Future of terrestrial broadcasting in the UHF band?

marno21

The Cush wrote: »

VHF isn't part of the transition plan, the major work items include 2 new UHF sites and new antennas and increased height for Kippure.

The new antennas on the Kippure mast will be 18m higher and increase coverage in line with analogue transmission. The existing antennas are to remain as emergency back-up. Kippure is the only main transmitter where work of this scale is to be carried out.

Ridiculous that Kippure went ahead in 2012 with less coverage than the UHF analogue broadcasts, would've made a lot more sense going full power from the start rather than reducing the footprint and now enlarging it again.

The Cush

marno21 wrote: »

Ridiculous that Kippure went ahead in 2012 with less coverage than the UHF analogue broadcasts, would've made a lot more sense going full power from the start rather than reducing the footprint and now enlarging it again.

It appears it wasn't possible to run at full power due to coordinated restrictions with the UK, post clearance these power restriction will remain in place but to increase coverage the antenna height is being raised by 18m.

Why wasn't this done during DSO the last time round I don't know, they had already carried out major mast work at 4 transmitter sites, Mullaghanish, Maghera, Truskmore and Mt Leinster. maybe time and cost was a factor.

Hotblack Desiato

ArKl0w wrote: »

I use a saorview/freeview UK terrestrial combination currently of the Arklow tx and preseli in Wales

It's currently impossible to receive saorview here from Clermont carn so I'd be hoping no interference from them if they choose preseli channels in 2019
They have the option not to.

The overall effect of the band clearances will definitely be to reduce out of area reception/overspill, the same or increased number of TXs have to fill a reduced number of channels so the possibility of a local signal drowning out the desired distant signal increases.

Worst case scenario is you'll have to go Freesat. We should count ourselves lucky it's pretty much physically impossible to have a satellite beam that includes Britain (never mind NI) but excludes Ireland. It's possible on Ka-band but that'd mean every Sky, Freesat and FTA sat box user in the UK changing their dish, LNB and receiver. Not going to happen any time soon!

Some funny stuff could still be possible, with highly directional aerials aligned "slightly off" their target to null a local signal, combiners and notch filters, etc. but there comes a point where it's just cheaper, easier and more reliable (weather wise) to just go satellite. Been using Sky and later Freesat for the last 13 years, in that time there's been 2 hours where weather caused problems with reception, the blackest cloud I've ever seen in my life materialised in the perfect spot to put lots of raindrops between us and Astra 28.2...

Antenna

Stasi 2.0 wrote: »

If Band 3 was ever used for TV in Ireland again would it make more sense to use 7 or 8 MHZ channel spacing ?

One advantage of 8MHz (same as UHF) VHF channels, would be that any UHF in-fill relays of a Band III transmission (or Vice-versa) would be simpler transposers (rather than needing to demodulate and re-modulate a DTT MUX).

Current Saorview approved gear is 7MHz only on VHF channels, but probably 8MHz can he enabled somehow (by a software update and/or by entering a hidden menu). Non Saorview receivers likely can select 8MHz on VHF if needs be (some cable TV systems elsewhere use DVB-T, 8MHz channels).

Sam Russell

Antenna wrote: »

One advantage of 8MHz (same as UHF) VHF channels, would be that any UHF in-fill relays of the Band III transmission would be simpler transposers (rather than needing to demodulate and re-modulate a DTT MUX).

Current Saorview approved gear is 7MHz on VHF channels only, but probably 8MHz can he enabled somehow (by a software update). Non Saorview receivers likely can select 8MHz on VHF if need be.

Would not a 7 mhz data stream on UHF be decoded correctly?

The Cush

Antenna wrote: »

Current Saorview approved gear is 7MHz only on VHF channels,

The reason being the 7 MHz raster is mandated in the ITU's Radio Rules following the GE06 agreement. It's also aligned with the DAB radio frequency plan, 4 DAB muxes = 1 VHF DTT mux e.g. VHF TV Ch.10 = DAB Mux 10A, 10B, 10C, 10D. A 8 MHz VHF mux would encroach into other neighbouring DAB frequencies already being used in other countries.

These frequencies were multilaterally coordinated during that planning conference back in 2006. Any changes could require another regional conference and cooperation of neighbouring counties to change frequency plans which is unlikely to happen in either case just for us when other European countries are already using 7 MHz muxes.

In any case we have 6 UHF muxes available under the current replan which are unlikely to be fully used and RTÉ have no plans to use the VHF band.

