Q-Flex Satellite Modem Installation and Operating Handbook
6-20
6.2.4.17 Modem/BUC Carrier
These allow the modem and BUC carriers to be switched on/off independently of each
other. BUC carrier control requires a control channel (i.e. FSK or RS485) to exist between
the modem and the BUC.
6.2.5 Edit->Tx-Rx->Service->Advanced Screen
The
Edit->Tx-Rx->Service->Advanced
screen is shown in
Figure 6-6
.
Figure 6-6 Edit->Tx-Rx->Service->Advanced Screen
6.2.5.1 DVB-S2 Tx/Rx Pilot Tones
Pilots are an On/Off control that controls whether DVB-S2 pilots, which are unmodulated
symbols, are injected into the carrier on a regular basis in order to help the demodulator
lock onto the carrier. The pilots are 36 symbols long and are injected every 1440
symbols, representing an additional overhead of around 2.4%. Pilots are recommended
for FEC rates below rate ½ and for situations where the receive signal may be degraded.