Digital Switchover - UTV Region (DigitalUK)

mrdtv2010

lawhec wrote: »

I remember a decade ago when living around Jordanstown, I didn't have DTT reception at the time, the area is primarily covered by the Carnmoney Hill relay. Reception from Divis on analogue 1-4 was strong, but suffered from horrendous multipath that made the pictures unwatchable. On the other hand, Channel 5 reception from Black Mountain had next to no ghosting on its picture and signal strength was good - it did suffer from co-channel interference on high pressure days though.

That was Cambret Hill pre-DSO. Ruined Black Mountain C5 in East Down, but now removed, and excellent Cambret Hill DTT in North Belfast, East Antrim and East Down. I suspect post DSO Divis DTT will put down a super signal in the Carnmoney Area rendering the use of that relay entirely moot. In the 405 days people depended on Caldbeck and Sandale for clean pictures there.

Peter Rhea

lawhec wrote: »

I remember a decade ago when living around Jordanstown, I didn't have DTT reception at the time, the area is primarily covered by the Carnmoney Hill relay. Reception from Divis on analogue 1-4 was strong, but suffered from horrendous multipath that made the pictures unwatchable. On the other hand, Channel 5 reception from Black Mountain had next to no ghosting on its picture and signal strength was good - it did suffer from co-channel interference on high pressure days though.

So the analogue transmissions probably would be missed by quite a few people & even a temporary HD mux from BM wouldn't compensate as it doesn't look as if C5 will be on it for the foreseeable future.

Digifriendly

mrdtv2010 wrote: »

That was Cambret Hill pre-DSO. Ruined Black Mountain C5 in East Down, but now removed, and excellent Cambret Hill DTT in North Belfast, East Antrim and East Down. I suspect post DSO Divis DTT will put down a super signal in the Carnmoney Area rendering the use of that relay entirely moot. In the 405 days people depended on Caldbeck and Sandale for clean pictures there.

Out of interest any examples in East Antrim? I thought Darvel was more likely in that neck of the woods?

mrdtv2010

Jordanstown, Carrick and Larne.

Mr. Rabbit

I suspect post DSO Divis DTT will put down a super signal in the Carnmoney Area rendering the use of that relay entirely moot.

Not in all areas of Carnmoney and certainly not in most parts of Glengormley, and areas along the Dough Road (in the shadow of Carnmoney Hill) along with many parts of Rathcoole etc., even after DSO.

Add to the fact that many TV aerials around this part of Jordanstown point to Carnmoney Hill (even though reception from Divis is fine), means that Carnmoney Hill is essential for many residents in the Newtownabbey area,post DSO.

Mr. Rabbit

mrdtv2010 wrote: »

Jordanstown, Carrick and Larne.

Only in Larne would reception of Darvel be possible.

Jordanstown is non existent, except under extremely good lift conditions. I would imagine Carrick would be similar.

Digifriendly

Mr. Rabbit wrote: »

Only in Larne would reception of Darvel be possible.

Jordanstown is non existent, except under extremely good lift conditions. I would imagine Carrick would be similar.

There are aerials for Scotland in Carrick - are these for Cambret Hill rather than Darvel?

Mr. Rabbit

Digifriendly wrote: »

There are aerials for Scotland in Carrick - are these for Cambret Hill rather than Darvel?

I would imagine so.

There are also a number of vertically polarised aerials pointing east in this area of Jordanstown as well, which I would assume are either for Portpatrick or Stranraer.

mrdtv2010

I didn't mention Darvel for East Antrim: that was from another poster. Darvel is receivable along the North Antrim coast up to Ballycastle. The best Scottish signal is from Cambret Hill because of the ERP and HAAT of that station. There are indeed signals from Portpatrick and, possibly, Stranraer but are much weaker.

mrdtv2010

Mr. Rabbit wrote: »

Not in all areas of Carnmoney and certainly not in most parts of Glengormley, and areas along the Dough Road (in the shadow of Carnmoney Hill) along with many parts of Rathcoole etc., even after DSO.

Add to the fact that many TV aerials around this part of Jordanstown point to Carnmoney Hill (even though reception from Divis is fine), means that Carnmoney Hill is essential for many residents in the Newtownabbey area,post DSO.

These areas were heavily affected by analogue multipath from Divis. The only issue for a digital signal to work is:

a) C/N about 20dB for T1 and T2

b) Sufficient signal strength ~ 30dBuV

c) COFDM is not affected by multipath.

Divis ERP is increasing almost fiftyfold on 24.10.2012 . I rather think people will be surprised by how well Divis works after then: this has been the experience in English DSO areas where previously analogue reception was ruined by multipath.

Richard

mrdtv2010 wrote: »

These areas were heavily affected by analogue multipath from Divis. The only issue for a digital signal to work is:

a) C/N about 20dB for T1 and T2

b) Sufficient signal strength ~ 30dBuV

c) COFDM is not affected by multipath.

Divis ERP is increasing almost fiftyfold on 24.10.2012 . I rather think people will be surprised by how well Divis works after then: this has been the experience in English DSO areas where previously analogue reception was ruined by multipath.

