SMD 989
– User Manual
Page 50 (105)
Modulation/FEC
: The modulations and supported code rates are shown in Figure 42. The
supported modes are selectable in the drop down list in the Modulation/FEC field.
The remaining settings include (Bold indicates default):
Pilot Insertion
(Only available in DVB-S2 and DVB-S2X Modes)
-
Enable
-
Disable
Description:
When enabled, every 16 slots of 90 symbols the modulator will insert 36
non-modulated symbols to aid in receiver synchronization. The use of a pilot allows the
receiver to maintain carrier recovery, even when the user data payload cannot be
decoded.
Frame Size
(Only available in DVB-S2 and DVB-S2X Modes)
-
Normal (64,800 bits)
-
Short (16,200 bits)
Description:
Short frames introduce more overhead but give a shorter encapsulation
delay. Short frames are 4 time shorter than normal frames.
Spectral Inversion
-
Normal
-
Inverted
Description:
Determines whether the spectrum is inverted or normal.
Note:
When the SMD 920 L-Band option is installed, the default spectral inversion is
inverted as the upconverter will invert. Setting the output to Inverted will give a normal
output from the upconverter. This is shown in the RF Output status for Spectral Inversion.
Alpha Filter Rolloff
-
0.35
-
0.25
-
0.20
-
0.15
-
0.10
-
0.05
Description:
The filter rolloff
is known as the Alpha coefficient (α). The smaller the α, the
less bandwidth will be required on the satellite.
Rate Adaptation
(Only available in DVB-S2 and DVB-S2X single modes)
-
Disable
-
Enable
