tracking sensor need help
 

i am a senior and am trying to build a tracking system that goes onto a robot and tracks something on a person or other robot. i also wanted it to tell distance but i may just use a ultrasonic sensor for that , the reason for not useing the ultrasonic sensor to locate it it needs the tim between send/ recive so it could track or tell relitive distance. i have looked at ir signals but nothing seems to work, radio signals seemed to work but again i dont know where to get them. this is for my senior project plz help.