How to pick up strong dab NI signal

jack12a

Hi all,
Looking for advice on how to pick up a good dab radio signal from Northern Ireland,
I live in Navan and I note there is a dab transmitter in Camlough Newry, which is about 60 Km away which may be the best to aim at.
I also note that there is an RTÉ dab transmitter in Dundalk 40Km away in the same general direction,
If I installed an outdoor roof dab directional aerial pointing at Camlough transmitter would it pull in both signals or are they just to far away.
I would be grateful for any advice on this matter regarding type / size aerial required and or conflicts re mixes I might run into, btw dab tuner has an f type aerial input.
Regards,
Jack

kazoo106

The Camlough TX can barely be picked up in Dundalk - with perfect visual Line of sight to the mast - if you have an old band 3 TV antenna which used to be used for Kippure, you have a better chance trying Brougher or Divis. Make sure the antenna is vertically polarised.
Now why you would want to listen to this mostly mono muck is another matter.

jack12a

Thanks kazoo 106,
From your advice Camlough is a none runner, Divis is transmitting dab at 10mhz and Brougher is at 5mhz, I don’t know if there’s much difference in which one I try as Divis is 135 km and Brougher is 80 km from me.

kazoo106

Divis, Camlough and Brougher are to by knowledge Single frequency networks (all on the same frequency, and all synced with each other) - You can play and see what the antenna picks up - if you aim for Divis from Navan, you should also take in RTE from Clermont Carn, however, I think Mount Oriel in Collon, might be a bit of an obstacle, depending on where you are. If you Wilkinstown you would be clear for divis

TAFKAlawhec

All three DAB ensembles at Camlough (Max ERP 3kW each) have large nulls towards its south with at least a 6db reduction between 150 - 260 degrees, peaking at 200 degrees with a 27.3db reduction. I would say you have no hope picking that up in Navan.

Brougher Mountain's three DAB ensembles are also shielded from an arc going ESE to WSW as well - it's the cause of a lot of reception problems in Fermanagh of DAB whereas FM and TV are usually OK.

At Divis the BBC national ensemble is in theory omnidirectional at 10kW, while Digital 1 and Sound Digital at the same site are at almost the same powers with only moderate reductions at certain directions. Next door at Black Mountain however the Bauer NI ensemble does have significant radiation restrictions southwards.

Armagh carries the BBC, D1 & Bauer NI ensembles at 5kW each with its main direction pointing southwards, and the transmitter site would be almost due north from Navan - it would probably be your best bet?

One thing to bear in mind would be adjacent channel interference, and with the RTÉ ensemble at Clermont Carn at 12C there's a strong chance that it'll knock out reception of the BBC Ensemble (12B) and Bauer NI (12D) - Digital 1 (11D) and Sound Digital (11A) would be less likely to have Clermont Carn causing problems to receiving them. IIRC the peak ERP direction for DAB from Clermont Carn is 220 degrees, so the maximum ERP lies somewhat towards Kells, not a good sign for wanting to avoid ACI.

Overall it might be worth a go if you can get an old, largish (at least 7 elements) VHF Band III aerial that was marketed as "wideband" or at least covered the old TV channels I & J, but I certainly wouldn't be confident in successful reception from the north - not to say it can''t be done. Years ago when I was still at home with my parents and the only BBC DAB transmitter in NI was on Divis the radio I had couldn't pick it up at all with its own whip aerial in an upstairs bedroom window facing Belfast, but when hooked up to a set of cheap unamplified rabbit ears in the attic and fed to the same radio in the same bedroom it received the signal from Divis no problem. That was a line-of-sight distance of 86km.

