CONTENTS

 

Policy on Intellectual Property Right (IPR)     ii
RECOMMENDATION  ITU-R  P.452-14     1
Prediction procedure for the evaluation of interference between stations on the surface of the Earth at frequencies above about 0.1 GHz     1
Scope     1
Annex 1     2
 1     Introduction  2
 2     Interference propagation mechanisms  2
 3     Clear-air interference prediction  4
        3.1     General comments  4
        3.2     Deriving a prediction  4
                  3.2.1     Outline of the procedure  4
Step 1: Input data     4
Step 2: Selecting average year or worst-month prediction     5
Step 3: Radiometeorological data     6
Large bodies of inland water     7
Large inland lake or wet-land areas     7
Effective Earth radius     7
Step 4: Path profile analysis     8
 4     Clear-air propagation models  8
        4.1     Line-of-sight propagation (including short-term effects) 8
        4.2     Diffraction  9
                  4.2.1     Median diffraction loss  9
Median diffraction loss for transmitter-side secondary edge     10
Median diffraction loss for the receiver-side secondary edge     11
Combination of the edge losses for median Earth curvature     11
                  4.2.2     The diffraction loss not exceeded for β0% of the time  12
Principal edge diffraction loss not exceeded for β0% time     12
Transmitter-side secondary edge diffraction loss not exceeded for β0% time     12
Receiver-side secondary edge diffraction loss not exceeded for β0% time     12
Combination of the edge losses not exceeded for β0% time     13
                  4.2.3     The diffraction loss not exceeded for p% of the time  13
        4.3     Tropospheric scatter (Notes 1 and 2) 14
        4.4     Ducting/layer reflection  14
        4.5     Additional clutter losses  16
                  4.5.1     General 16
                  4.5.2     Clutter categories  16
                  4.5.3     The height-gain model 17
                  4.5.4     Method of application  18
        4.6     The overall prediction  18
        4.7     Calculation of transmission loss  20
 5     Hydrometeor-scatter interference prediction  22
        5.1     Introduction  22
        5.2     Input parameters  24
        5.3     The step-by-step procedure  25
Step 1: Determination of meteorological parameters     25
Step 2: Conversion of geometrical parameters to plane-Earth representation     26
Step 3: Determination of link geometry     27
Step 4: Determination of geometry for antenna gains     32
Step 5: Determination of path lengths within the rain cell     35
Step 6: Attenuation outside the rain cell     38
Step 7: Numerical integration of the scatter transfer function     39
The extended trapezoidal rule     40
Step 8: Determination of other loss factors     42
Step 9: Determination of the cumulative distribution of transmission loss     44
Appendix 1 to Annex 1  Radio-meteorological data required for the clear-air prediction procedure     44
 1     Introduction  44
 2     Maps of vertical variation of radio refractivity data  45
 3     Map of surface refractivity, N0 46
 4     Implementation of maps in computer database form   46
Appendix 2 to Annex 1  Path profile analysis     47
 1     Introduction  47
 2     Construction of path profile  47
 3     Path length  49
 4     Path classification  50
 5     Derivation of parameters from the path profile  50
        5.1     Trans-horizon paths  50
                  5.1.1     Interfering antenna horizon elevation angle, θt 50
                  5.1.2     Interfering antenna horizon distance, dlt 51
                  5.1.3     Interfered-with antenna horizon elevation angle, θr 51
                  5.1.4     Interfered-with antenna horizon distance, dlr 51
                  5.1.5     Angular distance θ (mrad) 51
                  5.1.6     �Smooth-Earth� model and effective antenna heights  51
Appendix 3 to Annex 1  An approximation to the inverse cumulative normal distribution function for     x ≤ 0.5     54