Newbie level 2
I am trying to start a small project. My ultimate end goal is to have a small (as light weight as possible with a power source) transmitter that sends a signal to a hand held receiver. I would like the receiver to either beep at different rates (slow when far and steady like a metal detector when near) or have the sound the receiver emits change tone based on distance (deep when far, high when near). I would like the transmitter to transmit roughly 4 feet around itself so that more than one transmitter in a relatively small area will not interfere with the locating of another. I have no idea where to begin my research for this project. I have found some AM and FM transmitter/receiver projects but I am not sure if that is the best route to go for me. Any advice would be greatly appreciated.