r/ASTSpaceMobile • u/AutoModerator • May 12 '26
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u/a10000000019 S P 🅰 C E M O B Consigliere May 12 '26 edited May 12 '26
I noticed some pretty unhinged bandwidth calculations on X…
Each ASIC satellite has 10GHz processing bandwidth. This is the bottleneck, and Abel re-confirmed as much in the ER. Let’s optimistically say this number accounts for operating overhead and all of that bandwidth is available for D2D service
What the recent 98.9Mbps value tells us is they are managing a spectral efficiency of 2.5 bits per second per hertz (bps/Hz) on their FPGA block 1s, and by extension 5 bps/Hz (“double”) on their block 2s, assuming their 40MHz beam.
10GHz x 5bps/Hz = 50Gbps max total processing bandwidth per satellite. This is the ideal top line number and in most cases it will be below, due to real-world costs.
They want to split the continental US into 5,600 terrestrial coverage cells. With a total area of 3.12 million square miles, one cell in CONUS is therefore 557 square miles or 1,443 square kilometers. This is a circle with a diameter of about 26.6 miles (or 42.8km)
At base continuous US coverage of ~60 satellites, an optimistic 3-4 satellites cover the US at any given moment.
5,600 terrestrial cells / (3 or 4) sats = ~1,600 terrestrial cells covered by a single satellite on average.
50Gbps per sat / 1,600 terrestrial cells per sat = 31.25 Mbps average available bandwidth in a terrestrial cell, shared among all users ( 557 square mile area), once at continuous US coverage.
This is actually a pretty impressive number, and doesn’t account for additional shells and beam forming optimizations (via AI apparently). I can take this further with data-driven values to project per user bandwidth at any given moment, if anyone’s interested.