For reference, the link below to the Ofcom website allows you to download spreadsheets that give the details of all DAB transmissions in the UK, along with FM and MW as well.
https://www.ofcom.org.uk/spectrum/information/radio-tech-parameters

jack12a

Hi, kazoo 106,
Your info re Mount Oriel is spot on re blocking Divis transmitter, but at my location I am just able to pick up a good signal from Divis my line of sight to Divis is just the Slane side of Mount Oriel, neighbors a few hundred meters west of my location have always had to point at Brougher for NI tv signal.
Have an FM outdoor aerial pointing at Divis I can pick up bbc radio 1,2 radio Ulster good signal but classic fm,down town,northern sound are noisy 75% time.

jack12a

Hi TAFKAlawhec,
Thank you for your information re NI dab, your info re shielding of transmission to the south explains kazoo 106 point that Camlough signal is not available in Dundalk a short distance away.
I'll take on board your advice re Armagh and Divis being un shielded they appear to be the only viable options.
"Blake" appear to make an 8 element and 12 element dab aerial but are quite large, as aerial would have to be fitted vertically mast pole would be in front dipole would that cause a problem. Maybe some kind of stand off fitting would get round it?.
Before your advice I was looking at a 5 element Triax dab aerial which would be end fitted so mast pole would be behind dipole.
Also your point that Clermount Carn dab transmissions could block signal is significant. Plenty to think about now ��

George Sunsnow

TAFKAlawhec wrote: »

All three DAB ensembles at Camlough (Max ERP 3kW each) have large nulls towards its south with at least a 6db reduction between 150 - 260 degrees, peaking at 200 degrees with a 27.3db reduction. I would say you have no hope picking that up in Navan.

Brougher Mountain's three DAB ensembles are also shielded from an arc going ESE to WSW as well - it's the cause of a lot of reception problems in Fermanagh of DAB whereas FM and TV are usually OK.

At Divis the BBC national ensemble is in theory omnidirectional at 10kW, while Digital 1 and Sound Digital at the same site are at almost the same powers with only moderate reductions at certain directions. Next door at Black Mountain however the Bauer NI ensemble does have significant radiation restrictions southwards.

Armagh carries the BBC, D1 & Bauer NI ensembles at 5kW each with its main direction pointing southwards, and the transmitter site would be almost due north from Navan - it would probably be your best bet?

One thing to bear in mind would be adjacent channel interference, and with the RTÉ ensemble at Clermont Carn at 12C there's a strong chance that it'll knock out reception of the BBC Ensemble (12B) and Bauer NI (12D) - Digital 1 (11D) and Sound Digital (11A) would be less likely to have Clermont Carn causing problems to receiving them. IIRC the peak ERP direction for DAB from Clermont Carn is 220 degrees, so the maximum ERP lies somewhat towards Kells, not a good sign for wanting to avoid ACI.

Overall it might be worth a go if you can get an old, largish (at least 7 elements) VHF Band III aerial that was marketed as "wideband" or at least covered the old TV channels I & J, but I certainly wouldn't be confident in successful reception from the north - not to say it can''t be done. Years ago when I was still at home with my parents and the only BBC DAB transmitter in NI was on Divis the radio I had couldn't pick it up at all with its own whip aerial in an upstairs bedroom window facing Belfast, but when hooked up to a set of cheap unamplified rabbit ears in the attic and fed to the same radio in the same bedroom it received the signal from Divis no problem. That was a line-of-sight distance of 86km.

For reference, the link below to the Ofcom website allows you to download spreadsheets that give the details of all DAB transmissions in the UK, along with FM and MW as well.
https://www.ofcom.org.uk/spectrum/information/radio-tech-parameters

I've no problem with Dab upstairs in the house near Arklow with just the telescopic on a Roberts 93i
I presume it's omnidirectional,no nul at all? And that a dab signal behaves even better than a dtt signal in that the Roberts has no amplification at all and obviously the seapath helps?
We receive some welsh fm here with rds eg radio one etc

TAFKAlawhec

George Sunsnow wrote: »

I've no problem with Dab upstairs in the house near Arklow with just the telescopic on a Roberts 93i
I presume it's omnidirectional,no nul at all? And that a dab signal behaves even better than a dtt signal in that the Roberts has no amplification at all and obviously the seapath helps?
We receive some welsh fm here with rds eg radio one etc

What are you receiving on DAB on the Roberts? RTÉ or a UK ensemble?

Thurston?

