User's Manual

20
4000m
Fresnel Zone
Line of Sight Obstruction
Line of Sight
Figure 11 Worked Example over a hill
Calculation:
120 dB + 20 dB + 8 dB = 148 dB
The result of this calculation shows that this scenario would work continuously at 16QAM.
4.3 Mean Power
A Web Management page for Gemini has an important indicator of mean path loss. This is
shown in figure 16. Also on this Web Page is the range. Figure 12 gives the maximum mean
path loss vs range for guaranteeing that Gemini is installed in a position that will give 99.99%
availability. Note: The web page display is for the previous hour and the full fade cycle may not
be traversed for many days depending upon the components causing the fading.
0.1 0.5 1 5 10 50
range km
140
145
150
155
dB
Mean Path Loss BPSK16QAM
Figure 12 Mean path loss vs range for BPSK and 16QAM