[sdiy] Has anyone seen (or played with smthing like) this ?

[Richard Wentk]

On 24 Jun 2007, at 21:23, Mike wrote:

>>>> But here they use the LEDs themselves as sensors in Phode diode
>>>> mode ?
>>>
>>> Yep, and the thing is no use with any ambient light...
>>
>> Wouldn't it be easy to put together a negative version, where it
>> sensed lack of ambient light from whichever diodes were covered?
>>
> How about feeding the illuminated LED's from a PRBS source, and  
> correlating
> to remove the ambient? I've made this approach work for acoustic  
> radar.

That's a good solution too.

I don't see big fingers as an issue. You can deal with that by  
including some fairly simple averaging software across multiple LEDs.  
Assume X-Y independence to reduce it to a single dimensional problem  
on each axis and add some interpolation to stop sudden jumps -  
something you'll need anyway - and there's not much else needed.

Richard