rotational position sensing scheme?

robust

hello

i'm new to electromechanics. i am trying to find a way to track a person's (marked or unmarked) position angularly in a 180 degree area up to roughly 30 ft. i dont really care about knowing the depth of the person from the sensor, merely where he/she is in that semicircle angularly. i have gotten advice to mark the person with an infrared LED and use an array of infrared sensors to determine this. something similar to laser tag although instead of just knowing it is hit, knowing where it is hit from. is there a better/simpler way? i will be using the basic stamp 2 to interface them all with a servo which would angle our apparatus to point at the calculated position.

thanks much.

sean

robust

i was thinking of using something like this for the array: http://www.pololu.com/products/misc/0132/

and i'm not sure what one would use to produce the modulated IR signal.