thebigtower


black mountain

 


THE BLACK MOUNTAIN TRANSMITTER is the former ITA 405-line VHF main station for Northern Ireland and currently the carrier of multiple broadcast services to Belfast and the surrounding area.

As a former 405-line main station, it is typically one of two adjacent transmission sites, the other being the UHF main transmitter at Divis.

Sited near Hannahstown towards the west of Belfast, both the Black Mountain and Divis transmitters occupy ground within the range of hills that are now promoted for tourism purposes as 'Divis and The Black Mountain' in reference to the two main summits.  The Divis transmitter is sited between these summits, whilst the Black Mountain transmitter is in a more detached position, being located on slightly lower ground along the outer edge of the hills.

Of all the examples of adjacent-sited stations, Black Mountain and Divis are amongst the closest to each other, being just over a mile apart and probably only exceeded in proximity by Crystal Palace and Croydon in London. 

 

CURRENT UHF TRANSMISSIONS

Black Mountain performs the slightly unusual function of low-power UHF relay to the adjacent Divis main transmitter.  It also hosted the analogue Channel 5 service to the Belfast area until this ceased upon Digital Switchover on 24 October 2012.

Since Digital Switchover, the station has carried the three Public Service Broadcast (PSB) multiplexes and an additional local service multiplex (NImux) which incorporates services from the Republic of Ireland.

(See UHF HISTORY below for more information)


 

 

 

 

 

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STATION HISTORY (VHF TELEVISION)

Black Mountain was the site of the tenth installation in the Independent Television Authority (ITA) 405-line VHF Band III network of transmitters, extending the Independent Television (ITV) service to Northern Ireland.

The range of hills immediately to the west of Belfast, which had hosted the existing BBC Band I television transmitter at Divis since July 1955, provided an obvious choice of grounding for the station.  The chosen site provided an elevation of 987-ft (301m), slightly lower than that occupied by the Divis transmitter.  This combined with the limitation on mast height to 750-ft (228m), due to the presence of the nearby international aiport, ultimately placed some restriction on the station's coverage capabilities.

Scheduled to radiate on VHF Channel 9, the aerial system was designed with some degree of directional capability, primarily to minimise output eastwards in order to negate the risk of interfering with mainland stations on the same channel, in particular Winter Hill.  From a single vision and a single sound transmitter rated at 4kW and 1kW respectively, an Effected Radiated Power (e.r.p) of 100kW was directed to the north-west and south-west, with 70kW directly west and 20kW across the entire eastern arc.

Black Mountain commenced regular service on 31 October 1959, following the opening just four days earlier of the ninth ITA station at Mendlesham, and broadcasting the regional output of Belfast-based Ulster Television.

Whilst the station's coverage objectives were fundamentally achieved, the limit on mast height (and therefore aerial elevation) impacted upon West Ulster, where reception of the transmitter was in many places non-existent.  This required the ITA to construct a further station at Strabane, which was designated an unmanned satellite of Black Mountain. Uncharacteristically for a relay station, Strabane not only utilised a 1000-ft (306m) mast (both taller than the mast at the parent station and also the tallest structure in Ireland) it had the same maximum Effective Radiated Power (e.r.p) capability of 100kW (although the actual maximum operating power was 90kW).

Strabane came into operation on 18 February 1963 and combined with Black Mountain extended coverage to a total population across Northern Ireland of 1.375 million.

VHF Television transmissions from both sites ceased in January 1985 upon closure of the 405-line service.

 

STATION HISTORY (UHF TELEVISION)

The role of primary UHF main station for Northern Ireland was assigned to the Divis transmitter, from where transmissions began with BBC2 in 1967.

From the start of ITV colour transmissions from Divis in September 1970, the ITA Colour Control Room (CCR) at Black Mountain became operational, remotely servicing the ITA transmitter at Divis and those subsequently opened in Northern Ireland.

As far as viewer reception of Divis was concerned, one problem that became apparent was that low-lying areas immediately south of the high ground occupied by both the Black Mountain and Divis transmitters were suffering the effects of signals 'passing-over', whereby UHF transmissions, with their 'line-of-sight' tendency, were unable to percolate downwards across the lower ground.

To resolve this issue, the decision was taken to install a UHF relay at Black Mountain which, due to its positioning on the southern fringe of the high ground, had line-of-sight to the affected areas and could receive the signal from Divis just over a mile away and direct it downwards.  With the original 500kW (e.r.p) signal having barely left the source, the Black Mountain relay required an Effective Radiated Power of just 25 watts.  The relay came into operation on 8 August 1975 and became the only example of a 405-line-only main station functioning also as a broadcast relay of the adjacent UHF main transmitter.

The Colour Control Room at Black Mountain was closed in 1981 following absorption into the IBA Regional Operation Centre (ROC) at Black Hill, the last of four such operations built to replace all of the original fourteen CCRs.  

 

The start of Channel 5 from 31 March 1997 brought additional UHF responsibility to Black Mountain, NTL having installed the service here rather than Divis in line with the practice that resulted in Channel 5 transmitters also at Burnhope, Croydon, Lichfield and Mounteagle. Black Mountain was also one of the stations to utilise UHF Channel 37, which had been released from its previous non-broadcast functions for use by the Channel 5 network.

 


SITE INFORMATION


Location:

Upper Springfield Road, Hannahstown, BT17 0LZ

Grid Reference:

J278727

Landlord:

Arqiva (Legacy: ITA/IBA/NTL Broadcast)

Ground Height:

301m

BBC Region:

Northern Ireland

Mast Height:

228.6m

ITV Region:

UTV

Aerial Height: (*)

518m

 

UHF Tx Number:

10707

(*) Channel 5 aerial height above sea level (a.o.d)  

 

 


  CURRENT TRANSMISSIONS

Digital Television

 

 

Analogue Radio (FM)

 

 

 

 

 

 

 

 

 

Service

: Ch/Polarisation/e.r.p

 

 

 

Service:

(MHz)

(e.r.p)

PSB1

: 45 / V / 0.005kW 

 

 

 

City Beat:

96.7

.55kW

PSB2

: 42 / V / 0.005kW