User Manual Part 2

Lynx.GX Installation and Management
Reflection Point (international)
The formula for calculating the position of the reflection point on a path is
for K = 4/3
h
1
/d
1
– d
1
/17 = h
2
/d
2
– d
2
/17
for K = 2/3 h
1
/d
1
– d
1
/8.5 = h
2
/d
2
– d
1
/8.5
for K = ∞
d
1
= D • h
1
/(h
1
– h
2
.)
where:
h is in meters
d and D are in kilometers
(The K factor allows for consideration of atmospheric conditions by allowing for the path of the beam, relative to
the earth. K = 4/3 is normal for atmospheric conditions and K = infinity is for worst case flat-earth propagation
conditions.)
Fading Outages and Availability (USA)
The formula for calculating the unavailability, U, of a path (due to multipath fading) is:
U = a x b x 2.5 x 10
-6
x f x D
3
x 10
-F/10
where:
a = climate (0.1 to 0.5)
b = terrain (0.25 to 4)
f = frequency, GHz
D = path length, miles
F = fade margin, dB
The formula for calculating the availability, A, of a path is:
A = (1 - U) 100%
where:
U = unavailability
Appendix A. Installation Planning 50