98-175666-C
Appendix B: Dual antenna solution
B-2
Installation of the dual antenna solution
In a dual antenna configuration, the inactive (passive) antenna points where the
satellite was found at start-up or where last tracked while the antenna was active. The
inactive (passive) antenna uses the following criteria to dynamically maintain the
correct relative azimuth and elevation irrespective of whether the antenna can receive
the satellite signal or not (open loop algorithm):
1. The NMEA-0183 heading data, which must come from a gyro compass without drift,
deviation, speed or latitude errors.
2. The built-in rate sensors, accelerometers and GNSS receiver.
3. The calculated change in azimuth and elevation of the satellite position (Clarke
belt) as the vessel moves.
Parts needed
The following parts are needed for the SAILOR XTR GX-R2 Dual antenna solution:
• 1 x SAILOR XTR GX-R2 System (Master System)
• 1 x SAILOR XTR GX-R2 ADU (Slave Above Deck Unit)
• 1 x SAILOR XTR GX-R2 BDU (Slave Below Deck Unit)
• 1 x Accessory Kit for Dual Antenna operation
consists of 2 x RF Splitter/Combiner and 2 x Coax cables with F-connectors, RS-422
modem keyline/dual antenna splitter cable (37-179068)
Figure B-1: Dual mode antenna, connection diagram
Important
OPERATION ON INCLINED ORBIT SATELLITES
Dual antenna installations might experience degraded performance
when operated on inclined orbit satellites. These satellites change their
position during the day. The changed satellite position affects the
inactive (passive) antenna, resulting in mis-pointing to the satellite at the
time the antenna becomes active.
ADU (Slave)
ADU (Master)
Modem
ACU
(Master)
ACU
(Slave)
LAN
RX (L-Band)
TX (L-Band)
BUC M&C (RS-232)
ACU M&C (Ethernet)
Keyline (RS-422)
RX (L-Band)
RX (L-Band)
TX (L-Band)
TX (L-Band)
BUC M&C (RS-232)
ACU M&C (Ethernet)
Keyline (RS-422)
Keyline (RS-422)
TX Splitter
RX combiner