Configuring the internal baseband source
R&S
®
SMM100A
140
User Manual 1179.1341.02 ─ 05
Off
Differ-
ential
Phase
Diff.
Diff.+
Gray
Gray
GSM
NADC,
PDC,
PHS,
TETRA,
APCO25
(PSK),
PWT
TFTS/
TETR
A
INMARSAT,
ICO,
WCDMA,
cdma2000
VDL
APCO2
5 (FSK)
APCO25
(8PSK)
16APSK
X
32APSK
X
4.5.5.1
Common coding algorithms
In the notation used below, a
n
denotes the n
th
input symbol and b
n
denotes the corre-
spondingly coded output symbol. Individual bits in the symbols from the LSB (least sig-
nificant bit) to the MSB (most significant bit) are denoted by a
0n
, a
1n
, etc. The same
applies to the output symbols.
Common coding types are listed in
.
Table 4-8: Common coding algorithms
Coding
Coding algorithm
Applicable for
K bit/symbol
"None"
b
n
= a
n
k = 1...8
"Differential"
b
n
= (a
n
+ b
–1
) modulo 2
k
k = 1...7
"Differ Gray"
Gray coding with additional differential coding
k = 1...7
"Phase Differential"
b
1n
= [NOT (a
1n
EXOR a
0n
) AND (a
1n
EXOR b
1(n-1)
)] OR
[(a
1n
EXOR a
0n
) AND (a
1n
EXOR b
0(n-1)
)]
b
0n
= [NOT (a
1n
EXOR a
0n
) AND (a
0n
EXOR b
0(n-1)
)] OR
[(a
1n
EXOR a
0(n-1)
) AND (a
0n
EXOR b
1(n-1)
)]
-
"Coding > Phase Differential/INMARSAT" correspond to system standards Inmarsat-M
and DVB according to ETS 300 429. You can use INMARSAT coding for modulation
types with 2 bits/symbol, such as QPSK.
Examples
The following examples illustrate how some of the different common coding schemes
combined with a modulation method influence the signal.
Generating custom digital modulated signals
