Intel 8253 - Page 201

REAL SAMPLING
Input Waveform
Output SpectraInput Spectra Sampling Spectra
Sampled OutputSampling Function
f(t)
t
Fourier Analysis
t
h(t)
Τ t
t
g(t)
F(f) H(f) G(f)
f1
f
s
= 1/T
t /1
2f
s
f
1
f
s
2f
s
fff
Input signals are not truly
band limited
(
)
1
f2sf >
/
envelope
sin
x
x
Sampling cannot be done with
impulses so, amplitude of
signal is modulated by
Because of input spectra and
sampling there is aliasing and
distortion
x
xsin
Square Wave
f(t)
A
Period T
2/2/ tt +−
Envelope has the form






=
tp
tpt
f
fsin
T
A
E
t /1− t /1
0
T/A t
F(f)
Analog and Mixed Signal Center, TAMU