ITU Radio Regulations and Space Security Standards ITU-Space-Services-Art21-Art22-Art23-PFD-EPFD-Limits-NGSO-Constellation-Milestones-Bringing-Into-Use: ITU Radio Regulations Article 21 Terrestrial and Space Sharing + Article 22 Space Services + Article 23 Time Signal + PFD Power Flux Density + EPFD Equivalent PFD + NGSO Non-Geostationary Constellation Milestones + Bringing Into Use

Articles 21 + 22 + 23 of the ITU Radio Regulations establish the framework for space radiocommunication services + terrestrial-space sharing + and protection mechanisms. (1) Article 21 Terrestrial and Space Sharing: (a) Article 21.1-21.5 - applies to frequency bands shared between space service stations + terrestrial service stations + provides PFD Power Flux Density limits at Earth surface for space stations to protect terrestrial services; (b) Article 21.16 - maximum permissible PFD values in frequency bands shared between space services and terrestrial services per Table 21-4 (varies by service + band + elevation angle e.g. -154 dBW/m2/4 kHz for GSO FSS); (c) Article 21.5 - exceedance of PFD limits permitted upon agreement of affected administrations; (d) limits cover GSO FSS + GSO MSS + GSO BSS + NGSO FSS + NGSO MSS + amateur satellite + RNSS protection of GPS/GLONASS/Galileo/BeiDou + RAS Radio Astronomy Service protection. (2) Article 22 Space Services: (a) Article 22.1-22.5C - protection of GSO networks from NGSO satellite networks operating in same frequency bands - the Equivalent PFD (EPFD) Limits regime - applicable in shared GSO + NGSO bands; (b) EPFD-down + EPFD-up + EPFD-IS aggregate Equivalent Power Flux Density limits as specified in Articles 22.5C/D/E/F; (c) Maximum EPFD-down per Article 22.5C Table 22-1 (e.g. -195.9 dBW/m2 over 40 kHz for percentage of time + arc range); (d) NGSO operators must demonstrate compliance with EPFD masks via software (validate using ITU-R Recommendation S.1503 software tools - GSO Reference Earth Station + NGSO Constellation simulator); (e) Article 22.16-22.21 - Maximum coordination distances + operating limits in deep space + interservice protection; (f) Article 22.32 - protection of RAS Radio Astronomy Service from satellite operations per ITU-R Recommendation RA.769. (3) Article 23 Time Signal Transmissions: (a) Article 23.1-23.3 - service for dissemination of time signals + standard frequencies + including UTC + TAI Coordinated Universal Time + International Atomic Time; (b) Article 23.4-23.5 - terrestrial stations (WWVB Fort Collins USA + WWV/WWVH USA + DCF77 Germany + JJY Japan + BPC China + MSF UK + RBU Russia + RWM Russia + LOL Argentina + BPM China); (c) Article 23.6-23.10 - space stations (GPS L1/L2/L5 + Galileo E1/E5/E6 + GLONASS + BeiDou + IRNSS + QZSS); (d) frequency tolerances + transmission characteristics. (4) PFD Power Flux Density Limits: (a) measured in dBW/m2 in a reference bandwidth (usually 4 kHz or 1 MHz); (b) computed at Earth surface from satellite emissions; (c) varies with elevation angle 0-90 degrees; (d) Reference Earth Station antenna pattern per ITU-R Recommendation S.580 + S.732 + S.1428 + S.1855; (e) protection criteria for FS Fixed Service + MS Mobile Service. (5) EPFD Equivalent PFD Limits: (a) developed at WRC-2000 + further refined at WRC-23; (b) protect GSO services from aggregate emissions of NGSO constellations; (c) computed using software per ITU-R Recommendation S.1503 (now S.1503-4); (d) percentage of time + reference bandwidth + arc range; (e) NGSO operators must demonstrate compliance before BIU; (f) failure to demonstrate compliance prevents BIU. (6) NGSO Non-Geostationary Constellation Milestones per Resolution 35 (WRC-19): (a) at end of Year 2 - 10% of constellation satellites + Article 11 notification; (b) at end of Year 5 - 50% of satellites + BIU; (c) at end of Year 7 - 100% of satellites + BIU + all orbital planes deployed; (d) failure leads to limitation of recorded number of satellites to deployed satellites; (e) introduced to prevent paper constellations + ensure genuine deployment; (f) applies to NGSO FSS/MSS/BSS in 6 frequency bands. (7) Bringing Into Use (BIU) per Article 11.44/44B/47: (a) GSO satellites + 90-day in-station BIU period at notified orbital position; (b) NGSO satellites + first satellite of constellation BIU + complete BIU per Resolution 35 milestones; (c) BIU certification with technical evidence; (d) suspension up to 3 years before requiring reactivation. (8) Active NGSO Mega-Constellations: (a) SpaceX Starlink (~7000+ satellites V1/V2 + planned 42000); (b) Eutelsat OneWeb (~700 satellites Gen 1 + 2 planned Gen 2); (c) Amazon Project Kuiper (planned ~3236 satellites); (d) Telesat Lightspeed; (e) China GuoWang + Qianfan (Spacesail) ~13000 satellites; (f) ESA EU IRIS2; (g) Russian Sphera; (h) others including AST SpaceMobile + Lynk + Iridium NEXT + Globalstar + O3b mPOWER. (9) Direct-to-Device (D2D) Satellite: emerging service enabling standard smartphones to communicate directly with satellites + WRC-23 Agenda 1.2 considered + WRC-27 Agenda Items 1.2-1.4 will further consider + STARLINK Direct to Cell + AST SpaceMobile + Lynk Global + Globalstar Apple Emergency SOS. Coordinates with ITU-R SG4 Satellite Services + WP4A Earth Stations + WP4B + WP4C Cognitive + WG SatRC + Recommendation ITU-R S.1503-4 + ITU-R S.580 + RES 35 + WRC-23 Decisions on NGSO + Article 11.44 BIU + Appendices 30 + 30A + 30B BSS Plans + RR Article 32 EPFD limits in shared NGSO bands. ITU Articles 21 + 22 + 23 Space Services + PFD + EPFD + NGSO Milestones apply.