In addition to the foregoing in-band criteria are receiver saturation effects that can result from out-of-band signals of sufficient strength. ANTENNA POINTING AND GAIN The 64-m earth station antenna has a main beam gain of 62 dBi at 2.3 GHz and 72 dBi at 8.4 GHz. While tracking a particular spacecraft in or near the ecliptic plane, the beam from at least one earth station will intersect the geostationary orbit once a day. Assuming the CCIR reference antenna pattern, the receiving antenna gain in the direction of the geostationary orbit will never be less than -10 dBi. RELATIONSHIP TO SPS The SPS frequency of 2450 MHz is 150 MHz above the edge of the 2300-MHz deep-space band. The interference from SPS cannot yet be calculated since there is not enough data on transmitted noise sidebands. The satellite e.i.r.p. in the deep-space band must be less than -220-62+191 = -91 dB W/Hz not to violate the protection criteria while the earth station antenna is pointed at an SPS satellite, or less than -220+10+191 = -19 dB W/Hz for the minimum gain case. Considering the +98 dB W transmitter power of just one satellite, the combination of noise sidebands, transmitting antenna patterns, and 60 satellites can be expected to result in substantial degradation of deep-space communication links. Harmonic radiation is another potential problem. The 13th and 14th harmonics of the SPS frequency fall within the 32-GHz region of interest for future deep-space applications. While such high order harmonics are not normally considered problematic, the extremely high SPS power at least poses a question of interference. Lower order harmonics fall outside the deep-space bands. The concept of a "Goldstone in the sky" has been studied. An antenna and receiver for deep-space communication could be placed in geostationary orbit, yielding some important performance advantages. While not currently planned, the possibility of such a station in the time period of SPS implementation
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