EEE 432 Measurement and Instrumentation Lecture 7 Analog Signal processing Prof. Dr. Murat Aşkar İzmir University of Economics Dept. of Electrical and Electronics Engineering Signal processing . Signal processing is concerned with improving the quality of the reading or signal at the output of a measurement system, and one particular aim is to attenuate any noise in the measurement signal that has not been eliminated by careful design of the measurement system . Analog signal processing . Digital signal processing 2 1 Signal processing Analog Signal Processing . Filters . Signal Differentiation – Passive . Voltage follower (pre-amplifier) – Active . Voltage comparator . Signal amplification . Voltage-to-current converter . Signal attenuation . Current to-voltage converter . Differential amplification . Phase-sensitive detector . Signal linearization . Lock-in amplifier . Bias (zero drift) removal . Signal addition . Signal Integration . Signal multiplication 3 Signal processing Digital signal processing . Sample and hold circuit . Analog-to-digital (A/D) conversion . Digital-to-analog (D/A) conversion . Digital filtering . Autocorrelation . Other digital signal processing operations 4 2 Signal processing Filters Filter : a circuit that is designed to pass signals with desired frequencies and reject or attenuate others 4 types of filters: 1. Low-pass filter: passes low frequencies and stops high frequencies 2. High-pass filter: passes high frequencies and rejects low frequencies 3. Band-pass filter: passes frequencies within a frequency band and blocks or attenuates frequencies outside the band 4. Band-reject filter: passes frequencies outside a frequency band and blocks or attenuates frequencies within the band 5 Filters Low Pass Filter 6 3 Filters High Pass Filter 7 Filters Band Pass Filter 8 4 Filters Band Reject Filter 9 Filters Passive Filters 10 5 Filters Active Filters 11 Analog Signal Processing Signal Amplification 12 6 Analog Signal Processing Signal Attenuation 13 Analog Signal Processing Differential Amplification 14 7 Analog Signal Processing Signal Linearization Light intensity transducers typically have an exponential relationship between the output signal and the input light -aQ intensity, i.e.: VI = Ke where Q is the light intensity, VI is the voltage level of the output signal, and K and a are constants. 15 Analog Signal Processing Bias Removal 16 8 Analog Signal Processing Signal Integration 17 Analog Signal Processing Signal Differentiation dV V C in out 0 dt R dV V RC in out dt 18 9 Analog Signal Processing Voltage Comparator 19 Analog Signal Processing Voltage-to-Current Converter R2 I Vin R1R3 R1R3 R5 R2 R4 Vsat R4 R5 R3 Im Rml R3 R4 R5 20 10 Analog Signal Processing Current-to-Voltage Converter Vout IR 21 Signal processing Analog Signal Processing . Filters . Signal Differentiation – Passive . Voltage follower (pre-amplifier) – Active . Voltage comparator . Signal amplification . Voltage-to-current converter . Signal attenuation . Current to-voltage converter . Differential amplification . Phase-sensitive detector . Signal linearization . Lock-in amplifier . Bias (zero drift) removal . Signal addition . Signal Integration . Signal multiplication 22 11 Signal processing Digital signal processing . Sample and hold circuit . Analog-to-digital (A/D) conversion . Digital-to-analog (D/A) conversion . Digital filtering . Autocorrelation . Other digital signal processing operations 23 12.