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Preparing for the Digital Dividend

Steps taken prior to 2012 towards the Digital Dividend

The ITU World Radiocommunications Conference 2007 (WRC07) made part of the UHF TV band available to mobile telephony. 

In 2008 the Commission for Communications Regulation (ComReg) began discussions with their counterpart Ofcom in the UK. They jointly prepared a revised digital television plan. That plan fitted within the reduced spectrum available for TV in the UHF band. 

ComReg are responsible for international negotiations with neighbouring countries regarding the detail of spectrum use in Ireland. They also issue Wireless Telegraphy licences. ComReg undertook a number of consultations (ComReg 10/59) regarding this work.

The Broadcasting Act of 2009 requires ComReg to make spectrum available for Digital Television multiplex transmissions. Digital Television services started in May 2010. RTE kept the Department informed on the Saorview network roll out process.

Terrestrial television broadcasting completed migration from the traditional analogue transmission to digital transmission in October 2012. TV services stopped using the frequencies 790-862MHz (800MHz band),  in November 2012.  The first Digital Dividend happened when that spectrum was allocated to mobile telephony,
ComReg manage Ireland's spectrum resource. In 2012 ComReg auctioned the digital dividend 800MHz band spectrum with the existing 900MHz and 1800MHz band cellular telephony spectrum . The first digital dividend enabled cellular telephony systems to  use 60MHz of the 800MHz band.


There will be a second digital dividend in 2020.

 The ITU World Radiocommunications Conference 2012 (WRC12) made more UHF spectrum (694-790 MHz) available to mobile telephony. This spectrum is sometimes called the 700MHz band. This is a second digital dividend.  ITU groups and CEPT groups decided to adopt the mobile telephony band plan used in Asia for Europe. This band plan allows cellular telephony to use 60MHz in the 700MHz band. Experts think that security and emergency service radio systems could also use part of the second digital dividend spectrum.

ComReg has already completed discussions with neighbouring countries.  ComReg agreed a new TV channel plan with Ofcom UK. The replanning process included 2rn (formerly RTE Networks Ltd) and Arquiva, the transmission network operator in the UK.  ComReg will auctioned the 700MHz band spectrum with some other bands for cellular telephony spectrum within the next 18 months. Some DTT viewers may need to retuned, by performing a rescan on their equipment. This equipment is either a Set Top Box for over the air TV or a DTT (DVB-T) capable TV. Viewers will know this if the programme name in the on screen display reads "viewer advisory". Thsi will be apparent when you change channel or look at the Electronic Programme Guide (EPG).

TV manufacturers might install adequate filters in TV receivers after 2020. Otherwise households may need to fit new filters.


Filters may need to be fitted in some households.  

Since 2013 "Long Term Evolution (LTE)" 4G systems have operated on the frequencies previously used by TV. Some viewers may have to have a filter installed at their TV or Set Top Box. This is in order to reduce the strength of the cellular signal. Consumers may need to install different filters after 2020 when the mobile phone systems use the 700MHz band. Such filters improve the  compatibility (see EBU article) between TV and 4G mobile telephony systems. 

At present viewers will most likely need to use filters where DTT uses channel 58 (770MHz) or 59 (778MHz). Some viewers may need to fit filters where their TV or set-top-box receives DTT operating above channel 51. This is  due to the so called image channel "N+9" sensitivity of some receivers. Thus installations using the "group C/D" type aerial may need a filter. The probelma could be worse close to LTE base stations.  A number of suppliers offer such filters. Both  indoor filters   and outdoor filters  are available. For reception of channel 59 the filter will need to provide signal reductions above 790MHz whilst having a low loss in ch 59 (778MHz).

The Broadcasting Act of 2009 requires ComReg to make spectrum available for two PSB mulitplexes and four other multiplexes. ComReg has planned that these DTT services will not use ch 60 (786MHz). ComReg addressed this matter in Annex 9 of their document Multi-band Spectrum Release - Annexes to 12/25 (Response to Consultation and Decision on Multi-band Spectrum Release [D04/12]) (ComReg 12/25a).

Following the cessation of TV services above 694MHz in 2020, viewers should consider installing filters if DTT for their area operates on channels 46, 47 or 48. Viewers who had previously used a "group C/D" type aerial will need to replace this aerial. Group C/D aerials are used to receive DTT signals transmitting above channel 52. A group C/D type aerial will not be suitable for continued reception of DTT after March 2020.

Viewers should use the Saorview coverage checker to determine which channels DTT uses in their area.

Consumers should fit filters when they have also installed a mast head amplifiers.

All Installations which use a mast head amplifier for TV reception should use a filter. This is because mast head amplifiers are prone to overloading. An "overload" condition can occur if the signal level from either DTT or other sources is very strong.. In these overload conditions unintended signals called "intermodulation products" can be radiated causing interference to other users of the spectrum.

Viewers should only use mast head amplifiers for reception of DTT where there is a clear need to do so. Excessive amplification of a DTT signal can cause set top boxes not to work properly. The set top box appears not to be able to decode the DTT service even though there is a strong signal. 


Steps taken in preparation for March 2020

In September 2019 DTT services in Northern Ireland changed their frequencies to those agreed in the new TV plan. DTT uses a much reduced amount of spectrum in this plan. It will be much harder to combine signals for UK and Irish DTT from two transmitter sites. Viewers should consider using Satellite systems to receive the Free to Air services available to viewers from many UK broadcasters. 

Viewers receiving Saorview services on channels 52 and above needed to change aerial for continued reception of Saorview. Most other viewers should not have needed to change aerial to continue DTT reception from the same transmitter site. Some viewers needed to repoint their aerial thus changing the transmitter used for Saorview reception. They might have needed a new aerial to receive signals from a different transmitter. The Saorview website after 20th August 2019 had more information.

Irish DTT transmitted on both the old and new frequencies between 4th September 2019 and 4th March 2020. After 4th March 2020 the old frequencies used since 2013 ceased. Viewers needed to have completed any required rescan by 4th March 2020.

Sites which changed channel and where the parent transmitter did not change included Castletownbere, Bantry, Fermoy, Rosscarbery, Clonakilty in County Cork, Forth Mountain (south-east of Wexford town), Gorey in County Wexford and Greystones in County Wicklow. Viewers receiving these sites had to rescan their receiver.

In particular viewers in the coastal areas at Bantry Bay and Bere Island needed to ensure that they did a rescan on their receiver.