These standards assume state-of-the-art system noise temperatures, RA continuum bandwidths (10-100 MHz), 2000 sec integration, 10% error, and that the interfering source is in a far side lobe of the radio astronomy antenna. The meaning of protected band is shown in the illustration below: We will of course object to any infringement by SPS in a protected band and will seek legal means to have the source turned off. This is especially true of foreign radio astronomers acting through the government agencies that have cognizance over the treaties regulating frequency-spectrum management (Chairman's note: cf Appendix C). Note: In some frequency ranges the standard is below the level of some natural sources, such as the sun; in some cases we must work at night for most sensitive observations. We foresee special difficulties with SPS in that the standards would allow infinite power at 1 Hz outside the band edge. SPS would generate extremely strong out-of-band signals which are not proscribed by existing standards, and which may be impractical to reject completely with filters. We must expand our concerns to include the problems of overloading, cross-modulation noise generation, and other nonlinear effects of strong out-of-band signals. To obtain terrain shielding, radio observatories are located in remote sites. The SPS eliminates such protection. In fact, the siting requirements of rectennas and RA observatories are parallel in many respects. Not only far-out side lobes but also the 440-km grating lobes and near-in side lobes may fall on radio observatories.
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