Hi everyone, im after some guidance in regard to s project im doing.
Looking at using ~20 horizontal IR leds to detect a specific sized object as it passes through a field of beams.
They will span approximately 50cm vertically, and i need to know which beams are broken at exact points in time. (Sampling approx 2kHz)
The beams cover a 1.5m distance and have Tx / Rx alternating on each side.
I want to make the beams basicly laser accuracy without having to align the Tx and Rx, so want to modulate the LED's such that only the corellating Rx can detect the Tx it matches with on the other side of the beam. (As LEDs have a beam angle that would be received by many Rx on the opposing side.
Can i get away with just modulating at ~5 different frequencies and pattern them? would this require hardware? or would i need to use 5 different types of modulation and is that even possible on something like an arduino uno / mega. (cheap)
First microcontroller project and i've not chosen something easy.
Thanks
I think I would go about this differently - and I'm assuming you don't want to use carefully aligned laser beams which are an obvious solution.
I would mount each of the detecting photo transistors at the bottom of a tube that limits the angle over which they can detect light and then I would have a simple light source on the other side. There would be no need for modulation.
lbhawtspur:
First microcontroller project and i've not chosen something easy.
+Karma for honesty.
Why do you need to encode the IR sources at all. Just flood the detectors and look for individual detectors being blocked? Is there a reason that there has to be one sender for one detector?
It may help if you explained your project with a bit more detail.