STM SatLink 2000 - APPENDIX N. RECEIVER AND TRANSMITTER AUTO START

SatLink VSAT User Guide
Publication no. 101557
Copyright © 2009 – STM Group, Inc.
Page 157 (160)
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 + 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 STM SatLink VSAT is by factory default configured to be compliant with the SatLabs procedure for
timing compensation for DVB-S forward links, but can 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 :
#
The STM SatLink 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
STM SatLink 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
#
Never change the timing reference configuration without being instructed to do so by the
system operator as an incorrect timing reference configuration will prevent the VSAT
from logging on to the Hub.