1. PHASE-SENSITIVE DEMODULATION 2006200401 Tae-eui, Kim

2. ; 10Hz Sinusoid (Tx = 0.1s) ; High Freq. Signal (Tx = 0.02s) X(t)X(t) c(t) XOXO -X O 1 0.05s 0.1s0.05s0.1s Phase-sensitive Demodulation

4. Phase-sensitive Demodulation

5. Phase-sensitive Demodulation With Freq. 50Hz

6. < MATLAB PLOT WITH HIGH MAGNITUDE > Phase-sensitive Demodulation With Freq. 1000Hz

7. Given x(t) c(t) = y(t), find x(t) Phase-sensitive Demodulation XLPF

8. Phase Demodulation After LPF Phase-sensitive Demodulation

9. Capacitive Sensor – Problem 9 (a) Change of distance Metal plate A B L ; Capacitive is dependent on changing distance between chest and metal plate

10. A B Capacitive Sensor – Problem 9 (b)

12. Capacitive Sensor – Problem 9 (c) XLPF

13. Air ABC P1P1 P2P2 Atmospheric pressure X1X1 X2X2 Chamber rigid Diaphragm One is increased, The other is decreased At the same amount How to express by using equation from the sensor in order to analyze it is crucial (when ) ABC Goal is to measure “ “ Capacitive Sensor – Problem 10 (a)

14. A AC (Capacitor) C D B

15. Capacitive Sensor – Problem 10 (a)

16. ConstantxHigh Freq. Something we would like to measure Constant

17. Capacitive Sensor – Problem 10 (b) ConstantUnit less

18. Capacitive Sensor – Problem 10 (c)