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Thread: Determining vehicle speed based on sound
www.piclist.com/techref/io/audio.htm?key=sound
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face BY : David VanHorn email (remove spam text)



At 10:10 PM 2/11/01 -0500, you wrote:
>Hi Dave,
>
>I didn't know about the ELTs. I already have my method working for
>monotonic signals (i.e., if a sine wave generator goes by, it can
>determine the speed easily),the problem is that I don't have many
>suitable recordings of actual cars (which is a much more difficult case,
>since I have to determine speed from the engine noise and sound of the air
>going over the car). I don't have any recordings where I know (from some
>independent source) what speed the car was going.

Well, that's what I'm saying. It's not the absolute freq that matters, it's
the slope, and the amplitude of the slope.
You know the shape from your experiments.


>Yeah, I could go out and record by the side of a highway, but I still
>wouldn't know exactly how fast they were going, and I don't have enough
>time before the due date to get a radar gun or something like that, or to
>recruit other people to record a car at known speeds.
>(Come to think of it, it would be gratifying to see all those brake
>lights come on when I keyed the radar transmitter ;-)

Then they'd mung your data! :)


>Any idea where I can get such recordings?

EEk.. Hollywood, I'd guess, not cheap either.
Somewhere, there's a box of tapes with lables like "Car passing at 35, lane
2"

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