reflected ir receiver design

hi all im trying to make a ir transmitter and a receiver for receiving reflected ir from an obstacles .Can any one suggest some starting tips and future problems,

Check this to get some ideas:

I realize that you won't take the course, but it might provide some topics to search on the net.

for the above if u confidential about your circuit then take special measurements like receiving ir antenna.in that u must calculate elllipse shaped antenna in which at the foci u get maximum strengh of reflected signal.if u email me about the problem u get exact answer about this