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thebigtower |
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divis |
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THE DIVIS TRANSMITTER is the main high-power UHF and BBC National FM/DAB station that serves County Antrim and parts of County Down. Sited just outside Belfast, it is the primary UHF/FM main station in Northern Ireland and was originally the country's main BBC 405-line television transmitter, coming into operation in this capacity in July 1955. As such, it was the first permanent television transmitter to be established within Ireland. Although one of three UHF main stations in Northern Ireland, it is the only one to feature a stayed mast, the other stations at Brougher Mountain and Limavady both utilising smaller self-supporting towers. Stayed masts are however located at the UHF relay stations at Londonderry and Strabane (respectively former BBC and ITA 405-line relays) and at Black Mountain, the former ITA 405-line main station and current transmitter of 'Five' that is sited adjacent to Divis. The Divis station is located in a range of hills directly overlooking Belfast to the east, in an area which for many years was controlled by the Ministry of Defence, until it was sold in 2004 to the National Trust and subsequently opened to the public. It is sited between the peaks of Divis Mountain and Black Mountain and is ironically closer to the latter than the transmitter that is named after it. |
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Aerials> Landscape Enlargements> Supersize Portraits> UHF Coverage Map |
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THE MAST AND DIGITAL SWITCHOVER |
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The Divis mast is a square cross-section lattice stayed structure, typical of those sited on stations originally constructed by the BBC as medium-power installations for their 405-line television network. It stands at a basic height of 141.7 metres (465-ft) before the addition of the main UHF aerial array at the top. The main UHF aerial array is a multi-panel arrangement which was installed in 1992, replacing the original GRP-cylinder-based aerial system that had been in use since 1967. (See Aerials page). Having first come into operation in July 1955, the Divis mast is the longest serving in the UK for the purpose of continuous television transmission, earlier masts having been replaced or located on sites not used for broadcasting UHF. However, in January 2009 it was confirmed that Divis would join Black Hill, Caldbeck, Rowridge and Tacolneston in requiring a new mast to support the aerial system needed for Digital Switchover. The new structure will be taller than the original with a projected height of 192.7 metres (632-ft). Once the original mast is decomissioned, the honour of longest serving television mast will pass soon after to Pontop Pike at which site the structure became operational in November 1955. |
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Aerials> Landscape Enlargements> Supersize Portraits> UHF Coverage Map |
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TELEVISION HISTORY |
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Divis was opened by the BBC on 21 July 1955 as their permanent 405-line Band I transmission facility serving Northern Ireland. It superceded the temporary station at Glencairn, which was one of two transmitters (the other being Pontop Pike) to be rushed into operation on 1 May 1953, in time for the televised Coronation of Queen Elizabeth II. Although the BBC had by this time already obtained the Divis site, the need to construct the long access road was the primary factor preventing it's immediate use for a provisional installation. Divis was designated as a medium-power transmitter, on which type of installation the second phase of BBC Band I stations were based. In this respect, Divis was grouped with permanent installations at Meldrum, North Hessary Tor, Pontop Pike, Rowridge, Sandale and Tacolneston. Transmissions from Divis were on VHF Channel 1 at a peak output of 35kW vision e.r.p. In due course, a number of relay stations were established across Northern Ireland to enhance coverage from Divis, most notably at Brougher Mountain in County Fermanagh, the latter being the site of a future UHF main station. In the meantime, the Independent Television Authority (ITA) built their equivalent 405-line VHF Band III station close to Divis. Located at Black Mountain quarry, less than two miles to the south-west, this came into operation on 31 October 1959 and utilised a taller 750-ft mast. Divis however became the UHF main station for Belfast and surrounding area with BBC2 the first regular service commencing 18 March 1967. Colour UHF transmitters for BBC1 and ITV came into operation in September 1970. |
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Transmission Site Images |
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Both this site and Black Mountain are perhaps not surprisingly (bearing in mind the area history) dual ring-fenced for enhanced security, consequently limiting the views available. So for now, here are just two images from overhead. Larger versions included on Landscape Enlargements |
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The following two images show the adjacent Black Mountain mast from Divis. The first image was taken from the area access road ascending towards the peak of Divis Mountain, with the Divis transmitter site just out of view to the left. |
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Aerials> Landscape Enlargements> Supersize Portraits> UHF Coverage Map |
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SITE INFORMATION |
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Location: |
Hannahstown, County Antrim, BT17 0NG |
Grid Reference: |
J286750 |
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Landlord: |
Arqiva (Legacy: BBC/Crown Castle/NGW) |
Ground Height: |
365.8m |
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BBC Region: |
Northern Ireland |
Mast Height: |
141.7m |
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ITV Region: |
Ulster (UTV) |
Aerial Height: (*) |
512m |
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UHF Tx Number: |
10700 |
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(*) Average UHF aerial height above sea level (a.o.d) |
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CURRENT TRANSMISSIONS |
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Analogue Television (Until 2012) |
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Analogue Radio (FM) |
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Service |
: Ch/Polarisation/e.r.p |
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Service: |
(MHz) |
(e.r.p) |
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BBC1 |
: 31 / H / 500kW |
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BBC Radio 1: |
99.7 |
250kW |
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BBC2 |
: 27 / H / 500kW |
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BBC Radio 2: |
90.1 |
250kW |
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ITV1 |
: 24 / H / 500kW |
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BBC Radio 3: |
92.3 |
250kW |
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Ch4 |
: 21 / H / 500kW |
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BBC Radio 4: |
96.0 |
125kW |
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Five |
: No service - transmitted from Black Mountain |
BBC Radio Ulster: |
94.5 |
250kW |
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Classic FM: |
101.9 |
250kW |
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Digital Television (Until 2012) |
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Digital Radio |
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Service |
: Ch/Polarisation/e.r.p |
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Mux1 |
: 29 / H / 2.3kW |
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BBC National (Block 12B) |
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Mux2 |
: 33 / H / 2.3kW |
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MuxA |
: 23 / H / 2.3kW |
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MuxB |
: 26 / H / 2.3kW |
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MuxC |
: 48 / H / 3.0kW |
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MuxD |
: 34 / H / 2.7kW |
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