Ofcom makes proposals for HD on Freeview

Ofcom has put forward proposals for a reorganisation of DTT that could allow broadcasters to launch high definition (HD) services as soon as 2009.

The news comes within days of the BBC Trust approving plans for the BBC HD channel and the terrestrial broadcasters forming an alliance to champion the launch of HD channels on Freeview.

The plan would involve reallocating the channels presently available on Multiplex B, licensed to the BBC, to other multiplexes and using new transmission technologies to broadcast up to four HD services - BBC HD, ITV HD, Channel 4 HD and a proposed HD version of Five - on Multiplex B.

The advances include mode change, which Ofcom claims could increase capacity by 20%; adoption of the new European transmission, DVB-T2, which could increase capacity by "at least 30%"; and a switch from MPEG2 compression to MPEG4 compression on Multiplex B.

Taken together, Ofcom asserts that application of the advances in technology could, "in time, more than double the capacity of DTT to enable extra television channels, including those in high definition". The proposals assume that any extra bandwidth provided by analogue shutdown would not be allocated for TV broadcast use.

Viewers wanting to watch the new services from multiplex B would have to purchase a new set-top box or integrated TV compatible with the MPEG4 standard, although all existing set-top boxes would continue to function for channels broadcast using MPEG2.

Ofcom says the proposals - eventually to be decided upon by the culture secretary - will be judged on "efficiency of spectrum use" and "contribution to public service broadcasting", as well as "contribution to the range and diversity of television services available on DTT".