DTT Spectrum Planning - Department of Communications

The Cush

Came across this recently on the Dept of Communications website

DTT Spectrum Planning

Analogue TV planning within the UK and Ireland had been broadly based on 10 UHF channel groups, each with 4 channels. There are about 48 frequency channels available in the UHF band (channels 21-68, but excluding channel 36 received by Radio Astronomy at Jodrell Bank).

DTT planning for IRL cannot be done in isolation, it must also take into account NI, England, Scotland and Wales. During planning for DTT it became apparent that a particularly difficult area would be across the Irish sea between Wales and Ireland.

DTT planning had to fit around the analogue use, whilst endeavouring to retain the same receive aerial group. This was not always possible.

From the very early stages of planning for DTT in the late 1990’s it became clear that the best solution would be if MT Leinster and Preseli shared some channels. That enabled the best fit internally within Ireland, even though it posed challenges for Co. Wexford. The lack of service within the Irish Sea would not be relevant, and the reception of On Digital subscription services within Wexford was also not considered relevant. With a properly aligned aerial reception of DTT from Mt Leinster was considered possible even if frequencies were shared with the commercial multiplexes from Preseli.

An example of how engineering techniques have been used to allow very tight channel re-use can be seen where channel 53 is used for DTT at Clermont Carn near Dundalk and that channel used for an analogue relay in Leitrim Co Down and at Stranraer. During the period prior to 2013 the DTT signal from Clermont Carn cannot be received within Northern Ireland.

Whilst planning had been undertaken within the context of the 6 DTT multiplexes operated in the UK (meaning 10 frequencies use by the UK for analogue and digital TV services), the ITU RRC06 process allowed for equitable access DTT multiplexes within the UHF band. The UK and IRL agreed that 8 multiplexes each be planned, which mean that frequencies would be reuse more often that in the 4 channel per country analogue era. A further ITU restriction was that sites with less than 250 W ERP could not be entered into the RRC06 planning process. This was in order not to make the process to complex and thus only 43 Irish sites (some new) were included.. The GE06 outcome of the RRC06 was a reasonable match of DTT channels to existing analogue channels.

Since the GE06, the digital dividend has been mandated by the EC and thus the channels 61 - 68 are not available for DTT from 2013. This has required a replanning of the GE06 outcome. The UK intend to operate at least 6 DTT multiplexes, Irish legislation allows for 6 multiplexes (two PSB and four assigned by the BAI). Thus the DTT services move further from the analogue TV groups. As 2020 approaches there will be pressure for a second digital dividend before 2025. It may even be that the TV services will loose spectrum above 694MHz by 2020. This would mean that channels 49-40 would cease to be available for DTT. Associated with that will be even tighter reuse for frequency channels. Thus reception of TV services outside their core service area cannot be guaranteed.

It is also likely that Cognitive Radio Systems will have access to the unused "white space" frequencies in an area.

http://www.dcenr.gov.ie/Communications/Business+and+Technology/Radio+Communications+and+Radio+Spectrum/DTT+Spectrum+Planning.htm

watty

Such stupidity and arrogance.

Also "cognitive Radio" aka "white space" Radio is a delusion.

Mike 1972

watty wrote: »

Also "cognitive Radio" aka "white space" Radio is a delusion.

And the DoC of all people should know better

marclt

Interestingly the analogue MT. Leinster frequencies are retained for DTT use... so a sensible outcome may be to move frequencies post analogue switchover as has been the case in the UK.

A simple solution.

lucernarian

Read that last week. They claim that only sites greater than 250W ERP were brought to the table at RRC-06 but that doesn't explain why the planned relay in Drogheda was included with its ERP of 21dBW. (130W I think).

I also thought that Northern Ireland's RRC-06 allocations included relays near the border. Bigger ones like Camlough were there but so was the likes of Belcoo, which is definitely not going to have an ERP over 250W.

There's still nothing stopping this country from having the PSB muxes in the same group as the existing analogue channels for every Saorview site around the country. Ch 30 and 34 remain available I think. Let the commercial services look for multiplexes in other aerial groups.


I also cannot believe they're giving themselves a clap on the back for putting up a bunch of DTT panel antennas on Clermont Carn pointing in one quadrant only when Freeview and its predecessors had done all sorts of impressive and nifty tricks especially in the southeast of England I think to ensure as much of the service area could be covered without affecting analogue.

