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With latency as low as 25ms, SpaceX to launch broadband satellites in 2019

arstechnica.com

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Re: With latency as low as 25ms, SpaceX to launch broadband satellites in 2019

#141

Post by Retric »

dboreham wrote: post #137

Ugh. Are they really talking about Latency, or are the numbers they cite actually RTT? And are the numbers the loop latency, or end-to-end latency to some destination on the public network such as 8.8.8.8? For comparison my CableCo connection in the left-middle of America achieves a loop RTT of about 10ms (5ms Latency), and an RTT to 8.8.8.8 of 25ms (12.5ms Latency).

1,110km ~= 4ms each way so 8ms from ground to satellite to ground but that only get you to the internet and you need to do that again on the way back so 16ms is the minimum latency possible. However, ~25ms round trips seems possible especially if they have enough ground stations near major interchanges.

PS: Remember, they can put these stations near anything that people want low latency connections to.

Re: With latency as low as 25ms, SpaceX to launch broadband satellites in 2019

#142

Post by davrosthedalek »

seiferteric wrote: post #132
TeMPOraL wrote: post #113

Earlier quoted context omitted.

The antenna is already highly directional - those are LEO satellites we're talking about, you need to constantly track them. How phased array antennas respond to jamming is unfortunately beyond my knowledge.

That's my point, if you have high gain in a particular direction, wouldn't interference coming from a different direction be mostly rejected? The point being, this could offer internet to people in repressed countries that can't practically be blocked or tampered with. If they coupled this with a free tier with low bandwidth it could be huge, assuming people could smuggle in the equipment to make it work.

Not an expert, but here is my take: A phased array consists of many individual, non-directional antennas. The directionality comes by cleverly combining the signal of the antennas. If there is a jamming signal, all antennas would receive it. In theory, it would then cancel out when the signals are combined. The question is now: Before the signal is combined, is there any element which can be saturated by the large jamming signal? If so, you can jam. The phased array direction is tune-able, so I assume the combination is done in the digital domain. That means ADC in between, which can be saturated. So my guess is: yes.

Re: With latency as low as 25ms, SpaceX to launch broadband satellites in 2019

#143

Post by rhino369 »

Klathmon wrote: post #23
jseliger wrote: post #2

This may help explain why Verizon is cutting FiOS prices and increasing speeds: https://arstechnica.com/information-technology/2017/04/veriz...

Well, they are cutting options. The price for 50/50mbps is staying the same in my area, however they have dropped the 75/75, 100/100, 150/150, and 300/300 options entirely and now offer 50/50 or 1000/1000 (which is actually 940/880 which is around the limits of "normal" ethernet). And while they advertise $69.99 on the site, clicking through to "more info" shows it as $79.99 and calling in to ask about it they are te…

I negotiated them down to 75 bucks (im still on contract for 6 more months). I had to pay 90 bucks to install a new fiber termination point though. And my price is only set until Nov.

Re: With latency as low as 25ms, SpaceX to launch broadband satellites in 2019

#144

Post by donkeyd »

rsync wrote: post #129
namlem wrote: post #124

Earlier quoted context omitted.

Musk himself has stated the goal is to make money to help pay for colonizing Mars.

"Musk himself has stated the goal is to make money to help pay for colonizing Mars." Which I continue to misunderstand ... You can go to Mars ... you can have an outpost on Mars ... you can have scientists and tourists and so on go back and forth to Mars - all very positive and exciting. But you can't live on Mars for an extended period because the gravity is 1/3 of earths. Your teeth will decay. Your bones will weak…

> I fail to see how one could actually live on Mars without sacrificing 30 or more years of lifespan.

Maybe they just cant can't, but don't care. Some people could be willing to decrease their lifespan in order to colonize a different planet, making the human race interplanetary.

Also, theoretically, people will evolve over time to be able to handle those conditions. We're used to making plans a couple years ahead. When thinking of interplanetary colonization, we should think many generations ahead.

