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Requirements of the Broadcasting Industry

The current UHF spectrum base used for analogue TV is 470-862 MHz, the spectrum band that will be freed up after the digital switchover. The TV broadcasting industry would like to retain all of this spectrum to develop and enhance its services in DVB-T, Standard and High Definition TV, SDTV and HDTV.

However, digital terrestrial TV is many times more spectrally efficient than analogue TV because:

• It uses compression techniques on the number of bits needed to carry a video channel (MPEG2 and 4)
• It uses digital modulation (16 or 64 QAM)
• DVB-T : 8 MHz carrier (multiplex) can carry 4/5/6 channels now (SDTV)
• New set-top boxes will be able to carry twice as much as current boxes (using MPEG4) - (UK Ofcom view)
• It offers up to 4 High Definition channels on a single multiplex (8 MHz) (UK view)

What about the risk of interference between digital TV and mobile broadband services?
The risk of interference between digital TV and mobile phones will be lower after the digital dividend than it is today.

Currently there is a gap of 18MHz in between TV and mobile phone transmissions –– after the digital switchover, this gap will increase to 42MHz (see diagram below).

Detailed band planning and engineering solutions (sectored antennae, polarisation, down tilt) can all mitigate the risk of interference from base stations.

All you ever wanted to know about digital TV spectrum (but didn’t know who to ask)
Download the report 'Update of UHF Band Plan Options for Cellular Mobile Services Study' by Aegis Spectrum Engineering (August 2008) (PDF 147KB)

Notes:

1. Option I = 72 MHz of DD spectrum allocated to mobile
2. Option II = 112 MHz allocated to mobile
3. A mux (multiplex) = 6 normal quality TV channels or 4 high def channels
4. Sites = the number of broadcast sites at which all these are available. e.g. 100% get all 6 muxes (6 x 6 SD channels) using GE06 (no spectrum from the digital dividend)

Under Option I, 74.52% of sites carry all 36 channels. So if we drop from 6 to 5 (36 to 30) 94.3% of sites can carry 30 channels (if 72 MHz of spectrum is allocated).

KEY FACTS

• The broadcasting industry argues that TV content important for social reasons. This is certainly true. However, UHF is not the only delivery mechanism:
  • In developed markets many are moving to cable and satellite for TV content
  • The internet via broadband and iplayer is now a big potential player for TV
  • MobileTV is now an option (DVB-H)
  • Mobile broadband will eventually become a widely-used channel for TV
• All of the TV benefits promised by the broadcasting industry can be provided with around 300MHz of the digital dividend spectrum. Granting the mobile industry access to the remaining 100MHz means that consumers can also benefit from the rapid roll-out of mobile broadband and the enormous social and economic benefits which that will bring.

Download the report Broadcast migration study (pdf) on Optimising DTT Delivery in Europe to maximise the gains from the Digital Dividend, prepared by Spectrum Value Partners.