Tuesday 25th April 2006

Can they catch you using sound?

Acoustics developed as sneaky speeding deterrent

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Just watch for microphones

The next technology under development to catch you speeding is based on sound. According to New Scientist magazine, a system developed by the University of Tennessee and the Battelle Institute uses microphones hidden in the road verge to capture the sound of passing cars.

There's no radiation, radar or other telltale sign that there's a detector there, which might defeat the point of having detectors -- but that's another issue. It's what happens after the sound has been capture that's intriguing.

Captured sound is digitally filtered to remove background noise and then, according to the report, software can calculate the speed of the vehicle by the sound of its engine. It uses knowledge about the type of engine, the angle and type of road at the capture point, and the Doppler shift as the car passed by.

It can measure engine speed by detecting firing pulses and comparing the noise with a library of acoustic signatures. This allows it to estimate the size of engine, we're told. How it'll cope when most vehicles use just a handful of engines -- a point we're rapidly approaching -- isn't known.

It's been tested too, by recording vehicles travelling at known speeds and comparing results. The system measured the correct speed within a few percentage points in 32 out of 33 instances.

Developed with funding from the US Department of Energy, the system has been patented.

Scary or what?

[dax_j]

Not sure how this will work, I mean it can't tell which gear you are in and even if engines are the same doesn't mean that they will have the same gearing ratios.

[F.M]

speeding is the latest greatest crime...

[supermono]

The inginuity of these boffins defies belief. Just imagine how road deaths could be reduced if these guys concentrated on ways of improving road safety!

SM

[catso]

And an 8 cyl engine will sound twice as fast as a 4 at the same RPM........

[oldie]

there's two posts of this topic ---here and

www.pistonheads.com/gassing/topic.asp?t=263777&f=10&h=0&p=2.

T'OTHER ONE HAS 2 PAGES