Re: With latency as low as 25ms, SpaceX to launch broadband satellites in 2019

#146

Post by lmm »

candiodari wrote: post #128

Interesting. What would this be able to do ? Current wireless speeds, even with state of the art technology, is going to be something like 10Gbit. That'll have to be shared by an entire city at least (correction: about 2 satellites per state on average. Less for New York), and of course there won't be any CDNs or HTTP caches "upstairs" so to speak. So 1 bit in = 1 bit back out. Even at 4425 satellites that means, let…

Within the city there's usually wifi. Broadband that you can use anywhere on the world (or at least anywhere there aren't so many people), even Antarctica or Everest or Crimea or the middle of the ocean, seems like it would be worth paying quite a premium for.

Re: With latency as low as 25ms, SpaceX to launch broadband satellites in 2019

#147

Post by lmm »

mabbo wrote: post #90

It's been said before, but what people need to understand is that the goal of this service isn't to make money- it's to balance demand. SpaceX can plan to launch be 30% more launches than their actual customers need. All those extra rockets are used for internet satellites. If there's an accident (boom) or a sudden need for more rockets, the internet satellites get delayed, and the paying customer gets a rocket. If c…

But SpaceX already has a launch backlog as long as my arm. They don't seem to be wanting for customers.

Re: With latency as low as 25ms, SpaceX to launch broadband satellites in 2019

#148

Post by davrosthedalek »

wolfram74 wrote: post #89
mrinterweb wrote: post #82

Earlier quoted context omitted.

I doubt that the per/satellite cost would be anywhere close to $80-100 million. I remember hearing that the plan was for these satellites to have significantly less mass than other satellites and therefore, one orbital launch could deliver many satellites. With these satellites orbiting ~30-34x closer to Earth, the satellites would need to have significantly less mass if they were going to not have their orbital dist…

Saying their mass needs to be lower to reduce orbit degradation is the opposite of true. Assuming two spheres of equal size, their drag and thus change in momentum will be the same at the same altitude. But if one sphere was made of lead and the other made of styrofoam, the styrofoam one will decelerate much faster than the lead one. So: lighter satellite of the same shape means shorter life span. But drag dies down…

Well, they would probably have the same density, so they would be smaller. However, you are still right, as drag scales with r^2 but mass with r^3.

Re: With latency as low as 25ms, SpaceX to launch broadband satellites in 2019

#149

Post by kwhitefoot »

chii wrote: post #122
alkonaut wrote: post #114

Earlier quoted context omitted.

> but what leverage do they have? The buying, selling and using of satellite internet equipment will be outlawed in countries that don't allow free access to the internet (unless of course the internet satellite company signs agreements to impose the blocking of choice of the regime in question). SpaceX might be safe from the Turkish, Chinese or Egyptian governments, but the users won't be.

But what incentive would satellite communication providers have to agree? Wouldn't it be better to facilitate a black market by not putting any blocks?

Sometimes one government has more common ground with the government of another country than it has with its own citizens. A country that does not want its citizens to have SpaceX provided Internet could lobby the US government to require it to be blocked.

You can bet that the US government will want to exert control over it anyway to some degree so even if they are not always sympathetic to other governments requirements that lack of sympathy is a negotiating position not a matter of principle.

Re: With latency as low as 25ms, SpaceX to launch broadband satellites in 2019

#150

Post by avmich »

rsync wrote: post #129
namlem wrote: post #124

Earlier quoted context omitted.

Musk himself has stated the goal is to make money to help pay for colonizing Mars.

"Musk himself has stated the goal is to make money to help pay for colonizing Mars." Which I continue to misunderstand ... You can go to Mars ... you can have an outpost on Mars ... you can have scientists and tourists and so on go back and forth to Mars - all very positive and exciting. But you can't live on Mars for an extended period because the gravity is 1/3 of earths. Your teeth will decay. Your bones will weak…

> But you can't live on Mars for an extended period because the gravity is 1/3 of earths.

Can't you rather cheaply create a centrifuge where you'll sleep - and may be even work indoors - which will maintain 1G? Centrifuge big enough so no significant side forces would occur?

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