VIII

|

Contents

4

Measurement of Biosignals and Analog Signal Processing | 91

4.1

Measurement of Electrical Biosignals | 91

4.1.1

Electrodes | 93

4.1.2

Electrical Amplifier | 97

4.2

Signal Interference | 104

4.2.1

Network Disturbances | 104

4.2.2

Transient Disturbances | 109

4.2.3

High-Frequency Interference due to Electromagnetic Radiation | 109

4.3

Transducer for Non-Electrical Biosignals | 110

4.3.1

Sound Transducer | 110

4.3.2

Optical Sensors for Plethysmography and Determination of Oxygen

Saturation | 113

4.4

Interference Suppression and Analog Filtering | 115

4.5

Design of Analogue Filters | 123

4.5.1

Selective Filters to Optimise the Magnitude Frequency Response | 123

4.5.2

Selective filters with Group Delay Optimisation | 143

4.6

Post-Reading and Exercises | 144

5

Methods for Discrete Processing and Analysis of Biosignals | 149

5.1

Discretisation of Continuous Signals | 149

5.2

Discrete Transformations of Signal Processing | 154

5.2.1

The Discrete-Time Fourier Transform | 154

5.2.2

The Discrete Fourier Transform (DFT) | 155

5.2.3

Discrete Laplace Transform and z-Transform | 158

5.3

Methods for Analysis and Processing of Discrete Biosignals | 159

5.3.1

Time Domain Signal Analysis and Matching | 159

5.3.2

Signal Analysis in the Frequency Domain | 175

5.3.3

Signal Analysis in the Time-Frequency Domain | 183

5.3.4

Discrete Linear Time-Invariant Systems and Digital Filters | 190

5.4

Post-Reading and Exercises | 208

6

Applications and Methods in Biosignal Processing | 213

6.1

Signals of the Brain | 213

6.2

Signals of the Muscles and Motions | 220

6.2.1

Spectral Analysis of the One-Channel EMG | 222

6.2.2

Acoustic-Kinetic Analysis of Osteoarthrosis Patients | 224

6.3

Signals of the Cardiovascular System | 241

6.3.1

Electrocardiogram | 241

6.3.2

Phonocardiogram | 264

6.3.3

Determination of Oxygen Saturation and

Photoplethysmography | 274

6.3.4

Signal Classification of Multichannel Photoplethysmography | 277