Appendix M. Standardization of Timing Compensation
In May 2005, SatLabs specified the procedure a DVB-RCS VSAT should use to compensate for the delay
from and to the satellite plus internal delay in the VSAT in order to make sure that the logon burst sent by
the VSAT is received at the DVB-RCS Hub with correct timing when using DVB-S Forward Links.
The VSAT is by factory default configured to be compliant with the SatLabs procedure for timing
compensation for DVB-S Forward Links, as well as being configured to comply with any proprietary
timing compensation scheme.
To show what timing compensation method the VSAT is configured to use, enter the CLI command dvb
pos show.
Example:
# dvb pos show
Latitude : 59d 52.15'N ( 59d 52' 9''N )
Longitude : 10d 29.05'E ( 10d 29' 3''E )
Altitude : 60 m
Timing Reference : SatLabs
PositionSearchN : 0
Position Search Offset : 0
Pos Large Uncertainty : First
Pos LTU Done : No
#
#
The VSAT can also be configured to offset the timing of the logon burst a given number of NCR ticks
from the SatLabs timing reference by entering the CLI command dvb pos delayburst <ticks>
where <ticks> is the integer number of NCR ticks the logon burst will be delayed or advanced
compared to the SatLabs timing reference. The example below shows how to configure the VSAT to
delay the logon burst 30000 NCR ticks (100 us) compared to the SatLabs timing reference.
Example:
# dvb pos delayburst 30000
# dvb pos show
Latitude : 59d 52.15'N ( 59d 52' 9''N )
Longitude : 10d 29.05'E ( 10d 29' 3''E )
Altitude : 60 m
Timing Reference : Offset 30000 NCR ticks
PositionSearchN : 0
Position Search Offset : 0
Pos Large Uncertainty : First
Pos LTU Done : No
#
#
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