AP7 – 95 – MOD 1.2.3.2 A system specific methodology (SSM) to be used in determining the need for detailed coordination of non-GSO MSS (space-to-Earth) systems with fixed service systems The purpose of the SSM is to allow a detailed assessment of the need to coordinate frequency assignments to non-GSO MSS space stations (space-to-Earth) with frequency assignments to receiving stations in a fixed service network of a potentially affected administration. The SSM takes into account specific characteristics of the non-GSO MSS system and reference fixed service characteristics. Those administrations planning to establish the need for coordination between non-GSO MSS networks and fixed service systems are encouraged to use the most recent version of Recommendation ITU-R M.1143. While urgent additional development work is being undertaken in the ITU-R to facilitate the use of the methodology described in the most recent version of Recommendation ITU-R M.1143, administrations may be able to effect coordination by applying this SSM. (WRC-15) SUP 1.3 APPENDIX 7 (REV.WRC-15) Methods for the determination of the coordination area around an earth station in frequency bands between 100 MHz and 105 GHz ANNEX 4 Antenna gain toward the horizon for an earth station operating with non-geostationary space stations MOD 1 Determination of the horizon antenna gain In its simplest implementation, the TIG method depends on the minimum elevation angle of the beam axis of the earth station antenna (εsys), which is a system parameter that has the same value on all azimuths from the earth station. If the horizon elevation angle at an azimuth under consideration is εh (degrees), the minimum separation angle from the horizon at this azimuth to any possible pointing angle for the main beam axis of the antenna (φmin) is equal to the difference between these two angles (εsys − εh), but it is not less than zero degrees. The maximum separation angle from the horizon at this azimuth to any possible pointing angle for the main beam axis of the antenna (φmax) is equal to the difference between the sum of these two angles and 180° (180 − sys − h). The maximum and minimum values of horizon gain for the azimuth under consideration are obtained from the gain pattern of the earth station antenna at these off-axis angles. Where no pattern is available the pattern of § 3 of Annex 3 may be used.