as a new problem.
I'm going to go further: people are trying to replicate what they 
*imagine* is being replaced. This debate projects 2011 thinking 
backwards onto the early 20th century PSTN build.

The batteries are not the "secondary", "backup" or "continuity" power 
source in an analogue telephone exchange. They are the primary source of 
the 48V dc which, in Ye Olde Worlde, made the phone ring, etc. They 
exist not to keep the phones running in a blackout, but because you 
could get the phone on even back when you still had gaslights in the 
house. The "backup" role is a later spinoff.

If we were designing a ground-up PSTN today, would we design it around a 
requirement that it run a relatively inefficient DC-based parallel power 
grid? Probably not.

> The new problem is not "how do you keep the NBN up in times of power
> loss in an emergency?" but it should be "how do you provide emergency
> communications in times of power loss?" Just because the POTS could
> still be used when power was lost, doesn't mean that the NBN should
> provide the same solution.
Originally, I didn't agree. I fell into the lazy thinking that said "the 
PSTN has batteries, therefore the NBN must".

But while a fixed network is adequate for personal safety and 
emergencies - calling an ambulance, for example - it's too vulnerable in 
wide-scale emergencies (whether copper or fibre).
> And when you analyse the problem it becomes clear that power can be lost
> to a variety of systems (NBN, mobiles, TV, etc) and in a variety of
> circumstances (bushfire, storm, flood, earthquake, cyclone).
> It would be nice to have a solution that covered the real problem, not
> just part of it.
> But that would be a bit radical, especially when it comes to ICT.
We don't need a single solution to emergency communications, in my 
opinion: a number of overlapping networks - fixed, mobile, and parallel 
emergency services radio networks - add up to more survivable 
communications already.

As to the battery question: I don't think "every NBN termination must 
have backup batteries". They should be available for personal safety 
where requested.


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