Instrument Function
R&S
®
SMBV100A
288Operating Manual 1407.6062.32 ─ 08
OFF Differ-
ential
Phase
Diff.
Diff.
+Gray
Gray GSM NADC,
PDC,
PHS,
TETRA,
APCO25
(PSK),
PWT
TFTS/
TETRA
INMARSAT,
ICO,
WCDMA,
cdma2000
VDL APCO25
(FSK)
APCO25
(8PSK)
32QAM EDGE X
64QAM X X X X X
128QAM X X X X X
256QAM X X X X X
1024QAM X X X X X
Modulation type pi/4DQPSK
With differential coding switched on at the same time, a constellation diagram is obtained
for pi/4DQPSK which is similar to that obtained for 8PSK. Phase shifts are however
assigned to the individual modulation symbols. The following tables show the assignment
of modulation symbols to phase shifts of the I/Q vector in relation to the selected coding.
Table 5-4: Phase shifts for pi/4DQPSK
Modulation symbol a
n
(binary indication: MSB, LSB)
00 01 10 11
Phase shifts without coding + 45° + 135° - 135° - 45°
Phase shifts with coding NADC, PDC, PHS,
TETRA or APCO25 (PSK)
+ 45° + 135° - 45° - 135°
Phase shifts with coding TFTS - 135° + 135° - 45° + 45°
Coding algorithms
Common coding types are listed in the following table.
Table 5-5: Coding algorithms
Coding Coding algorithm Applicable for K bit/symbol
NONE b
n
= a
n
k = 1...8
Differential
b
n
= (a
n
+ b
n-1
) modulo 2
k
k = 1...7
Differential + Gray Gray coding with additional differ-
ential coding
k = 1...7
GSM dc
n
= not (d
n
exor d
n-1
) k = 1
Baseband Signal - Baseband Block
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