A POTENT blend of technology, coincidence and political lobbying is about to give European satellite operator Eutelsat a one-off chance to crack the satellite TV monopoly which Rupert Murdoch has built up with his BSkyB service.
The new technology, which Eutelsat has been developing with Dutch electronics company Philips, makes it possible to modify a dish aerial so that it collects signals from both the Eutelsat satellite systems and the Luxembourg-based Astra systems used by Murdoch.
The coincidence arises because Astra is now launching satellites to provide digital broadcasts. These use different transmission frequencies from Astra鈥檚 analogue programmes, so Astra鈥檚 existing viewers will have to pay for their dishes to be modified if they want to watch the new programmes (Technology, 22 April). Eutelsat hopes to persuade viewers that, since they are calling in the engineers anyway, they should also adapt their receivers to accept signals from Eutelsat.
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Astra currently has four satellites in orbit at 19掳 East which transmit BSkyB鈥檚 programmes. Most channels are scrambled and available only to viewers who pay a subscription. Eutelsat has two satellites at 13掳 East, with several more planned from next summer. It transmits mainly unscrambled programmes.
Conventional dish aerials cannot receive signals from both satellites. They have an electronic device called a low noise block converter at the focal point, and when the dish is pointed at Astra, the LNB receives nothing from Eutelsat. But if two LNBs are mounted side by side and slightly offset from the focal point, one will receive signals from Astra and the other from Eutelsat.
To prevent the signals interfering with each other when they are fed to the receiver, Eutelsat has been working with Philips on a system called Diseqc, or digital satellite equipment controller. An intelligent circuit connected between the satellite receiver and the two LNBs distinguish between programme channels on Astra and Eutelsat. When the viewer selects a TV channel, the Diseqc circuit automatically selects the signal from the appropriate LNB.
Diseqc also works with the new Universal LNBs, which are needed to receive the digital signals from Astra鈥檚 digital satellites. Diseqc can switch the LNB between the low-frequency band used for today鈥檚 analogue broadcasts and the high frequency band allocated to both Astra and Eutelsat for digital transmissions.
Eutelsat鈥檚 biggest problem is that many of the dual-purpose dishes would require planning permission, because they are larger than existing dishes. Eutelsat鈥檚 signals are weaker than Astra鈥檚, and off-setting the LNBs further reduces the amount of signal which the dish collects. For clear pictures, the dual-purpose dish must be 20 centimetres wider than the 60-centimetre dishes currently used to receive Astra鈥檚 programmes.
The Department of the Environment鈥檚 planning regulations currently limit the size of the dishes to 70 centimetres in the south of Britain and 90 centimetres in the north, where satellite signals are weaker. Eutelsat is seeking blanket permission for 90-centimetre dishes.
The company has spent the last few weeks lobbying the Labour and Conservative party conferences and is 鈥渙ptimistic鈥� that the government now sees larger dishes as a way of creating more competition in the satellite market. The DoE says it is 鈥渃onsidering鈥� the issue.
Graham Allen MP, Labour鈥檚 media spokesman, was guest speaker at a meeting in Brighton where Eutelsat put its case for a larger dish. 鈥淲e are very keen indeed for Eutelsat to become effective competition to Astra,鈥� says Allen. 鈥淭here are environmental considerations but if we can help Eutelsat, we will.鈥�(see Diagram)
