Brief Description of Vector Signal Analysis
R&S
®
FSV-K70
30
Operating Manual 1176.7578.02 ─ 09
Derivation of OQPSK
Table 2-13: I/Q diagram and constellation diagram
QPSK
OQPSK (delayed Q component)
0
1
2
3
4
5
6
7
8
9
1
0
-2
-1
0
1
2
Inphase
0
1
2
3
4
5
6
7
8
9
1
0
-2
-1
0
1
2
Quadratu
re
Time
[symbols]
0
1
2
3
4
5
6
7
8
9
1
0
-2
-1
0
1
2
Inphas
e
0
1
2
3
4
5
6
7
8
9
1
0
-2
-1
0
1
2
Time
[symbols]
Quadratur
e
PSK vector diagram with alpha = 0.35
OQPSK vector diagram with alpha = 0.35
-2
-1
0
1
2
-2
-1
0
1
2
Inphase
Quadrature
-2
-1
0
1
2
-2
-1
0
1
2
Inphase
Quadrature
Offset QPSK reduces the dynamic range of the modulated signal (with respect to "nor-
mal" QPSK) and, therefore, the demands on amplifier linearity by avoiding zero cross-
ings.
A distinction is made in the analyzer display:
In the Vector I/Q result display of the measurement (or reference) signal, the time
delay is not compensated for. The display corresponds to the physical diagram shown
in (
In the Constellation I/Q result display of the measurement (or reference) signal, the
time delay is compensated for. The display corresponds to the logical mapping as in
Symbol Mapping
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