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
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