Fibre optic broadband speeds

Fibre optic broadband comes in two forms Fibre to the Cabinet (FTTC) and Fibre to the Premises (FTTP).   FTTC, the slower & less expensive of the two, will be/ is available in Catherington  but FTTP will not be available for some, possibly many, years.

Fibre broadband can deliver significantly faster download broadband speeds than conventional broadband, and the FTTC service offers download speeds up to 76 Mbps.  Few of us will however get anywhere near this speed.

Conventional broadband is carried along copper cables all the way from the BT exchange to a local (green) street cabinet and then to your home or workplace. Inevitably, the broadband signal suffers attenuation (loss) as it travels along the copper cable from the exchange to the street cabinet (particularly if the exchange is some distance away).

From the street cabinet, the broadband signal has to travel even further to your home or workplace.

The distance between the BT exchange and your premises can be relatively long –  several kilometres for most premises in Catherington.

As the broadband signal is attenuated as it travel along the copper cable, it also becomes more susceptible to interference, so the long lines can be problematic in terms of both speed and reliability.

Fibre broadband eliminates the need for the “lossy” copper cable between the BT exchange and the street cabinet, and thus significantly increases both reliability & broadband speeds.

With FTTC, a new fibre street cabinet is installed near to the conventional street cabinet , and this new street cabinet is connected to the BT exchange with a fibre-optic cable.

The broadband equipment previously housed in the exchange (known as the Digital Subscriber Line Access Multiplexer or DSLAM), is now located in the new street cabinet. In effect, the BT exchange has moved to the street cabinet and the signal loss along the copper cable between the exchange and the conventional street cabinet has been avoided.

FTTC still makes use of the copper wires between the street cabinet and nearby residential and business premises, However, the distances involved are typically much shorter than the original copper cabling all the way back to the BT exchange. As a result, significant speed improvements are achieved.

As shown in the graph below download speeds fall to about 60 Mbps when located 500 metres from the street cabinet, to about 28 Mbps when located about 1 km from the street cabinet.  Please bear in mind that these are not “straight line” distances, but the actual route the cable takes which is likely to be significantly greater.


The actual speed you get from FTTC can only really be ascertained when it is installed, but you should insist that your ISP (Internet Service Provider) gives you an estimate when you sign up for FFTC.

Finally I would like to again acknowledge the help & support received from   George Hollingbery MP, and our Hampshire, East Hampshire & Horndean Parish councillors, without which it might have been years before we got a decent broadband service in Catherington.

Nigel J S Steward – Chairman CVRA