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생체계측 II Report #2 2005200427 송성진

생체계측 II Report #2 2005200427 송성진. Phase–sensitive Demodulation. : 10Hz sinusoid (T x = 0.1s). : 50Hz sinusoid (T c = 0.02s). x(t)c(t). x(t). x 0. t. t. -x 0. 0.05s. 0.1s. 0.05s. 0.1s. Matlab 1. When Xo = 2, x(t) is figured by using matlab. c(t) is figured by

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생체계측 II Report #2 2005200427 송성진

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  1. 생체계측 II Report #22005200427 송성진 Medical Instrumentation II

  2. Phase–sensitive Demodulation : 10Hz sinusoid (Tx = 0.1s) : 50Hz sinusoid (Tc = 0.02s) x(t)c(t) x(t) x0 t t -x0 0.05s 0.1s 0.05s 0.1s Medical Instrumentation II

  3. Matlab 1. When Xo = 2, x(t) is figured by using matlab Medical Instrumentation II

  4. c(t) is figured by using matlab Medical Instrumentation II

  5. x(t)c(t) is figured by using matlab Medical Instrumentation II

  6. When c(t) is changed, figured by Matlab Medical Instrumentation II

  7. When c(t)’s frequency is 1000, x(t)c(t) is figured by using matlab Medical Instrumentation II

  8. Gi ven x(t)c(t) = y(t) , find x(t) = ? x(t)c(t)² X LPF ? y(t) O(t) c(t) = sin(2πx50t) Because 2fc is High frequency, cut off by LPF Medical Instrumentation II

  9. Problem 9. • A conductor board is setting chest at 1mm, this is one of capacitor. Distance to chest and conductor board is changed by heart rate, A change is x(t) = 1 + 0.2sin(2πft) [mm]. At this time f is heart rate frequency. You measure x(t) that is chest’s motion by heart rate. A is 5cm² and dielectricconstant ε₀ is 8.8 x 10⁻¹² F/m, heart rate is 60bpm. • (a) represent Cx by x function. Desire for max and min capacitance. • (b) Vi(t) = sin(2π x 10⁴t) V, C₀ is 4.4pF, V ₀(t) = ? • (c) Propose Phase-sensitive demodulator that desire x(t) by amplifier output V ₀(t) Medical Instrumentation II

  10. Capacitive Sensor Non contact measure Chest B A x(t) Cx A B Co Vo Vi Medical Instrumentation II

  11. Matlab 2. Vi(t) X LPF Vo(t) Constant is calculated and Vo(t) is figured by using matlab Medical Instrumentation II

  12. Problem 10. • This is x₁ = x₀ + α(P1-P2), x₂ = x₀ - α(P1-P2), C₁ = εA/x₁, C₂ = εA/x₂, C₀ = εA/x₀. Ѵs = Vs <0 ̊ Phase is 1KHz. • (a) Instrument Amplifier’s input voltage is Vi. Represent x₀, α, (P1-P2) and Ѵs. • (b) Ѵs = 1[v], x₀ = 100[μm], α = 2[μm/mmHg]. Define Instrument Amplifier gain that output voltage phasor, V₀ sensitive magnitude is 0.1 [v/mmHg] • (c) For desire (P1-P2) in V₀, using phase-sensitive demodulator, Represent circuit and explain drive principal Medical Instrumentation II

  13. Problem 10. Solution P1 P2 open C B A Blow air C1 C2 rigid C A B X1 X2 Diaphragm = very flexible When P1 = P2, C1 = C2 X1 increase / X2 decrease P1 > P2 P1 < P2 Medical Instrumentation II

  14. C1 C0 A C IA B C2 C0 Medical Instrumentation II

  15. Medical Instrumentation II

  16. Because High frequency, cut off by LPF LPF X y(t) sin(2πx10³t) Medical Instrumentation II

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