thebigtower


black hill

 

Above: The two masts at Black Hill in April 2010, the earlier structure appearing the taller from this northerly position.


THE BLACK HILL TRANSMITTER is the UHF and BBC National FM main station for the central lowlands of Scotland, serving both Glasgow and Edinburgh and much of the surrounding territory across Lanarkshire, Renfrewshire, Ayrshire, Lothian and Fife.

It was originally the main ITV 405-line VHF transmitter for the same area and also the first ITA transmitter to be established in Scotland.  Typically, it is sited adjacent to what was formally the equivalent BBC 405-line Band I station for the area, this being the transmitter at Kirk o'Shotts which now broadcasts various DAB radio services.

Previously, the Black Hill site has housed an IBA Regional Operation Centre (ROC) and a BBC Monitoring and Information Centre (MIC), respectively centralised since to Emley Moor and Warwick.  The latter accounts historically for the larger of the two main building complexes on this site, located to the right of the main entrance. (See Site Building Images 2003)


Aerials (1)>  Aerials (2)>  Site Buildings Index>  Supersize Images>  Landscapes (800x600 or 1024x768)>  UHF Map


 

 

 

 

 

 

 

 

 

 

 

 

 

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THE MAST AND DIGITAL SWITCHOVER

Black Hill originally transmitted UHF from the station's 1961 structure which is a 306.5 metre (1005-ft) triangular cross-section lattice stayed mast.  Originally built to replace the initial 1957 structure (see VHF History below) it was however unable to meet the engineering requirements for Digital Switchover and therefore succeeded for the purpose of television transmission by a further new mast, construction of which began in the latter part of 2008 and completed in 2010.

The replacement of an existing 306-metre (1000-ft) mast has also taken place at Caldbeck, this being the one other site of ITA origin to require a new structure for Digital Switchover.  The stations at Divis, Rowridge and Tacolneston, which are all former BBC sites, have also undergone mast replacement for the switchover.

Black Hill became the last main transmitter site in Scotland to complete Digital Switchover, the two stages of the process taking place on 8 June 2011 (DSO1) and 22 June 2011 (DSO2) respectively.  Since then, all television transmissions have been from the new mast with the original structure expected to be retained at reduced height to continue with FM and DAB radio transmissions.

AERIAL GROUPING

Originally placed within Group B aerial bandwidth based on the original analogue channel allocation, Black Hill required Group E receiving aerials in order for all the pre-DSO digital multiplexes to be received (based on the channels assigned to MuxC and MuxD).  However, under the switchover Black Hill has reverted to Group B as all the current PSB/COM multiplexes fall within the group parameter.  (See CURRENT TRANSMISSIONS table below)  


 

 

 

 

 

 

 

 

 

 

 

 

Aerials (1) - Original Mast

 

Aerials (2) - New Mast

 

UHF Coverage Map

 

 

 

 

 

 

 

 


UHF AERIAL SYSTEM (PRE-DSO)

The 1961 mast at Black Hill featured a highly non-conventional UHF aerial system, comprising a multitude of multi-panel arrays installed on the upper 60m (200ft) of the structure, as opposed to a GRP-cylinder based system or multi-panel array mounted on top.  (See UHF Aerials page for close-up images)

The station has a history of unusual aerial installations dating back to the 405-line VHF system. (See VHF History below). 


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Images from 2003

 

Images from 2008 (800x600 or 1024x768 version)

 


VHF TELEVISION HISTORY

BACKGROUND

The Black Hill station was built by the Independent Television Authority (ITA) in order to establish an ITV service in Central Scotland on the original 405-line VHF Band III system.

The area was the fourth in the ITV network roll-out with Black Hill the ITA's fifth transmitting station - two having been required for the North of England region.  The Black Hill site was approximately fifteen miles east of Glasgow and roughly halfway between the aforementioned and Edinburgh.

It was also close to the existing high-power BBC Band I transmitter at Kirk o'Shotts, enabling the ITA to once again adhere to the practice of adjacent siting, having deviated from this with their third and fourth stations located in Northern England.

 

THE ORIGINAL MAST AND AERIAL

The catchment area of the transmitter would naturally include both Glasgow and Edinburgh but the ITA also aimed to cover the city of Dundee, some 50-60 miles away on the east coast.  This required, as it did at may other sites, the development of an aerial with highly-directional capabilities but in this instance the authority went against convention by designing a system that would sit inside the mast framework instead of the normal external mounting, mainly to reduce the effects of both ice and wind loading on the structure.  This was made possible in part by the equally unconventional use of a 750-ft (228m) mast with square cross-section rather than the usual triangular.  From this aerial system, the maximum effective radiated power of 475kW (vision) was directed north-east towards Dundee whilst 250kW was directed south-west towards Ayrshire, with the north-west and south-east receiving 150kW, all delivered from two 10kW (actual power) vision transmitters and two 2.5kW sound transmitters.

However, it was clear before the station came into regular service that this system was not performing as predicted, the problems ranging from insufficient power in some directions (most significantly towards Dundee) to more complex issues such as a shift in signal polarisation from the intended vertical to horizontal in respect of transmissions towards the south-west.  The overall effect of this was a somewhat reduced and partially displaced coverage area.

