Virtual Field Trip!

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#cs480

Continuous Signal

Analog

Infinite Accuracy and Infinite Measurements

Electrical Signals

Mechanical Signals

Hydraulic Signals

Optical Signals

Chemical Signals

Electrical Potentials/Activity like ECG, EEG..

Vibrations such as Mechanomyogram (MMG)

pH measurement, urinalaysis (UA), blood glucose, electrolyte levels, cholesterol..

blood vessel wall shear stress

some imaging methods (X-ray, NIRS..)

blood pressure?

Accustical Signals

blood pressure.

Sensors

Analog

Sensors

Digital

Analog to Digital Converter (ADC)

Continuous Signal

Analog

Infinite Accuracy and Infinite Measurements

Discrete Signal

Digital

Limited Accuracy and Limited Measurements

From Analog...

...to Digital

Distortions

Sampling Limitations

Noise

Sampling

Analog

Sampling Rate

Samples per second [1/s]

Hertz [Hz]

Analog Signal

2 Samples per second

0

1

time [s]

6 Samples per second

10 Samples per second

6 Hz

10 Hz

2 Hz

Aliasing

Original Signal

Sampled Points

Reconstructed Signal

Sampling Rate too low

A higher sampling rate is better

?

2 Floats

6 Floats

10 Floats

It's a trade-off!

Nyquist-Shannon Theorem

sampling frequency > 2x signal frequency

guarantees perfect reconstruction

What does that mean? And how do we get the signal frequency?

Fourier Analysis

From Analog...

...to Digital

Distortions

Sampling Limitations

Noise

What is the sampling rate here?

19/6000s = 0.0032 Hz

[104, 104, 104, 103, 103, 102, 101, 101, 100, 100, 99, 99, 98, 98, 98, 99, 99, 100, 100]

How to represent the data?

Next time

Fourier Analysis

Intro to Research

How to read a paper

How to write a paper

+ 9 Meetings

CS480 Lecture 02

By Daniel Haehn

CS480 Lecture 02

Slides for CS80 Biomedical Signal and Image Processing at UMass Boston. See https://cs480.org!

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