Severe Kilkeel reception problems, DTT multiplexes detected

lucernarian

Yesterday, I noticed that yet again there was no reception from Kilkeel. There is a FTA satellite setup working for one TV, so it wasn't a big deal. But just out of curiousity, I got the TV in question (an idTV) to do an automatic scan to see what DTT channels were being picked up. The TV stopped for over a minute at Ch.39 and also significant times for 42, 45 and 49. It also picked up channels 47, 53, 54 and 61. No suprise there.

So I went to the service check screen. When I selected ch. 39, I got a signal strength check of around 60% and signal quality varying rapidly from anywhere between 20 and 100%. I tried to scan ch.39 by itself but no channels were found.

What is going on here? I thought that if it was the Mt. Leinster multiplex jamming my NI stations too, that I would scan the Irish channels successfully.

Irish channels are receiving as strongly as ever (TV3 a bit ghosty and weak last night however)

Rick_

What transmitter(s) do you normally receive from. Being in Louth I suspect Clermont is one but are you receiving any northern transmitters for BBC etc?

lucernarian

Eh?

I'm writing about the kilkeel transmitter sure. What's happening is that reception I normally get is now gone to pot, albeit vaguely watchable today. Yes I also receive from Clermont Carn.

Did I understand you right there?

The references to Chs. 47, 53, 54, 61. were the DTT multiplexes I get from Three Rock/Kippure, Clermont Carn and Cairn Hill.

Rick_

Ahh I see, I misunderstod. Apologies.

You appear to be picking up dtt from either cairn hill or mt leinster.
Cairn hill has been known to be interfering with a relay on the isle of man which recently increased power.
I know those are mt leinster frequencies but I'm not sure if they are also cairn hill.
If they are,then thats the culprit.
I'd be amazed but not surprised if mt leinster is making it's way up to you.
After all the top of mt leinsters mast would be circa 3000ft asl so there would be nothing in the way except if by fluke you were in a los for lugnaquilla.
Dublin would have no hope of mt leinster as it's too close to the wicklow mt's which would completely shadow it but it's conceivable that you are far enough away from them for mt leinster to peak above the horizon at times weather depending.

lucernarian

Cairn hill would be a big suprise, especially as there are areas which can receive both Cairn Hill and Mt. Leinster. Putting both of them on 39,42,45,49 would be problematic.

I wouldn't mind so much but there's just a vertically polarised grid aerial picking up Kilkeel and Clermont Carn. I also had a feeling this might happen some day, but I don't know why it's only become an issue lately. Maybe it's RTÉ's attempt at jamming Preseli that did it?:P

My reasons for suspecting Mt. Leinster in particular, are that I can receive Ch.23 TG4 for example on the TV, with some snowy vision but nicam sound. I've received EBU grade 5 vision with a grid aerial with right alignment and polarity at height outside. Unfortunately Kilkeel is not in the same position. The reception I can see of Mt. Leinster on Ch. 23 appear to be only slightly weather-variable.

It's mt leinster then.
3000ft up in the air,it and Kippure must be 2 of the highest tx's on these islands?
maybe mrdtv could tell us.

You are relatively near kilkeel too!

Ironically none of that in the Dublin area where kilkeel is used as mt leinster would be completely blocked by the shadow of the wicklow mtns.

mrdtv

Deleted User wrote: »

It's mt leinster then.
3000ft up in the air,it and Kippure must be 2 of the highest tx's on these islands?
maybe mrdtv could tell us.

You are relatively near kilkeel too!

Ironically none of that in the Dublin area where kilkeel is used as mt leinster would be completely blocked by the shadow of the wicklow mtns.

New Year Greetings. At the distance in Louth its more likely to be interference from Moel-y-Parc which is cochannel with Kilkeel. This is causing CCI problems in South Down since MyP went high power. I think its too far away from Mount Leinster. The classic digital interference is noise on video and rasping sound on analogue TV. Mount Leinster is too far south but Louth is in the firing line for MyP which is now 20kW omni and that's a very high site (easily received in East Down and on IOM.) You are protected as Kilkeel is vertical and MyP is horizontal so that gives a 20dB protection ratio. Mount Leinster is possible in lift conditions but the weather has been very poor so it could be a curious mix of MyP and Mount Leinster. If you point the aerial out to sea and you change its polarity then if you retune you may well get MyP which is causing chaos in the Granada region.

