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Question about the Clermont Carn transmitter?
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04-11-2022 10:49am#1
I have a question about the RTE FM frequencies being used at Clermont Carn?
Normally all across Ireland the FM frequencies would be beginning with RTE Radio 1, 2FM, RNaG and then Lyric FM, in that order.
However at Clermont Carn, it's differen,t it's RTE Radio 1, then Lyric FM, then 2FM and then RNaG.
Is there a particular reason for this difference?
After all, all of the Clermont Carn frequencies by RTE have the same power, all 40kW, - probably with intention to cover a bit of NI?
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I think it's mainly because of its proximity to Northern Ireland. BBC radio services would be allocated frequencies in the bands that the RTE services would normally be in. Also, Clermont Carn didn't open until 1981 so it was a fairly late addition to the network; the BBC services would have been well established by then (with the exception of BBC Radio 1 of course, which was MW only until the late 80s, early 90s).
Originally, RTE Radio 1 was on 95.2 and Lyric was on 87.8 but they were flipped around the time of the 567 MW closedown, because 87.8 had better coverage in Belfast.
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I would tend to think that lower frequencies would go further, but that's also negligible.
Belfast is also interesting. Normally in the UK it's Radio 2, Radio 3, Radio 4, BBC Local, Commercial, then Classic FM, BBC Local and then Commercial again.
However in Belfast they have BBC Local after Radio 3 and then BBC Radio 4. In parts of Scotland it's interestingly similar.
Only difference in Belfast, is the BBC Radio 4 frequency in Divis has less power than that of BBC Radio Ulster. Maybe that's it?
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I don’t think they started FM until 1984/5? Their RnaG signal on 102.7 caused Nova to move up the dial slightly.
That 102.7 has some coverage; I can get it in the car down at New Ross during the summer.
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102.7 came on the air almost 37 years ago to the day !
First week of November '85 when a tone appeared on 102.7 causing interference in Louth /Meath to Novas main FM tx on 102.7.
At the time UK police and ambulance services were slowly moving off the 100-108 Mhz so RnaG had a range of frequencies to choose from and chose 102.7 resulting in Nova moving to 103.1 and switching off 103.2
Albert Reynolds promoted the idea or RTE having a 'border blaster ' relay after seeing a news clip on 'border blasters ' aimed at East Germany .
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Was it then possible for the public to listen in to the UK police and ambulance services if they were between 100 and 108 kHz? It would seem so.
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you mean MHz
I don't believe that ambulances were located there, but UK police certainly were (and below 100). Transmissions were generally AM, but could easily be heard (if with distortion) on an FM receiver with analogue tuning by detuning slightly either side of the carrier frequency (and with 'AFC' switched off, if the receiver had an AFC switch). UK utilities such as gas boards also used frequencies up to 108. Obviously it was an unsatisfactory situation for a number of reasons, and were liable to interference from European countries using the full FM band for high-power FM stations during Sporadic-E and lifts in the summer especially.
The above recordings from 1983 has pirates and as well as RTE radio received from Ireland whilst tuning around on a hill overlooking the Irish Sea near Aberystwyth Wales. Welsh police transmissions can be heard disrupting FM reception of Arklow Community Radio and Kilkenny community Radio (KCR) who apparently were transmitting around 99-100 on FM.
