User Manual

Table Of Contents
Application layers
99-137719-D Confidential - For internal use 8-45
8888
Control interface
The BGAN XL Radio Module both delivers a wide and a narrow power estimate in
which the filter bandwidths can be configured independently (see more in section
6.8.8 on page 6-52). The wide power estimate is in general calculated in a 36 kHz
bandwidth and the narrow power estimate is calculated in a 14 kHz bandwidth as
illustrated in the right section of Figure 8-24.
The key parameters for determination of the narrow bandwidth are listed in the table
below.
In a worst-case pointing scenario the long term stability of the built-in reference
oscillator could mis-align the global bearer with up +/- 7 ppm. This is illustrated in the
left part of the figure below. If the global bearer is misaligned a large percentage of the
energy from the wanted bearer will be removed by the narrow band filter making the
power estimate more or less useless and it complicates the pointing significantly. To
accommodate for this problem another power estimate is calculated with a wider
bandwidth. The key parameters for the wide bandwidth are:
Parameters Value
Global beam bearer type F80T025Q1B
Symbol rate (f
symb
) 8400 symbols/sec
Roll-off factor 0.25
Maximum system frequency offset (f
offset
) 1400 Hz
Frequency doppler uncertainty (f
doppler
)350 Hz
Minimum pass-band (f
symb
*1.25/2) + f
offset
+ f
doppler
6125 Hz
Table 8-82: Narrow band filter specifications.
Parameters Value
Global beam bearer type F80T025Q1B
Symbol rate (f
symb
) 8400 symbols/sec
Roll-off factor 0.25
Maximum system frequency offset (f
offset
) 1400 Hz
Frequency doppler uncertainty (f
doppler
)350 Hz
Reference oscillator stability ~7ppm (f
lts
) 11000 Hz
Minimum pass-band (f
symb
*1.25/2) + f
offset
+ f
doppler
+ f
lts
11625 Hz
Table 8-83: Wide band filter specifications.