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Digital Terrestrial TV Spectrum

Digital Terrestrial TV (DTT) Spectrum

TV planning for Ireland  must also take into account Northern Ireland, England, Scotland and Wales.

Twenty years ago frequency planners in the UK and Ireland planned TV services broadly based on 10 UHF channel groups, each with 4 channels. There were 49 frequency channels in the UHF band, known as channels 21-69. No transmitters operated on channel 38 because scientists made Radio Astronomy observations at Jodrell Bank on channel 38. Furthermore for Airport radar in the UK operated on channel 36 and many radio microphones operated on channel 69 .


Planners within the UK and Ireland initially based Digital TV planning  on the same groups in order to fit around the analogue service. In the UK, planners planned 6 DTT transmissions from each mast. Planners made every effort to allow viewers to use the same household aerial, this was not always possible.

Frequency planners agreed the GE06 Plan for European digital TV in 2006. The ITU process allowed for an equal number of DTT multiplexes in Ireland and the UK. The UK and IRL agreed to plan 8 multiplexes each. This meant that frequencies would be reused more often than in the 4 channel analogue era.  However after ITU WRC 2007 the revised Radio Regulations permitted mobile telephony operators to use channels 61-69, known as the 800MHz band. Governments called this a Digital Dividend. Frequency planners replanned TV service for the 800MHz digital dividiend. Countries determined at ITU WRC2012 that from 2016 mobile telephony operators could use channels 49-60, known as the 700MHz band. and Frequency planners have replanned the TV services again.

Irish legislation allows for 6 TV multiplexes. Saorview operate two Public Service Broadcasting (PSB) multiplexes. The legislation permits the Broadcasting Authority of Ireland (BAI) to assigned four multiplexes. The first Saorview PSB multiplex launched in Ireland in May 2010. The Government decided to cease Analogue TV services in October 2012.  The EC Radio Spectrum Policy Programme required that from 2012 digital TV services no longer use channels 61-69.  A second Saorview PSB multiplex was launched at that time.

Replanning to clear TV from the channels 49-60 is currently underway in conjunction with the UK. The Department expects that TV services will clear the channels 49-60 by about 2021, creating a second digital dividend.  Associated with that will be much tighter reuse of frequency channels. The Department does not guarantee reception of TV services outside their core service area. The Department expects that some households currently receiving UK TV signals from Northern Ireland or Wales will no longer be able to do so. This is because of transmissions from Irish TV transmitters in neighbouring areas.
   
Experts believe that Cognitive Radio Systems will also have access to the unused "white space" frequencies in an area.

Cognitive technologies is the terminology used to describe equipment which can determine itself which frequency to use. Experts believe that Cognitive radio technologies will enable more efficient use of spectrum and provide more dynamic access to spectrum. Cognitive radios have the ability to use spectrum which is already used by other spectrum users. Cogntive radio systems will not operate all of the time or everywhere, thus sharing of spectrum is possible.  Cognitive Radio systems could use the "white spaces" not used for TV transmission in the 470-790 MHz frequency band in an area. Experts consider that these technologies will be able to make use of unused spectrum, ensuring the maximum use of spectrum in all areas.

Research by the CTVR is taking place in Ireland on Cognitive Radio Systems and technologies.