RECOMMENDATION ITU-R SM.1542 - The protection of passive* services from unwanted emissions

The ITU Radiocommunication Assembly, considering a) that it is desirable that unwanted emissions of new stations in any radio service should not render existing stations, operating in accordance with the Radio Regulations (RR) in those or other services, unable to operate effectively; b) that, in some cases, passive services and services employing high-power transmitters have been allocated to adjacent or nearby frequency bands; c) that in many cases passive services and space services (space-to-Earth) have been allocated to adjacent or nearby frequency bands; d) that in some cases space-based passive services and services using uplink earth stations or high density terrestrial stations have been allocated to adjacent or nearby frequency bands; e) that, in making these allocations, transmitter and receiver compatibility may not have been considered; f) that the RAS, the EESS (passive) and SRS (passive) are based on the reception of emissions at much lower power levels than are generally used in other radio services; g) that, due to these low received power levels, these passive services are generally more susceptible to interference from unwanted emissions than other services; h) that several footnotes to the Radio Regulations (RR) (such as Nos. 5.149, 5.340, 5.372) draw attention to the protection of these passive services, particularly from spaceborne, airborne, or high altitude platform stations (HAPSs), (for the radio astronomy stations) and from earth stations, HAPS, and high density fixed system (HDFS) stations (for the space-based passive services); j) that there are various operational practices and mitigation techniques that can be used by the passive and active services to minimize the impact of interference on the passive services; k) that there may be practical and economic limitations on the applicability of these mitigation measures; l) that general limits for spurious emissions may not protect to the desired extent the passive services from interference;