I'm looking for a method, without the use of GPS, to have one object output a signal (ultrasonic I'm thinking right now) and an Arduino board with LED blink faster and faster as you approach the hidden object.
This hidden object that is transmitting a signal is not in line of site, so IR can not be used. This hidden object can be behind another object, so PING sensors can not be used. Most importantly this hidden object needs to be identifiable, in other words if it transmits a signal the Arduino that's receiving the signal must know it's receiving the correct signal. This is required because there may be multiple hidden objects and I need to make sure the Arduino is setup to detect a specific one.
My best guess on how to do this would be to setup a beacon type device that transmits a RF signal at a specified frequency. Then have an Arduino board capable of detecting the specified frequency. As the transmission becomes stronger and stronger have an LED either become brighter or blink faster.
Any ideas on the type of hardware I could use to do this?