2. Final Project Search and Rescue

3. 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.

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

5. Microphone

7. 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)

8. Gain Amplfier

9. TLC2272

10. CD4066

12. 74HC4051

13. Bandpass Filter

14. Transfer Characteristic

15. Design Equations

16. Absolute Value

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

18. 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????

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

20. TLC3702

21. Tone Decoder IC

22. LM567

23. The sky is the limit!