迈向真正共存：每颗卫星的发射与辐射限值，以在1-14 GHz频段保护射电天文和大地测量甚长基线干涉测量（VLBI）免受卫星星座干扰
Towards Genuine Coexistence: Per-Satellite Emission and Radiation Limits to Protect Radio Astronomy and Geodetic VLBI at 1-14 GHz from Satellite Constellations
AI总结：
本研究针对1-14 GHz频段，建立卫星星座的等效功率通量密度模型，推导每颗卫星的杂散发射与无意电磁辐射限值，发现当前卫星已突破射电天文保护限值，且2620 MHz DTD下行链路的二次谐波已造成大地测量VLBI至少59%的数据损失
AI中文摘要：
大地测量甚长基线干涉测量（VLBI）是射电天文业务（RAS）中易受干扰的应用：它提供了天球参考架与地球参考架之间的基本联系，是唯一能唯一确定UT1-UTC的技术。下一代大地测量VLBI全球观测系统（VGOS）通过在3-14 GHz频段内合成32×32 MHz通道的群延迟，实现了毫米级精度，其中大部分通道位于RAS主要分配频段之外。SNIFFLES-I调查（Indermuehle等人，2026年）测量了非地球静止轨道（NGSO）系统在1-26 GHz频段内的有意发射、无意发射（杂散发射，特别是谐波）以及无意电磁辐射（UEMR）。在此基础上，我们对当前及未来星座的等效功率通量密度（EPFD）进行建模，并与国际电信联盟无线电通信部门（ITU-R）RA.769的保护限值进行对比。分析扩展至SNIFFLES-I已检测到的无射电天文分配的频段。针对大地测量VLBI，我们在AuScope VGOS台站运行蒙特卡洛EPFD模型，并采用经过验证的方法，将当前已编目星座（约12000颗卫星）的总数据规模扩展至文件中记录的数十万颗卫星。通过将EPFD分析与内插得到的RA.769阈值进行逆运算，得出杂散发射和UEMR的最大可容忍每颗卫星限值，以标准制定机构要求的10米处的场强限值（单位：dB(μV/m)）表示。我们将太阳同步轨道上拟议的轨道数据中心视为受UEMR主导的特殊情况。研究发现，如今已有两个主要RAS频段的单天线保护限值被突破；对于大地测量VLBI而言，主要威胁来自2620 MHz频段的设备直连（DTD）下行链路的杂散发射，其在5240 MHz处的二次谐波如今已造成至少59%的数据损失。（摘要已针对arXiv字数限制修改）
英文摘要：
Geodetic very long baseline interferometry (VLBI) is a vulnerable application of the radio astronomy service (RAS): it provides the fundamental link between the celestial and terrestrial reference frames, and is the only technique that uniquely determines UT1-UTC. The next-generation geodetic VLBI Global Observing System (VGOS) achieves millimetre accuracy by synthesising group delay across 3-14 GHz using 32x32 MHz channels, most of which lie outside RAS primary allocations. The SNIFFLES-I survey (Indermuehle et al 2026) measured intended emissions, unwanted emissions (spurious emissions, notably harmonics), and unintended electromagnetic radiation (UEMR) of NGSO systems from 1-26 GHz. On this basis we model the equivalent power flux density (EPFD) of current and future constellations and compare against protection criteria of ITU-R RA.769. The analysis extends to frequencies without radio astronomy allocations where SNIFFLES-I made detections. For geodetic VLBI, we run a Monte-Carlo EPFD model at the AuScope VGOS stations and scale the aggregate from the present catalogued fleet (~12000 satellites) to the hundreds of thousands on file with a validated method. Inverting the EPFD analysis against the interpolated RA.769 thresholds yields maximum tolerable per-satellite levels for spurious emissions and for UEMR, expressed as a field-strength limit in dB(uV/m) at 10 m for standard-setting bodies. We treat proposed orbital-data-centres in Sun-synchronous orbit as a distinctively UEMR-dominated case. We find that already today the single-dish protection criteria are exceeded in two primary RAS bands. For geodetic VLBI, the dominant threat is spurious emission from the 2620 MHz Direct-to-device (DTD) downlink, whose second harmonic at 5240 MHz already causes at least 59% data loss today. (Abstract modified for arxiv limits)
