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Sunday, June 20, 1999 Published at 11:56 GMT 12:56 UK


Pictures on the radio

Pictures transmitted without need for expensive satellites in space

By Tristan Chytroschek of BBC Science

A new way to transmit pictures has been developed that could hugely cut the cost of sending information around the world.

The same technology used to transmit shortwave radio signals could be used to send images without the need for expensive cables or satellites.

High-frequency radio waves can be picked up virtually anywhere in the world with a relatively cheap radio set, as everyone who listens to the BBC World Service on shortwave knows.

But radio waves that can carry sound and voice can also carry data. This has been exploited by engineers working for the British Defense Evaluation and Research Agency and for Lancaster University in the UK, who have developed a system that connects a digital camera to a radio transmitter.

Static problems

Pictures taken with the camera are translated into electrical signals and then transmitted via radio without the need for expensive landlines or satellites. But there is one problem - static.

Paul Arthur: Unique coding technique
The interference that often makes it impossible to listen to radio transmissions. The scientists faced the same problem when they tried to transmit their pictures, but they say they can separate the signal from the background noise.

"We've come up with a special unique coding technique that actually gives enough protection to the data, so that when it's passed over this quite distortive medium, we can still get images out at the other end," said scientist Paul Arthur.

They have successfully tested this system by sending pictures over a distance of 80 kilometres and the nature of shortwave radio means it is actually simpler to transmit signals over much longer distances.

This system could be used to transmit x-ray photographs between hospitals, send electronic books to schools or simply as a fax machine without a telephone network.

For many people living in remote areas, pictures on the radio could open a whole new window to the world.

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