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Glaceon has pretty much described it well. Clermont Carn was a "late developer" in RTÉ's TV & FM radio network and was essentially a transmitter aimed for the eastern to south eastern areas of NI that weren't reachable by either Kippure or the Monaghan relay (i.e. a damn good bit of it), just a shame for them that (a) The Mournes block a good bit of the signal, and (b) it had trouble adequately serving much of Belfast, reception varying from reasonable (good mono FM) to almost unlistenable. Otherwise it was perhaps the best location of several possible contenders especially in trying to cover Belfast. However it's location even allowing for heavily restricted transmitting patterns to its east & south-east meant that it had to protect a lot of VHF FM & UHF allocations already in use in the UK and for the radiated powers RTÉ wanted to broadcast on FM, finding frequencies in the 88.1 to 94.6MHz sub-band that was usually reserved for it proved impossible, so non-standard frequencies were employed. Originally 95.2 MHz for RTÉ Radio 1 & RnaG and 97.0 MHz for Radio 2/2FM. Later when RTÉ Radio 1 went full time on FM, 102.7 MHz was opened up for RnaG & FM3. The original plan was for the FM radio transmissions on Clermont to have mixed polarisation with a maximum ERP of 80kW (40kW per plane), but eventually only vertical polarisation was employed. Later on in the late 80's Century FM was allocated 87.8 MHz from Clermont Carn but I don't know if they ever came on air on this frequency. When Radio Ireland/Today FM went on the air they started broadcasting on 105.5 MHz instead. 87.8 MHz was finally put into action full time for the launch of Lyric FM.
Again, as Glaceon mentions, when RTÉ was in the process of ending Radio 1 transmissions on MW, there was an issue in Belfast concerning reception of RTÉ Radio 1 from Clermont Carn on 95.2 MHz - this was/is due to the Carnmoney Hill relay station in the north of the city broadcasting broadcasting BBC Radio Ulster on 95.3 MHz, despite having an ERP of only 20 watts it and other FM radio services from Carnmoney can be picked up well in much of the city and this "rogue" BBC R Ulster transmission caused interference to reception of 95.2 MHz. With no other RTE FM transmission able to penetrate Belfast, the decision was made to swap frequencies with Lyric FM putting RTÉ Radio 1 on 87.8 MHz just a few days before the plug was pulled at Tullamore - the thinking being that there was a much greater listener base in the city to RTÉ Radio 1 than Lyric FM and thus less complaints, and I'm pretty sure they're right.
As an addition, the UHF analogue TV transmissions from Clermont Carn also followed a non-standard pattern in that they were high-powered vertical polarisation transmissions as opposed to horizontal for all other high-powered UHF sites in Ireland & the UK, as well as the channel allocations being on 52 (RTÉ1) & 56 (RTÉ2) which were largely "spare" frequencies not normally used for groups of frequencies employed in the UK & Ireland, these were supplemented by two more similarly "spare" frequencies at the top of the UHF broadcast band when TnaG/TG4 came on air (68) and later TV3 (66). Another problem with the Clermont Carn UHF TV transmissions were originally that the allowed ERP to the north of the site was restricted to around 12kW, meaning that acceptable reception was only possible in varying parts of counties Down, Armagh, the southern third of Antrim, SE Derry & the eastern third/quarter of Tyrone. At some point during the 00's these power restrictions were eased, greatly enhancing reception especially in locations that struggled beforehand, taking the acceptable reception coverage to as far north as Ballymena & as far west as parts of Omagh. I don't think the FM radio transmission ever faced such severe directional restrictions into NI, but along that direction of the arc there are still some moderate restrictions - certainly not the 40kW maximum that is aimed to the south to south west.
As for addition number two, when DTT (Saorview) launched at Clermont Carn, its reception northwards was originally heavily restricted northwards meaning that its reception wasn't reliable much further north than Newry except in a few lucky cases. This changed at DSO/ATO when they switched to using the old analogue TV aerials for transmission (there was about a one month period before the old original DTT transmission was switched off). A similar restriction was in place for the RTÉ DAB broadcasts at the site while they existed, with very little signal going north.
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The reasons are quite simple - it's down to the legacy of the BBC FM network being built from the 1950's onwards.
Once it was decided to use FM in VHF Band II as opposed to AM, a frequency plan was adopted (from the Stockholm 1952 frequency allocation conference) of separating the Light, Third & Home services at each transmitter by a standard 2.2 MHz gap, with the Light service covering 88.1 to 90.2 MHz, the Third from 90.3 to 92.4 MHZ & the Home service from 92.5 to 94.6 MHz. At the time the Home Service was regionalised both on FM & MW. There were a couple of notable exceptions - given their proximity to France, the Les Platons stations in Jersey had to use standalone frequencies that didn't follow this pattern, while in Wales there were transmissions for two separate Home Services, for the West of England & Wales - the Welsh service was broadcast on 96.7 MHz (I think) which was out of band from the rest of the BBC FM radio network in place. Frequencies above 95MHz at the time in the UK were allocated to the Home Office, and special government permission was granted on the basis that reception of the 96.7 MHz transmissions would only be protected inside Wales.
