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THE TRANSMISSION GALLERY

FREMONT POINT

The introduction of 625-line UHF colour television to the Channel Islands presented a problem to BBC and IBA engineers. 405-line VHF tv programmes reached the islands via an off-air feed from the mainland but providing a similar arrangement at UHF was a little trickier.

One of the most difficult problems facing the engineers was the long sea path between the Channel Islands and the mainland. The link receiving station on Alderney was rebuilt, including the installation of a very special type of computer-controlled, adaptive receiving aerial array developed by IBA engineers and called SABRE (Steerable Adaptive Broadcast Reception Equipment). This system, believed, at the time, to have been the most technically  advanced form of receiving aerial to be built for the re-broadcasting of television signals anywhere in the world, is designed automatically to minimise interference from other stations. It is used, together with large 10-metre diameter 'dish' aerials of more conventional design, to pick up the weak signals from the Stockland Hill transmitter in South Devon, more than 80 miles away. The 'beam' of the SABRE aerial is automatically steered towards Stockland Hill while at the same time sectors of reduced sensitivity ('nulls') automatically reduce interference from a changing pattern of other stations, each of which may fade or gain in strength with changing radio propagation conditions.

Today it seems that while ITV1 and Ch4 are fed to the islands by fibre-optic cable BBC1/BBC2 for Fremont Point are now sourced from the Astra 2D digital satellite transmissions with all widescreen programmes - including Sport - at 14:9 and teletext inserted locally.


The prototype SABRE aerial undergoing tests at the IBA's Engineering Centre in Hampshire.

Steerable Adaptive Broadcast Reception Equipment | Fremont Point

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