Waveform Encoding - Digital Communication: Principles and System Modelling - page 26

~

Fig. 2.12 Waveform
reconstruction through PCM
receiver as shown in Fig. 2.11

x q ( t )

x ( t ) x ( t )

Δ 3

Δ 2

Δ 1

Δ 0

2.2.4 Quantization Error

It is now understood that, the process of quantization is nothing but approximation to
nearer level of voltage/current. Due to this approximation, there a random amount of
difference occurs between actual and quantized value, named as quantization error.
As the error is like a random number and adds noise to modulation process, the error
can also be viewed as a noise called as quantization noise Fig. 2.13 .

Quanti z ation err o r charact e ristics

5

4

3

2

1

0

- 1

- 2

- 3

- 4

- 5

- 4 - 3 - 2 - 1 0 1 2 3 4

x(kT s )-->

Fig. 2.13 Quantization error characteristics