Sound Source Localization System
This is a piece of work for the 3rd Hardware Design Competition. The subject was Sound Source Localization Based 3D Mouse in which contestants were required to show the coordinates of the buzzer using microphone arrays. The difficult point lay in the realization of the hardware, which covered a variety of analog and digital technologies. Also, it was a challenge for the contestants' practical ability who were still sophomore.
My solution was to use three pairs of microphones whose location were known and fixed. Two in a pair were placed within a range shorter than a wavelength of sound. The received signal would first be amplified, then pass a bandpass filter, and finally be shaped to square wave. The phase difference in a pair was detected by a flip-flop and RC circuits with a large time constant, so that the result had a linear relationship with the capacitor voltage. After that, an MCU was employed to calculate the coordinates of the source according to the microphone arrays' output by solving an equation set.