1. Measurement Systems

2. Measurement Hardware

3. A Simple Measurement System Sensor: Transducer: Signal Conditioner: Signal Processor:

4. Some Sensors Is this a sensor? strain gage (R=  L/A) hot-film probe (or RTD) R=R o [1+  (T-T o )] thermistor R=R o exp[  (1/T-1/T o )]

5. Now to Filters and Beyond ! filtersA/D converters

6. Filters A filter removes a signal’s unwanted frequency components. A filter alters both the magnitude and the phase of the signal.

7. Figure 6.9 Filter Terminology cut-off frequencies

8. Simple RC Filters Figure 6.10

9. Filter Distortion of Signal Figure 6.11 A filter alters the signal by introducing a phase lag and a magnitude attenuation circular frequency for this signal = cyclic frequency for this signal =

10. Analog-to-Digital (A/D) Converters An A/D converter converts an analog signal (continuous in time and magnitude) to a digital signal (discrete in both time and magnitude) The signal is converted into binary using various methods, such as successive-approximation and ramp-conversion.

11. A/D Conversion Process Figure 6.15 analog, discrete and digital signals

12. M-bit Terminology

13. 39.0619.53 corrections

14. In-Class Example A: What is the flow velocity if  p = 58 Pa ? A-B: Wheatstone bridge (pp. 72-75) where E o =E i [ R 1 /(R 1 +R 2 ) - R 3 /(R 3 +R 4 )] (Eqn.4.26)

15. In-Class Example A-B: What is R x needed to give E o =0 V at U = 0 m/s ? B-C: What is the amplifier gain to achieve 80 % of the full-scale range of the A/D board at the highest U ? B-C: If a non-inverting opamp is used (see p. 147), what should be the values of its resistances ? A-B: At the highest U, R 1 increases by 20 % because of an increase in R s. What is E o at the highest U?

16. In-Class Example C-D: What type of filter would be appropriate to use ? D-E: What bit A/D board is required to have less than 0.2 % error in the voltage reading of the highest-U condition ?