Page 146 - Fundamentals of Communications Systems
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4.22 Chapter Four
xt ()
I
1
T 2T 3T 4T t
−1
xt ()
Q
1
T 2T 3T 4T t
−1
Figure 4.18 x I (t) and x Q (t).
x t()
A
1
T 2T 3T 4T t
x t()
π P
π/2
T 2T 3T 4T t
−π/2
−π
Figure 4.19 The amplitude and phase of a bandpass signal.
y t()
x t() LPF I
I
+
(
2cos 2πf t( c ) ∑ x c (t) 2cos 2πf t +θ(t))
c
−
π/2 π/2
−y t()
− x t() Q
Q LPF
Figure 4.20 A downconverter with a phase offset.