TAFKAlawhec

Just to point out, any idea to use VHF Band III for Saorview at the original DSO/ASO in 2012 would have required a "flash-cut" switchover as there simply wasn't enough spectrum to allow even a single DTT multiplex simulcast without affecting analogue reception in the same band. At this stage it's just a case of fantasy frequency allocations.

Antenna

TAFKAlawhec wrote: »

Just to point out, any idea to use VHF Band III for Saorview at the original DSO/ASO in 2012 would have required a "flash-cut" switchover as there simply wasn't enough spectrum to allow even a single DTT multiplex simulcast without affecting analogue reception in the same band. At this stage it's just a case of fantasy frequency allocations.

The issue of possible use of VHF Band III is being raised in the context of what happens if there is even more reduction of UHF TV spectrum in the future, might Band III have to be considered in some parts of this country to satisfactorily broadcast the current 2 MUXs ??
spectrum 'repacking'/ and closer geographic reuse of UHF channels could well mean unacceptable periods of no reception due to co-channel interference (depending on atmospherics) in outlying areas of coverage where it isn't a problem now.

Apart from the above, one wonders if some of the main UHF transmitters in the UK and Ireland switched from horizontal polarisation to vertical polarisation - might it be overall of help in combating future co-channel issues? It would be a big upheaval in the affected areas I realise.

Sam Russell

Currently, the two muxes are significantly under occupied, even if TV3 and TG4 go HD. The loss on 1 mhz of bandwidth would not make any difference if one of the muxes moved to VHF in whole or in part. Mount Leinster might cover much of Wales if it was VHF with only DAB for competition.

VHF coverage would certainly help reduce the 2% that is served by Saorsat.

However, Saorsat should be made a full copy of Saorview and should be incorporated into the pricing structure of Saorview. Alternatively, why not put all channels on Saorsat into HD? In fact, why not put all of Saorview in HD onto Saorsat?

Thurston?

Sam Russell wrote: »

... VHF coverage would certainly help reduce the 2% that is served by Saorsat.

This VHF being transmitted from where? The main tx sites which formerly had RTE in band III, & still needed fill-in sites, the switching off of which I would think was what left most people who formerly had terrestrial coverage now needing Saorsat?

Or maybe some of the relays were put up in preparation for an all-UHF network? I wonder how many of them were only built when TG4 & TV3 came along.

Thurston?

Hotblack Desiato wrote: »

The overall effect of the band clearances will definitely be to reduce out of area reception/overspill, the same or increased number of TXs have to fill a reduced number of channels so the possibility of a local signal drowning out the desired distant signal increases.

I would think other UK sites using the same channels will be the problem, not the 'locals'.

Sam Russell

Thurston? wrote: »

This VHF being transmitted from where? The main tx sites which formerly had RTE in band III, & still needed fill-in sites, the switching off of which I would think was what left most people who formerly had terrestrial coverage now needing Saorsat?

Or maybe some of the relays were put up in preparation for an all-UHF network? I wonder how many of them were only built when TG4 & TV3 came along.

I am not sure how well a digital VHF signal fares vs a VHF analogue from the same site. I assume that the DTT signal wold not suffer from international interference as they are low power dab programmes. Also, would upping the power solve some of the problems?

UHF is very good for infill, but look at how many analogue fill-ins were abandoned with DTT. Again, with only one mux in band III, greater coverage is not a lot of use if the UHF mux is not getting there.

The Cush

Antenna wrote: »

The issue of possible use of VHF Band III is being raised in the context of what happens if there is even more reduction of UHF TV spectrum in the future, might Band III have to be considered in some parts of this country to satisfactorily broadcast the current 2 MUXs ??

By the time the simulcast transmissions are switched off in March 2020 we'll have had 2 Digital Dividends with the loss of 43% of broadcast spectrum in less than a decade, the good news for broadcasters and terrestrial viewers is that the remainder of the broadcast spectrum is being locked down until at least 2030 in proposed EU legislation currently nearing enactment.

Beyond that we're possibly looking at something like a DD3 (600 MHz band, 606-694 MHz) but to compensate by then we'll have new generation transmission and compression standards beyond DVB-T2 and HEVC, even today these standards are up to 50% more efficient over what Saorview uses today. No decisions on this will be made until WRC-2023 when the whole UHF band (470-960 MHz) will be reviewed.

Of course by then we may all be watching TV over fibre, the NBP should be nearing completion by then, 2030???

Antenna wrote: »

Apart from the above, one wonders if some of the main UHF transmitters in the UK and Ireland switched from horizontal polarisation to vertical polarisation - might it be overall of help in combating future co-channel issues? It would be a big upheaval in the affected areas I realise.