 

THE NEW MAST

Pending a solution to these problems, the station came into regular operation on 31 August 1957 with Glasgow-based Scottish Television providing the regional service.  The solution to the aerial problem, which eventually came in 1959, was to scrap the 'inside the mast' system in favour of a standard externally mounted arrangement.  The only way to implement this without interrupting the service was to install the replacement aerial on a new mast.  With this being the sole viable option, the ITA took the opportunity to upgrade the site to a 1000ft (306m) mast in order to augment the performance of the new aerial.

Construction of the new triangular cross-section mast, in close proximity to the existing structure, began in August 1960 and became fully operational on 10 July 1961.  The original mast was then dismantled and soon re-erected at the new Selkirk station in the Scottish Borders, from where it became operational again from 1 December that same year.

The performance of the new mast and aerial was deemed to be 'satisfactory' producing an overall improvement in reception and an expanded service area that was as near as it could be to that originally intended.  In practice, this meant that fringe areas saw a significant improvement in reception, with the exception of the Dundee/Tayside area which remained problematic and which by this time was also receiving mediocre coverage from the then recently opened Durris transmitter.  This issue would be resolved finally in October 1965 when the Dundee area received its own local transmitter at Angus, with Scottish Television formally losing the territory to Grampian Television in the process.


Aerials (1)>  Aerials (2)>  Site Buildings Index>  Supersize Images>  Landscapes (800x600 or 1024x768)>  UHF Map


 

 

 

 

 

 

 

 

 

 

 

 

 

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UHF HISTORY

On 9 July 1966, Black Hill began transmitting BBC2 and as such became the first transmitter in Scotland to broadcast UHF.  With a high mast capable of supporting UHF aerials and a site with plenty of ground for expansion, Black Hill was an obvious choice for UHF compared to the BBC Kirk o'Shotts site.  

UHF transmission for BBC1 and ITV commenced from Black Hill on 13 December 1969, the station falling within the second group of transmitters to have these services upgraded to 625-line colour.

From the same date, the ITA Colour Control Room (CCR) for Central Scotland came into operation at Black Hill.  This continued until 1981, when the station followed Croydon, Emley Moor and St Hilary in becoming the base of one of the four IBA Regional Operation Centres (ROCs) built to replace the original fourteen Colour Control Rooms.  The Black Hill ROC was responsible for monitoring IBA transmitters across the whole of Scotland and Northern Ireland, thereby absorbing the CCRs at both Durris and Black Mountain.

Later on, the BBC moved their equivalent Monitoring and Information Centre (MIC) from Kirk o'Shotts to Black Hill, resulting in the construction of an additional operations complex near the mast base.


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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STATION INFORMATION


Location:

Duntilland Road, Salsburgh, North Lanarkshire

Grid Reference (+):

NS828647

Landlord:

Arqiva (Legacy: ITA/IBA/NTL Broadcast)

Ground Height:

275m

BBC Region:

Scotland

Mast Height:

306.5m

ITV Region:

STV Central

Aerial Height: (*)

543m

 

UHF Tx Number:

10500

(*)  Average UHF aerial height above sea level (a.o.d)  

 

 

(+)  Ofcom indicate NGR for new mast as NS831645

 

 


CURRENT TRANSMISSIONS

Digital Television  

 

Analogue Radio (FM)

 

 

 

 

 

 

 

 

 

Service

: Ch/Polarisation/e.r.p

 

 

 Service:

(MHz)

(e.r.p)

PSB1

: 46 / H / 100kW 

 

 

BBC Radio 1:

99.5

250kW

PSB2

: 43 / H / 100kW 

 

 

BBC Radio 2:

89.9

250kW

PSB3

: 40 / H / 100kW 

 

 

BBC Radio 3:

92.1

250kW

COM4

: 41 / H / 100kW 

 

 

BBC Radio 4:

95.8

250kW

COM5

: 44 / H / 100kW

BBC Radio Scotland:

94.3

250kW

COM6

: 47 / H / 100kW 

 

 

BBC Radio nan Gaidheal:

104.7

10kW

 

 

 

Classic FM:

101.7

250kW

Digital Radio

 

 

Clyde 1:

102.5

15kW

 

 

 

 

Forth:

97.6

100kW

Glasgow (Block 11C)

 

 

Capital FM Scotland:

106.1

20kW

Edinburgh (Block 12D)

 

 

Real Radio Scotland:

100.3

20kW

BBC National and others from Kirk o'Shotts

 

Smooth Radio Glasgow:

105.2

30kW

 

 

 

 

 

 

 

PRE-DIGITAL SWITCHOVER UHF TRANSMISSIONS

(Shutdown completed 22 June 2011)

Analogue Television 

 

 

 

Digital Television

 

 

 

 

 

 

 

 

 

Service

  Ch/Polar/e.r.p

 

 

 

 

Service

 Ch/Polar/e.r.p

BBC1

: 40 / H / 500kW

 

 

 

 

Mux1

: 41 / H / 20kW

BBC2

: 46 / H / 500kW  

 

 

 

 

Mux2

: 47 / H / 20kW

ITV1

: 43 / H / 500kW 

 

 

 

 

MuxA

: 44 / H / 20kW

Ch4

: 50 / H / 500kW

 

 

 

MuxB

: 51 / H / 20kW

Ch5

: 37 / H / 500kW

 

 

 

 

MuxC

: 55 / H / 20kW

 

  

 

MuxD

: 65 / H / 20kW

 

 

 

 

 

 

 

 

 


Black Hill Transmitter @ A.T.V (Aerials and Television)

 

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