[LINK] VDSL/FTTN alternative to NBN-GPON - variation in temperature and reliability

[Robin Whittle]

Hi Nick,

Thanks for your reply.  I don't have anything more concrete to add to
the general concerns I wrote about regarding the latest generation very
high density electronics being installed in street cabinets for a decade
or more.

There are low-noise, low distortion GHz amplifiers in metal boxes
underground and strung on wires for the HFC (Hybrid Fibre Coaxial =
cable TV/Internet) systems.  Some of these contain electro-optical
conversion - so they also have lasers, photodiodes etc. and more
amplifiers.  They also have microcontroller-based management systems.
These are powered from the coaxial cable itself, which has an AC voltage
- 50 to 90 volts I recall - imposed on it from mains power supplies and
perhaps battery-backed up inverters.  These amplifiers (an amplifier in
each direction, with filters, for two different frequency ranges) and
electro-optical converters are totally sealed against water and dust and
are passively cooled via their aluminium enclosures.

However, an HFC amplifier is not at all as complex or power-hungry as a
hundred or so VDSL transceivers and a cabinet, with all the fancy
gigabit switching and management circuitry, power supplies, battery
backup in the box etc. which is required for Fibre to the Curb (the
Coalition's preferred plan instead of the NBN's Passive Optical Network
fibre to the premises plan).

I am concerned about dust, moisture, fungus, insects and spiders, flood,
extreme high temperatures and daily temperature cycling.  These cabinets
would need to be well protected from vehicles running into them, since
they would be expensive to replace and would take many days to install,
wire up to the remaining cables etc.  Without wanting to sound too
paranoid, there could also be a theft problem with the backup batteries
and perhaps even the gold and copper scrap value.  Plain fibre has no
scrap value at all.

 - Robin


On 2013-04-23 11:17 AM, Nick Ross wrote:

> Hi Robin,
> 
> Did anyone follow up on this? It's a very interesting point. I've asked the
> question of some FTTN cabinet specialists.
> 
> I've heard enough about datacenters to know that some flavours of the newer
> ones are designed to run very hot indeed - the electronics can cope with it.
> 
> However, I asked about cooling i cabinets before and was told that they
> have several fans in them. But that's surely not going to cut it in an
> Australian summer? Or any perma-hot parts of Australia???
> 
> What other hot countries have FTTN (at least in their hot parts)?
> 
> N