# Different analog and digital signal:

## Analog signal :

**(i) Unit step signal:**

**(i) Unit step signal:**

**(ii) Unit ramp signal: **

The unit ramp signal is defined as,

**(iii) Unit impulse signal : **

The impulse signal is a signal with infinite magnitude and zero duration, but with the unit area. The unit impulse function is also known as the Dirac delta function.

**(iv) Exponential signal : **

Exponential signals are of two types :

**(a) Real exponential signal:**

**(b) Complex exponential signal:**

The real part of the complex frequency variable is * called attenuation or growth constant*. It denotes how much amount of amplitude of the signal is increased or decreased. The imaginary part of a complex frequency variable is called angular frequency with a usual meaning.

*Digital signal*:

### (i) Unit step sequence :

The unit step sequence is mathematically defined as,

**(ii) Unit ramp sequence :**

Unit ramp sequence is defined as,

**(iii) Unit sample sequence : **

Unit sample sequence is defined as,

**(iv) Exponential sequence : **

Exponential sequences are of two types :

**(a) Real exponential sequence :**

(b) * Complex exponential sequence* :

**(v) Rectangular pulse sequence :**

Let L be a positive odd integer. An important example of a discrete-time signal is the discrete-time rectangular pulse function rect[n ] of length L defined by,

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