George Sunsnow wrote: »

... I presume it's omnidirectional,no nul at all? And that a dab signal behaves even better than a dtt signal in that the Roberts has no amplification at all and obviously the seapath helps?
We receive some welsh fm here with rds eg radio one etc

You probably already know, but you can find photos of the transmitting arrays on MB21.

Here's Haverfordwest, a good clear example, with 4 dipoles on a cantilever at the top of the mast. (Dir. max ERP 260 degrees, according to the ofcom data linked to in a previous post.)

There's usually no reason for a coastal transmitter to be omni, except say the likes of Divis, that also serves parts of Scotland & IOM.

soporific

I placed a cheap (15 quid) dab aerial on the Tv mast yesterday to see what would happen. I live south of drogheda in Meath close to the sea. I pulled in 46 dab stations - the usual Irish ones and 3 NI muxes. But the surprising thing is that the signal strength on the PC software I use shows full strength for the BBC and other NI muxes. Now i have the justification to get a fancy Dab receiver!

jack12a

Hi, soporific

That's really great news, can you advise regarding size / type of aerial you used,

Was signal solid and the sound good ?. Assuming you could listen to stations on PC. That must be Divis Belfast transmission your picking up with 3 muxes, you must be over 100km from it,

Are you using any amplification on aerial ?. I really appreciate that information.

lgs 4

Any chance of getting Northern Dab in Tallaght

Gerry Wicklow

lgs 4 wrote: »

Any chance of getting Northern Dab in Tallaght

Not unless you're up high such as Bohernabrenna I would imagine.

Capt'n Midnight

https://ukfree.tv/radio/multiplexes/12D/N_Ireland

Appears broken for now

soporific

Hey Jack

the aerial I'm using is a Mercury dab aerial which can be got with kit at amazon for 13.99
https://www.amazon.co.uk/Mercury-Outdoor-DAB-Radio-Aerial/dp/B00EHIJX9K/ref=sr_1_7?s=electronics&ie=UTF8&qid=1519656452&sr=1-7&keywords=dab+aerial&dpID=218DpMV%252Bj6L&preST=_SX300_QL70_&dpSrc=srch

I have it going into a labgear masthead amp (which has a VHF input for dab/fm)
https://www.amazon.co.uk/Labgear-KIT415V-LTE-Masthead-Amplifier-Supply/dp/B01E9Q6AL8/ref=sr_1_8?s=electronics&ie=UTF8&qid=1519656584&sr=1-8&keywords=labgear+masthead+amp

I must try to bypass the masthead amp and go direct to the PC to see if the amp is necessary (next time I venture up to the attic)

The software says the three muxes are full strength. I've played various stations for a few hours with no garbled breakups - so it works perfectly for me.

I've noted the the mux blocks which are 11d, 12b, and 12d and so i think they are three different locations (divis, camlough and newcastle).
I know dab gets a bad rap in terms of quality - but its a bit of fun to get it working!!

Im not sure what captain midnight is referring to but all the NI dab muxes were working last night

soporific

Oh forgot to add that the usb stick i'm using for the computer is an astrometa dvb-t2, dab fm thing from china which cost about 15 euro. it's ok but produces frequent errors and breakups on dvb-t tv (which don't happen with other dvb-t sticks). So if it's possible to get listenable dab with a cheapo usb stick, then any decent dab radio should work fine

Thurston?

soporific wrote: »

... I've noted the the mux blocks which are 11d, 12b, and 12d and so i think they are three different locations (divis, camlough and newcastle).

Nah, it doesn't work like that, the same frequencies are used everywhere. 11D (222.064 MHz) is Digital One, 12B (225.648 MHz) is the BBC national mux, 12D (229.072 MHz) is the regional mux.

