When the Federal Communications Commission retired its 1990s Equivalent Power Flux Density (EPFD) limits in May, it answered a question of philosophy: static emission masks are out, performance-based protection of geostationary (GSO) systems is in. What it did not fully answer was the question of arithmetic—against exactly what assumed GSO link does an NGSO operator's interference get measured? On May 28, 2026, the Space Bureau within the Commission opened that question for comment in a public notice published as Federal Register document 2026-10617, and for anyone tracking who actually wins satellite spectrum disputes, this sequel may matter more than the headline rule.
A "reference link" is a standardized model of a geostationary satellite link—its assumed antenna gain, carrier bandwidth, modulation, and link margin—that the regulator uses as the protected baseline. When the new framework asks whether an NGSO constellation degrades GSO "performance," the reference link is the definition of the performance being protected. Tighten the reference link assumptions and the regime behaves almost like the old EPFD mask; relax them and NGSO operators gain headroom. The parameters are not a footnote; they are the dial that sets the entire regime's strictness.
"Ensuring the GSO reference links appropriately reflect typical and widespread GSO satellite operations in the United States will promote efficient spectrum sharing among today's broadband satellite systems."— Federal Register, source
The phrase to underline is "typical and widespread." The Bureau is signaling that it wants reference links calibrated to how GSO systems are actually operated today, not to a worst-case or legacy configuration that might be technically permissible but rarely deployed. That framing tilts toward NGSO interests: if the protected baseline reflects ordinary GSO operations rather than the most demanding possible link, the margin an NGSO operator must preserve shrinks. GSO incumbents, predictably, will argue that their networks must be protected against the configurations they could deploy, not merely those they typically run.
Why a comment round is the real arena
It is easy to dismiss a notice seeking comment as procedural housekeeping. In satellite spectrum policy it is the opposite. The Report and Order set the framework, but a Report and Order is hard to relitigate; the reference-link parameters are still open, and they are where the technical record gets written. Operators that file detailed engineering submissions—measured antenna patterns, realistic carrier plans, statistically representative link budgets across the GSO arc—will shape the parameters that every future coordination dispute is decided against. Operators that sit out the comment round will live with numbers their competitors helped draft.
This is also where definitional anchors earn their keep. The reference link is not a single number but a bundle of assumptions, and each assumption is a small fight: which antenna reference pattern, which assumed bandwidth, which availability target. A reference link defined around a high-gain, narrow-beam GSO antenna protects incumbents more aggressively than one defined around the wider operational beams common in consumer broadband service. The Bureau's invitation to revise the set adopted in the Order is effectively an invitation to relitigate those assumptions one parameter at a time, on the technical merits.
What this signals about the regime's trajectory
The sequencing tells a story. The Commission adopted the framework first and then, almost immediately, opened the parameters for refinement—an acknowledgment that the hard, contestable engineering had not been fully resolved when the headline rule issued. That is not unusual in spectrum policy, where the principle is often settled before the numbers are, but it does mean the new regime's real strictness is still being negotiated. Until the reference links are finalized, an NGSO operator cannot say with confidence how much headroom the post-EPFD world actually grants it.
For the competitive-intelligence reader, the proceeding rewards attention to who shows up and what they file. Reference-link advocacy is a window into each operator's true engineering posture: the antenna patterns and carrier assumptions a company defends in comments reveal how its own system is built and where it believes its interference advantage lies. The submissions function as a soft disclosure layer, often more candid about real-world operations than marketing ever is.
Two watch items follow. First, whether the Bureau adopts reference links closer to "typical" operations—favoring NGSO entrants—or to conservative worst-case configurations that preserve more of the protection incumbents enjoyed under EPFD. Second, how durable the finalized parameters prove: reference links that are seen as gameable will invite repeated petitions to revise, keeping the regime in flux. Either way, the comment round is not a formality. It is the place where the abstract promise of "efficient spectrum sharing" gets converted into the concrete numbers that decide a close call between a GSO incumbent and an NGSO challenger.
There is a deeper lesson here about how satellite policy actually gets made. The dramatic, quotable decisions—scrapping a quarter-century-old framework—draw the headlines, but the operative substance migrates into proceedings like this one, where the work is dense, technical, and easy to overlook. A reference link is the kind of artifact that never makes the trade press yet quietly determines billions of dollars of capacity. The companies that understand this allocate their best RF engineers to comment drafting, not their communications staff to press releases. For the reader trying to forecast the post-EPFD balance of power, the honest answer is that it is not yet knowable, and will not be until the Bureau publishes the finalized reference links and the first hard coordination dispute tests them. Watch the docket, not the headline.