DVB-S2 Configuration and Settings
R&S
®
SMCVB-K168
28
User Manual 1179.1064.02 ─ 03
Roll Off
Sets the roll-off alpha factor value.
The output signals are pulse-shaped by an FIR filter, yielding a root raised cosine char-
acteristic. Signaling of RO bits in the MATYPE-1 field of the BB frame header is
defined in the specification.
A smaller alpha value produces a steeper drop of the modulation spectrum but the
stopband attenuation is lower. A larger alpha value produces a flatter drop of the mod-
ulation spectrum. The spectrum is wider but the stopband attenuation is higher.
The 3
dB point of the modulation spectrum is the same for all alpha values.
"0.05"
Signalized as 10
bin alternated with 11
bin.
"0.10"
Signalized as 01
bin alternated with 11
bin.
"0.15"
Signalized as 00
bin alternated with 11
bin.
"0.20"
Default value. Signalized as 10
bin.
"0.25"
Signalized as 01
bin.
"0.35"
Signalized as 00
bin.
Remote command:
[:SOURce<hw>]:BB:DVBS2:ROLLoff
Num. Time Slices
Requires "Annex M > On".
Sets the number of time slices
You can set up to 8 time slices. Time slice
1 uses data symbols from FEC encoding, all
other time slices use PRBS symbols.
A decoder decodes only one time slice. Real data transmission is only possible with
time slice
1.
Every time slice is transmitted once per time slice cycle. The duration of a time slice
depends on the settings of this time slice. The duration of a complete time slice cycle
depends on the settings of all time slices.
Remote command:
S2-X
Enables S2-X features.
For DVB-S2-X, additional modulation coding settings are defined to obtain a finer SNR
granularity compared to classical S2 modulation coding:
●
Clear sky conditions (e.g. 256
APSK)
●
Linear channel models (marked with"-L")
●
Very low SNR conditions (VL-SNR)
●
...
Related to a DVB-S2-X modulation coding setting is a corresponding LDPC code rate
and a FEC frame type. If the order of the modulation coding is higher than QPSK, a bit
interleaver pattern is related to this modulation coding setting.
Note:
VL-SNR modulation coding, super frame and channel bonding are released in a
later version.
Coding Settings