As the late 60's seen the BBC National radio services become Radios 1-4, this was reflected in how they replaced their old names on FM. The Light service on FM was mostly replaced by Radio 2, with some time allocated to Radio 1 (whom otherwise were left with MW only), the Third became Radio 3 while the Home Service became Radio 4, still with regional opt-outs at the time although this gradually changed with the piecemeal roll out of BBC local radio in England (given their own FM frequencies) as well as the establishment of "national regions" stations in Northern Ireland, Scotland and Wales that replaced the Radio 4 regional opt-outs there. So as an example in Northern Ireland, BBC Radio Ulster took over the FM & MW frequencies from BBC Radio 4 (with NI opt-outs), meaning that reception of the general Radio 4 service was lost for most in NI except for when Radio Ulster was off-air and relayed it until the big MW frequency reshuffle in November 1978 where MW new allocations sprang up to provide the general BBC Radio 4 service to the parts of NI, Scotland & Wales that had originally lost them - in NI this added 720 kHz from Lisnagarvey & Derry while 774 kHz from Enniskillen was added in the early 1980's. In Scotland, the launch of BBC Radio Scotland largely followed the technical pattern of that in NI, with the old Radio 4 (Scotland opt-out) FM & MW frequencies transferred to Radio Scotland with the general Radio 4 service restored by the addition of two LW transmitters at Westerglen & Burghead & one low powered MW TX at Redmoss. In Wales, due to political issues regarding the Welsh language, two new stations were instead spun out, the Welsh language Radio Cymru taking Radio 4's FM network in Wales while the English language Radio Wales took the MW network. When BBC Radio 4 transferred to 198 kHz in 1978, it pretty much covered all of the principality.
While it went into the 80's, the BBC FM radio network retained the three national FM services with Radios 1/2 & 3 on two FM frequencies and another being allocated to BBC Radio 4 in England and the "national regionals" in NI, Scotland & Wales. In due course with the original BBC FM network now needing to be upgraded as original equiptment was nearing end-of-life, as well as additional frequencies in VHF Band II now being opened up in one part thanks to the Geneva 1984 frequency convention formally opening up the band across Europe to 108 MHz and also in part to the UK clearing 87.5 - 108 MHz of non-broadcasting use (though this took time - the last bit of the band cleared for broadcast use, 105-108 MHz was only available from the start of 1996). This included re-engineering the transmissions to mixed polarity from horizontal only (in most cases), the opening up of Radio 1's own FM sub-band between 97.7 to 99.8 MHz (also meaning Radio 2 could now be on FM all the time too) and also Classic FM launching as the first national independent commercial radio station also in its own sub-band of 99.9 to 102.0 MHz. In between all this were the creation of smaller sub-bands that accommodated local (and later regional) commercial radio as well as BBC local radio. When BBC Radio 1 was starting to get fully rolled out across the UK in the early 1990's efforts were also made to add BBC Radio 4 on FM to sites where their original frequencies were taken when Radio Ulster/Scotland/Cymru began. In most cases frequencies were found in the sub-bands that were otherwise mostly used for BBC local radio in England between 94.6 to 96.1 MHz & 103.5 to 104.9 MHz. However in some cases power restrictions had to apply to protect other users compared to the power used for other BBC national radio services. Two notable ones in Northern Ireland is at Divis (62.5 kW compared to 125 kW - originally 125 kW & 250 kW) and at Derry/Sherrif's Mountain (10kW compared to 31kW).
With the increasing amount of additional commercial FM transmitters as well as community stations being slotted into dial space where they can be found, the original sub-band plan for both Ireland and the UK has a heck of a lot more exception holes than it used to, but as a very rough guide it goes by the following pattern...
