On 29/10/10 11:26, Youda He wrote:
> I would like to hear all ideas on the project, and we may try few of
> them to see which one is better in detecting speed, cheaper, lower
> maintenance. So the door is wide open, the backup plan is using radar,
> but it is kind of expensive.
>
> the speed detector will be placed about 120M apart in the middle id
> the subway tunnel, each segment will have 5 or more th detect the
> speed of the train. The train is not running at constant speed, it
> either accelerate or decelerate, therefore the video frame will need
> to be adjust constantly.
>
> -- Youda
>
encoded laser beam aimed across the tunnel a bit above the rail.
preferably red so it looks cool.

Off the brick/concrete on the other side your not going to get much=20
reflection, of the shiny lip on the inside of the wheel you should get=20
plenty.

Use something like a 40khz modulator on it to take out the influence of=20
external light sources.

Need some tweaking to get the levels right but that shouldn't be too bad.
--=20
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