文档介绍：Signals and Systems
Chapter 1
Signals
Signals are functions of independent variables that carry information.
The independent variables can be continuous or discrete.
The independent variables can be 1-D, 2-D, ••• , n-D.
For this course: Focus on a single (1-D) independent variable which we call “time”.
Continuous-Time signals: x(t), t-continuous values.
Discrete-Time signals: x(n), n-integer values only.
Examples
Electrical signals — voltages and currents in a circuit.
Acoustic signals — audio or speech signals.
Video signals — intensity variations in an image.
Biological signals — sequence of bases in a gene.
……
……
A Simple RC Circuit
The patterns of variation over time in the source voltage Vs and capacitor voltage Vc are examples of signals.
A Speech Signal
A Picture
Vertical Wind Profile
Systems
For the most part, our view of systems will be from an input-output perspective.
A system responds to applied input signals, and its response is described in terms of one or more output signals.
Example
RLC circuit
By interconnecting simpler subsystems. We can build more complex systems.