87.6 - 88.0 MHz :: Commercial Radio (IRL), Restricted Licence Services (UK)
88.1 - 90.2 MHz :: RTÉ Radio 1 (IRL), BBC Radio 2 (UK)
90.3 - 92.4 MHz :: RTÉ 2FM (IRL), BBC Radio 3 (UK except in much of Wales), BBC Radio Wales (much of Wales)
92.5 - 94.6 MHz :: RTÉ RnaG (IRL), BBC Radio 4/Ulster/Scotland/Cymru (UK)
94.7 - 96.1 MHz :: Commercial Radio (IRL),
96.2 - 97.6 MHz :: Commercial Radio (IRL), Local Commercial Radio (UK)
97.7 - 99.8 MHz :: RTÉ Lyric FM (IRL), BBC Radio 1 (UK)
99.9 - 102.0 MHz :: Today FM (IRL), Classic FM (UK)
102.1 - 103.5 MHz:: Commercial Radio (IRL), Local Commercial Radio (UK)
103.6 - 105.0 MHz :: Commercial Radio (IRL), BBC Local Radio (England), BBC Radio 4/Cymru (NI/Soctland/Wales)
105.1 - 106.0 MHz :: Commercial Radio (IRL), Regional Commercial Radio (UK)
106.1 - 107.0 MHz :: Commercial Radio (IRL), Local & Regional Commercial Radio (UK)
107.1 - 108.0MHz :: Newstalk (IRL), low(er) powered local commercial radio (UK)*
* When the 107-108 band was opened in the UK, the first stations licenced on it were limited to an ERP of 100 watts. In due course these powers at some transmitter sites were allowed to increase, I think 800 watts is now the maximum.
Post edited by TAFKAlawhec on4 -
Very interesting and informative. Presumably 98FM in Dublin should be on 96.7, not 98.1 ... and 98.1 should be Lyric FM?
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They were originally allocated 105.5 but complained to the regulator that many radios of the day wouldn't go over 100 or 104. So they were allocated 98.1 on what was meant to be a temporary basis. An attempt was made to move them but they objected on the grounds that the frequency was an integral part of their brand.
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98.1 was apparently meant to allocated to Century for the....
wait for it....
Clermont Cairn site!!
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Thanks for the insight.
What about the 98,3 in Cork? Shouldn't they be on a different frequency as well?
Also, isn't Radio Nova on 100,3 supposed to be on a different frequency?
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I've no idea about Cork to be honest but Nova is using its intended frequency. 100.3 was allocated to Today FM from Three Rock initially but it was decided to move that to 100.9 at lower power to give Nova better coverage of the commuter belt that it's licensed for (and because Today FM in Dublin is already fairly well serviced from Kippure and Clermont Carn anyway).
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Great insight from Tafkalawhec.
To reply to tinytobe: originally 97-102mhz was allocated to the police in the UK, other utilities used above that.
As the band was reallocated with the higher end clearer , stations started appearing above 102mhz .
Police services still used <102 which led one station newly assigned circa 104 to use the classic strapline 'on the right side of the law '
Glaceon is spot re Nova , 100.3Mhz in Dublin is allocated power of up to 10kw. It was always to be a temporary frequency for Today FM , 101.8 is allocated a power of 2kw .(we won't mention the filler on 97.3).
Back to Clermont Cairn - when was 107.9 Newstalk added and is it at a lower power than the other nationals?
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Newstalk 107.9 has a more restricted pattern to avoid significant signal into Northern Ireland (unlike RTE.. )
A couple of interesting closeup views linked below of CLermont Carn in 2017 and then 2021. The most noticeable change between the two dates is to the lower of the two UHF stacks (a backup). The lower stack in the 2017 view was the initial DTT/Saorview (which avoided NI), before moving to the higher, less directional, stack at Analogue Switch Off 2012.
Note to the right, the stub of the original Clermont Carn tower still in use for various links etc. Defunct disused low-VHF comms aerials removed between 2017 and 2021
2017 :
2021:
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