The ultrasonic spotlight tracker is a system that uses a wireless beacon to track a target’s location using both RF signals and ultrasound waves. It then drives a light source to point at the location of the target.

In this project, we limit our remote unit’s degree of freedom to two dimensions to prove the concept, although it can be very easily extended to three dimensions. To locate the target, we need to measure the distance of the target from at least two known points. The distances are measured by counting the time it takes for sound to travel from the target to the base station and multiplying it by the speed of sound waves. The speed of sound in air is about 334 meters per second. The 16 MHz microcontroller avr can count time intervals on the order of 0.0625 microseconds, which gives a theoretical accuracy of 0.02 mm.

In this project, we limit our remote unit’s degree of freedom to two dimensions to prove the concept, although it can be very easily extended to three dimensions. To locate the target, we need to measure the distance of the target from at least two known points. The distances are measured by counting the time it takes for sound to travel from the target to the base station and multiplying it by the speed of sound waves. The speed of sound in air is about 334 meters per second. The 16 MHz microcontroller avr can count time intervals on the order of 0.0625 microseconds, which gives a theoretical accuracy of 0.02 mm.