New Scientist
magazine reports that researchers at the University of Tennessee and Batelle Institute have applied for patents on a
system that detects the speed of a passing vehicle based on its exhaust note.
The system uses microphones to
capture the sound of a passing car, and then filters out all but the sound made by the engine. By measuring the doppler
shift of the engine sound as it moves past the speed trap, the system can calculate the vehicle’s speed.
While the sound detector is unobtrusive and completely passive (therefore undetectable by a conventional radar/laser
detector), identifying speeders will require something a little less stealthy, like a traffic camera. Of course, other
early detection systems are possible, like the subtle warning in the accompanying picture.
Hmmm. Sounds like
better muffler technology is in order.
[Source: New Scientist]