(r) that geographical separations which permit sharing between terrestrial services and deep-space research operations are typically several hundreds of kilometres, and may be greater than 500 km in the absence of terrain shielding; that separations of this magnitude are not readily obtainable in many parts of the world; and that the spacecraft are visible over large areas of the Earth; (s) that considerable difficulties can be expected when sharing frequencies between deep-space research operations and other services, due to the technical problems of furnishing the required protection against both terrestrial and near-Earth satellite transmissions, UNANIMOUSLY RECOMMENDS 1. that frequencies for deep-space manned and unmanned telecommunication links be located in the frequency band between 100 MHz and 30 GHz, with additional links for use during near-Earth and recovery phases of manned space-flights in the frequency bands below 25 MHz, in accordance with the following guidelines: 1.1 frequencies in the HF range below 25 MHz are technically suitable for two-way voice and other communications during manned mission near-Earth and recovery phases; 1.2 the band between 100 MHz and I GHz is generally more suitable for narrow-band telemetering, tracking, telecommand and voice from launch to intermediate distances; 1.3 the band between 1 GHz and 6 GHz is generally more suitable for wideband telemetering, precision tracking, telecommand, voice and television from launch to extreme distances; 1.4 the band above 6 GHz is generally more suitable for very wideband telemetering, very precise tracking and television at various distances; 1.5 that special consideration should be given to the availability of coherently related frequencies, spaced at 7% or more of the higher frequency in the bands above 1 GHz, and to the availability of frequencies in three bands, widely separated in frequency, such as the 2 GHz, 8 GHz and 15 GHz regions for precision tracking systems; 2. that spectrum space of the order of 2 to 4 MHz per link (due account being taken of the dependency of the radio-frequency bandwidth on the type of modulation used) is technically suitable for the transmission of wideband information for lunar flights. 3. that spectrum space of the order of 2 to 6 MHz per link is technically suitable for the transmission of wideband signals for precision two-way ranging; 4. that bandwidths of the order of 40 to 400 MHz per link are technically suitable for the transmission of very wideband signals for very precise two-way tracking; 5. that tracking be time-multiplexed with lunar television or planetary facsimile where practicable; 6. that where practicable, frequencies be shared among deep-space probes with different launch periods and different celestial coordinates, but not generally with spacecraft with the same celestial coordinates; 7. that the protection criteria for earth stations be established as follows: the total time during which the power spectral density of noise-like interference, or the total power of CW-type interference in any single band and all sets of bands 1 Hz wide, is greater than —222 dB(W/Hz) in the 2 GHz region, -220 dB(W/Hz) in the 8 GHz region, and —218 dB(W/Hz) in the 15 GHz region, at the input terminals of the receiver, shall not exceed an aggregate of five minutes on any one day without prior planning; for frequencies below 1 GHz, the permissible interference power level may be increased at the rate of 20 dB per decreasing frequency decade; 8. that the protection criteria for space stations be established as follows: the total time during which the power spectral density of noise-like interference or the total power of CW-type interference in any single band and all sets of bands 1 kHz wide, is greater than — 171 dB(W/kHz) in the 2 GHz region, — 170 dB(W/kHz) in the 7 GHz region and - 168 dB(W/kHz) in the 15 GHz region, at the input terminals of the receiver, shall not exceed an aggregate of five minutes of any one day; for frequencies less than 300 MHz, the permissible interference may be increased at the rate of 20 dB per decreasing frequency decade; 9. that, when necessary for emergency purposes, manned deep-space flights use the recognized distress frequencies in accordance with the Radio Regulations; 10. that a deep-space research service cannot share Earth-to-space bands with: 10.1 receiving aeronautical mobile stations, 10.2 receiving satellite stations, and 10.3 transmitting terrestrial stations and earth stations utilizing high average e.i.r.p.; for example, transmitting trans-horizon stations, and transmitting fixed satellite earth stations. When coordination is practicable, sharing is feasible with other stations of all services. In some cases, coordination distances may be unacceptably great;
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