Does this mean Divis will carry further into Scotland (and maybe England) than it does now?

Peter Rhea

Divis is co-channel with Caldbeck on all but one mux (UHF 21), also cc with Darvel on the com. muxes.

Anyway, the transmissions are tailored to cover the same area as before (without ruining others' coverage), not "carry further".

Peter Rhea

mrdtv2010 wrote: »

c) COFDM is not affected by multipath.

It is if the delay is long enough (relative to GI) or if you get the "0dB echo" (more risk in a SFN) where carriers can be completely cancelled by similar signals arriving 180 degrees out of phase.

reslfj

Peter Rhea wrote: »

It is if the delay is long enough (relative to GI) or if you get the "0dB echo" (more risk in a SFN) where carriers can be completely cancelled by similar signals arriving 180 degrees out of phase.

No. The phase relation between two signals has nothing to do with the GI - but the phase relation is the root course for the 0dB echo problem(fading).

Assume channel 37 around 602 MHz
One DVB-T COFDM symbol last 896 usec + GI (28usec) = 924 usec. 602 MHz x 924usec = 556248 carrier cycles in a symbol time.

The phase relation happens on only a 1/556248 scale of the COFDM symbol time. 180 degree out of phase is only half that time.

While two signals, with the same strength arriving out of phase, will create a deep fade, it will only affect a small number of all the COFDM carriers. Two equal signals will add for about 2/3 of the carries while 1/3 will fade. Only very few carriers will see a 'deep fade'.

The DVB-T2 uses - with much success - 'Rotated constellations' to fight the 0dB echo problem and improve the performance in Rayleigh channels (typical indirect signals)

0dB echo is a much larger problem when non directional aerials are used e.g. typical with DAB receivers. This is one of the reasons DAB needs to operate with 4-QAM and an effective coderate of just 1/2.

Now Divis and Caldbeck (or Darvel) is not operating in any form of SFN. The CCI is not dependent upon the actual muxes transmitted - but only on the ERP and the geography.


Lars

watty

Scrap DAB and use the 1.7MHz DVB-T2-lite with AAC codec. Ideally on 68Mhz to 87MHz rather than the 200MHz approx as the coverage would be better.

Or just extend FM to use 65.8 to 74.0 MHz and 74MHz to 87.5MHz too (Japan is 76MHz to 90MHz) and forget about Digital Radio. It's a solution for a problem that doesn't exist and DAB isn't a very good solution. With the FM band extension idea a cheap adaptor (€6) converts any existing car radio and any home radio with an aerial socket. Actually just make the extension exactly 20.5MHz and then all existing FM radio sets have exactly double the stations. The adaptor simply has Normal/Extra switch. The normal position is actually "off" + bypass.

Peter Rhea

reslfj wrote: »

No. The phase relation between two signals has nothing to do with the GI - but the phase relation is the root course for the 0dB echo problem(fading).

There was no need for me to bring the 0dB thing into it I suppose, I'm a bit out of my depth with that stuff tbh.

Is there any point in trying to equate ghosting on analogue with possible multipath problems on DVB-T or T2?

Would the presence of a strong ghost image offset by at least 50% display width be any kind of indicator or would this still be within the working limits of the (UK/ROI) digital signal (or of no relevence whatsoever, I know there are no simple answers)?

Mr. Rabbit

lawhec wrote: »

I remember a decade ago when living around Jordanstown, I didn't have DTT reception at the time, the area is primarily covered by the Carnmoney Hill relay. Reception from Divis on analogue 1-4 was strong, but suffered from horrendous multipath that made the pictures unwatchable. On the other hand, Channel 5 reception from Black Mountain had next to no ghosting on its picture and signal strength was good - it did suffer from co-channel interference on high pressure days though.

Around this area of Jordanstown, analogue reception from Divis is OK with only slight ghosting.

A lot of terrestrial aerials (at least a third) still point towards divis rather than Carnmoney Hill, even though the Carnmoney Hill transmitter is visble. After DSO, I would imagine freeview reception from Divis will be fine I this area. Not sure about the RTE mini mux from black Mountain.

formerly scottish paddy

Does anyone know if RTE on Freeview in Northern Ireland will be restricted in the same way as it is on SKY for certain sports etc?

Digifriendly

formerly scottish paddy wrote: »

Does anyone know if RTE on Freeview in Northern Ireland will be restricted in the same way as it is on SKY for certain sports etc?

Nobody knows for sure but at a guess I would say it probably will due to rights issues. However remember that the ROI DTT 'Saorview' signals will be increased northward after DSO so some will pick these up who can't at present and there can be naturally no blacking out with these. Also remember that sport on TG4 e.g.European Cup rugby is not blacked out due to Irish language rights for the whole of the island so AFAIK at present restrictions refer to : (1) Premiership Soccer Highlights on RTE2;
(2) Champions League Soccer on RTE 2 and I have in recent weeks seen both these programmes 'in the clear' via Sky Digital (though blacked out also) so it is possible that this could all be sorted out by time of RTE mini-mux next autumn. Even Irish Open Golf in the summer was 'in the clear' despite previous tournaments being blacked out.

