## Deterministic signal

Deterministic signals can be described by a mathematical expression, lookup table or some well-defined rule.

Examples: Sine wave, cosine wave, square wave, etc.

[caption id="attachment_1559" align="aligncenter" width="287"] Deterministic signal[/caption]

A sine wave can be represented mathematically as,

**x(t) = A sin (2πft)**

where

- A is the amplitude of a signal
- f = frequency of a signal

Note: The deterministic signals such as sine wave, cosine wave, etc. are periodic in nature. Besides this, some deterministic signals may not be periodic. The exponential signal is an example of a non-periodic signal.

## Random Signal

A signal which cannot be described by any mathematical expression is called as a random signal. Therefore, it is not possible to predict the amplitude of such signals at a given instant of time.

Example: A good example of a random signal is noise in the communication signal. Below figure shows one of the random signals.

[caption id="attachment_1558" align="aligncenter" width="283"] Random Signal[/caption]

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