is a function of one or more variables that indicate some (usually physical) phenomenon; serves as carriers of information between communication devices, They can convey different types of information depending on the application required

signals can be classify based on their what?

These signals are continuing and infinitely varying with time parameters or can take any value within a given range. These signals are represented by the sine wave.

A signal that is a function of discrete variables (e.g., an integer variable) is said to be discrete time and this is represented in binary form (0s and 1s). More robust against noise. Commonly used in computer systems.

can be described exactly by a formula or rule; If you know the formula, you can predict the signal at any time.

Changes unpredictably, you can’t know it’s exact value at any moment ; We use probability and statistics to analyze it

Depends on one independent variable, usually time (t) ; Represented as a line graph vs. time.

Depend on two independent variables, usually spatial (x,yx, yx,y) ; Represented as a surface or image instead of a line.

Depend on three or more variables; Used in advanced applications like video processing or scientific simulations.

Measurable properties that describe a signal’s characteristics:

Height of a wave from the undisturbed/normal position to its crest ; As energy increases, it also increases ; Sound waves (longitudinal) and light waves (transverse) both exhibit amplitude.

How often the signal repeats in one second; Measured in Hertz (Hz).

The smallest time after which the signal repeats itself.

The position of a waveform relative to time zero.

The distance a signal travels in one cycle ; Commonly used in electromagnetic waves like radio or Wi-Fi signals.

 is the study and application of techniques to analyze, modify, and interpret signals to extract useful information or improve quality; It involves taking a signal (sound, images, sensor data), processing it mathematically or electronically, and producing a better or more meaningful output.

Works with digital signals (discrete values, usually 0s and 1s) ; Uses computers or digital processors; More flexible and powerful than analog processing.

Works with continuous-time signals (smooth, no breaks); Common before digital computers became popular; Uses analog circuits like amplifiers, filters, and modulators.

Total magnitude of the signal over its duration; Used for signals that start and stop within a finite time.

Average strength of a signal that lasts indefinitely; Used for signals that never end or repeat forever. Example: Sine wave from a power line, continuous broadcast signal.

strength of wireless signals

energy of digital images for compression

_{_________} defines how far a signal can travel; _________ defines total transmission cost.

In _____________, signals represent real-world information (audio, images, biomedical readings, communication data).