PIRATE radio broadcasts are usually easy to ignore鈥攗nless they are
squatting on the frequency of your favourite station. But illegal radio
operators in Britain have now hit on a way of forcing hapless motorists to
listen to them. And their trick will work in any country using the
internationally agreed Radio Data System (RDS) standard, which is used across
Europe and South Africa and is now being adopted in Australia, China and the
US.
RDS buries digital code in FM signals so that radios can seek out any local
stations broadcasting traffic news. The local 鈥渢raffic announcement鈥� signals
temporarily switch the car radio from another station鈥攐r any tape or CD
someone happens to be playing鈥攖o receiving the traffic update. Afterwards,
RDS takes the listener back to what they were listening to.
But Britain鈥檚 Radio Investigation Service says the pirate
broadcasters鈥攐ften ingenious engineers鈥攈ave now harnessed RDS for
their own ends. They appear to have used the published RDS standards to make
devices that constantly transmit a traffic news signal to grab listeners. The
strong signal swamps any car radio in the pirate鈥檚 coverage area, forces it to
recognise the unauthorised 鈥渢raffic鈥� signal and tune in to the pirate鈥檚 station.
Because the pirate continually transmits the phoney flag, the radio stays tuned
in until the car goes out of range or the driver switches off the RDS
feature.
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The radio investigators say they are now close to raiding and seizing the
equipment of an RDS pirate operation鈥攁 move which will allow them to find
out precisely how they operate their listener-stealing trick. They then hope to
help broadcasters around the world develop countermeasures.