Annex 1
1 Introduction
2 Interference propagation mechanisms
3 Clear-air interference prediction
3.1 General
comments
3.2 Deriving
a prediction
3.2.1 Outline of the procedure
Step 1: Input data
Step 2: Selecting average year or worst-month prediction
Step 3: Radiometeorological data
Large bodies of inland water
Large inland lake or wet-land areas
Effective Earth radius
Step 4: Path profile analysis
4 Clear-air propagation models
4.1
Line-of-sight propagation (including short-term effects)
4.2
Diffraction
4.2.1 Median diffraction loss
Median diffraction loss for transmitter-side secondary edge
Median diffraction loss for the receiver-side secondary edge
Combination of the edge losses for median Earth curvature
4.2.2 The diffraction loss not exceeded for β0% of the time
Principal edge diffraction loss not exceeded for β0% time
Transmitter-side secondary edge diffraction loss not exceeded for β0% time
Receiver-side secondary edge diffraction loss not exceeded for β0% time
Combination of the edge losses not exceeded for β0% time
4.2.3 The diffraction
loss not exceeded for p%
of the time
4.3
Tropospheric scatter (Notes 1 and 2)
4.4
Ducting/layer reflection
4.5 Additional
clutter losses
4.5.1 General
4.5.2 Clutter categories
4.5.3 The height-gain model
4.5.4 Method of application
4.6 The
overall prediction
4.7
Calculation of transmission loss
5 Hydrometeor-scatter
interference prediction
5.1
Introduction
5.2
Input parameters
5.3
The step-by-step procedure
Step 1: Determination of meteorological parameters
Step 2: Conversion of geometrical parameters to plane-Earth
representation
Step 3: Determination of link geometry
Step 4: Determination of geometry for antenna gains
Step 5: Determination of path lengths within the rain cell
Step 6: Attenuation outside the rain cell
Step 7: Numerical integration of the scatter transfer function
The extended trapezoidal rule
Step 8: Determination of other loss factors
Step 9: Determination of the cumulative distribution of transmission
loss
Appendix 1 to Annex 1 Radio-meteorological data required for the
clear-air prediction procedure
1 Introduction
2 Maps of vertical
variation of radio refractivity data
3 Map of surface
refractivity, N0
4 Implementation
of maps in computer database form
Appendix 2 to Annex 1 Path profile analysis
1 Introduction
2 Construction of path profile
3 Path length
4 Path classification
5 Derivation of
parameters from the path profile
5.1
Trans-horizon paths
5.1.1 Interfering antenna
horizon elevation angle, θt
5.1.2 Interfering antenna horizon distance, dlt
5.1.3 Interfered-with
antenna horizon elevation angle, θr
5.1.4 Interfered-with antenna horizon distance, dlr
5.1.5 Angular distance θ (mrad)
5.1.6 “Smooth-Earth”
model and effective antenna heights
Appendix 3 to Annex 1 An approximation to the inverse cumulative normal
distribution function for x ≤ 0.5