Final Project Search and Rescue

Objective As part of the search and rescue contest, you will need to find a high frequency (4 – 6 kHz) sound located somewhere in the room. There will be low frequency (< 500 Hz) sound source in the room, also.

BRAINSTORMING How can we locate a sound source?????

Microphone

Sound Pressure Levels Sound pressure levels are measured in Pascals (Pa). If someone is yelling at you from 2-3 feet away that is about 1 Pa i.e. (1 Volt out of microphone) If he is speaking in a normal voice, that would be about 0.1 Pa. (100 mV out of microphone) If he is whispering (very softly) that might be 1 mPa. (1 mV out of microphone)

Gain Amplfier

TLC2272

CD4066

74HC4051

Bandpass Filter

Transfer Characteristic

Design Equations

Absolute Value

Path Difference d l2l2 l0l0 l1l1 Sound Source Left Mic Right Mic  If l 0 >> d,  l = d * sin(  )

Phase Delay If c = speed of sound = 340 m/s, then  t =  l / c.  = arc_sin{(c *  t) / d} So, how can I measure  t????

Phase Comparison V phase = V dd * (  t / T) So  t = V phase * T / V dd

TLC3702

Tone Decoder IC

LM567

The sky is the limit!