RES539 – 340 – invites 1 administrations planning to operate non-GSO BSS (sound) systems in accordance with this Resolution, to take measures to design the system to minimize interference to terrestrial services outside the non-GSO BSS (sound) service area, for example as in considering d) above; 2 administrations, whose territory is geographically close to the territory of an administration planning to operate a non-GSO BSS (sound) system in accordance with this Resolution, and for which there is a correspondingly high elevation angle to the active satellite, to take measures to facilitate the operation of non-GSO BSS (sound) systems, resolves 1 that any BSS (sound) system using non-geostationary orbits brought into operation in the frequency band 2 605-2 655 MHz in Region 3 shall be operated such that the minimum elevation angle over the service area is not less than 55 , for the purposes of sharing with terrestrial services; 2 that, before an administration notifies to the Radiocommunication Bureau or brings into use a frequency assignment for a BSS (sound) system using non-GSO satellites in the frequency band 2 630-2 655 MHz, for which complete Appendix 4 coordination information or notification information has been received after 2 June 2000, and in the frequency band 2 605-2 630 MHz for which complete Appendix 4 coordination information or notification information has been received after 4 July 2003, the following regulatory arrangements shall apply. The following mask of power flux-density values at the Earth’s surface produced by emissions from a space station for all conditions and for all methods of modulation shall be used as the basis of the regulatory procedures of this Resolution: −130 dB(W/(m2 · MHz)) for 0 5 −130 + 0.4 ( − 5) dB(W/(m2 · MHz)) for 5° < 25° −122 dB(W/(m2 · MHz)) for 25° < 45° −122 + 0.2 ( − 45) dB(W/(m2 · MHz)) for 45° < 65° −118 + 0.09 ( − 65) dB(W/(m2 · MHz)) for 65° < 76° −117 dB(W/(m2 · MHz)) for 76° < 90° where is the angle of arrival of the incident wave above the horizontal plane, in degrees. These values relate to the power flux-density and angles of arrival which would be obtained under free-space propagation conditions. Furthermore: – for angles of arrival less than 76° in the power flux-density mask above, if the limits are exceeded, the notifying administration shall obtain the explicit agreement from any administration identified by the Bureau in its examination below; – for angles of arrival from 76° to 90° in the power flux-density mask above, the coordination procedure with respect to those administrations identified by the Bureau in its examination below will be that of No. 9.11;