Mike 1972

From the very early stages of planning for DTT in the late 1990’s it became clear that the best solution would be if MT Leinster and Preseli shared some channels. That enabled the best fit internally within Ireland, even though it posed challenges for Co. Wexford. The lack of service within the Irish Sea would not be relevant, and the reception of On Digital subscription services within Wexford was also not considered relevant. With a properly aligned aerial reception of DTT from Mt Leinster was considered possible even if frequencies were shared with the commercial multiplexes from Preseli.

Someone in COMREG seems to be having a case of the emperors new clothes ?

The Cush

To_be_confirmed wrote: »

They claim that only sites greater than 250W ERP were brought to the table at RRC-06 but that doesn't explain why the planned relay in Drogheda was included with its ERP of 21dBW. (130W I think).

Drogheda and a number of others are listed at 24 dBW which is just over 251 Watts.

To_be_confirmed wrote: »

I also thought that Northern Ireland's RRC-06 allocations included relays near the border. Bigger ones like Camlough were there but so was the likes of Belcoo, which is definitely not going to have an ERP over 250W.

Just had a look at the UK allocations and Belcoo is listed at 24 dBW (251W). The planned ERP is 70W. I guess the idea was at the time plan for it now - may not use it later.

To_be_confirmed wrote: »

There's still nothing stopping this country from having the PSB muxes in the same group as the existing analogue channels for every Saorview site around the country. Ch 30 and 34 remain available I think. Let the commercial services look for multiplexes in other aerial groups.

The spectrum planners here appear to be following the lead of the UK in relation to Chs 31-37 and keeping them clear for now. Planning for Digital Dividend 2 is at a very early stage and these frequencies may be required if a second digital dividend sub-band is introduced. Comreg plans to consult on this next summer.

lucernarian

That's still peculiar. An Irish border relay (Carlingford) has an ERP of 60W, only slightly less than Belcoo and it did not feature in the negotiations. Even Lisbellaw was included in the UK RRC-06 outcome. I don't see where Drogheda was listed at 24dBw.

Channel 30 is still cleared for TV use in the UK after the switchover in the UK. Using 30 and the lowest next available channel (39) wouldn't be so bad for the installed Group A aerials.

Also, the digital dividend in the UK was only changed to leave out Ch 39 and 40 after Mt. Leinster started broadcasting on the 39-42-45-49 group of channels. So the Irish authorities were not entirely concerned at paralleling the spectrum policy of OfCom. They may be doing so now I suppose.

By the time it became clear that only two PSB multiplexes would be used, efforts should have been made to have reduced coverage with Chs. 30 and 39 for the moment and then a switchover at DSO for the Ch. 39 mux to one of the other Group A allocations. Frequency changes to multiplexes are part and parcel of DSO in the UK so far. I haven't found any problems with that plan compared to using Group B aerials for Saorview.

lawhec

To_be_confirmed wrote: »

That's still peculiar. An Irish border relay (Carlingford) has an ERP of 60W, only slightly less than Belcoo and it did not feature in the negotiations. Even Lisbellaw was included in the UK RRC-06 outcome. I don't see where Drogheda was listed at 24dBw.

I get the feeling that some of the NI border relays which are only very low powered for analogue were sought for much higher powers for DTT as a way of protecting allocations from the outset, otherwise international clearance would need to be sought.

watty

Warning Rant

No-one is interested in bidding for 31 to 37. That's Ofcom fantasy.

There is no equipment.

Snipping off a few more channels at 59 to 61 makes more sense as "bigger" bands are FAR more use than separate ones.

That's why it's crass stupidity that they don't combine 872 -960 as Downlink and 750MHz to 862MHz as uplink if they serious about Internet/Broadband. Also mandate a single wholesale operator.

But Ofcom isn't interested in the "best" solutions, only maximum revenue.

You'd think the Managers in Ofcom and Comreg are only Bean Counters and none know about Spectrum Management. They don't seem to listen to their own excellent engineers.

The Cush

To_be_confirmed wrote: »

I don't see where Drogheda was listed at 24dBw.

The ITU RRC planning display software - http://www.itu.int/ITU-R/index.asp?category=conferences&rlink=rrc-04-planning-software-display&lang=en

To_be_confirmed wrote: »

Also, the digital dividend in the UK was only changed to leave out Ch 39 and 40 after Mt. Leinster started broadcasting on the 39-42-45-49 group of channels. So the Irish authorities were not entirely concerned at paralleling the spectrum policy of OfCom. They may be doing so now I suppose.

