Signal
The term "signal" refers to the temporal variation of a measurable physical quantity (such as current, voltage, force, temperature, pressure, etc.). These physical signals are mathematically modelled as functions dependent on a variable representing time .
Key Points:
- Physical representation conveys information.
- Entity utilised for the transmission of information.
Figure 1: Representation of a Signal x(t).
Example :
• A microphone delivers an acoustic wave (speech, music, etc.).
• Biological signals: ECG
• Voltage across a capacitor under charge
• Geophysical signals: seismic vibrations
• Finance: stock market price
• Flow of the Seine
• Pictures
• Videos
• ... and more.