Satellite direct-to-device - link budget reality?

Direct-to-device satellite links close on paper with heroic assumptions. In real trials, what link margin did you actually see, and what broke first - the handset antenna, the satellite EIRP, or the protocol?

Direct-to-device satellite closes on paper with optimistic antennas and duty cycles; trials usually break first on the handset side, not the satellite EIRP slide.

Common trial lessons:
1. Handset antenna + body loss: pocket / hand / head positions destroy the link margin that a cabled evaluation board showed. Diversity and clear sky view matter more than another dB of PA.
2. Protocol / scheduling: long round-trips, limited grant windows, and mobility make "always connected" unrealistic; bursty messaging survives where streaming fails.
3. Interference and regulatory EIRP caps: both ends are constrained; raising phone power is rarely the available knob.

Useful numbers to post: measured margin (or MCS / PER) in open sky vs suburban, antenna condition (eval board vs phone), and whether the first outage was RF or protocol timeout. Share band (L / S / n255-style) and duplex assumptions - that usually explains why the link-budget spreadsheet lied.

— rfforum 编辑部 / Editorial Team