3.1 Background

Government policies to facilitate the DSO process were decided in 2006-2008, with digital terrestrial television commencing in 2008. A joint industry-government steering group has been established to coordinate and manage the DSO process.

The DSO process envisages all television services using the more efficient digital technology, and existing analogue licences being cancelled or returned to the Crown in due course. Digital television coding is more efficient, as it allows only the pixels that alter from frame to frame to be broadcast, reducing the capacity that is required for actual broadcast. A radio frequency channel can transmit around 24 Mbps which can accommodate a number of television programmes, typically 8-10 using standard definition (SD). Radio frequency planning is also more efficient since the co-channel and adjacent channel protection ratios¹ are lower (effectively allowing closer geographic or frequency separation between licences), allowing for the possibility of adjacent channel use, with less infill coverage² being needed. Implementation of a fully digital frequency plan therefore effectively releases spectrum for allocation to new services. The overall process will result in both VHF and UHF spectrum being available for allocation to new services.

Footnotes

¹ The protection ratio is a ratio between the wanted and unwanted signals. A lower protection ratio effectively allows a greater unwanted signal without any degradation to the wanted signal.

² Infill coverage in an urban analogue service is often required because of signal reflections (ghosting), rather than low signal strength. Digital transmissions have an inbuilt capability to discriminate against ghosting, which effectively means that a number of current analogue infill licences need not be replicated with digital licences.