Not realistic, take Winter Hill for example, a main transmitter with the largest population coverage affected by the 700 MHz band clearance, approx. 2.7m households, the estimate is about 1% of Freeview users in the coverage area will currently require aerial work, imagine a polarisation change and the resulting percentage increase.

The Cush

Sam Russell wrote: »

I am not sure how well a digital VHF signal fares vs a VHF analogue from the same site. I assume that the DTT signal wold not suffer from international interference as they are low power dab programmes. Also, would upping the power solve some of the problems?

While interference in may not be a issue, interference out could be an issue to DAB in the UK. Taking Kippure UHF as an example, power output is restricted towards the UK but to compensate they are increasing height to increase coverage.

marno21

The Cush wrote: »

By the time the simulcast transmissions are switched off in March 2020 we'll have had 2 Digital Dividends with the loss of 43% of broadcast spectrum in less than a decade, the good news for broadcasters and terrestrial viewers is that the remainder of the broadcast spectrum is being locked down until at least 2030 in proposed EU legislation currently nearing enactment.

Beyond that we're possibly looking at something like a DD3 (600 MHz band, 606-694 MHz) but to compensate by then we'll have new generation transmission and compression standards beyond DVB-T2 and HEVC, even today these standards are 33% and 50% more efficient respectively over what Saorview uses today. No decisions on this will be made until WRC-2023 when the whole UHF band (470-960 MHz) will be reviewed.

Of course by then we may all be watching TV over fibre, the NBP should be nearing completion by then, 2030???



Not realistic, take Winter Hill for example, a main transmitter with the largest population coverage affected by the 700 MHz band clearance, approx. 2.7m households, the estimate is about 1% of Freeview users in the coverage area will currently require aerial work, imagine a polarisation change and the resulting percentage increase.

Are the UK holding onto all their muxes after 700MHz clearance? 10 muxes from Winter Hill is nuts in fairness, especially after the 700MHz band is cleared

The Cush

marno21 wrote: »

Are the UK holding onto all their muxes after 700MHz clearance? 10 muxes from Winter Hill is nuts in fairness, especially after the 700MHz band is cleared

No, Muxes 7 & 8 will be switched off at migration in 2019. The local muxes will continue I believe.

marno21

The Cush wrote: »

No, Muxes 7 & 8 will be switched off at migration in 2019. The local muxes will continue I believe.

Cheers. The local muxes are less power anyway. Most of the stuff on the COM7 & COM8 muxes are a waste of bandwidth anyway. An awful lot of hassle to roll them out for a few years service.

The Cush

marno21 wrote: »

The local muxes are less power anyway. Most of the stuff on the COM7 & COM8 muxes are a waste of bandwidth anyway. An awful lot of hassle to roll them out for a few years service.

True enough but at least the spectrum wasn't lying idle.

Happy New Year, good night.

Thurston?

Antenna wrote: »

... one wonders if some of the main UHF transmitters in the UK and Ireland switched from horizontal polarisation to vertical polarisation - might it be overall of help in combating future co-channel issues? It would be a big upheaval in the affected areas I realise.

Maybe transmit both pols., like Rowridge, on a 'take it or leave it' basis? Obviously this can't be a reciprocal arrangement, but would suit at sites that are already directional, & can be used to combat incoming interference rather than limit outgoing.

Sam Russell wrote: »

I am not sure how well a digital VHF signal fares vs a VHF analogue from the same site. I assume that the DTT signal wold not suffer from international interference as they are low power dab programmes. Also, would upping the power solve some of the problems?

There's probably more scope (I've seen it mentioned elsewhere anyway) for using brute force with digital to overcome diffraction loss, as the multipath experienced in the affected area won't be the problem it would have been with analogue. How this actually works out in reality, I've no idea.

Then there's the fact that all the VHF main sites left at switchover had or will be having mast works too, whether this was done with an eye to trying to match the former VHF coverage with the new Saorview, or whether VHF & UHF analogue already matched pretty well, due to the higher power & higher aerial heights of the latter, again, I could only speculate.

TAFKAlawhec

Antenna wrote: »

The issue of possible use of VHF Band III is being raised in the context of what happens if there is even more reduction of UHF TV spectrum in the future, might Band III have to be considered in some parts of this country to satisfactorily broadcast the current 2 MUXs ??

As The Cush has pointed out, there is no need to be concerned in the short-medium term as the 470-698MHz spectrum is allocated for broadcasting in ITU region 1 until 2030, and won't be discussed again at any ITU conference until 2023 at the earliest. Nobody can say for any certainty what the terrestrial broadcasting landscape in Europe will be in a decade's time.

