Calibration
98-146706-A
Chapter 6: Configuration
6-13
Confi
guration
Tracking for satellite elevation between 5 and 75 degrees
When the system has found the satellite and is in pointing mode, the performance of a
system with heading input and a system without heading input will be very similar. Note
that this is only the case for a satellite elevation range from 5 to 75 degrees.
If the satellite is an inclined orbit satellite, the missing heading information introduces a
polarization error depending on the satellite elevation and the inclination. Normally it is
required that the polarization is controlled within 1 degree towards the satellite. This gives
the following limit for use of inclined orbit satellites (a purely physical limit), and all systems
without heading input have this limit.
Tracking for satellite elevation above 75 degrees
It is not possible to use a system without heading input from the vessel's gyro compass with
satellites at an elevation of higher than 75 degrees because the system will not have the
required polarization accuracy of the transmitted signal.
6.2.7
Fixed TX IF principle
The SAILOR 900 Ka uses a TX IF gain concept. After calibration it provides a fixed average
gain from the TX-port of the ACU to the input of the BUC. Advantages of the fixed TX IF
gain principle are:
• Average TX IF gain independent of antenna cable length
1
• Compatibility with the TX Power control feature
When installing the SAILOR 900 Ka you make a cable calibration. At that point every
installation adjusts to the same average TX IF gain regardless of the ADU cable length.
Additionally the SAILOR 900 Ka system also compensates for variations of the cable
characteristics or loss over frequency.
Satellite elevation
Max allowed inclination
<20
2.5
<50
0.7
<70
0.3
75
0
Table 6-5: Satellite elevation and max. allowed inclination
1. You find the maximum allowed cable loss at
SAILOR900Ka-IM-98-146706.book Page 13 Thursday, July 16, 2015 11:07 AM
