final project search and rescue objective as part of the search and rescue contest, you will need to...
TRANSCRIPT
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!