The move to digital is the biggest project in UK broadcasting history - in comparison, the original introduction of television was far smaller scale, and growth was gradual.

On the horizon now is a region-by-region switch to digital terrestrial broadcasting for the UK's 22 million households. The programme will see the UK's entire terrestrial television infrastructure - which took 30 years to build - replaced and rebuilt within five years.

The transmitter network rarely receives any attention mainly because it is so reliable; it is not very often that your terrestrial picture disappears off the screen.  With the transition from analogue to digital it will have a brief period in the limelight. The current analogue system has been in operation, albeit re-engineered, since the mid-60s and the present Digital Terrestrial Television (DTT) system has now been on air for seven years.

The overall DSO project is a national programme in support of a UK Government mandate. Industry has adopted the ‘Arqiva transition plan', which has been designed to deliver minimal disruption to the nation's TV viewers, while maximising the possibility of technical success within the Government's mandated timescales.

One of our key objectives in developing our transition plan has been to minimise the impact of this work on the other users of our transmission masts. These other users include radio broadcasters, the emergency services and mobile operators. We will be consulting fully with these organisations as our plans develop.

The physical work on re-engineering elements of the network will commence during mid-2006, even though it will be 2008 before the first regions are ‘switched over' to digital.

The task before us now is to make the transition from analogue to an all-digital world.  Ideally the new digital system would be rolled out and, after a suitable period of time, the analogue closed down.  Unfortunately there is not enough spectrum for them to co-exist so something has to give.  The strategy that has been developed is a phased withdrawal of analogue coupled with phased rollout of the new high-power DTT system over a period of four years.

The scale of this project is enormous.  Some 5000 analogue transmitters on 1154 sites have to be removed and disposed of, similarly the existing DTT system comprising 500 transmitters will be removed and replaced by 4000 transmitters to give near national coverage for the Public Service Broadcasting (PSB) multiplexes and somewhat less for the additional 'commercial' services. 

To add to the complication there will be major work to strengthen many of the tall masts (up to 385 metres tall) and at least two will need total replacement.  At the top of the masts the transmitting antennas at the major sites will need replacement or major upgrade.

The capital cost to deliver the whole programme will be near £500m and will require some 600 person years of effort.