Mendip transmitting station

Mendip
The Mendip UHF Television Mast
Height of mast	293 metres (961 ft)
Grid reference	ST564488
Built	1967
BBC region	BBC West
ITV region	ITV West

The Mendip UHF Television Mast

The Mendip transmitting station is a broadcasting and telecommunications facility, situated on the summit of Pen Hill, part of the Mendip Hills range in Somerset, England, at 305 metres (1,001 ft) above sea level. The station is located in St Cuthbert Out civil parish in Mendip district. It includes a 281.6 metres (924 ft) tall mast, which was built in 1967 and weighs around 500 tonnes, and is the tallest structure in the southwestern England. The mast currently broadcasts digital television, FM analogue radio and DAB digital radio, and had broadcast analogue colour television from 1967 until 2010.

Until 2008 a GRP aerial cylinder, which contains the analogue television transmitting antennas, was located at the top of the mast, bringing the total height of the structure to 305 metres (1,001 ft). With a mean height of 596 metres (1,955 ft) above sea level, the analogue television antennas were amongst the highest in the UK. The analogue television antennas were removed in 2010, the original antenna cylinder being replaced with a new antenna assembly, ready for digital switchover in 2010. The new assembly is slightly shorter than the previous cylinder causing the overall mast height to be reduced from 305 metres (1,001 ft) to 293 metres (961 ft).^[1]

There are around twelve red aircraft warning lamps (six sets of two lights) up the mast with two lights on top. The lights were upgraded in February 2007^[2] to comply with CAA 2000 Air Navigation Order, designed to prevent low flying aircraft from hitting the mast in adverse weather conditions.

The station is owned and operated by Arqiva (which acquired the National Grid Wireless, previously Crown Castle.)

The mast was entirely repainted during 2007.

The mast has become a well known and loved Mendip landmark and can provide some spectacular images when engulfed in fog or cloud or illuminated in full sunlight. It also provides a unique method of identifying the hills from a distance.

Television

Mendip was set up as a C/D group transmitter when it entered service with analogue PAL transmissions. In July 2007, Ofcom confirmed that it would remain a C/D group transmitter at digital switchover. The mast broadcasts digital television over a large area of the west of England, including Somerset, Wiltshire, North Somerset, Bath and North-East Somerset, Bristol, South Gloucestershire and Southern Gloucestershire. The station also covers the coastal areas of south east Wales, and in the days of analogue TV, many households used it in preference to their more local station, Wenvoe. This is because prior to the digital switchover, Mendip carried Channel 4 and Channel 5, whereas Wenvoe only carried S4C, which broadcast a lot of Welsh language programming. Indeed many houses still have aerials directed at both stations. Power on analogue transmissions was 500 kW (erp) on channels 1 to 4 but only 126 kW on Channel 5. The latter was transmitted outside of the original C/D grouping of the transmitter but most people in reasonable signal areas could receive it anyway, see aerial gain curves. All 6 digital multiplexes were transmitted at 10 kW until switchover in 2010 when the power on the "BBC A", "BBC B/HD" and "D3&4" multiplexes was boosted to 100 kW. In 2011, SDN was boosted to 50 kW and in 2012 the remaining two Arqiva multiplexes will be boosted to 50 kW too. Mendip's population coverage is around 1.5 million, although some homes in the immediate vicinity, such as those in Cheddar are unable to receive a signal due to being in the shadow of the Mendip Hills and therefore have to depend on local relays.

Radio

Mendip broadcasts FM (analogue VHF) radio for BBC Somerset and the Severn Estuary Regional service of Galaxy 101 (now known as Kiss 101). It transmits high power Digital Audio Broadcasting (DAB) signals for Digital One and BBC National DAB multiplexes, as well as a lower power local service to Glastonbury for MXR Severn Estuary. These three multiplexes carry approximately ten digital radio stations each. An additional DAB multiplex, MuxCo Somerset, was awarded a licence in 2008 to broadcast local and national services to Somerset. As of 2010, it is expected that MuxCo Somerset will use the Mendip station, though transmissions have yet to commence.^[3]

Output

Radio

Analogue

Frequency	kW[4]	Service
95.5 MHz	5	BBC Somerset
101.0 MHz	40	Kiss 101

Digital

Frequency	Block	kW[5]	Operator
222.064 MHz	11D	5	Digital One
225.648 MHz	12B	5	BBC National DAB
227.360 MHz	12C	0.75	MXR Severn Estuary

Television

Analogue

Mendip radiated all 5 analogue services until the digital switchover between 24 March - 7 April 2010.