Mr. Rabbit

Digifriendly wrote: »

Nobody knows for sure but at a guess I would say it probably will due to rights issues. However remember that the ROI DTT 'Saorview' signals will be increased northward after DSO so some will pick these up who can't at present and there can be naturally no blacking out with these. Also remember that sport on TG4 e.g.European Cup rugby is not blacked out due to Irish language rights for the whole of the island so AFAIK at present restrictions refer to : (1) Premiership Soccer Highlights on RTE2;
(2) Champions League Soccer on RTE 2 and I have in recent weeks seen both these programmes 'in the clear' via Sky Digital (though blacked out also) so it is possible that this could all be sorted out by time of RTE mini-mux next autumn. Even Irish Open Golf in the summer was 'in the clear' despite previous tournaments being blacked out.

Yep, very little is blocked out on RTE's northern Sky service these days, as far as I can see.

I do remember the Boxing day racing from Leopardstown being blocked a couple of years ago, and someone subsequently forgot to take the block off. As such, RTE 2 was unavailable on Sky to NI viewers for several days.

formerly scottish paddy

I would have thought that rights holders may now have started charging RTE on an all Ireland basis anyway, and with the new RTE mux in the North there is not going to be much point in blocking stuff on Sky.

lawhec

Mr. Rabbit wrote: »

Around this area of Jordanstown, analogue reception from Divis is OK with only slight ghosting.

A lot of terrestrial aerials (at least a third) still point towards divis rather than Carnmoney Hill, even though the Carnmoney Hill transmitter is visble. After DSO, I would imagine freeview reception from Divis will be fine I this area. Not sure about the RTE mini mux from black Mountain.

I think the main black spots that Carnmoney is meant to serve is around Rathcoole IIRC. It seems to hold some importance as a relay considering it carries TV, FM radio (BBC and Citybeat) and DAB.

Mr. Rabbit

lawhec wrote: »

I think the main black spots that Carnmoney is meant to serve is around Rathcoole IIRC. It seems to hold some importance as a relay considering it carries TV, FM radio (BBC and Citybeat) and DAB.

Yes, and more significantly in areas in directly the shadow of Carnmoney Hill itself (i.e all along the Dough Road up to Ballyduff, Kings Park, Cloughfern etc.) as well as parts of Glengormley and the Antrim/ Whitewell Roads that are in the shadow of Cave Hill.

I would imagine some parts of North Down (e.g. Bangor/Groomsport) might find it useful for the mini RTE mux also, especially if they have problems with Black Mountain and Clermont Cairn.

watty

formerly scottish paddy wrote: »

I would have thought that rights holders may now have started charging RTE on an all Ireland basis anyway, and with the new RTE mux in the North there is not going to be much point in blocking stuff on Sky.

RTE has been deliberately "firing" Analogue UHF into NI since the 1970s. Look at coverage and location of Claremont Cairn and Holywell Hill. Also Longford's Carn Hill, while further from the border, puts a significant signal into N.I.

It's also likely that as alternate to the reduced package of channels on the Minimux that Saorsat will for for N.I. Is the Mini-Mux a political sop for West Belfast?

Mr. Rabbit

Look at coverage and location of Claremont Cairn and Holywell Hill

Indeed, seem to remember protests from some Uniionist politicians when both transmitters were built in the early eighties.

Mind you, virtually all houses along the Shankhill Road and in East (along the Newtownards Road for example) and South Belfast have aerials pointing towards Clermont Cairn, so their protests probably fell on deaf ears.

Like it or not, people on both sides of the community up here are keen to receive RTE.

watty

Football matches?

Digifriendly

Mr. Rabbit wrote: »

Indeed, seem to remember protests from some Uniionist politicians when both transmitters were built in the early eighties.

Mind you, virtually all houses along the Shankhill Road and in East (along the Newtownards Road for example) and South Belfast have aerials pointing towards Clermont Cairn, so their protests probably fell on deaf ears.

Like it or not, people on both sides of the community up here are keen to receive RTE.

When RTE first beamed their UHF signals into NI there was no such thing as Sky and only live football shown by UK channels in regular season was FA Cup Final and England vs Scotland. RTE in contrast showed a live First division match most Saturdays,live FA Cup matches and League Cup Final live. No wonder forests of aerials appeared in East Belfast as well as West Belfast! I can even remember RTE showing live international rugby from Twickenham that was only covered in highlights by BBC as well as an England soccer qualifier (can't remember whether it was EC or WC). RTE sport in those days before Sky was great for NI sports loving viewers like myself.

Mr. Rabbit

Any word on who won the tendering process to provide the new RTE mini mux ? It should bave been completed by now.

The Cush

Mr. Rabbit wrote: »

Any word on who won the tendering process to provide the new RTE mini mux ? It should bave been completed by now.

Far from completed, this from the tender information document

Peter Rhea

http://www.digitaluk.co.uk/transmitternetwork/tools__and__resources/almanac/pdfs/DSOTx_Northern_Ireland_Jan12v2.0.pdf

See Kilkeel's got a bit of a boost (up from 200W iirc?).