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ntl looks towards DSL for providing HDTV on demand services
Wednesday 16 March 2005 08:32:00 by Andrew Ferguson

ntl has published its full year results for 2004 to investors, a copy of which can be downloaded from here. The document provides some insight into what the current ntl vision is for future expansion.

It appears that ntl was quietly trialling ADSL2+ in February 2005, and this has proven their ability to deliver 18Mbps downstream, using the copper phone line ntl has to each of its existing cable customers. In March ntl has also started a trial to look at delivering on-demand HDTV (high-definition TV) channels over an IP Broadband infrastructure using ADSL2+.

Why is ntl suddenly looking at deploying DSL technologies? Well it would seem ntl are going to exploit the fact they have a dedicated copper pair of wires normally used for just the telephone line to each building that has a cable service, this is in addition to the standard coax cable that the normal cable TV and broadband service is provided over. By using a dedicated pair, it will allow ntl to stream HDTV to different households without fear of contention.

The ntl document also reveals some interesting details on the layout of their copper local loop versus the BT one. 95% of homes are within 1000 meters of the ntl fibre network, whereas with BT only 90% are within 5000 meters. In fact they show that only 5 per cent of the BT network have loop lengths of less than 1km. This is important as ADSL2+ speeds fall off very rapidly once you have a loop length of 1km or more. It is estimated that only around 50% of the BT copper loop would manage 4.5Mbps if ADSL2+ were deployed. Of course BT could improve this by starting a programme of rolling out fibre to the street cabinets and installing DSLAMs, but this will take time and money and is one of the potential changes the 21st Century Network vision will bring about.


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