Viewing profile — portillo

This is exactly right! I think that 5M is a high number (at least with the current number of satellites and their architecture), specially if they do not apply data caps. I would s…

There are multiple pictures of OneWeb´s assembly line in their website, https://onewebsatellites.com/factory/ , including pseudo-blueprints: https://bit.ly/32QSDBS Still far from w…

A satellite dish does not transmit any information to the satellite. Satellite TV is a pure broadcast system in the forward direction. Moreover, comparing a parabolic receiver with…

Reminds me of OpenLASE: - https://github.com/marcan/openlase - https://www.youtube.com/watch?v=hoWCNKhZCbk

You can get 24/7 connectivity to LEO right now (and 25 years ago too) using TDRSS. The system costs a fraction of what Starlink will cost, as you only need 3 GEO satellites.

The current satellites do not have crosslinks, and in any case, in their FCC filings SpaceX talks about optical crosslinks, not RF.

I agree, this was the real reason why the project failed. Moreover, it was not clear at all that fractionation would bring any lifecycle costs savings, neither that any of the alle…

Sure, operated manually by a bunch of people with PhDs.

I think so too. In addition, they seem to have regenerative payloads on-board (otherwise I don't get how they get ~20Gbps/sat with a single Ka-band antenna), so they need to do ful…

Hi Mark, Thanks for your reply. I agree with you, using user-terminals is extremely challenging, especially from a link-budget perspective. You cannot pump enough data to make it w…

These analyses are quite optimistic as they only consider propagation delay. Moreover, the idea of using user-terminals/gateways as ground-relays to bounce signals up-and-down is q…

That is not the round trip time, it's the one-way delay. Also, processing time can be significant in satellite networks. Finally, given the current architecture of SpaceX without c…

It will not work. Their use case is low data rate applications. It's one of those case where you pick 2 among high number of users, high bandwidth, and low gain user terminals.

> to a self-described expert, who unfortunately didn't provide a ton of context), Are you questioning the expertise of Tim Farrar? If that is the case, you couldn't be more wrong. …

In their original FCC filing, they were estimating 386 kg per satellite. The ones launched in May were 227 kg each, and those last month 260 kg (they added the Ka-band antennas). I…

I am the author of the slides/paper. The analysis was done with the best data available at the time, but I am interested in knowing what parameters you think are off / have changed…

NSR has some public estimates here: https://www.nsr.com/leo-survival-of-the-fittestor-the-smarte... NSR estimates for SpaceX are higher than what SpaceX claims (Gwynne Shotwell jus…

It will only have lower latency when they have the inter-satellite links. Until then, they will have the latency of fiber PLUS the RTT from the user terminal - satellite - gateway …

I would bet that there will be no more than 1,200 (if they raise the money needed to launch and manufacture that many). And I would also bet that even in an 8 year time-horizon, th…

This is, in my opinion, kind of a myth. In the markets where the average revenue per user is high (Europe, USA, Canada, Australia) there is already (or there will be very shortly w…

It was ordered by the "Juzgado Central de Instrucción número 6" of the "Audiencia Nacional" which is presided by Manuel Maria Garcia-Castellon. The police cannot request taking-dow…

> So from far away, I would question the neutrality of the Centre d'Studis d'Opinió. They are the "Department of Statistics" of Catalonia, and they are controlled by the local gove…

I hope that ends up happening, it will be a bigger innovation than all these constellations!! I don't think it will happen in the next 3 years though. I think that most of the manu…

My PhD research is on how to use space and aerial networks to serve the unconnected and undeserved. I have been studying these networks (and things like Google's loon, mmwave, etc)…