AN INVENTION intended to help emergency vehicles cut through traffic has run into trouble.
Called the Warn-Tone, the device has been developed by James Hutchison, a firefighter from Buckinghamshire. His idea is to warn drivers an emergency vehicle is coming before they hear its siren.
Although most drivers react quickly to sirens, many others cause delays and accidents by responding too slowly, or by driving dangerously once they realise they鈥檙e causing an obstruction.
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Hutchison, who regularly has to negotiate crammed streets in a 12-tonne fire engine, blames improved vehicle soundproofing, high-output stereos, and a simple lack of road awareness on the part of drivers.
Warn-Tone transmits a spoken message that interrupts car radios and CD players, alerting drivers up ahead that an emergency vehicle is approaching. The root of the controversy is the question of just how far the signal will spread.
Hutchison claims only vehicles up to 100 metres ahead of the device should be affected, but Mark Thomas, head of engineering at the Radio Authority, the body which licenses radio frequencies in Britain, disagrees. 鈥淔or a variety of reasons, notably interference with radio receivers over a radius of several kilometres, the whole concept is logically flawed,鈥� Thomas says.
The device is designed to scan the seven strongest radio signals in an area through which the emergency vehicle is travelling. It then broadcasts a warning tone on each frequency in turn 鈥� cycling once a minute. Additionally, it uses an alarm function that鈥檚 part of the standard Radio Data System (RDS) to interrupt non-radio output such as cassette tapes and CDs.
Hutchison claims that a transmitter power of tens or perhaps hundreds of milliwatts would be sufficient for the system to work without causing interference in nearby homes and offices, because car radios are far more sensitive than domestic radios, and a directional antenna will ensure the signal is only transmitted forwards in a narrow beam.
His idea has been well received by fire chiefs, who are under government pressure to get to emergencies faster. More than 20 fire departments in Britain have expressed their support. The next step, Hutchison argues, is to test the system on the roads.
鈥淲e鈥檝e been offered a Fire Service training ground so we can acquire data on the practical issues involved,鈥� he says. 鈥淲e need to try different transmitter levels and antenna combinations, but without the test licence, we鈥檙e stuck.鈥�
But the Radio Authority remains unconvinced, citing its knowledge of the way radio waves propagate over long distances. 鈥淭here鈥檚 no point in allowing these tests, because we know what the results will be,鈥� Thomas told New 杏吧原创.