Cable TV
Cable TV typically (though not exclusively) means "Virgin Media", which offers a subscription service similar to Sky. This is of interest to viewers who cannot install a satellite dish, either because of an unsuitable location or because of local planning restrictions.
The Virgin Media service isn't available everywhere - the distribution network uses optical fibre, which is available only where it's installed. Combined packages with broadband and telephone are available, with different options according to requirements. See the Virgin Media website for details.
Although the network uses fibre optic cable, the connection from the street into the home is via a coax cable, which connects directly into the back of the cable TV box. UHF aerial in and out sockets are also provided (similar to a Sky box) which adds the cable TV channel being watched as a UHF signal for distribution to other TVs.
Virgin Media boxes are available with different functionality - standard definition, high definition and PVR capability are all available, but require different subscription options.
BT Vision is a rather different approach to the concept of cable TV, and is sometimes referred to as internet TV (or IPTV, since it uses the internet to access some of its content.). The V-box incorporates Freeview, together with a 2Mb internet connection to download TV programmes and films via a broadband telephone connection. This gives the box a high definition capability (from an internal upscaler and HDMI interface) which isn't currently available on Freeview.
The BT Vision equipment has a good specification - it provides a twin tuner Freeview capability with a 160Gb hard drive recorder, as well as the ability to download programme content via the internet.
However, to access this functionality some other conditions have to be met:
A "BT Vision Connection Pack" has to be bought (e.g. £30 from Argos).
The connection pack provides a phone number to request the delivery of the BT Vision box, and a unique code used to activate the BT Vision service.
The BT Vision box is designed to be connected to a BT Home Hub modem, which is included (free) in BT's Option 2 & 3 broadband service. The Home Hub is only available by signing up to a BT Broadband contract. Connection to a different modem may be possible however - see the digital spy forum for more information.
The BT Vision box requires a high speed modem connection (2Mb/s), and won't boot up unless that connection is available.
The electronic programme guide for recording is obtained via the internet connection, and not from the Freeview transmission, hence the PVR functionality is dependent on the internet also.
The BT Vision box is only supplied "free" when signing up for a minimum one year broadband contract (or 1½ years with an Option 1 contract). The BT Vision box has to be connected to the internet within 28 days of delivery and has to remain connected for the minimum contract term. If these conditions aren't met, the BT Vision box costs £199.
Proivded you have a BT phone line, a BT home hub, a BT broadband service with a minimum speed of 2Mb/s and an activation code then the BT Vision box should work very well.
There is no charge for any of the Freeview programmes, but the web-based programmes are either charged on a per-programme basis, or by a monthly subscription package. The BT Vision website contains more details.
The internet connection for the BT Vision box can either be connected directly to a Home Hub, or connected via the house mains wiring circuit using the Powerline Adapters (useful when the TV is located in a different room than the Home Hub). Interference issues have been evident with some radio equipment when using Powerline Adapters however.
Out of the box, the setup procedure for a BT Vision box is extraordinarily slow - scanning for software updates and installation takes an age, and then the channel scan (looking for Freeview signals) is also very slow.