Please see my replies below:

On Sun, 11 Feb 2001, David VanHorn wrote:

> 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.
>

Well, with the sine generator case, I can determine the speed without
knowing what freq the generator was set to. The problem I'm having with
the cars is that it is hard to determine what the original car engine
spectrum looks like. It isn't purely periodic, so there is some spreading
already, before the doppler effect. The amount of spreading affects my
measurement. On top of that, most of the recordings I have are for cars
which were revving their engines up as they approach, and possibly
throttling back when they pass, so there are non-doppler induced frequency
changes.


Also, I'm not sure what you mean by "amplitude of the slope".

> Then they'd mung your data! :)

True, but I'd like to see that :-) I think some companies sell (used to
sell?) little 10 GHz CW transmitters in a small case with a transmit
button on them. You could go near a highway and just press the button and
see all the lights come on. Not sure if this cased any accidents, though.
I never had one.

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

Yeah, that's exactly what I need. I used to think you could find almost
anything on the internet, but I'm not having luck with this. Any hints on
keywords to search?

Thanks,

Sean


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