thebigtower


fremont point

 

 


THE FREMONT POINT TRANSMITTER is the UHF main station for the Channel Islands, located on the central northern coast of Jersey in the district of St John.

From here the station serves all of the Channel Islands, either directly or via its various dependent relays sited across Jersey, Guernsey and Alderney.

Digital television transmissions from Fremont Point are currently restricted to the three Public Service Broadcast (PSB) multiplexes due to bandwidth limitations placed upon it as a result of its close proximity to mainland Europe.  For the same reason, there were no digital terrestrial (DTT) UHF services to the Channel Islands prior to Digital Switchover (DSO) which took place on 17 November 2010, having been originally scheduled for 2013.  

Fremont Point was originally built by the Independent Television Authority (ITA) to provide the islands with their 405-line service on VHF Band III.

The Channel Islands were the last area in the network to receive Independent Television (ITV) due to both legal issues and the technical problems with providing a reliable programme feed from the UK mainland.  The latter would also result in the Channel Islands becoming the last area to broadcast 625-line UHF colour.  Had Digital Switchover taken place in 2013 as initially planned, the islands would have also been the last in the UK network to switch completely to digital.

The mainland broadcast source, currently implemented by modern methods including fibre-optic links, historically involved various feeds from mainland transmitters.  (See STATION HISTORY below)

Fremont Point currently also provides Independent Local Radio (ILR) service Channel 103 on 103.7FM.

The Les Platons transmitter, formally the BBC 405-line station serving the Channel Islands, is sited approximately two miles east of Fremont Point and currently transmits BBC National and Local FM radio and BBC National DAB radio..

TRANSMISSION STRUCTURE

Fremont Point utilises a 139-metre (456-ft) self-supporting lattice tower to carry its transmissions.  The structure is one of only four self-supporting lattice towers over 121 metres (400-ft) in height to be used for UHF broadcasting in the UK.  The heighest structures are at Crystal Palace and Croydon in London, whilst the fourth structure at Craigkelly in Fife is almost a twin of the Fremont Point tower.

The Fremont Point tower was previously used at another site having been originally deployed at Lichfield to launch the Midlands ITV service in 1956.  Likewise, the Craigkelly tower had a previous existence as the first transmitting structure at Emley Moor.


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Tower Images

 

Aerial Images

 

Station Images

 

 

 

 

 

 

 

 

 

 

 


STATION HISTORY

Fremont Point was constructed by the Independent Television Authority (ITA) to provide a local Independent Television (ITV) service to the Channel Islands.

Up until this point, viewers in the islands (particularly the northern isles) wishing to receive ITV had mainly utilised distant signals from Chillerton Down on the Isle of Wight, carrying the local programmes of Southern Television on VHF Channel 11.

The extension of ITV coverage to the Channel Islands required an amendment to the Television Act of 1954, which at the time of passing had not included the islands within the areas to be covered.

Having overcome the legal issues, the next challenge for the ITA was how to supply the islands with a stable programme feed from the UK mainland for re-broadcast from a local transmitter.  The BBC had achieved a fairly reliable link between North Hessary Tor on the mainland and their Jersey station at Les Platons, but this was with the benefit of VHF Band I which as always was more robust than the ITV VHF Band III signal in overcoming both geographic and atmospheric obstacles.

Whilst there were no major geographic obstructions here, there was some sixty miles of sea water between the mainland and Alderney, the most northerly of the Channel Islands.  This meant any inbound signal to the islands was subject to susbstantial fluctuations in strength due to the varying conditions of propagation that occur above the sea. 

Added to this, the ITA were constrained by the need to avoid interfering with transmitting stations in France, severely limiting the frequency channel options.

Having decided the best location for the broadcast transmitter in the islands was on the northern tip of Jersey, the site at Fremont Point was acquired by the ITA, placing it near the existing BBC station at Les Platons.  To carry the transmiting aerial, the ITA re-deployed the 450-ft free-standing lattice tower used at Lichfield from 1956 to 1961.

The nearest mainland transmitter at Stockland Hill in Devon, around eighty miles from Alderney, was designated as the 'feed' station to the islands.  However, this station transmitted on VHF Channel 9 which the ITA had ascertained as being the only viable frequency for use by Fremont Point.  This made a direct feed from Stockland Hill to Fremont Point impossible due to the co-channel interference issue.

With Fremont Point on the most southerly of the Channel Islands, the solution was to deploy an 'off-air' receiver station on Alderney, from where the signal from Stockland Hill could be picked up on Channel 9 and then relayed over a forty-mile multi-channel microwave link to Fremont Point.

Additionally, the Fremont Point signal would be horizontally polarised in order to mitigate the risk of co-channel interference with the vertically polarised signal from Stockland Hill.

From Fremont Point, an Effective Radiated Power (e.r.p) of 1kW (vision) was broadcast southwards, providing sufficient power to cover Jersey whilst minimising the risk of interference to France.  A further signal of 10kW was directed towards Guernsey, lying twenty-five miles to the north-west.

