1. Real world measurements

2. Measuring things Making accurate measurements is an essential part of all branches science and engineering. Much (all?)of our understanding of the world was born from experimental measurements (often ones that disagreed with the current theory). Models of systems are useless without validation. Performance of engineered systems must always be measured and tested. “Experiment is the sole judge of scientific truth” Feynman

3. Berkeleyearth.org Measurements are debated

4. Measurements are important in healthcare

5. Transportation is not safe without measurements

6. Measurements can tell us how the universe is built Michelson-Morley 1887 Large hadron collider

7. What you will learn (hopefully) Make a set of physical measurements. Analyze and present experiment data. Conduct basic error analysis of data. Design a basic computer based experimental system. Use measurements test physical models. This class is just the beginning

8. Course structure (some details TBD) Week 1Individual Lab: Intro to data acquisition - acceleration Week 2Individual Lab: EKG Week 3Individual Lab: Mechanical – Stress/strain Week 4Individual Lab: Ballistocardiograph Week 5Individual Lab: Pulse Oximeter Week 6Individual Lab: Pulse Oximeter Week 7Individual Lab: Mechanical vibrations Week 8Team Lab: Remote experiments - arduino Week 9Team Project Week 10Team Project Week 11Team Project Week 12Team Project Week 13Team Project Week 14Team Project Spring break

9. Projects Projects can focus on a reasonably challenging sensor/circuit using commercial sensors and focus on the experiment and the data.

10. A few things. This is not an EE course – but many measurements are electronic (all in this course). Ninjas. Lab reports – focus mainly on results. Weekly labs will be individual. Team project will be in groups of about 4.

11. Grades – yes we have to give them Storey conjecture: If you turn everything in on time, come to class, spend a reasonable amount of time on homework, and put forth a reasonable effort, the lowest grade you will receive is a B. Corollary: You can easily get a C, D, or F by not doing the above mentioned tasks.

12. So… let’s get down to business

13. Hardware – USB data acquisition

14. Analog to digital conversion What is the sample rate? Our system has a 14 bit ADC, if we set the range to ±10 V, what is resolution?

15. Resolution 14 bit ADC: 00101011101101 2 14 =16384 numbers Resolution = range/16384 Eg: range is +10 to -10 V; 20/16384=1.2 mV range is +1 to -1 V; 2/16382 = 0.12 mV

16. Aliasing error

17. Noise What are sources of noise?

18. Simple voltage divider demo What’s this voltage? = =5V R R

19. USB 6009 – input impedance = =5V R R i i is not 0!

20. Generic sensor measurement Sensor Measurement- DAQ If R source is small, and Rmeas is big, then you measure Vsensor Otherwise, you might be measuring something else!

21. The electrocardiogram

22. Me Time (sec) V (arb)

23. EKG The EKG is a powerful diagnostic tool. Regularly used by cardiologists.

24. Disclaimers We are not real doctors. Neither are you. Do not try to interpret your EKG.

25. Safety

26. We will review this in lab, but basically – 100 K resistors between you and breadboard. – Unplug your laptop while collecting data.

27. Privacy Your EKG could be considered private medical information under Federal HIPAA laws. If using this data makes you at all uncomfortable – then use one of the instructors as your subject.

28. The circuit AD623 – Instrumentation amplifier

29. The Op-Amp

30. Simplification for op-amp circuit analysis 1.Assume no current flows into the inputs. 2.If the op-amp is wired with negative feedback, and other circuit dynamics are “slow” (less than ~100 kHz), then Then the two input voltages are equal.

31. What does this circuit do?

34. The instrumentation amplifier Wikipedia

35. AD623 Data sheet

36. AD623 – Instrumentation amplifier Let’s look at the filters now

37. Linear circuits – Double the input, double the output. – A sinusoidal input results in a sinusoidal output of the same frequency.

38. How to characterize a linear circuit (at sinusoidal steady state) We can fully characterize the system with two parameters: Magnitude of output/Magnitude of input (B/A) Phase difference between input and output (theta) Your linear circuit

39. The Bode plot Developed 1930s Published 1945