DIYbanter - View Single Post - Broadband for all

Terry Casey

In article ,
says...

Telepest (now Virgin) did install fibre a long time before BT got around
to fibre to the cabinet. There was a lot of objections to the disruption
caused by the contractors digging up pavements and restoring them in a
**** state. In my case they sent a letter out approx 6 weeks in advance
of the work saying it would commence "sometime" in that 6 week period -
that was the only notification. I woke up late one morning to find a
trench and a pile of debris across my driveway and I couldn't get my car
out! This was followed up by cold calling foot in the door scum posing
as Telepest salespeople!

All cable operators were dependent on contractors to build
their network and were let down badly by the way these outfits
performed.

As for fibre, ntl: - now also part of virgin, of course - was
no different to Telewest. The background to how the networks
developed is often poorly understood, so here goes.

These companies originally provided TV and telephone services
only. The signal quality of the TV signal is tightly specified
as part of the licence in terms of noise and distortion. These
degrade as the number of amplifiers increases so the solution
was to cable areas on an individual basis and feed from the
headend to the local launch amplifier over fibre.

Amplifier bandwidths increased over time from 450MHz to
550MHz, then 600MHz and, by the time the networks were
upgraded for DTV, a bandwidth of 750MHz was chosen as
providing sufficient extra bandwidth whilst minimising the
amount of network upgrading necessary.

In 1997, the first version of the DOCSIS spec (Data Over Cable
Service Interface Specification) was released. This allowed
40Mbs of internet data to be carried in a 6MHz (US) TV
channel. A modification created EuroDOCSIS which allowed the
full 8MHz bandwidth of European channels to be used. On the
network I worked on, the first broadband internet offering was
a 'whopping' 600kbs!

Note that this was over 10 times the maximum 56kps available
on dial-up.

Another point to bear in mind is that as the network is
designed to carry high quality TV signals unlike the voice
networks used for ADSL, it doesn't matter where you are on the
copper part of the network, the signal quality does not
degrade!

Revisions of DOCSIS continued until, in 2006, 1.2Mbs was
available in one channel - but there was more.

As the cable networks had been upgraded to digital it become
possible to replace all the subscriber analogue set top boxes
with digital ones and turn off the analogue channels - which
hogged the lion's share of the bandwidth. DOCSIS now allowed
multiple channels to be bonded together, vastly incresing the
available capacity and enabling higher speeds for subscribers.

As well as the vast speed increase, it was now possible to
bond several channels together - the last time I checked my
modem it was connected to 5 channels. As the speed per channel
increased in 2013 to 10Gbs per channel I could, in theory,
have 50Gbs of data all to myself!

Why VM should want to supply FTTP in any of the existing areas
beats me - Their FTTC offering still beats BT's offering hands
down because it doesn't suffer from the local copper loop
problems that affect so many users.

Anyone who thinks FTTC is new is 20 years out of date!

--

Terry