7 Comments

Re: Unanswered question:

Don’t confuse a satellite’s service area (the thousands of km diameter of ground it can see) with its beam spot size, which is how tightly it can beam its signal, and how close together two ground antennas on the same channel can be without interfering.

Spot size is approx

Altitude * (wavelength/antenna diameter)

So ASTS’s bigger antenna can put down more non-interfering spots on the ground.

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author

Got it, thank you for the clarification.

So what you’re saying is the ASTS antenna’s serviceable cell may be a good bit smaller than the beam diameter of 2,800km?

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Aug 26, 2022Liked by Space Case

Yes, at 30 GHz , (1 cm wavelength), and 5m for the antenna size, from a height of 700 km, the beam spots can be on the 1-2 km scale. So hundreds of thousands of potential beam spots in the visible ground area. If each spot has one or more customers, a few dozen GB/s total capacity for a satellite is not going to allow everyone to stream high-def video. Maybe you can do voice in the off-peak, but SMS is good.

That’s why Starlink, with many more satellites already than ASTS’s planned constellation, is already near capacity in most somewhat-populated cells.

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With 168 satellites and 9-13 Gbps of throughput per satellite it seems impossible to provide 5G internet to a meaningful user base. I think that ASTS is overpromising and their services will be similar to that of SpaceX and Lynk. I will gladly hear from you if you think that I am wrong though. I still believe that ASTS can capture the biggest share of this market btw.

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author

To be honest, I don’t have enough of a technical background to provide a meaningful opinion here. I’ve relied on the analysis of others for that kind of diligence

However, I’ve heard your opinion voiced by a number of technical consultants on Twitter—namely Pierre Lionnet and Tim Farrar

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We live in interesting times ! Perhaps you could expand this analysis, or have another post, to consider also Charles Miller's Lynk, and Iridium (who have had great success lately). Will be watching the next Apple Sept 7 launch event in anticipation as well. "A Feint Within A Feint Within A Feint " but never under-estimate SpaceX... they have proven they can execute....plus if we add in Swarm and some recent vague comments from Sara Spagnolo you could make a case that SpaceX is intent on owning the entire SatComs space ; Broadband, iOT and cellphone service

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author

Yes I’ve enjoyed learning more about Iridium—I did a summary of their 2Q earnings call, where they posted great results

I’d love to learn more about Lynk, but given that it’s a private company I haven’t spent a ton of time on them…yet! Perhaps it’s time I do.

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