# 1: Introduction to Signals

- Page ID
- 22843

- 1.1: Signal Classifications and Properties
- This module will begin our study of signals and systems by laying out some of the fundamentals of signal classification. It is essentially an introduction to the important definitions and properties that are fundamental to the discussion of signals and systems, with a brief discussion of each.

- 1.2: Signal Size and Norms
- A module concerning the size of a signal, more specifically norms.The "size" of a signal would involve some notion of its strength. We use the mathematical concept of the norm to quantify this concept for both continuous-time and discrete-time signals. As there are several types of norms that can be defined for signals, there are several different conceptions of signal size.

- 1.3: Signal Operations
- This module will look at two signal operations affecting the time parameter of the signal, time shifting and time scaling. These operations are very common components to real-world systems and, as such, should be understood thoroughly when learning about signals and systems.

- 1.4: Common Continuous Time Signals
- Presents several useful continuous time signals.

- 1.5: Common Discrete Time Signals
- Before looking at this module, hopefully you have an idea of what a signal is and what basic classifications and properties a signal can have. In review, a signal is a function defined with respect to an independent variable. This variable is often time but could represent any number of things. Mathematically, discrete time analog signals have discrete independent variables and continuous dependent variables. This module will describe some useful discrete time analog signals.

- 1.6: Continuous Time Impulse Function
- Explains the use of the continuous time impulse function: the Dirac Delta Function.

- 1.7: Discrete Time Impulse Function
- In engineering, we often deal with the idea of an action occurring at a point. Whether it be a force at a point in space or some other signal at a point in time, it becomes worth while to develop some way of quantitatively defining this. This leads us to the idea of a unit impulse, probably the second most important function, next to the complex exponential, in this systems and signals course.

- 1.8: Continuous Time Complex Exponential
- Describes the complex exponential function.

- 1.9: Discrete Time Complex Exponential
- Describes the complex exponential function for discrete time.