SHAPING THE FUTURE OF SATELLITE COMMUNICATIONS
8.2 Pilots in DVB-S2
8.2.1 What are Pilots
Pilots are unmodulated symbols grouped in blocks that can be added on the
physical layer framing level.
8.2.2 Why are pilots used in DVB-S2
• Reduce the phase noise influence;
Phase noise is created by the frequency components around the main carrier
frequency.
This noise contains components at many frequencies with randomly changing
phase.
• Pilots are used to increase the reliability and the continuous receiver
synchronization.
8.2.3 When are Pilots Used in DVB-S2
It is adviced to use pilots in the following cases.
• In ACM mode (always on).
• When a noticable amount of phase noise is present;
• At low data rates;
• When distortion is present on the signal for example due to non linearity.
• When using one of the following ModCods. (this is due to the ModCod
structure)
- 8-PSK 3/5 and 2/3
- 16-APSK 3 /4
- 32 APSK 3/5
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