19. Types Of Biological Signals

Question 1

Classification of signal according to time

Answer 1

Static - time dependant

Question 2

5 classifications of signals

Answer 2

1. Analog / digital
2. Periodic (sine wave) / non periodic (pulse)
3. Random / deterministic (physical description is fully known)
4. Electric / non electric
5. Analog / digital

Question 3

Amplitude and frequency range of electromechanical transducer

Answer 3

A = 100microV - 10mV
f = 100mHz - 1Hz

Question 4

Amplitude and frequency range of ECG signal

Answer 4

A = 50 microV - 5mV
f = 100mHz - 200Hz

Question 5

Amplitude and frequency range of phonocardiogram?

Answer 5

A = 50microV - 4mV
f = 1Hz - 1000 Hz

Question 6

Amplitude and frequency range of electromyography

Answer 6

A = 1microV - 50 microV
f = 2Hz - 50kHz

Question 7

Amplitude and frequency range of electroencephalogram

Answer 7

A = 500nV - 30microV
f = 1Hz - 50Hz

Question 8

Amplitude and frequency range of intracellular voltage

Answer 8

A = 1mV - 80mV
f = 100mHz - 10kHz

Question 9

What is a signal?

Answer 9

physical quantity that transmits/stores information

Question 10

What is the Fourier theorem for periodic and non-periodic signals?

Answer 10

all periodic functions can be expressed as a sum of sin and cosin functions from the fundamental frequency and overtones with decreasing amplitudes
- or : each periodic function is a sum of discrete sinusoidal components

Question 11

What is the fundamental frequency?

Answer 11

lowest frequency of a periodic waveform

Question 12

What is an overtone?

Answer 12

integral multiples of the fundamental frequency (so always higher freq than fundamental)

Question 13

What is a voltage divider?

Answer 13

a linear circuit that produces an output voltage that is a fraction of its input voltage

Question 14

What happens when you use voltage dividers with capacitors?

Answer 14

you can create low-pass and high-pass filters

Question 15

What is the function of a filter circuit for AC?

Answer 15

remove unwanted frequency components from the signal

Question 16

Why do we need capacitors for the filters?

Answer 16

because capacitors react differently depending on the AC frequency, but not resistors

Question 17

How does the High pass low cut filter work?

Answer 17

capacitor blocks all low frequencies until fc is reached

Question 18

How does the low pass high cut filter work?

Answer 18

capacitor : impedance is high for low frequencies, send high frequencies to the ground and let low frequencies go

Question 19

What is the transfer curve?

Answer 19

graph which shows the relationship between the input and output signal of the amplifier : n(dB) vs frequency (log scale)

Question 20

What is the output feedback proportional to in the feedback amplifier?

Answer 20

to the difference in voltage bw the 2 inputs of the amplifier : Vo = A(v+ - v-)

Question 21

What are analog signals?

Answer 21

continuous electrical signals

Question 22

What are digital signals?

Answer 22

non-continuous signals. Digital infromation exists as either 1 or 0 : bits

Question 23

What is a byte?

Answer 23

the sequence of 1 and 0 that constitute information

Question 24

What are the 2 steps of digitization?

Answer 24

1. discretization = reading analog signal at regular time intervals (each reading = 1 sample)
2. quantization = rounding the samples as a set of numbers

Question 25

What is the Shannon-Nyquist theorem?

Answer 25

to have a complete reconstruction of a signal, the minimum sampling frequency should be twice the frequency of the highest overtone of the signal

Question 26

What is and integral discriminator?

Answer 26

with integral and differential discriminators

Question 27

What is the medical application of pulse signal processing?

Answer 27

coulter-counter