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.
Thank you! Doesn't that seem like a weird metric? I would think MHz/POP would make more sense. I guess the idea is to assume unlimited and independent channels to everyone as a first order?
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.
I think multiplying by population serves as a way to normalize for link speed. Ten people who use a lot of spectrum are probably bigger customers than ten people who use a tiny sliver of spectrum, and thus constitute a bigger user base.
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.
My understanding was that was just a limitation on the first batch, as they're still developing the design, but they're intending to cross link in future. Is that not the case?
Sure, but that's significant feature. Other satellites will be built and launched by the time they get there, and they absolutely need to OSL for capacity.
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.
See the cost of phased array, which Leo needs to work. They're significantly more expensive than standard parabolic dishes, and there's no evidence SpaceX has changed that.
Based on Elon's standard playbook, I'm guessing he's going to try to bring down unit economics with much larger scale in phased array manufacturing than we've seen in the past. If he didn't think he could do this, I don't think they'd be launching Starlink.
That said, I know almost nothing about phased arrays, so I don't know if it's expensive due to some fundamental reason, or if it's partly because it's been a niche/low volume device before now.
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.
