EEE 432 Measurement and Instrumentation Lecture 7 Analog processing

Prof. Dr. Murat Aşkar İzmir University of Economics Dept. of Electrical and Engineering

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 . 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 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

R1R3  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