On a wider note it will be interesting to see if Irish DTT is actually launched next year and with which DVB transmission system. I have my own views and I am guided by the economics...

Happy New Year!

lucernarian

I've already said I can easily receive Mt. Leinster analogue. EBU Grade 5 reception when I align the aerial properly. On a continouos basis, not weather dependent. So why is it so unlikely to be Mt. Leinster DTT?

Also, if I were to point an aerial towards Moel-Y-Parc, I'd have to point it exactly through the middle of a steep hill, which I live on the NW slope of. It almost shields me from Three Rock but it's southerly enough to avoid the peak of this hill.

There's also a hill to the north of me which also blocks Kilkeel but it's far enough away not to stop it totally.

johnneyboy

To_be_confirmed wrote: »

Yesterday, I noticed that yet again there was no reception from Kilkeel. There is a FTA satellite setup working for one TV, so it wasn't a big deal. But just out of curiousity, I got the TV in question (an idTV) to do an automatic scan to see what DTT channels were being picked up. The TV stopped for over a minute at Ch.39 and also significant times for 42, 45 and 49. It also picked up channels 47, 53, 54 and 61. No suprise there.

So I went to the service check screen. When I selected ch. 39, I got a signal strength check of around 60% and signal quality varying rapidly from anywhere between 20 and 100%. I tried to scan ch.39 by itself but no channels were found.

What is going on here? I thought that if it was the Mt. Leinster multiplex jamming my NI stations too, that I would scan the Irish channels successfully.

Irish channels are receiving as strongly as ever (TV3 a bit ghosty and weak last night however)

try manual tune three rocks can be got in louth not channel its either 54 or 61 the other is kippure full dtt on both

lucernarian

What?? I know I can pick up Ch. 54 and 61 among others.

The problem is with Ch 39, 42, 45 and 49 which is what I get Kilkeel on. Did you read the post?

johnneyboy

To_be_confirmed wrote: »

What?? I know I can pick up Ch. 54 and 61 among others.

The problem is with Ch 39, 42, 45 and 49 which is what I get Kilkeel on. Did you read the post?

ring rte technical department on monday

lucernarian

And ask them why I can't receive NI channels?!;)

johnneyboy

To_be_confirmed wrote: »

And ask them why I can't receive NI channels?!;)

if rte are blocking the singal , i am sure that they will come out to check to see what the problem is, you may need a filter ,is your box meg2 or new meg4 frreeview, freeview will be meg4 by this summer for bbc hd and itv hd

Gerry Wicklow

To_be_confirmed wrote: »

The problem is with Ch 39, 42, 45 and 49 which is what I get Kilkeel on.

What you describe sounds the same as I get with Mt Leinster jamming Preseli. Strong signal bouncing up and down every few seconds, no matter which way I beam the aerial, the two cancel each other. I only get RTE on CH39. 42, 45 and 49 are useless to me. And yes you are correct in RTEs attitude to us getting our overspill jammed... "TOUGH S@#~":mad:

mrdtv

Gerry Wicklow wrote: »

What you describe sounds the same as I get with Mt Leinster jamming Preseli. Strong signal bouncing up and down every few seconds, no matter which way I beam the aerial, the two cancel each other. I only get RTE on CH39. 42, 45 and 49 are useless to me. And yes you are correct in RTEs attitude to us getting our overspill jammed... "TOUGH S@#~":mad:

The Soviet era jamming is rather pointless: all it does is wreck both sets of signals! This is the problem with COFDM signals as they are rather good at handling reflections and if they are uncorrelated they fail hard if both sets of signals are above the decode threshold. The CCI is effectively rendering 42,45 and 49 unusable in SE Ireland. A similar CCI problem has been seen in an interaction between an English and SW Wales transmitter where the cochannel COFDM signals are completely wrecked. A pointless exercise, a waste of electricity and no tangible benefit to any putative Irish pay-Tv operator for whom these channels will be commercially unusable. With the worsening economic situation in Ireland big spending cuts at RTE are inevitable this year and engineering charades of this nature will probably be axed in the inevitable swingeing cost-cutting which must happen at RTE.