Also seems to be SDL national mux on 11A (216.928 MHz), only transmitted from Divis in NI, so you'd know where that was coming from if you had it.

soporific wrote: »

I have it going into a labgear masthead amp (which has a VHF input for dab/fm)
https://www.amazon.co.uk/Labgear-KIT415V-LTE-Masthead-Amplifier-Supply/dp/B01E9Q6AL8/ref=sr_1_8?s=electronics&ie=UTF8&qid=1519656584&sr=1-8&keywords=labgear+masthead+amp

I must try to bypass the masthead amp and go direct to the PC to see if the amp is necessary

Looks like it only amplifies the UHF input, & VHF will be 8.5dB down due to the 4-way split.

dxhound2005

The Divis map page is a bit out of date possibly. Not listing the 12D mux.

https://ukfree.tv/transmitters/dab/Divis

But the coverage shows some small areas well south of the border, and a good aerial would get them in other places. Camlough and Newcastle are much weaker transmitters and unlikely to get very far south.

soporific

Thurston? wrote: »

Nah, it doesn't work like that, the same frequencies are used everywhere. 11D (222.064 MHz) is Digital One, 12B (225.648 MHz) is the BBC national mux, 12D (229.072 MHz) is the regional mux.

Ah, ok. So without 11A, I must be picking up the muxes from somewhere other than Divis? And I noticed this evening some breakup on 12D so it must be weaker. Is there anyway to work out where the signal is coming from?

soporific

Thurston? wrote: »

Looks like it only amplifies the UHF input, & VHF will be 8.5dB down due to the 4-way split.

I never noticed that 8.5db loss quote till now! So a straight run of cable from the dab aerial to a receiver would be better.

TAFKAlawhec

The Bauer NI ensemble (12D) isn't transmitted from Divis, but from Black Mountain.

With regards to reception nr. Drogheda, initial perceptions would indicate that reception is coming from Divis/Black Mountain. It won't be Camlough due to TX restrictions I mentioned earlier, and you won't be getting reception from Newcastle either as the TX is not only directional towards the north but is also well geographically shielded to the south thanks to Slieve Donard (plus Digital 1 (11D) doesn't TX from Newcastle). However the lack of reception of the Sound Digital ensemble (11A) and that the Bauer NI ensemble from Black Mt. has restrictions to the south of the site, would make me think that reception is likely coming from Armagh which carries the three ensembles mentioned, but not Sound Digital.

There is a TX identifier broadcast in the ensemble from a site which can be read using an SDR and appropriate software which can be read against Ofcom's transmitter list, but I've not tried it myself yet.

soporific

TAFKAlawhec wrote: »

The Bauer NI ensemble (12D) isn't transmitted from Divis, but from Black Mountain.

With regards to reception nr. Drogheda, initial perceptions would indicate that reception is coming from Divis/Black Mountain. It won't be Camlough due to TX restrictions I mentioned earlier, and you won't be getting reception from Newcastle either as the TX is not only directional towards the north but is also well geographically shielded to the south thanks to Slieve Donard (plus Digital 1 (11D) doesn't TX from Newcastle). However the lack of reception of the Sound Digital ensemble (11A) and that the Bauer NI ensemble from Black Mt. has restrictions to the south of the site, would make me think that reception is likely coming from Armagh which carries the three ensembles mentioned, but not Sound Digital.

There is a TX identifier broadcast in the ensemble from a site which can be read using an SDR and appropriate software which can be read against Ofcom's transmitter list, but I've not tried it myself yet.

It's detective work for sure! Looking at the coverage map for armagh dab, if that signal is reaching south of drogheda then surely much of Louth should be covered.
https://ukfree.tv/transmitters/dab/Armagh

Rick_

I was back home in Armagh over the weekend and by chance turned on the DAB on my alarm clock and noticed that I can pick up a lot more stations than I used to and that was without even having to move the rather paltry aerial into a good position, so has the power been increased recently? I used to only get the BBC ones and a handful of others were very temperamental, now I can get seemingly another 10 stations and they all come in perfectly.

TAFKAlawhec

soporific wrote: »

TAFKAlawhec wrote: »

The Bauer NI ensemble (12D) isn't transmitted from Divis, but from Black Mountain.

With regards to reception nr. Drogheda, initial perceptions would indicate that reception is coming from Divis/Black Mountain. It won't be Camlough due to TX restrictions I mentioned earlier, and you won't be getting reception from Newcastle either as the TX is not only directional towards the north but is also well geographically shielded to the south thanks to Slieve Donard (plus Digital 1 (11D) doesn't TX from Newcastle). However the lack of reception of the Sound Digital ensemble (11A) and that the Bauer NI ensemble from Black Mt. has restrictions to the south of the site, would make me think that reception is likely coming from Armagh which carries the three ensembles mentioned, but not Sound Digital.

