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portylloon Emergency SOS via satellite

MHz-POP makes the most sense in cell networks, where an operator (AT&T, T-Mobile,...) wants to acquire a spectrum license in a particular region of the country. Evaluating the MHz-POP makes sense as the price they are willing to pay varies a lot depending on the population density in that region area. In general, cell networks can reuse spectrum more easily (deploy more towers, add more sectors), and they design their network deployment to hit whatever MHz/customer they are targeting (which mostly depends on the technology 3G/4G/5G).

In sat-networks, well, MHz-POP doesn't matter that much, because, generally, every operator is licensed to operate in the whole country. As you mentioned, what really matters is (a) the bandwidth of their license allocation (e.g., Globalstar is 11.5 MHz), and (b) how efficiently can they reuse spectrum:

* how many beams can they land (# satellite x # beams / satellite)?

* how much freedom do they have to chunk bandwidth and allocate it to individual beams based on demand?

* what type of satellite are they using, bent-pipe or regenerative payload?

* how big are these beams?

* can they allocate resources dynamically or is everything fixed?

* how much power does the satellite have? how big are the terminal antennas? what kind of link-budget can they close?

In the end, the MHz/customer they can achieve depends on the answer to all these questions.

portylloon Emergency SOS via satellite

A MHz-POP is just bandwidth times population covered by the Geographic Service Area (i.e., where the company is licensed to operate). For example, in the US, they would have 11.5 MHz x 330 M = 3.79 Billion MHz-POP.

portylloon MIT engineers fly first-ever plane with no moving parts (2018)

This made it to the cover of Nature with a similar headline [0]. I guess that they are also "overhyping everything".

[0] https://pbs.twimg.com/media/DsmahXYXoAAkaoI?format=jpg&name=...

portylloon Orbital edge computing: nano satellite constellations as a computer system

No, it will not be possible, no matter what Elon says.

Starlink operates in portions of the Ku and Ka bands that are reserved for Earth-to-space comms, not for space-to-space comms.

portylloon Orbital edge computing: nano satellite constellations as a computer system

There is plenty of bandwidth to achieve more than 1 Gbps of throughput from a 3-U cubesat (see Planet with their latest X-band comms-system [1], which results in more than 50 GB per pass). If you really need more than that, new free space optical communications systems under-development will bring multi-Gbps to small-sats [2]. For me, the real problem with nanosats is that they generate barely no power and they are really volume-constrained compared to the bigger birds (so you cannot have high-resolution sensors, and cannot fit in there a good optical-comms system, you need to be mindful of your power consumption all time during the mission...).

Finally, note that nowadays Planet downloads 10 TB/day, and they could go up to 40 TB/day once they upgrade their fleet with the latest X-band antenna, which is comparable to the 80 TB/day that DigitalGlobe generates.

[1] https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=4... [2] https://www.tesat.de/images/tesat/products/TOSIRIS_Data-Shee...

portylloon Amazon Seeks Permission to Launch 3k Internet Satellites

http://systemarchitect.mit.edu/docs/delportillo19a.pdf

I am one of the authors.

This was donde in Sept 2018 so its a little bit outdated by now.

portylloon Amazon Seeks Permission to Launch 3k Internet Satellites

Well, look at Oneweb as an example. They have raised 3+ billions, still need more funding and their total system throughout is not that much larger than Viasat-3's,which has a cost of ~1 billion (?). I don't think that Starlink is gonna be significantly (maybe a factor of 0.5x) cheaper in terms of cost per Mbps.

portylloon Amazon Seeks Permission to Launch 3k Internet Satellites

Developing compatible systems would be very expensive. There are very few standards in Space Comms., specially for satellite-to-satellite Comms.

portylloon Amazon Seeks Permission to Launch 3k Internet Satellites

SpaceX satellites cannot handle 1 Tbps each, they can handle 23 Gbps each according to their FCC filling.

portylloon Amazon Seeks Permission to Launch 3k Internet Satellites

Specially now that the satellites have no crosslinks.

portylloon Amazon Seeks Permission to Launch 3k Internet Satellites

It's not true. LEO systems are far more CAPEX intensive than GEO, and neither Starlink, Oneweb, Telesat, or Kuiper will be cheaper than Viasat-3 and will not be able to compete in terms of cost per Gbps.