Winter Hill transmitting station

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Winter Hill

Click to view the hi-res version and see the supporting cables
Height 315.4 metres (1,035 ft)
Grid Reference SD660145
BBC Region BBC North West
ITV Region ITV Granada

The Winter Hill transmitting station is a broadcasting and telecommunications site situated on Winter Hill between Chorley and Bolton, in Lancashire, England. It is owned and operated by Arqiva.

Contents

[edit] Height

The main mast structure is 309.48 metres (1,015 ft) tall and has a diameter of 2.75 metres (9.0 ft). The DTT antenna attached to the top of the mast brings the overall height to 315.4 metres (1,035 ft)[1]. It is one of the tallest structures in the United Kingdom, the tallest being the mast at Belmont with a height of 385.6 metres (1,265 ft). At 778.1 metres (2,553 ft) above sea level, Winter Hill has the highest television transmitting antenna in the UK. After digital switchover, the DTT antenna on top of the mast will be removed, reducing its overall height to 309.48 metres (1,015.4 ft)[1].

[edit] Construction

A view of the mast from beneath, illustrating the tubular structure
A view of the mast from beneath, illustrating the tubular structure

Unlike most masts, which are of a lattice design, Winter Hill mast is of a tubular construction. 5 other masts in England share this design (Belmont, Bilsdale, Mendip, Waltham and the original ill-fated structure at Emley Moor). Support wires, to hold the mast vertical, are pitched at 120° when viewed from above. These are connected at 5 heights, giving 15 supports in total. In recent years, these wires have been strengthened, and 150 tons of dampening chains have been fitted by Arqiva to reduce the oscillations caused by high winds that were a factor in the collapse of Emley Moor's original structure in 1969[2].

[edit] Maintenance

An advantage of the tubular design is that engineers can ascend the inside of the mast and not be subject to adverse weather, which is a problem on frame structures. Maintaining the outside of the mast is typically performed using a bosun's chair.

The mast has always had a series of red aircraft warning lights but in October 2006 these lights were substantially brightened making the mast far more visible to passing aircraft. These lights can be maintained from the inside, as the bulbs swing inwards for maintenance.

Eight external platforms encircle the mast along its height, these can be accessed from the inside of the mast, and are used to maintain the supporting wires, and the ILR antennas.

[edit] Coverage

The mast has an average coverage of 50 miles (80 km) circumference, encompassing approximately 6.3 million people, although this is a theoretical figure, it all depends on having a "line of sight" reception path to the transmitter. It is relatively common to find locations only a few miles away (say behind a hill or large building) who will receive a very poor signal and under these circumstances alternative transmitter(s) would be utilised, see external links. Although not the correct television region, it is the preferred region for some in North Wales, mainly due to the fact of the carriage of Channel 4 (as opposed to S4C), Five and its much more powerful digital terrestrial output compared to the Welsh transmitters. The region's ITV franchisee, Granada Television (which launched in 1956), was also on air much earlier than North Wales' franchisee, WWN (Teledu Cymru) (which launched 1962), giving viewers more choice than they would with the Welsh transmissions. After Digital Switch Over, the Welsh transmitters will be broadcasting DTT at a much higher power than present, of which Channel 4 and Five are included in the line-up. However, because of terrain and rough landscapes of North Wales, many will find it easier to stay with Winter Hill (as small local relays will only broadcast half the digital channels as Winter Hill will and does). In July 2007 it was confirmed by Ofcom that Winter Hill would be remaining a C/D group transmitter after DSO (Digital Switchover).

[edit] Output

[edit] Television

[edit] Analogue Television

Overall, the Winter Hill Transmitting Station broadcasts television signals on a total of 14 UHF frequencies using horizontal (H) polarisation. Aerial Group C/D. As with UK standards, the analogue television is output 625 line PAL, with NICAM stereo sound. Analogue channels 1-4 broadcast at 500 kW ERP. Five broadcasts at 12.5 kW ERP.

[edit] Digital Television

DTT transmissions are also carried from the site, and have been since 1998. Multiplexes 1, 2, B, C and D broadcast at 10 kW, while multiplex A (SDN / Five) broadcasts at 5 kW. As of 2006, a test transmission of a new multiplex (rumoured to accommodate a trial of BBC HD, however still unconfirmed) fluctuates broadcasting on UHF 50 at a lower power. [1] The provider name carried on multiplex itself reads "NGW", National Grid Wireless.

also

Frequency planning for DTT from Winter Hill proved difficult and it was not possible for two of the 6 main channels to cover enough of the target area. Two of Winter Hills MUXES (on CH60 and 63) are co-channel with Llanddona in North Wales see frequency table. As a consequence these two frequencies are not transmitted towards the West/South West and Ll Multiplexes C & D are therefore broadcast on two two different frequencies from 2 sets of more directional aerials, known as Winter Hill B. The duplicated copy (at UHF 43 and 40 respectively) acts as a filler for the area which the first pair could not cover. The network label carried on the HD Trial Multiplex also reads "Winter Hill B". Although CH40 and 43 are not technically within Winter Hill's original C/D group they should still be picked up on a C/D aerial see graph.

This temporary complication will come to an end with Digital Switchover, where more suitable frequencies can be used to accommodate both multiplexes to the entire region, plus the overall power of digital transmissions will be increased greatly.

[edit] Radio

[edit] FM

† Relays the signal from Holme Moss to cover South and Central Lancashire

[edit] DAB

  • CE Manchester: 11C (CE Manchester broadcasts from a directional aerial to cover Greater Manchester)
  • Digital One Network: 11D
  • EMAP Central Lancashire: 12A (EMAP Central Lancashire broadcasts from a directional aerial to cover Central Lancashire (Wigan, Preston, Southport, Blackpool and surrounding areas))
  • BBC National DAB: 12B
  • MXR North West: 12C


[edit] Plane crash

On February 27, 1958, a Silver City Bristol 170 Freighter (G-AICS) travelling from the Isle of Man to Manchester crashed into Winter Hill (also known as Rivington Moor) several hundred yards away from the mast. 35 people died and 7 were injured. The weather that night was so severe that none of the engineers working in the transmission centre were aware of the crash. Several feet of snow hampered rescue efforts, and a snow cat vehicle had to be diverted from the A6 to cut a path for emergency vehicles.

Further information: Winter Hill (air disaster)

[edit] Timeline

  • 1956: Granada Television commences black and white television broadcasting prior to main mast construction.
  • 1958: Fatal plane crash kills 35 people, 7 survive.
  • 1962: BBC commence broadcasting.
  • 1965: Main mast is completed, replacing the old 450' construction, which is removed.
  • 1966: VHF transmissions start.
  • 1968: ITV build the single storey engineering building.
  • 1969: ITV and BBC transmit in UHF.
  • 1970: Relaying service set up with Emley Moor mast.
  • 1974: Local radio stations set up wire frame ILR transmitters on the hill.
  • 1981: Channel 4 create additional engineering building.
  • 1982: Additional ILR transmitter put into operation for further local radio. Channel 4 commences transmission.
  • 1983: Channel 4 set up relay service.
  • 1997: Channel 5 commences transmission
  • 1998: Century FM radio start broadcasting from the main mast.

[edit] References

  1. ^ a b Chorley Council - Planning Applications - Ref: 07/00056/FUL
  2. ^ The Transmission Gallery - Winter Hill

[edit] See also

[edit] Further reading

  • The Devil Casts His Net, Steve Morrin, ISBN 0-9534503-1-7, The Winter Hill Air Disaster.

[edit] External links

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Coordinates: 53°37′32″N, 2°30′53″W