There is a TX identifier broadcast in the ensemble from a site which can be read using an SDR and appropriate software which can be read against Ofcom's transmitter list, but I've not tried it myself yet.

It's detective work for sure! Looking at the coverage map for armagh dab, if that signal is reaching south of drogheda then surely much of Louth should be covered.
https://ukfree.tv/transmitters/dab/Armagh

I don't trust the maps on that site at all. None of the coverage maps for TV & radio TXs in NI that I've seen there look realistic.

The Armagh DAB TXs are all directional with a max ERP of 5kW directed roughly southerly IIRC (on mobile here so can't easily check). If a straight line from the TX to RX isn't hindered by the Mournes and the distance isn't too great, no co-channel interference etc. then a roof mounted folded dipole could be enough to bring the signals in. I'd imagine however that the further north in Louth you then go, the more the shielding by the Mournes comes into play.

dxhound2005

The map is showing that Armagh only broadcasts 12B, the BBC channels. Is it up to date?

TAFKAlawhec

dxhound2005 wrote: »

The map is showing that Armagh only broadcasts 12B, the BBC channels. Is it up to date?

No. The Ofcom txparams spreadsheet shows both Digital 1 and Bauer NI ensembles transmitting from the Armagh site. Also if you go the transmission gallery on mb21.co.uk and select the Armagh site, it'll show what is being broadcast from there (it's a PSB relay of Divis for TV as well as a DAB transmission site).

Rick_

That would explain the much better DAB reception then. Glad they have finally got round to adding more stations locally.

soporific

TAFKAlawhec wrote: »

There is a TX identifier broadcast in the ensemble from a site which can be read using an SDR and appropriate software which can be read against Ofcom's transmitter list, but I've not tried it myself yet.

I've tried using software called Dab Player - but the trasmitter ID Info is greyed out within the FIG statistics. Is it true that a dab receiver can combine signals from two or more transmitters (i read that on some forum). The signal for 11D is significantly stronger than for the other two NI ensembles.

Thurston?

soporific wrote: »

... Is it true that a dab receiver can combine signals from two or more transmitters (i read that on some forum). The signal for 11D is significantly stronger than for the other two NI ensembles.

Well, DAB (& DVB-T) signals can certainly cope with multiple versions of the same signal, be they multipath from the same transmitter, or signals from multiple sites using the same frequency. Factors that can be adjusted include the locations of the transmitters themselves, & the timing of their signals relative to each other, as well as the 'guard interval' in the signal itself.

Not sure how much combining/constructive interference goes on.

soporific

Some updates on NI Dab reception in East meath (just outside Drogheda). I got a Denon M41Dab receiver recently and it seems to have a sensitive dab tuner. I've had burble-free dab reception from the irish and UK stations so far and even picked up the 11A SDL mux from Divis. It was very broken up and I doubt even good weather would improve things - but interesting that any signal is getting through. As i said earlier, I'm using a cheap 15 euro dab aerial (on the mast under the Tv aerial) so I'm sure the Blake one or something equivalent would complete the job.

jack12a

Hi Soporific,
I have also been trying to pick up dab from Divis, I can pick up the 2 commercial muxes pretty good most of the time but they appear to drop out in the middle of the day and more so in good weather ??.
I have had no success picking up the mux from Divis carrying BBC Radio stations
It appears RTÉ dab transmitter at Dundalk is blocking it out completely.

soporific

Hey Jack I just checked your first post again and see that you're in navan. I think someone mentioned that there might be a gap between the mountains that allow some signal from Divis to leak into parts of Meath. When i drive around in the car, the dab stations fade in and out and where I live just happens to be a good spot. I think the BBC mux is not from Divis. The 11A stations are definitely Divis and they only come through occassionally and are burbly. You could try the Blake dab aerial which is supposed to be the best.