Northern Irish DSO - a calm look before the storm comes!

lawhec's picture

While in the Republic there is some progress, albeit a bit muddy, on the horizon regarding Saorview and (hopefully) Saorsat, in the North the digital terrestrial future has a much more steady path. While exact dates have yet to be confirmed the second half of 2012 should see, bar any hiccups (which could be the case in either N.I., the Republic or even in Britain, as the London switch off is roughly scheduled to be around the time of the 2012 Olympics which could cause some headaches) the switch over take place when analogue & low-power digital signals will be shut down and replaced with higher power digital signals.

Northern Ireland will be the last UK region to have its analogue signals switched off. When the schedule was announced at first both the Ulster and Channel ITV regions were put to the end of the line. Channel's date was simply "TBA" but has now been brought forward to this November when a "flash-cut" will take place across the Channel Islands, designed to complete the switch over in one night. Interestingly, these two places were perhaps kept to last because both areas are significantly covered by non-UK terrestrial broadcasts, both required good co-operation with relevant authorities (Comreg in Ireland & the CSA in France). The dragging out of getting DTT services up and running in the Republic while such broadcasts have been taking place north of the border for over a decade now has been the cause of wild rumours to spread about. It's no joy trying to correct them, nor trying to explain to people who aren't fussed or interested in technical differences like MPEG2 vs. MPEG4 etc.

With regards to the transmitters and relays in Northern Ireland, the plans are pretty much set in stone even without firm dates at present.

  • There are three main transmitter sites which combined have 41 dependent relays.
  • Each main transmitter will have a two-stage switch over, as has been the case so far in most switch overs in Britain that have now been completed.
  • All main transmitters and relays will get a three multiplex service including the five main NI terrestrial broadcasters (which will bring Channel Five for the first time to some homes), all BBC digital terrestrial services and at least three HD channels (BBC HD, UTV HD, Channel 4 HD and possibly BBC1 NI HD as well).
  • Viewers receiving directly from the three main transmitters may also get a further three multiplexes provided by commercial broadcasters depending on the condition of their aerial installation, location and possible sources of interference (PSB broadcasters get the better frequencies).
  • Limavady (& its relays) is destined to shut over first, then Brougher Mountain and finally Divis.
  • Work at the three main transmitter sites have been completed or is currently being worked on to prepare for the switch over. A new mast is going up at Divis, the second tower at Brougher Mountain has been completed and work is going on at Limavady too.

All sounds good, but there may be teething problems ahead, which will be looked at in more detail in future blog posts...

  • From the provisional list of frequencies planned for the new digital services, viewers of all transmitters and relays should not require an aerial change for PSB broadcasts except for the small Plumbridge relay. Plumbridge serves the village of the same name lying in the Glenelly Valley in the Sperrin mountains. Even current aerial installations may be good enough for the two non-HD multiplexes after switch over, but HD multiplex reception may require a new aerial installation. Current analogue services from Plumbridge require a Group C/D aerial, but the new digital services require a Group B aerial.
  • There's the possibility of some people who right now receive all current low-power DTT services will lose some of them after the switch over takes place. Potential cases in Derry city, as well as counties Tyrone and Fermanagh have been identified. This is because of co-channel interference issues.
  • Confusion about how RTÉ services will be impacted to viewers in the north. Until Saorview can get fully up and running, specific issues cannot be fully addressed. There is also the issue of RTÉ viewers in Tyrone and Fermanagh who may still depend on the VHF service from Truskmore but don't have a UHF aerial for TV3 & TG4 yet.
  • The impact on terrestrial viewers of N.I. services in the Republic. The impact of possible co-channel interference from DTT services there may cause a loss of some services from the north.