WHAT IS A SIGNAL?

WHAT IS A SIGNAL?

1. It is an ordered sequence of numbers that describes trends and variations of a quantity

   • The importance of signal analysis processing lies in extracting important knowledge visible to the human eye, enabling diagnostics..
     • It is also necessary to understand the signals in time, which relates to the ordering axis
       • But not all signals are based on time; some are also based on space.

2. Some examples of one-dimensional signals include:

   • The recording of the electrical activity of the heart muscles, known as an electrocardiogram (ECG).
     • Widely used for diagnosing the cardiovascular system.
   • The electroencephalogram (EEG), which is a signal that records the electrical activity of the brain.
     • Used for diagnosing the central nervous system.

3. Signals are divided into analog, discrete, and digital.

   • Analog Signals
     • They are continuous in both time and amplitude.
   • Discrete Signals
     • These signals are continuous in amplitude but discrete in time.
       • An advantage of digital signals is that they require less storage space compared to analog signals.
   • Digital Signals
     • Digital signals are discrete in both time and amplitude.
       • A digital signal is defined only at certain specific times, and the amplitude of the signal at each sample can only be one of a fixed, finite set of values.

4. Processing and Transformation of a Signal

   • A signal can be analyzed or processed in various ways, aiming to extract, highlight, and emphasize certain properties of the signal.
   • The transformation of these signals can occur in the time domain, the frequency domain, or through other transformation techniques.
   • The Fourier Transform is designed to represent a signal in the frequency domain.
     • Highlight the important knowledge in the frequency variations of a signal.
   • The Wavelet Transform allows describing a signal in both the frequency and time domains.
   • A transformation does not add or remove information from a signal.
     • It only changes the interpretation by shifting between the time domain and the frequency domain, and Adverse.