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Extravehicular operations. 4. ORBITER SYSTEMS Avionics AVIONICS 50В5Ү5ТЕМ5................... 4-41 Guidance, Navigation, and Control Systems The Orbiter uses four separate communications systems: S-band PM, S-band frequency- modulated (FM), Ku-band, and ultrahigh frequency (uhf). The S- and Ku-bands are microwave systems. The pressurization system components.