To further prevent interference to the Channel 9 signal received at Alderney from Stockland Hill, the output from Fremont Point towards Alderney (lying north-north-east of Jersey) was limited to 200 watts.  As a result, Alderney was left more or less unserved by Fremont Point.  To appease Alderney residents, the ITA promoted the service that could be received from Chillerton Down, even though this excluded Alderney viewers from local programming and also the reliability of this signal was dictated by the volatile overseas path in the same way as it was from Stockland Hill.

To allow for changing atmospheric conditions over the sea path from Stockland Hill, the Alderney station was also capable of receiving the Channel 11 signal from Chillerton Down for eventual re-broadcast by Fremont Point.  Additionally, in 'tropospheric lift' situations, whereby atmospheric conditions resulted in signals travelling beyond their intended area, Fremont Point was equipped to directly receive the normally out-of-range Channel 12 transmission from Caradon Hill as another re-broadcast source.  Both these options provided viable alternatives which were implemented when conditions rendered the Stockland Hill signal unusable.

Fremont Point entered regular programme service on VHF Channel 9 from 1 September 1962.

 

CLICK ON THIS LINK FOR A TECHNICAL ARTICLE REGARDING VHF FEED TO ALDERNEY FROM CHILLERTON DOWN

 

 

 

 

 

 

 

 

 

Coverage Maps

 

UHF-COLOUR AND SABRE

The provision of colour television on 625-line UHF had proved challenging in many parts of the UK as the higher frequencies of UHF Bands IV and V meant that signals were even more susceptible to the effects of geographic obstacles and atmospheric changes.

In the case of the Channel Islands, this meant the problems associated with providing a reliable VHF Band III signal from the mainland across a sea path were exacerbated with the change to UHF.  Whilst the existing VHF receiving aerial at Alderney had been designed to allow for fluctuation in the Stockland Hill signal, this capability required dramatic enhancement for UHF.

Feasibility studies concluded that the existing link from Stockland Hill to Fremont Point via Alderney remained the best option for UHF.

In addition to the issue of feed stability, the larger network of transmitters required for UHF meant there was a substantially greater risk of unwanted co-channel signals being picked up at Aldermey.

Finding a solution to these issues was placed in the hands of the engineers at the Independent Broadcasting Authority (IBA) and from their headquarters at Crawley Court (Winchester) they developed SABRE (Steerable Adaptive Broadcast Reception Equipment).

This was an extremely sophisticated computer-controlled receiving aerial system with the ability to adjust its reception pattern to (a) allow for the fluctuation in strength and direction of the signal received from Stockland Hill and (b) filter out unwanted signals received from elsewhere.

(A detailed feature on SABRE elaborating on the technicalities of the system can be found here at Mike Brown's mb21).

With SABRE successfully deployed and tested at Alderney, a UHF-Colour service for the Channel Islands commenced at Fremont Point from 26 July 1976.  The relay station at Les Touillets on Guernsey was in service from the same date, with the Alderney station becoming the second broadcast relay of Fremont Point from 1 April 1977.

In the mid-1980s, Channel Television changed their network link provider from Stockland Hill-associated Television South-West (TSW) to Television South (TVS) resulting in a new feed from the TVS studios in Southampton to Alderney via Chillerton Down.

 


  STATION INFORMATION


Location:

Fremont Point, Vingtaine du Nord, St John, Jersey

Grid Reference:

XD908280

Landlord:

Arqiva (Legacy: ITA/IBA/NTL Broadcast)

Ground Height:

166m

BBC Region:

South-West (Channel Islands Opt-out)

Tower Height (+):

139m

ITV Region:

Channel

Aerial Height (-):

244m

 

UHF Tx Number:

12800

(+) Main structure height excluding UHF antenna

 

 

(-) Average UHF 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

: 44 / H / 3.2kW 

 

 

Channel 103:

103.7

2kW

PSB2

: 41 / H / 3.2kW 

 

 

BBC National and Local:

 Les Platons

PSB3

: 47 / H / 3.2kW

 

 

 

 

 

COM4

: No service

 

 

Digital Radio

COM5

: No service  

 

 

 

 

 

COM6

: No service

 

 

Broadcast from Les Platons

 

 

 

 

 

 

 

 

PRE-DIGITAL SWITCHOVER UHF TRANSMISSIONS

(Shutdown 17 November 2010)

Analogue Television 

 

 

 

Digital Television

 

 

 

 

 

 

 

 

 

Service

  Ch/Polar/e.r.p

 

 

 

 

Service

 Ch/Polar/e.r.p

BBC1

: 51 / H / 20kW

 

 

 

 

 

 

BBC2

: 44 / H / 20kW  

 

 

 

 

No pre-DSO service

ITV1

: 41 / H / 20kW

 

 

 

 

 

 

Ch4

: 47 / H / 20kW

 

 

 

 

 

 

Ch5

: No Service

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Les Platons

 

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