IR (or visible light) isn't often used for this, as it doesn't reflect well off many surfaces, you've also got the problem that the speed of light is too fast to measure easily. If you want more range ultrasonics are more suitable.
hi.im a final year student.we as a group of 5 have decided to do a project on low power fm transmitter.power is around 250 to 300mw.we found many designs but none suiting to our interests.the carrier frequency range is about 88MHz to 108MHz.We really need to get the appropriate design as soon as possible and hope that you could help us.If theres any other kind of information you would like to know we would be more than ready to give you the same.
Thank You.