Frequency	UHF	kW	Service
599.25 MHz	37	126	Channel 5
735.25 MHz	54	500	Channel 4
767.25 MHz	58	500	BBC One
791.25 MHz	61	500	ITV1
815.25 MHz	64	500	BBC Two

On 24 March 2010 BBC Two was switched off on UHF 64 and ITV1 was switched from UHF 61 for its final weeks of service. UHF 61 was then used to carry the digital BBC A multiplex at full power (100 kW), the first digital multiplex to reach full power from the site.

Frequency	UHF	kW	Service
599.25 MHz	37	126	Channel 5
735.25 MHz	54	500	Channel 4
767.25 MHz	58	500	BBC One
815.25 MHz	64	500	ITV1

Digital switchover was completed on 7 April 2010. All analogue TV was discontinued permanently from this date. See below for the initial configuration of the digital TV transmissions.

Digital

Digital terrestrial television was first transmitted from the Mendip mast from 15 November 1998 using the frequency gaps between the analogue TV broadcasts. In order to limit possible interference to the analogue transmissions, power output on the digital multiplexes was comparatively very low. Until the start of the Digital Switchover process on 28 March 2010 the frequencies were:

Frequency	UHF	kW	Operator
746.2 MHz	55+	10	Digital 3&4 (Mux 2)
754.2 MHz	56+	10	Arqiva (Mux C)
778.2 MHz	59+	10	BBC (Mux 1)
802.2 MHz	62+	10	SDN (Mux A)
826.2 MHz	65+	10	BBC (Mux B)
842.0 MHz	67	10	Arqiva (Mux D)

On 28 March 2010, Multiplex 1 on UHF 59+ was closed and replaced by BBC A on UHF 61 (which had just been vacated by analogue ITV1). BBC A was transmitted at full power (100kW) and in 64QAM, 8k carriers mode from the start. Until 7 April 2010, the frequency allocation was now:

Frequency	UHF	kW	Operator
746.2 MHz	55+	10	Digital 3&4 (Mux 2)
754.2 MHz	56+	10	Arqiva (Mux C)
794.0 MHz	61	100	BBC A
802.2 MHz	62+	10	SDN (Mux A)
826.2 MHz	65+	10	BBC (Mux B)
842.0 MHz	67	10	Arqiva (Mux D)

Following the completion of analogue TV shutdown on 7 April 2010, Mendip transmitted all of its higher powered multiplexes at 100 kW. From this date until the second-stage switchover of 27 September 2011 the frequency allocation was:

Frequency	UHF	kW	Operator
738.0 MHz	54	100	Digital 3&4
754.2 MHz	56+	10	Arqiva A
770.0 MHz	58	100	BBC B
794.0 MHz	61	100	BBC A
802.2 MHz	62+	10	SDN
842.0 MHz	67	26	Arqiva B

With the completion of digital switchover at Oxford, all multiplexes could be moved to their final channel allocations with the exception of Arqiva A. SDN increased to full power output. From 28 September 2011 to 28 March 2012 the current frequency allocation is:

Frequency	UHF	kW	Operator
690.0 MHz	48	50	SDN
722.0 MHz	52	26†	Arqiva B
738.0 MHz	54	100	Digital 3&4
770.0 MHz	58	100	BBC B
794.0 MHz	61	100	BBC A
842.0 MHz	67††	12.5†	Arqiva A

† Power level expected to be increased to 50kW in March 2012 after completion of digital switchover at Salisbury.
†† Temporary parking channel. Final channel TBC, awaiting completion of digital switchover at Salisbury.^[6]

See also

• List of masts
• List of radio stations in the United Kingdom
• List of tallest buildings and structures in Great Britain

References

1. ^ Planning Application Details
2. ^ http://www.cheddarvalleygazette.co.uk/displayNode.jsp?nodeId=216909&command=displayContent&sourceNode=216903&contentPK=16636764&moduleName=InternalSearch&formname=filtersearch
3. ^ "South West England and Wales". Frequency Finder. http://frequencyfinder.org.uk/DAB_SW_map1.pdf. Retrieved 23 August 2011. 
4. ^ Radio Listeners Guide 2010
5. ^ Radio Listeners Guide 2010
6. ^ 'Digital UK' Press Release

External links

• The Transmission Gallery: photographs, coverage maps and information
• Pictures and info on Mendip including co-receivable transmitters
• Entry at skyscraperpage.com
• Mendip Transmitter at thebigtower.com

Coordinates: 51°14′13″N 2°37′31″W / 51.23694°N 2.62528°W / 51.23694; -2.62528