Digital Signal ProcessingLecture and Solution -DSP EIE315 Introduction and Questions.pdf

Introduction

Discrete-time signals are obtained by sampling
continuous-time signals.
They are represented by sequence of numbers
The nth number in the sequence is represented
with x[n]




Figure 3 (a) Continuous-time signal x(t). (b) Representation of x(t) as a discrete-
time signal x[n].

, Example of sequence

• Unit-sample sequence (n)

 Sometime call (n) 1 n  0
( n )  
 a discrete-time impulse; or
0 n  0
 an impulse

(n)


n
-8 -7 -6 -5 -4 -3 -2 -1 1 2 3 4 5 6 7 8 9 10

, • Unit-step sequence u(n)

1 n  0
u ( n)  
0 n  0

In term of unit sample
sequence (n)  u(n)  u(n  1)

u(n)


n
-8 -7 -6 -5 -4 -3 -2 -1 1 2 3 4 5 6 7 8 9 10

, • Real exponential sequence


x(n)  a n


x(n)
...
... n
-8 -7 -6 -5 -4 -3 -2 -1 1 2 3 4 5 6 7 8 9 10