19. Types Of Biological Signals Flashcards
Classification of signal according to time
Static - time dependant
5 classifications of signals
- Analog / digital
- Periodic (sine wave) / non periodic (pulse)
- Random / deterministic (physical description is fully known)
- Electric / non electric
- Analog / digital
Amplitude and frequency range of electromechanical transducer
A = 100microV - 10mV f = 100mHz - 1Hz
Amplitude and frequency range of ECG signal
A = 50 microV - 5mV f = 100mHz - 200Hz
Amplitude and frequency range of phonocardiogram?
A = 50microV - 4mV f = 1Hz - 1000 Hz
Amplitude and frequency range of electromyography
A = 1microV - 50 microV f = 2Hz - 50kHz
Amplitude and frequency range of electroencephalogram
A = 500nV - 30microV f = 1Hz - 50Hz
Amplitude and frequency range of intracellular voltage
A = 1mV - 80mV f = 100mHz - 10kHz
What is a signal?
physical quantity that transmits/stores information
What is the Fourier theorem for periodic and non-periodic signals?
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
What is the fundamental frequency?
lowest frequency of a periodic waveform
What is an overtone?
integral multiples of the fundamental frequency (so always higher freq than fundamental)
What is a voltage divider?
a linear circuit that produces an output voltage that is a fraction of its input voltage
What happens when you use voltage dividers with capacitors?
you can create low-pass and high-pass filters
What is the function of a filter circuit for AC?
remove unwanted frequency components from the signal
Why do we need capacitors for the filters?
because capacitors react differently depending on the AC frequency, but not resistors
How does the High pass low cut filter work?
capacitor blocks all low frequencies until fc is reached
How does the low pass high cut filter work?
capacitor : impedance is high for low frequencies, send high frequencies to the ground and let low frequencies go
What is the transfer curve?
graph which shows the relationship between the input and output signal of the amplifier : n(dB) vs frequency (log scale)
What is the output feedback proportional to in the feedback amplifier?
to the difference in voltage bw the 2 inputs of the amplifier : Vo = A(v+ - v-)
What are analog signals?
continuous electrical signals
What are digital signals?
non-continuous signals. Digital infromation exists as either 1 or 0 : bits
What is a byte?
the sequence of 1 and 0 that constitute information
What are the 2 steps of digitization?
- discretization = reading analog signal at regular time intervals (each reading = 1 sample)
- quantization = rounding the samples as a set of numbers
