Final Project

Search and Rescue

ObjectiveAs 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

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

CD4066

74HC4051

Bandpass Filter

Transfer Characteristic

Design Equations

Absolute Value

Path Difference

d

l2

l0l1

Sound Source

Left Mic Right Mic

If l0 >> 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

Vphase = Vdd * (t / T)

So t = Vphase * T / Vdd

TLC3702

Tone Decoder IC

LM567

The sky is the limit!