In Nov 2005 Ofcom announced their plans for the broadcasting spectrum digital dividend. An upper and lower sub-band was chosen, Ch 31-40 and Ch 63-68.

In 2009 Ofcom decided to align the upper Digital Dividend sub-band with the ITU and EU plan i.e. Ch 61-69 (790-862). As DTT was now cleared from Chs 61-62 the lower release band Chs 39-40 was returned to DTT use and PMSE to Ch 38 to compensate for the loss of spectrum in the upper sub-band. There was no mention of Mt Leinster.

The Cush

watty wrote: »

No-one is interested in bidding for 31 to 37. That's Ofcom fantasy.

There is no equipment.

I agree. The focus for the next 10 years be on the Digital Dividend 2 and the sub-band 49-60. How much will be released?

A new EU Directive will be in place by the end of the year which will put the discussion on an official footing, a review/consultation is planned by Comreg next summer.

Chs 31-37 could be used to clear any further release of DTT spectrum.

Kensington

watty wrote: »

Warning Rant

No-one is interested in bidding for 31 to 37. That's Ofcom fantasy.

There is no equipment.

Snipping off a few more channels at 59 to 61 makes more sense as "bigger" bands are FAR more use than separate ones.

That's why it's crass stupidity that they don't combine 872 -960 as Downlink and 750MHz to 862MHz as uplink if they serious about Internet/Broadband. Also mandate a single wholesale operator.

But Ofcom isn't interested in the "best" solutions, only maximum revenue.

You'd think the Managers in Ofcom and Comreg are only Bean Counters and none know about Spectrum Management. They don't seem to listen to their own excellent engineers.

Come on watty, when do the engineers opinions ever get listened to over the bean counters?

Mike 1972

watty wrote: »

Warning RantNo-one is interested in bidding for 31 to 37. That's Ofcom fantasy..

If they were going to snip channels from Band 4 surely it would have made more sense to pick 21 to 27

NewHillel

watty wrote: »

Warning Rant

You'd think the Managers in Ofcom and Comreg are only Bean Counters and none know about Spectrum Management. They don't seem to listen to their own excellent engineers.

I agree that there are some excellent engineers, and technicians, in Comreg. I also know some excellent managers, all with professional qualifications.

lucernarian

The Cush wrote: »

In Nov 2005 Ofcom announced their plans for the broadcasting spectrum digital dividend. An upper and lower sub-band was chosen, Ch 31-40 and Ch 63-68.

In 2009 Ofcom decided to align the upper Digital Dividend sub-band with the ITU and EU plan i.e. Ch 61-69 (790-862). As DTT was now cleared from Chs 61-62 the lower release band Chs 39-40 was returned to DTT use and PMSE to Ch 38 to compensate for the loss of spectrum in the upper sub-band. There was no mention of Mt Leinster.

My point there was that "The spectrum planners here appear to be following the lead of the UK in relation to Chs 31-37 and keeping them clear for now" doesn't completely stack up. When the UK originally had a view to selling off Ch 31-40, the Irish authorities did not follow their lead entirely at the time. Of course, they may have planned a move from Ch.39 were those 10 channels to be auctioned off in the UK for DSO but I would be suprised if this were true. Mt. Leinster was merely an example of a site which used Ch.39 and needed clearance with the UK.

The Cush

To_be_confirmed wrote: »

When the UK originally had a view to selling off Ch 31-40, the Irish authorities did not follow their lead entirely at the time. Of course, they may have planned a move from Ch.39 were those 10 channels to be auctioned off in the UK for DSO but I would be suprised if this were true. Mt. Leinster was merely an example of a site which used Ch.39 and needed clearance with the UK.

Ch 39 was coordinated with the UK long before the Digital Dividend plan and RRC06 and confirmed again at RRC06. If Mt Leinster 39 is transmitting within the coordinated parameters then any interference with services other than DTT on Ch 39 would've been for Ofcom to resolve before any auction. In any case as it stands now it will be used for DTT both sides of the Irish sea.

The Cush

The Cush wrote: »

Chs 31-37 could be used to clear any further release of DTT spectrum.

According to a report over in http://www.ukfree.tv/fullstory.php?storyid=1107051875 Ofcom has decided to allocate cleared Chs 31-37 to DTT with auction expected in Q2 2012.

The source of the information is a planning submission by Arqiva regarding the Tacolneston transmitter.

"The decision has now been taken to reallocate spectrum at 600 MHz for additional terrestrial television broadcast services and OFCOM is tasked with the preparatory work leading up to the auction of this spectrum."