Signal Sampling and Quantization - Digital Signal Processing: Fundamentals and Applications - page 16

Band-limited
signal

Digital
signal

Processed
digital signal

Output
signal

Analog
input

Analog
output

Analog
filter

Reconstruction
filter

ADC DSP DAC

FIGURE 2.1
A digital signal processing scheme.

Signal samples

x ()

Analog signal/continuous-time signal

5

Sampling interval T

0

5

nT

0 2 T 4 T 6 T 8 T 10 T 12 T

FIGURE 2.2
Display of the analog (continuous) signal and the digital samples versus the sampling time instants.

x ()

Voltage for ADC

Analog signal

5

0

5 nT

0 2 T 4 T 6 T 8 T 10 T 12 T

FIGURE 2.3

Sample-and-hold analog voltage for ADC.

For a given sampling interval T , which is defined as the time span between two sample points, the
sampling rate is therefore given by

1
T

f s ¼ samples per second ð Hz Þ

For example, if a sampling period is T ¼ 125 microseconds, the sampling rate is f s ¼ 1 = 125 ms ¼
8 ; 000 samples per second (Hz).