2.2.5 Interference protection for deep-space earth station receivers Interruption of telecommunications can result from interference that is strong enough to cause receiver capture or saturation. Weaker interference may result in degraded carrier tracking and telemetering performance. The level of interference that can be tolerated is determined by acceptable performance degradation. To protect deep-space earth station receivers, the power spectral density of wideband interference, or the total power of CW interference, in any single band and all sets of bands 1 Hz wide, should not be greater than the values shown in Table V, for an aggregate of five minutes in any one day *. Table V also shows the maximum power flux-density of interference, considering the effective area of a 70 m earth station antenna. TABLE V - Interference protection for earth station receivers 2.3 Co-ordination considerations The practicability of co-ordination is determined partially by the number of stations with which co-ordination must be effected. This is in turn controlled by the co-ordination distance. For deep-space research, the practicable co-ordination distance is currently considered to be 1500 km. Co-ordination distance may be calculated by the method of Appendix 28 of the Radio Regulations. An alternative method of evaluating propagation factors is given in Report 724. The two ways of determining distance give different results. For example, assuming a transhorizon station (i.e., 93 dB(W/10 kHz), in the 2.3 GHz band), the distances are 2100 and 800 km, respectively. A decision on the practicability of sharing with transhorizon stations is thus not possible, and further study is necessary. 3. Deep-space station parameters and protection pertinent to sharing The principal deep-space station parameters which pertain to interference and sharing are antenna gain and pointing, transmitter power and receiver sensitivity. Details of these parameters are given in [CCIR 1974-78b]. Space station and earth station receivers for deep-space research function in a similar manner, except that the space station does not include a maser. Space stations are as susceptible to interference as described earlier for earth stations. The criterion for protection of deep-space station receivers is that interference power must be no stronger than receiver noise power. Compared to deep-space earth station criteria, this is less severe and is a consequence of generally larger performance margins on the earth-to-space link. For protection of deep-space stations, the power spectral density of wideband interference, or total power of CW interference, in any 1 kHz band should be no larger than the amount shown in Table VI, for an aggregate of 5 minutes per day. Deep-space station e.i.r.p. is normally reduced while near the Earth, thus minimizing the potential for interference to other stations. 4. Sharing considerations: Earth-to-space bands Table VII and the following paragraphs consider the possibility of interference in the deep-space research Earth-to-space bands. ♦ Five minutes per day is generally taken as 0.001% of the time, as discussed in Report 536-1.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==