My experience of DVB-T on VHF Band III in Australia is that it's not the magic bullet some might make it out to be, and I found it more hassle to get alignment right on indoor reception compared to UHF on the same sites. Nevertheless in theory it should provide better over-the-horizon performance compared to UHF.

marno21

TAFKAlawhec wrote: »

As The Cush has pointed out, there is no need to be concerned in the short-medium term as the 470-698MHz spectrum is allocated for broadcasting in ITU region 1 until 2030, and won't be discussed again at any ITU conference until 2023 at the earliest. Nobody can say for any certainty what the terrestrial broadcasting landscape in Europe will be in a decade's time.

My experience of DVB-T on VHF Band III in Australia is that it's not the magic bullet some might make it out to be, and I found it more hassle to get alignment right on indoor reception compared to UHF on the same sites. Nevertheless in theory it should provide better over-the-horizon performance compared to UHF.

As things stand I'd imagine people in DTT blackspots would prefer the rollout of fibre-to-the-home broadband and get their TV that way instead of VHF transmissions from Mullaghanish again.

Stasi 2.0

The Cush wrote: »

No, Muxes 7 & 8 will be switched off at migration in 2019. The local muxes will continue I believe.

marno21 wrote: »

Most of the stuff on the COM7 & COM8 muxes are a waste of bandwidth anyway.

By that time the practice of duplicating the same channels in HD and SD will hopefully deemed no longer necessary.

They might even move all remaining SD only channels onto DVB-T2

The Cush

marno21 wrote: »

As things stand I'd imagine people in DTT blackspots would prefer the rollout of fibre-to-the-home broadband and get their TV that way instead of VHF transmissions from Mullaghanish again.

With only 1 VHF frequency allocated per transmitter, even using DVB-T2 with a max capacity of up to 35 Mbps, may not have enough capacity to combine the services carried on the 2 existing UHF muxes into DTT blackspot areas.

Sam Russell

The Cush wrote: »

With only 1 VHF frequency allocated per transmitter, even using DVB-T2 with a max capacity of up to 35 Mbps, may not have enough capacity to combine the services carried on the 2 existing UHF muxes into DTT blackspot areas.

There's the rub. Extended coverage of the VHF mux would be no use if the second mux carried popular channels, so we would be back to the analogue days with TV3 not paying for carriage other than the 17 main transmitters. Mind you 35 Mbs would carry both muxes at present.

The Cush

Sam Russell wrote: »

so we would be back to the analogue days with TV3 not paying for carriage other than the 17 main transmitters. Mind you 35 Mbs would carry both muxes at present.

TV3 were on just 12 transmitters in analogue covering approx. 85% of the population.

To avail of a 35 Mbps mux you require a DVB-T2 compatible receiver, probably fairly standard now but a 3-4 year old TV may not have one.

Sam Russell

The Cush wrote: »

TV3 were on just 12 transmitters in analogue covering approx. 85% of the population.

To avail of a 35 Mbps mux you require a DVB-T2 compatible receiver, probably fairly standard now but a 3-4 year old TV may not have one.

... and they may not have a VHF tuner. I think that Nordig requires one, so if they are Saorview approved they probably do.

My 8 year old TV has a VB-T2 tuner.

The Cush

Sam Russell wrote: »

My 8 year old TV has a VB-T2 tuner.

The standard wasn't approved until September 2009 so it may have been one of the first models to include the standard because many later TVs didn't have it including Saorview STBs.

That's correct. My Samsung C530 from 2010 doesn't have T2. It's not even Saorview approved (the D series onwards are) but it never gave me an ounce of trouble with Saorview reception. Everything works as if it were approved.

Thurston?

The Cush wrote: »

With only 1 VHF frequency allocated per transmitter, even using DVB-T2 with a max capacity of up to 35 Mbps, may not have enough capacity to combine the services carried on the 2 existing UHF muxes into DTT blackspot areas.

Right, so there must be definite areas where using band III would help? They're not all of the nature of steep-sided valleys that probably don't even have band II reception?

Can any of the seeming band III advocates here give an example of such a place that would benefit, even evidence of someone who may have had usable band III analogue reception but can't now get Saorview?

The Cush

Thurston? wrote: »

Can any of the seeming band III advocates here give an example of such a place that would benefit, even evidence of someone who may have had usable band III analogue reception but can't now get Saorview?

If I remember correctly from the time ASO happened parts of Wicklow (Kippure tx) and areas around Co. Kerry lost aerial reception when analogue was switched off. I have a recollection of a report on the News of people no longer receiving a signal.