Michael Bossi, Montana Bowman, Changjun Park, and Michael Reymond

Overview

This project uses three mbeds each with omnidirectional microphone to find the direction of a source of sound. The source of sound will be 900 Hz sine wave tone played somewhat close to the device. Each mbed will capture diferent phases which will be used to calculate the direction. This is run 10 times, which will be averaged then displayed on uLCD screen.

Program

It will take couple seconds for the Master mbed to finish initializing. Once ready, play a constant 900 Hz sine wave tone close to the mbed (e.g. from a phone) and press the button to start recording. Try to keep the source of sound stationary and elevated slightly so each microphone can hear directly from the source (instead of parts on the board in the way). Once it gets 10 valid values, it will undergo voting/averaging, then result will be displayed on uLCD screen, with red arrow being the middle, orange lines being 20 degrees away, and yellow lines being 45 degrees away from the average.

Wiring

Codes

Three mbeds each with a omnidirectional microphone are required for this project.

Code for Master

Code for Slave1

Code for Slave2

Angle of Arrival Estimator program was used to figure out the direction in which the sound comes from.

Future Work

There is still some work that could be done to make this project better. Below is a list of some ideas.

• better filter so that noise can be cancelled
  • currently does not have a filter, not needed if the source of the sound is fairly close and loud
• sampling faster consistently
• communication betwen the master and slaves
  • currently relies on wait statements to avoid collision, can get results much faster without wait statements
• incorporating another mbed for managing timing of start of recording between different slave mbeds recording